linear and branched poly ( ethylenimine )( pei ) are some of the most efficient cationic polymers currently used for in vitro transfections . however , the use of pei for in vivo applications has been limited due to difficulties in formulation ( aggregation in salt ) and toxicity of the polymer ( chollet et al . 2001 j of gene med ). approaches for improving the formulation conditions of pei include grafting of the polymer with poly ( ethylene glycol ) ( peg ) and grafting of polyplexes with peg ( ogris et al . 1999 gene ther 6 : 595 - 605 ; and erbacher et al . 1999 j gene med 1 : 210 - 222 ). however , pei - peg does not condense dna into small , spherical particles , and grafting of polyplexes with peg is difficult to control and to scale - up . therefore , current pei systems for in vivo , systemic delivery have not been promising . linear cyclodextrin - based polymers ( cdps ) have previously been shown to have low toxicity both in vitro ( in many different cell lines ) and in vivo ( gonzalez et al . 1999 bioconjugate chem 10 : 1068 - 1074 ; and hwang et al . 2001 bioconjugate chem 12 ( 2 ): 280 - 290 ). we observed that removal of the cyclodextrins from the polymer backbone results in high toxicity of the cationic polymer . this observation led us to conclude that cyclodextrin is able to reduce the toxicity of cationic polymers . in certain embodiments , the present invention is directed to the development of a new method of using cyclodextrins in cationic , cyclodextrin - based polymers to impart stability and targeting ability to polyplexes formed from these polymers . since the current linear cdps transfect poorly into mammalian cell lines (& lt ; 2 % transfection ), cyclodextrin - modified polymers of the invention combine the good qualities of the pei ( efficient chloroquine - independent transfection ) with the good qualities of the cyclodextrin - based polymers ( low toxicity and ability to modify and stabilize the polyplexes ). therefore , as described below , cyclodextrin - grafted polyethylenimine polymers were synthesized and tested . accordingly , in certain embodiments , preferred carbohydrate - modified polymers of the invention are cyclodextrin - modified polymers , such as cyclodextrin - modified poly ( ethylenimines ). the present invention is generally related to a composition comprising carbohydrate - modified polycationic polymers and nucleic acid . in various embodiments , the nucleic acid may be an expression construct , e . g ., including a coding sequence for a protein or antisense , an antisense sequence , an rnai construct , an sirna construct , an oligonucleotide , or a decoy , such as for a dna - binding protein . in certain embodiments , the present compositions have several advantages over other technologies . most technologies either have high transfection and high toxicity ( pei , lipofectamine ) or low transfection and low toxicity ( linear cdps , other cationic degradable polymers ). however , the polymers disclosed herein , such as cd - pei , have high transfection and low toxicity in vivo . galactosylated and mannosylated pei have also been demonstrated to have high transfection with lower toxicity than unmodified pei , but these polymers do not have any stabilization ability and is likely to aggregate in vivo . the carbohydrate - modified polymers disclosed herein are readily adaptable for in vivo applications via the inclusion - complex modification technology . this would allow for stabilization and targeting of these polyplexes . in addition , the method of carbohydrate modification described herein can increase the ic 50 by ˜ 100 - fold , whereas the galactose - and mannose - modified pei &# 39 ; s increase ic 50 &# 39 ; s only around 10 - 20 fold . for convenience , certain terms employed in the specification , examples , and appended claims are collected here . the term “ ed 50 ” means the dose of a drug that produces 50 % of its maximum response or effect . an “ effective amount ” of a subject compound , with respect to the subject method of treatment , refers to an amount of the therapeutic in a preparation which , when applied as part of a desired dosage regimen causes a increase in survival of a neuronal cell population according to clinically acceptable standards for the treatment or prophylaxis of a particular disorder . the term “ healthcare providers ” refers to individuals or organizations that provide healthcare services to a person , community , etc . examples of “ healthcare providers ” include doctors , hospitals , continuing care retirement communities , skilled nursing facilities , subacute care facilities , clinics , multispecialty clinics , freestanding ambulatory centers , home health agencies , and hmo &# 39 ; s . the term ‘ ic 50 ’ refers to the concentration of an inhibitor composition that has 50 % of the maximal inhibitory effect . where the inhibitor composition inhibits cell growth , the ic 50 is the concentration that causes 50 % of the maximal inhibition of cell growth . the term “ ld 50 ” means the dose of a drug that is lethal in 50 % of test subjects . a “ patient ” or “ subject ” to be treated by the subject method are mammals , including humans . by “ prevent degeneration ” it is meant reduction in the loss of cells ( such as from apoptosis ), or reduction in impairment of cell function , e . g ., release of dopamine in the case of dopaminergic neurons . generally , as used herein , a therapeutic that “ prevents ” a disorder or condition refers to a compound that , in a sample , reduces the occurrence of the disorder or condition in the sample , relative to an untreated control sample , or delays the onset of one or more symptoms of the disorder or condition . the term “ prodrug ” is intended to encompass compounds that , under physiological conditions , are converted into the therapeutically active agents of the present invention . a common method for making a prodrug is to include selected moieties that are hydrolyzed under physiological conditions to reveal the desired molecule . in other embodiments , the prodrug is converted by an enzymatic activity of the host animal . the term “ therapeutic index ” refers to the therapeutic index of a drug defined as ld 50 / ed 50 . a “ trophic factor ” is a molecule that directly or indirectly affects the survival or function of a neuronal cell , e . g ., a dopaminergic or gabaergic cell . a “ trophic amount ” of a subject compound is an amount sufficient to , under the circumstances , cause an increase in the rate of survival or the functional performance of a neuronal cell , e . g ., a dopaminergic or gabaergic cell . ‘ acyl ’ refers to a group suitable for acylating a nitrogen atom to form an amide or carbamate , a carbon atom to form a ketone , a sulfur atom to form a thioester , or an oxygen atom to form an ester group , e . g ., a hydrocarbon attached to a — c (═ o )— moiety . preferred acyl groups include benzoyl , acetyl , tert - butyl acetyl , pivaloyl , and trifluoroacetyl . more preferred acyl groups include acetyl and benzoyl . the most preferred acyl group is acetyl . the term ‘ acylamino ’ is art - recognized and preferably refers to a moiety that can be represented by the general formula : wherein r 9 and r ′ 11 each independently represent hydrogen or a hydrocarbon substituent , such as alkyl , heteroalkyl , aryl , heteroaryl , carbocyclic aliphatic , and heterocyclic aliphatic . the terms ‘ amine ’ and ‘ amino ’ are art - recognized and refer to both unsubstituted and substituted amines as well as ammonium salts , e . g ., as can be represented by the general formula : wherein r 9 , r 10 , and r ′ 10 each independently represent hydrogen or a hydrocarbon substituent , or r 9 and r 10 taken together with the n atom to which they are attached complete a heterocycle having from 4 to 8 atoms in the ring structure . in preferred embodiments , none of r 9 , r 10 , and r ′ 10 is acyl , e . g ., r 9 , r 10 , and r ′ 10 are selected from hydrogen , alkyl , heteroalkyl , aryl , heteroaryl , carbocyclic aliphatic , and heterocyclic aliphatic . the term ‘ alkylamine ’ as used herein means an amine group , as defined above , having at least one substituted or unsubstituted alkyl attached thereto . amino groups that are positively charged ( e . g ., r ′ 10 is present ) are referred to as ‘ ammonium ’ groups . in amino groups other than ammonium groups , the amine is preferably basic , e . g ., its conjugate acid has a pk a above 7 . the terms ‘ amido ’ and ‘ amide ’ are art - recognized as an amino - substituted carbonyl , such as a moiety that can be represented by the general formula : wherein r 9 and r 10 are as defined above . in certain embodiments , the amide will include imides . ‘ alkyl ’ refers to a saturated or unsaturated hydrocarbon chain having 1 to 18 carbon atoms , preferably 1 to 12 , more preferably 1 to 6 , more preferably still 1 to 4 carbon atoms . alkyl chains may be straight ( e . g ., n - butyl ) or branched ( e . g ., sec - butyl , isobutyl , or t - butyl ). preferred branched alkyls have one or two branches , preferably one branch . preferred alkyls are saturated . unsaturated alkyls have one or more double bonds and / or one or more triple bonds . preferred unsaturated alkyls have one or two double bonds or one triple bond , more preferably one double bond . alkyl chains may be unsubstituted or substituted with from 1 to 4 substituents . preferred alkyls are unsubstituted . preferred substituted alkyls are mono -, di -, or trisubstituted . preferred alkyl substituents include halo , haloalkyl , hydroxy , aryl ( e . g ., phenyl , tolyl , alkoxyphenyl , alkyloxycarbonylphenyl , halophenyl ), heterocyclyl , and heteroaryl . the terms ‘ alkenyl ’ and ‘ alkynyl ’ refer to unsaturated aliphatic groups analogous in length and possible substitution to the alkyls described above , but that contain at least one double or triple bond , respectively . when not otherwise indicated , the terms alkenyl and alkynyl preferably refer to lower alkenyl and lower alkynyl groups , respectively . when the term alkyl is present in a list with the terms alkenyl and alkynyl , the term alkyl refers to saturated alkyls exclusive of alkenyls and alkynyls . the terms ‘ alkoxyl ’ and ‘ alkoxy ’ as used herein refer to an — o - alkyl group . representative alkoxyl groups include methoxy , ethoxy , propyloxy , tert - butoxy , and the like . an ‘ ether ’ is two hydrocarbons covalently linked by an oxygen . accordingly , the substituent of a hydrocarbon that renders that hydrocarbon an ether can be an alkoxyl , or another moiety such as — o - aryl , — o - heteroaryl , — o - heteroalkyl , — o - aralkyl , — o - heteroaralkyl , — o - carbocylic aliphatic , or — o - heterocyclic aliphatic . the term ‘ alkylthio ’ refers to an — s - alkyl group . representative alkylthio groups include methylthio , ethylthio , and the like . ‘ thioether ’ refers to a sulfur atom bound to two hydrocarbon substituents , e . g ., an ether wherein the oxygen is replaced by sulfur . thus , a thioether substituent on a carbon atom refers to a hydrocarbon - substituted sulfur atom substituent , such as alkylthio or arylthio , etc . the term ‘ aralkyl ’, as used herein , refers to an alkyl group substituted with an aryl group . ‘ aryl ring ’ refers to an aromatic hydrocarbon ring system . aromatic rings are monocyclic or fused bicyclic ring systems , such as phenyl , naphthyl , etc . monocyclic aromatic rings contain from about 5 to about 10 carbon atoms , preferably from 5 to 7 carbon atoms , and most preferably from 5 to 6 carbon atoms in the ring . bicyclic aromatic rings contain from 8 to 12 carbon atoms , preferably 9 or 10 carbon atoms in the ring . the term ‘ aryl ’ also includes bicyclic ring systems wherein only one of the rings is aromatic , e . g ., the other ring is cycloalkyl , cycloalkenyl , or heterocyclyl . aromatic rings may be unsubstituted or substituted with from 1 to about 5 substituents on the ring . preferred aromatic ring substituents include : halo , cyano , lower alkyl , heteroalkyl , haloalkyl , phenyl , phenoxy , or any combination thereof . more preferred substituents include lower alkyl , cyano , halo , and haloalkyl . ‘ carbocyclic aliphatic ring ’ refers to a saturated or unsaturated hydrocarbon ring . carbocyclic aliphatic rings are not aromatic . carbocyclic aliphatic rings are monocyclic , or are fused , spiro , or bridged bicyclic ring systems . monocyclic carbocyclic aliphatic rings contain from about 4 to about 10 carbon atoms , preferably from 4 to 7 carbon atoms , and most preferably from 5 to 6 carbon atoms in the ring . bicyclic carbocyclic aliphatic rings contain from 8 to 12 carbon atoms , preferably from 9 to 10 carbon atoms in the ring . carbocyclic aliphatic rings may be unsubstituted or substituted with from 1 to 4 substituents on the ring . preferred carbocyclic aliphatic ring substituents include halo , cyano , alkyl , heteroalkyl , haloalkyl , phenyl , phenoxy or any combination thereof . more preferred substituents include halo and haloalkyl . preferred carbocyclic aliphatic rings include cyclopentyl , cyclohexyl , cyclohexenyl , cycloheptyl , and cyclooctyl . more preferred carbocyclic aliphatic rings include cyclohexyl , cycloheptyl , and cyclooctyl . a ‘ carbohydrate - modified polymer ’ is a polymer that is covalently or associatively ( i . e ., through an inclusion complex ) linked to one or more carbohydrate moieties . the term ‘ carbohydrate moiety ’ is intended to include any molecule that is considered a carbohydrate by one of skill in the art and that is covalently bonded to a polymer . carbohydrate moieties include mono - and polysaccharides . carbohydrate moieties include trioses , tetroses , pentoses , hexoses , heptoses and monosaccharides of higher molecular weight ( either d or l form ), as well as polysaccharides comprising a single type of monosaccharide or a mixture of different monosaccharides . polysaccharides may be of any polymeric conformation ( e . g . branched , linear or circular ). examples of monosaccharides include glucose , fructose , and glucopyranose . examples of polysaccharides include sucrose , lactose and cyclodextrin . the term ‘ carbonyl ’ is art - recognized and includes such moieties as can be represented by the general formula : wherein x is a bond or represents an oxygen or a sulfur , and r 11 represents a hydrogen , hydrocarbon substituent , or a pharmaceutically acceptable salt , r 11 ′ represents a hydrogen or hydrocarbon substituent . where x is an oxygen and r 11 or r 11 ′ is not hydrogen , the formula represents an ‘ ester ’. where x is an oxygen , and r 11 is as defined above , the moiety is referred to herein as a carboxyl group , and particularly when r 11 is a hydrogen , the formula represents a ‘ carboxylic acid ’. where x is an oxygen , and r 11 ′ is hydrogen , the formula represents a ‘ formate ’. in general , where the oxygen atom of the above formula is replaced by sulfur , the formula represents a ‘ thiocarbonyl ’ group . where x is a sulfur and r 11 or r 11 ′ is not hydrogen , the formula represents a ‘ thioester .’ where x is a sulfur and r 11 is hydrogen , the formula represents a ‘ thiocarboxylic acid .’ where x is a sulfur and r 11 ′ 0 is hydrogen , the formula represents a ‘ thioformate .’ on the other hand , where x is a bond , r 11 is not hydrogen , and the carbonyl is bound to a hydrocarbon , the above formula represents a ‘ ketone ’ group . where x is a bond , r 11 is hydrogen , and the carbonyl is bound to a hydrocarbon , the above formula represents an ‘ aldehyde ’ or ‘ formyl ’ group . ‘ ci alkyl ’ is an alkyl chain having i member atoms . for example , c4 alkyls contain four carbon member atoms . c4 alkyls containing may be saturated or unsaturated with one or two double bonds ( cis or trans ) or one triple bond . preferred c4 alkyls are saturated . preferred unsaturated c4 alkyl have one double bond . c4 alkyl may be unsubstituted or substituted with one or two substituents . preferred substituents include lower alkyl , lower heteroalkyl , cyano , halo , and haloalkyl . ‘ halogen ’ refers to fluoro , chloro , bromo , or iodo substituents . preferred halo are fluoro , chloro and bromo ; more preferred are chloro and fluoro . ‘ haloalkyl ’ refers to a straight , branched , or cyclic hydrocarbon substituted with one or more halo substituents . preferred haloalkyl are c1 - c12 ; more preferred are c1 - c6 ; more preferred still are c1 - c3 . preferred halo substituents are fluoro and chloro . the most preferred haloalkyl is trifluoromethyl . ‘ heteroalkyl ’ is a saturated or unsaturated chain of carbon atoms and at least one heteroatom , wherein no two heteroatoms are adjacent . heteroalkyl chains contain from 1 to 18 member atoms ( carbon and heteroatoms ) in the chain , preferably 1 to 12 , more preferably 1 to 6 , more preferably still 1 to 4 . heteroalkyl chains may be straight or branched . preferred branched heteroalkyl have one or two branches , preferably one branch . preferred heteroalkyl are saturated . unsaturated heteroalkyl have one or more double bonds and / or one or more triple bonds . preferred unsaturated heteroalkyl have one or two double bonds or one triple bond , more preferably one double bond . heteroalkyl chains may be unsubstituted or substituted with from 1 to about 4 substituents unless otherwise specified . preferred heteroalkyl are unsubstituted . preferred heteroalkyl substituents include halo , aryl ( e . g ., phenyl , tolyl , alkoxyphenyl , alkoxycarbonylphenyl , halophenyl ), heterocyclyl , heteroaryl . for example , alkyl chains substituted with the following substituents are heteroalkyl : alkoxy ( e . g ., methoxy , ethoxy , propoxy , butoxy , pentoxy ), aryloxy ( e . g ., phenoxy , chlorophenoxy , tolyloxy , methoxyphenoxy , benzyloxy , alkoxycarbonylphenoxy , acyloxyphenoxy ), acyloxy ( e . g ., propionyloxy , benzoyloxy , acetoxy ), carbamoyloxy , carboxy , mercapto , alkylthio , acylthio , arylthio ( e . g ., phenylthio , chlorophenylthio , alkylphenylthio , alkoxyphenylthio , benzylthio , alkoxycarbonylphenylthio ), amino ( e . g ., amino , mono - and di - c1 - c3 alkylamino , methylphenylamino , methylbenzylamino , c1 - c3 alkylamido , carbamamido , ureido , guanidino ). ‘ heteroatom ’ refers to a multivalent non - carbon atom , such as a boron , phosphorous , silicon , nitrogen , sulfur , or oxygen atom , preferably a nitrogen , sulfur , or oxygen atom . groups containing more than one heteroatom may contain different heteroatoms . ‘ heteroaryl ring ’ refers to an aromatic ring system containing carbon and from 1 to about 4 heteroatoms in the ring . heteroaromatic rings are monocyclic or fused bicyclic ring systems . monocyclic heteroaromatic rings contain from about 5 to about 10 member atoms ( carbon and heteroatoms ), preferably from 5 to 7 , and most preferably from 5 to 6 in the ring . bicyclic heteroaromatic rings contain from 8 to 12 member atoms , preferably 9 or 10 member atoms in the ring . the term ‘ heteroaryl ’ also includes bicyclic ring systems wherein only one of the rings is aromatic , e . g ., the other ring is cycloalkyl , cycloalkenyl , or heterocyclyl . heteroaromatic rings may be unsubstituted or substituted with from 1 to about 4 substituents on the ring . preferred heteroaromatic ring substituents include halo , cyano , lower alkyl , heteroalkyl , haloalkyl , phenyl , phenoxy or any combination thereof . preferred heteroaromatic rings include thienyl , thiazolyl , oxazolyl , pyrrolyl , purinyl , pyrimidyl , pyridyl , and furanyl . more preferred heteroaromatic rings include thienyl , furanyl , and pyridyl . ‘ heterocyclic aliphatic ring ’ is a non - aromatic saturated or unsaturated ring containing carbon and from 1 to about 4 heteroatoms in the ring , wherein no two heteroatoms are adjacent in the ring and preferably no carbon in the ring attached to a heteroatom also has a hydroxyl , amino , or thiol group attached to it . heterocyclic aliphatic rings are monocyclic , or are fused or bridged bicyclic ring systems . monocyclic heterocyclic aliphatic rings contain from about 4 to about 10 member atoms ( carbon and heteroatoms ), preferably from 4 to 7 , and most preferably from 5 to 6 member atoms in the ring . bicyclic heterocyclic aliphatic rings contain from 8 to 12 member atoms , preferably 9 or 10 member atoms in the ring . heterocyclic aliphatic rings may be unsubstituted or substituted with from 1 to about 4 substituents on the ring . preferred heterocyclic aliphatic ring substituents include halo , cyano , lower alkyl , heteroalkyl , haloalkyl , phenyl , phenoxy or any combination thereof . more preferred substituents include halo and haloalkyl . heterocyclyl groups include , for example , thiophene , thianthrene , furan , pyran , isobenzofuran , chromene , xanthene , phenoxathin , pyrrole , imidazole , pyrazole , isothiazole , isoxazole , pyridine , pyrazine , pyrimidine , pyridazine , indolizine , isoindole , indole , indazole , purine , quinolizine , isoquinoline , hydantoin , oxazoline , imidazolinetrione , triazolinone , quinoline , phthalazine , naphthyridine , quinoxaline , quinazoline , quinoline , pteridine , carbazole , carboline , phenanthridine , acridine , phenanthroline , phenazine , phenarsazine , phenothiazine , furazan , phenoxazine , pyrrolidine , oxolane , thiolane , oxazole , piperidine , piperazine , morpholine , lactones , lactams such as azetidinones and pyrrolidinones , sultams , sultones , and the like . preferred heterocyclic aliphatic rings include piperazyl , morpholinyl , tetrahydrofuranyl , tetrahydropyranyl and piperidyl . heterocycles can also be polycycles . ‘ lower alkyl ’ refers to an alkyl chain comprised of 1 to 5 , preferably 1 to 4 carbon member atoms , more preferably 1 or 2 carbon member atoms . lower alkyls may be saturated or unsaturated . preferred lower alkyls are saturated . lower alkyls may be unsubstituted or substituted with one or about two substituents . preferred substituents on lower alkyl include cyano , halo , trifluoromethyl , amino , and hydroxyl . throughout the application , preferred alkyl groups are lower alkyls . in preferred embodiments , a substituent designated herein as alkyl is a lower alkyl . likewise , ‘ lower alkenyl ’ and ‘ lower alkynyl ’ have similar chain lengths . ‘ lower heteroalkyl ’ refers to a heteroalkyl chain comprised of 1 to 4 , preferably 1 to 3 member atoms , more preferably 1 to 2 member atoms . lower heteroalkyl contain one or two non - adjacent heteroatom member atoms . preferred lower heteroalkyl contain one heteroatom member atom . lower heteroalkyl may be saturated or unsaturated . preferred lower heteroalkyl are saturated . lower heteroalkyl may be unsubstituted or substituted with one or about two substituents . preferred substituents on lower heteroalkyl include cyano , halo , trifluoromethyl , and hydroxyl . ‘ mi heteroalkyl ’ is a heteroalkyl chain having i member atoms . for example , m4 heteroalkyls contain one or two non - adjacent heteroatom member atoms . m4 heteroalkyls containing 1 heteroatom member atom may be saturated or unsaturated with one double bond ( cis or trans ) or one triple bond . preferred m4 heteroalkyl containing 2 heteroatom member atoms are saturated . preferred unsaturated m4 heteroalkyl have one double bond . m4 heteroalkyl may be unsubstituted or substituted with one or two substituents . preferred substituents include lower alkyl , lower heteroalkyl , cyano , halo , and haloalkyl . ‘ member atom ’ refers to a polyvalent atom ( e . g ., c , o , n , or s atom ) in a chain or ring system that constitutes a part of the chain or ring . for example , in cresol , six carbon atoms are member atoms of the ring and the oxygen atom and the carbon atom of the methyl substituent are not member atoms of the ring . ‘ pharmaceutically acceptable salt ’ refers to a cationic salt formed at any acidic ( e . g ., hydroxamic or carboxylic acid ) group , or an anionic salt formed at any basic ( e . g ., amino or guanidino ) group . such salts are well known in the art . see e . g ., world patent publication 87 / 05297 , johnston et al ., published sep . 11 , 1987 , incorporated herein by reference . such salts are made by methods known to one of ordinary skill in the art . it is recognized that the skilled artisan may prefer one salt over another for improved solubility , stability , formulation ease , price and the like . determination and optimization of such salts is within the purview of the skilled artisan &# 39 ; s practice . preferred cations include the alkali metals ( such as sodium and potassium ), and alkaline earth metals ( such as magnesium and calcium ) and organic cations , such as trimethylammonium , tetrabutylammonium , etc . preferred anions include halides ( such as chloride ), sulfonates , carboxylates , phosphates , and the like . clearly contemplated in such salts are addition salts that may provide an optical center where once there was none . for example , a chiral tartrate salt may be prepared from the compounds of the invention . this definition includes such chiral salts . ‘ phenyl ’ is a six - membered monocyclic aromatic ring that may or may not be substituted with from 1 to 5 substituents . the substituents may be located at the ortho , meta or para position on the phenyl ring , or any combination thereof . preferred phenyl substituents include : halo , cyano , lower alkyl , heteroalkyl , haloalkyl , phenyl , phenoxy or any combination thereof . more preferred substituents on the phenyl ring include halo and haloalkyl . the most preferred substituent is halo . the terms ‘ polycyclyl ’ and ‘ polycyclic group ’ refer to two or more rings ( e . g ., cycloalkyls , cycloalkenyls , heteroaryls , aryls and / or heterocyclyls ) in which two or more member atoms of one ring are member atoms of a second ring . rings that are joined through non - adjacent atoms are termed ‘ bridged ’ rings , and rings that are joined through adjacent atoms are ‘ fused rings ’. the term ‘ sulthydryl ’ means — sh , and the term ‘ sulfonyl ’ means — so 2 —. a ‘ substitution ’ or ‘ substituent ’ on a small organic molecule generally refers to a position on a multi - valent atom bound to a moiety other than hydrogen , e . g ., a position on a chain or ring exclusive of the member atoms of the chain or ring . such moieties include those defined herein and others as are known in the art , for example , halogen , alkyl , alkenyl , alkynyl , azide , haloalkyl , hydroxyl , carbonyl ( such as carboxyl , alkoxycarbonyl , formyl , ketone , or acyl ), thiocarbonyl ( such as thioester , thioacetate , or thioformate ), alkoxyl , phosphoryl , phosphonate , phosphinate , amine , amide , amidine , imine , cyano , nitro , azido , sulthydryl , alkylthio , sulfate , sulfonate , sulfamoyl , sulfonamido , sulfonyl , silyl , ether , cycloalkyl , heterocyclyl , heteroalkyl , heteroalkenyl , and heteroalkynyl , heteroaralkyl , aralkyl , aryl or heteroaryl . it will be understood by those skilled in the art that certain substituents , such as aryl , heteroaryl , polycyclyl , alkoxy , alkylamino , alkyl , cycloalkyl , heterocyclyl , alkenyl , alkynyl , heteroalkyl , heteroalkenyl , and heteroalkynyl , can themselves be substituted , if appropriate . this invention is not intended to be limited in any manner by the permissible substituents of organic compounds . it will be understood that ‘ substitution ’ or ‘ substituted with ’ includes the implicit proviso that such substitution is in accordance with permitted valence of the substituted atom and the substituent , and that the substitution results in a stable compound , e . g ., which does not spontaneously undergo transformation such as by rearrangement , cyclization , elimination , hydrolysis , etc . as used herein , the definition of each expression , e . g ., alkyl , m , n , etc ., when it occurs more than once in any structure , is intended to be independent of its definition elsewhere in the same structure . the abbreviations me , et , ph , tf , nf , ts , and ms represent methyl , ethyl , phenyl , trifluoromethanesulfonyl , nonafluorobutanesulfonyl , p - toluenesulfonyl , and methanesulfonyl , respectively . a more comprehensive list of the abbreviations utilized by organic chemists of ordinary skill in the art appears in the first issue of each volume of the journal of organic chemistry ; this list is typically presented in a table entitled standard list of abbreviations . the abbreviations contained in said list , and all abbreviations utilized by organic chemists of ordinary skill in the art are hereby incorporated by reference . the terms ortho , meta and para apply to 1 , 2 -, 1 , 3 - and 1 , 4 - disubstituted benzenes , respectively . for example , the names 1 , 2 - dimethylbenzene and ortho - dimethylbenzene are synonymous . the phrase ‘ protecting group ’ as used herein means temporary substituents that protect a potentially reactive functional group from undesired chemical transformations . examples of such protecting groups include esters of carboxylic acids , silyl ethers of alcohols , and acetals and ketals of aldehydes and ketones , respectively . the field of protecting group chemistry has been reviewed ( greene , t . w . ; wuts , p . g . m . protective groups in organic synthesis , 2 nd ed . ; wiley : new york , 1991 ; and kocienski , p . j . protecting groups , georg thieme verlag : new york , 1994 ). for purposes of this invention , the chemical elements are identified in accordance with the periodic table of the elements , cas version , handbook of chemistry and physics , 67th ed ., 1986 - 87 , inside cover . also for purposes of this invention , the term ‘ hydrocarbon ’ is contemplated to include all permissible compounds or moieties having at least one carbon - hydrogen bond . in a broad aspect , the permissible hydrocarbons include acyclic and cyclic , branched and unbranched , carbocyclic and heterocyclic , aromatic and nonaromatic organic compounds which can be substituted or unsubstituted . contemplated equivalents of the compounds described above include compounds which otherwise correspond thereto , and which have the same useful properties thereof , wherein one or more simple variations of substituents are made which do not adversely affect the efficacy of the compound . in general , the compounds of the present invention may be prepared by the methods illustrated in the general reaction schemes as , for example , described below , or by modifications thereof , using readily available starting materials , reagents and conventional synthesis procedures . in these reactions , it is also possible to make use of variants that are in themselves known , but are not mentioned here . the subject polymers include linear and / or branched poly ( ethylenimine ) polymers that have been modified by attaching carbohydrate moieties , such as cyclodextrin , to the polymer backbone ( e . g ., through attachment to nitrogen atoms in the polymer chain ). the polymers ( prior to carbohydrate modification ) preferably have molecular weights of at least 2 , 000 , such as 2 , 000 to 100 , 000 , preferably 5 , 000 to 80 , 000 . in certain embodiments , the subject polymers have a structure of the formula : wherein r represents , independently for each occurrence , h , lower alkyl , a carbohydrate moiety ( optionally attached via a linker moiety , such as an alkylene chain or a polyethylene glycol oligomer ), or m , independently for each occurrence , represents an integer greater than 10 , e . g ., from 10 - 10 , 000 , preferably from 10 to 5 , 000 , or from 100 to 1 , 000 . in certain embodiments , r includes a carbohydrate moiety for at least about 1 %, more preferably at least about 2 %, or at least about 3 %, and up to about 5 % or even 10 %, 15 %, or 20 % of its occurrences . in certain embodiments , the polymer is linear , i . e ., no occurrence of r represents in certain embodiments , the carbohydrate moieties make up at least about 2 %, 3 % or 4 % by weight , up to 5 %, 7 %, or even 10 % of the carbohydrate - modified polymer by weight . where the carbohydrate moieties include cyclodextrin , carbohydrate moieties may be 2 % of the weight of the copolymer , preferably at least 5 % or 10 %, or even as much as 20 %, 40 %, 50 %, 60 %, 80 %, or even 90 % of the weight of the copolymer . in certain embodiments , at least about 2 %, 3 % or 4 %, up to 5 %, 7 %, or even 10 %, 15 %, 20 %, or 25 % of the ethylenimine subunits in the polymer are modified with a carbohydrate moiety . in certain such embodiments , however , no more than 25 %, 30 %, 35 %, 40 %, or 50 % of the ethylenimine subunits are so modified . in preferred embodiments , the level of carbohydrate modification is selected such that the toxicity is less than 20 % of the toxicity of the unmodified polymer , yet the transfection efficiency is at least 30 % of the efficiency of the corresponding polymer modified at 5 % of the ethylenimine subunits . preferably , one out of every 6 to 15 ethylenimine subunits is modified with a carbohydrate moiety . copolymers of poly ( ethylenimine ) that bear nucleophilic amino substituents susceptible to derivatization with cyclodextrin moieties can also be used to prepare cyclodextrin - modified polymers within the scope of the present invention . exemplary extents of carbohydrate modification are 10 - 15 % of the ethyleneimine moieties , 15 - 20 % of the ethylenimine moieties , 20 - 25 % of the ethylenimine moieties , 25 - 30 % of the ethylenimine moieties , 30 - 40 % of the ethylenimine moieties , or a combination of two or more of these ranges . where the carbohydrate moiety is attached through a linker , the linker group ( s ) may be an alkylene chain , a polyethylene glycol ( peg ) chain , polysuccinic anhydride , polysebacic acid ( psa ), poly - l - glutamic acid , poly ( ethyleneimine ), an oligosaccharide , an amino acid chain , or any other suitable linkage . more than one type of linker may be present in a given polymer or polymerization reaction . in certain embodiments , the linker group itself can be stable under physiological conditions , such as an alkylene chain , or it can be cleavable under physiological conditions , such as by an enzyme ( e . g ., the linkage contains a peptide sequence that is a substrate for a peptidase ), or by hydrolysis ( e . g ., the linkage contains a hydrolyzable group , such as an ester or thioester ). the linker groups can be biologically inactive , such as a peg , polyglycolic acid , or polylactic acid chain , or can be biologically active , such as an oligo - or polypeptide that , when cleaved from the moieties , binds a receptor , deactivates an enzyme , etc . various oligomeric linker groups that are biologically compatible and / or bioerodible are known in the art , and the selection of the linkage may influence the ultimate properties of the material , such as whether it is durable when implanted , whether it gradually deforms or shrinks after implantation , or whether it gradually degrades and is absorbed by the body . the linker group may be attached to the moieties ( e . g ., the polymer chain and the carbohydrate ) by any suitable bond or functional group , including carbon - carbon bonds , esters , ethers , amides , amines , carbonates , carbamates , ureas , sulfonamides , etc . in certain embodiments the linker group ( s ) of the present invention represent a hydrocarbylene group wherein one or more methylene groups is optionally replaced by a group y ( provided that none of the y groups are adjacent to each other ), wherein each y , independently for each occurrence , is selected from , substituted or unsubstituted aryl , heteroaryl , cycloalkyl , heterocycloalky , or — o —, c (═ x ) ( wherein x is nr 1 , o or s ), — oc ( o )—, — c (═ o ) o , — nr 1 —, — nr 1 co —, — c ( o ) nr 1 —, — s ( o ) n — ( wherein n is 0 , 1 , or 2 ), — oc ( o )— nr 1 , — nr 1 — c ( o )— nr 1 —, — nr 1 — c (═ nr 1 )— nr 1 —, and — b ( or 1 )—; and r 1 , independently for each occurrence , represents h or a lower alkyl . in certain embodiments the linker group represents a derivatized or non - derivatized amino acid . in certain embodiments linking groups with one or more terminal carboxyl groups may be conjugated to the polymer . in certain embodiments , one or more of these terminal carboxyl groups may be capped by covalently attaching them to a therapeutic agent or a cyclodextrin moiety via an ( thio ) ester or amide bond . in still other embodiments linking groups with one or more terminal hydroxyl , thiol , or amino groups may be incorporated into the polymer . in preferred embodiments , one or more of these terminal hydroxyl groups may be capped by covalently attaching them to a therapeutic agents or a carbohydrate ( e . g ., cyclodextrin ) moiety via a carbonate , carbamate , thiocarbonate , or thiocarbamate bond . in certain embodiments , these ( thio ) ester , amide , ( thio ) carbonate or ( thio ) carbamate bonds may be biohydrolyzable , i . e ., capable of being hydrolyzed under biological conditions . in certain embodiments , carbohydrate moieties can be attached to the polymer via a non - covalent associative interaction . for example , the polymer chain can be modified with groups , such as adamantyl groups , that form inclusion complexes with cyclodextrin . the modified polymer can then be combined with compound that includes a cyclodextrin moiety and , optionally , a carbohydrate moiety ( which may be a second cyclodextrin moiety , e . g ., the compound may be symmetrical ) under conditions suitable for forming inclusion complexes between the polymer and the compound , resulting in a complex such as polymer - adamantane :: cyclodextrin - linker - carbohydrate . in this way , a polymer can be modified with carbohydrates without covalently attaching carbohydrates to the polymer itself . similarly , a cyclodextrin - modified polymer as described herein can be treated with molecule having polyethylene glycol ( peg ) chains linked to groups that form inclusion complexes with cyclodextrin . as described in greater detail below , particles of polymers modified in this way are stabilized ( e . g ., due to the presence of a peg “ brush layer ” on their surface ) relative to particles in which no such inclusion complexes have been formed . alternatively or additionally , inclusion complexes can be used to couple ligands to the polymer ( e . g ., for targeting the polymer to a particular tissue , organ , or other region of a patient &# 39 ; s body ), or to otherwise modify the physical , chemical , or biological properties of the polymer . exemplary cyclodextrin moieties include cyclic structures consisting essentially of from 6 to 8 saccharide moieties , such as cyclodextrin and oxidized cyclodextrin . a cyclodextrin moiety optionally comprises a linker moiety that forms a covalent linkage between the cyclic structure and the polymer backbone , preferably having from 1 to 20 atoms in the chain , such as alkyl chains , including dicarboxylic acid derivatives ( such as glutaric acid derivatives , succinic acid derivatives , and the like ), and heteroalkyl chains , such as oligoethylene glycol chains . cyclodextrin moieties may further include one or more carbohydrate moieties , preferably simple carbohydrate moieties such as galactose , attached to the cyclic core , either directly ( i . e ., via a carbohydrate linkage ) or through a linker group . cyclodextrins are cyclic polysaccharides containing naturally occurring d -(+)- glucopyranose units in an α -( 1 , 4 ) linkage . the most common cyclodextrins are alpha (( α )- cyclodextrins , beta ( β )- cyclodextrins and gamma ( γ )- cyclodextrins which contain , respectively . six , seven , or eight glucopyranose units . structurally , the cyclic nature of a cyclodextrin forms a torus or donut - like shape having an inner apolar or hydrophobic cavity , the secondary hydroxyl groups situated on one side of the cyclodextrin torus and the primary hydroxyl groups situated on the other . thus , using ( β )- cyclodextrin as an example , a cyclodextrin is often represented schematically as follows . the side on which the secondary hydroxyl groups are located has a wider diameter than the side on which the primary hydroxyl groups are located . the hydrophobic nature of the cyclodextrin inner cavity allows for the inclusion of a variety of compounds . ( comprehensive supramolecular chemistry , volume 3 , j . l . atwood et al ., eds ., pergamon press ( 1996 ); t . cserhati , analytical biochemistry , 225 : 328 - 332 ( 1995 ); husain et al ., applied spectroscopy , 46 : 652 - 658 ( 1992 ); fr 2 665 169 ). additional methods for modifying polymers are disclosed in suh , j . and noh , y ., bioorg . med . chem . lett . 1998 , 8 , 1327 - 1330 . cyclodextrins have been used as a delivery vehicle of various therapeutic compounds by forming inclusion complexes with various drugs that can fit into the hydrophobic cavity of the cyclodextrin or by forming non - covalent association complexes with other biologically active molecules such as oligonucleotides and derivatives thereof . for example , see u . s . pat . nos . 4 , 727 , 064 , 5 , 608 , 015 , 5 , 276 , 088 , and 5 , 691 , 316 . various cyclodextrin - containing polymers and methods of their preparation are also known in the art . comprehensive supramolecular chemistry , volume 3 , j . l . atwood et al ., eds ., pergamon press ( 1996 ). therapeutic compositions according to the invention contain a therapeutic agent and a carbohydrate - modified polymer of the invention , such as , for example , a cyclodextrin - modified polymer of the invention or a carbohydrate - modified polymer having an ic 50 for cells in culture of greater than 25 μg / ml . the therapeutic agent may be any synthetic or naturally occurring biologically active therapeutic agent including those known in the art . examples of suitable therapeutic agents include , but are not limited to , antibiotics , steroids , polynucleotides ( e . g ., genomic dna , cdna , mrna and antisense oligonucleotides ), plasmids , peptides , peptide fragments , small molecules ( e . g ., doxorubicin ) and other biologically active macromolecules such as , for example , proteins and enzymes . therapeutic compositions are preferably sterile and / or non - pyrogenic , e . g ., do not substantially raise a patient &# 39 ; s body temperature after administration . a therapeutic composition of the invention may be prepared by means known in the art . in a preferred embodiment , a copolymer of the invention is mixed with a therapeutic agent , as described above , and allowed to self - assemble . according to the invention , the therapeutic agent and a carbohydrate - modified polymer of the invention associate with one another such that the copolymer acts as a delivery vehicle for the therapeutic agent . the therapeutic agent and carbohydrate - modified polymer may associate by means recognized by those of skill in the art such as , for example , electrostatic interaction and hydrophobic interaction . the degree of association may be determined by techniques known in the art including , for example , fluorescence studies , dna mobility studies , light scattering , electron microscopy , and will vary depending upon the therapeutic agent . as a mode of delivery , for example , a therapeutic composition of the invention containing a copolymer of the invention and dna may be used to aid in transfection , i . e ., the uptake of dna into an animal ( e . g ., human ) cell . ( boussif , o . proceedings of the national academy of sciences , 92 : 7297 - 7301 ( 1995 ); zanta et al . bioconjugate chemistry , 8 : 839 - 844 ( 1997 )). a therapeutic composition of the invention may be , for example , a solid , liquid , suspension , or emulsion . preferably a therapeutic composition of the invention is in a form that can be injected , e . g ., intratumorally or intravenously . other modes of administration of a therapeutic composition of the invention include , depending on the state of the therapeutic composition , methods known in the art such as , but not limited to , oral administration , topical application , parenteral , intravenous , intranasal , intraocular , intracranial or intraperitoneal injection . depending upon the type of therapeutic agent used , a therapeutic composition of the invention may be used in a variety of therapeutic methods ( e . g . dna vaccines , antibiotics , antiviral agents ) for the treatment of inherited or acquired disorders such as , for example , cystic fibrosis , gaucher &# 39 ; s disease , muscular dystrophy , aids , cancers ( e . g ., multiple myeloma , leukemia , melanoma , and ovarian carcinoma ), cardiovascular conditions ( e . g ., progressive heart failure , restenosis , and hemophilia ), and neurological conditions ( e . g ., brain trauma ). in certain embodiments according to the invention , a method of treatment administers a therapeutically effective amount of a therapeutic composition of the invention . a therapeutically effective amount , as recognized by those of skill in the art , will be determined on a case by case basis . factors to be considered include , but are not limited to , the disorder to be treated and the physical characteristics of the one suffering from the disorder . another embodiment of the invention is a composition containing at least one biologically active compound having agricultural utility and a linear cyclodextrin - modified polymer or a linear oxidized cyclodextrin - modified polymer of the invention . the agriculturally biologically active compounds include those known in the art . for example , suitable agriculturally biologically active compounds include , but are not limited to , fungicides , herbicides , insecticides , and mildewcides . the invention now being generally described , it will be more readily understood by reference to the following examples , which are included merely for purposes of illustration of certain aspects and embodiments of the present invention , and are not intended to limit the invention . branched pei 25 , 000 ( 295 . 6 mg , aldrich ) and 6 - monotosyl - β - cyclodextrin ( 2 . 287 g , cyclodextrin technologies development , inc .) were dissolved in 100 ml of various h 2 o / dmso solvent mixture ( table 1 ). the resulting mixture was stirred at 70 ° c . for 72 h . the solution turned slightly yellow . the solution was then transferred to a spectra / por mwco 10 , 000 membrane and dialyzed against water for 6 days . water was then removed by lyophilization to afford a slightly colored solid . cyclodextrin / pei ratio was calculated based on the proton integration of 1 h nmr ( varian 300 hz , d 2 o ) δ 5 . 08 ppm ( s br ., c 1 h of cd ), 3 . 3 - 4 . 1 ppm ( m br . c 2 h - c 6 h of cd ), 2 . 5 - 3 . 2 ppm ( m br . ch 2 of pei ). the cyclodextrin loading on pei was found to increase with decreasing amounts of h 2 o in the reaction mixture ( table 1 ). low loading : linear pei ( 50 mg , polysciences , inc ., mw 25 , 000 ) was dissolved in dry dmso ( 5 ml ). cyclodextrin monotosylate ( 189 mg , 75 eq ., cyclodextrin technologies development , inc .) was added to the solution . the solution was stirred under argon at 70 - 72 ° c . for 4 days . then this solution was dialyzed in water ( total dialysis volume around 50 ml ) for six days ( spectra / por 7 mwco 25 , 000 membrane ). 1pei - cd ( 46 mg ) was obtained after lyophilization . 1 h nmr ( bruker amx 500 mhz , d 2 o ) δ 5 . 09 ( s br ., c1 of cd ), 3 . 58 - 4 . 00 ( m br ., c2 - c6 of cd ), 2 . 98 ( m br ., pei ). 8 . 8 % of pei repeats were conjugated with cd . high loading : linear pei ( 50 mg , polysciences , inc . mw 25 , 000 ) was dissolved in dry dmso ( 10 ml ). cyclodextrin monotosylate ( 773 mg , 300 eq ., cyclodextrin technologies development , inc .) was added to the solution . the solution was stirred under argon at 70 - 72 ° c . for 4 days . then this solution was dialyzed in water ( total dialysis volume around 50 ml ) for six days ( spectra / por 7 mwco 25 , 000 membrane ). precipitation in dialysis bag was observed . the precipitate ( unreacted cd - monotosylate ) was removed using 0 . 2 μm syringe filter and the filtrant was dialyzed in a 25 , 000 mwco membrane for another 24 hours . 1pei - cd ( 75 mg ) was obtained after lyophilization . 1 h nmr ( bruker amx 500 mhz , d 2 o ) δ 5 . 09 ( s br ., c1 of cd ), 3 . 58 - 4 . 00 ( m br ., c2 - c6 of cd ), 2 . 98 ( m br ., pei ). 11 . 6 % of pei repeats were conjugated with cd . linear pei 25 , 000 ( 500 mg , polysciences , inc .) and 6 - monotosyl - β - cyclodextrin ( 3 . 868 g , cyclodextrin technologies development , inc .) were dissolved in 36 ml of dmso . the resulting mixture was stirred at 70 ° c . for 6 days . the solution turned slightly yellow . the solution was then transferred to a spectra / por mwco 10 , 000 membrane and dialyzed against water for 6 days . water was then removed by lyophilization to afford a slightly colored solid . cyclodextrin / pei ratio was calculated based on the proton integration of 1 h nmr ( varian 300 mhz , d 2 o ) δ 5 . 08 ppm ( s br ., c 1 h of cd ), 3 . 3 - 4 . 1 ppm ( m br . c 2 h - c 6 h of cd ), 2 . 5 - 3 . 2 ppm ( m br . ch 2 of pei ). in this example , the cyclodextrin / pei ratio was 8 . 4 . plasmid dna ( pgl3 - cv , plasmid containing the luciferase gene under the control of an sv40 promoter ) was prepared at 0 . 5 mg / ml in water . branched cd - pei was prepared at 2 . 0 mg / ml in water . ad - peg 5000 was prepared at 10 mg / ml and 100 mg / ml in water . ( see examples 22 - 28 of u . s . patent application ser . no . 10 / 021 , 312 , filed dec . 19 , 2001 , for details .) polyplexes were prepared by mixing the desired amount of ad - peg 5000 with 6 μl of branched cd - pei . this polymer solution was then added to 6 μl of dna solution . polyplex solutions were transferred to a light - scattering cuvette . 1 . 6 ml of pbs ( 150 mm ) was added and particle size measured immediately following salt addition for 10 minutes using a zeta pals dynamic light scattering detector ( brookhaven instruments ). results are depicted in fig1 . oligo dna ( fitc - oligo ) was prepared at 0 . 5 mg / ml in water . branched cd - pei was prepared at 2 . 0 mg / ml in water . ad - peg 5000 was prepared at 10 mg / ml and 100 mg / ml in water . polyplexes were prepared by mixing the desired amount of ad - peg 5000 with 6 μl of branched cd - pei . this polymer solution was then added to 6 μl of dna solution . polyplex solutions were transferred to a light - scattering cuvette . 1 . 6 ml of pbs ( 150 mm ) was added and particle size measured immediately following salt addition for 10 minutes using a zeta pals dynamic light scattering detector ( brookhaven instruments ). results are depicted in fig2 . pc3 cells were plated at 200 , 000 cells / ml in 24 - well plates . after 24 hours , the cells were transfected with 3 μg / well of pegfp - luc ( plasmid containing the egfp - luc fusion gene under the control of a cmv promoter ) complexed with branched cd - pei at a 5 : 1 weight ratio . ( for each well , transfection mixtures were prepared in 60 μl of water and then 1 ml of optimem ( a serum - free medium from life technologies ) was added to the solutions . the final solutions were then transferred to the cells .) 4 hours after transfection , media was removed and replaced with 5 ml of complete media . cells were analyzed by flow cytometry for egfp expression 48 hours after transfection . egfp expression was observed in 25 % of analyzed cells . pc3 cells were plated at 300 , 000 cells / well in 6 - well plates . after 24 hours , the cells were transfected with 3 μg / well of fitc - oligo complexed with branched pei ( modified and unmodified ) or branched cd - pei at a 5 : 1 weight ratio . 15 minutes after transfection , cells were washed with pbs , trypsinized and analyzed by flow cytometry for uptake of the fluorescent oligos . egfp expression was observed in 25 % of analyzed cells . results are depicted in fig3 . pc3 cells were transfected with several cd - pei polymers as listed below . polymer mass / monomer ethylenimine / cd b - pei2000 - cd - l 178 9 . 5 b - pei2000 - cd - h 216 7 . 4 b - pei10000 - cd - l 89 27 b - pei10000 - cd - h 111 19 b - pei70000 - cd - l 98 23 b - pei70000 - cd - h 119 16 . 8 l - pei25000 - cd - l 155 11 . 4 l - pei25000 - cd - h 192 8 . 6 the nomenclature is defined as follows : b - pei2000 - cd - l is cyclodextrin grafted to branched pei of 2000 mw . a prefix of ‘ 1 ’ indicates a linear pei substrate . the “ l ” and “ h ” stands for “ lighter ” and “ heavier ” grafted polymers ( see the respective ethylenimine / cd ratios as listed on the right - most column ). the cd - pei polymers were prepared according to the protocol described in example 1 . pc3 cells were plated at 200 , 000 cells / well in 6 - well plates . after 24 hours , the cells were transfected with 3 μg of plasmid of pegfp - luc plasmid assembled with cd - pei polymers at 15 n / p in 1 ml of optimem . five hours after transfection , 4 ml of complete media was added to each well . cells were trypsinized , collected , and analyzed by flow cytometry for egfp expression 48 hours after transfection . the results are shown in fig4 . high transfection efficiency was observed with increasing molecular weight . linear - pei - based conjugates transfected with higher efficiency than branched - pei - based conjugates . pc3 cells were plated at 60 , 000 cells / ml in 96 well plates ( 0 . 1 ml per well ). after 24 hours , polymer solutions in media were added to the third column and diluted serially across the rows . the cells were incubated for 24 hours , after which they were washed with pbs and 50 μl of mtt ( 2 mg / ml in pbs ) per well was added , followed by 150 μl of complete media per well . the wells were incubated for 4 hours . the solutions were then removed and 150 μl of dmso was added . adsorbance was then read at 540 nm . results for branched cd - pei are depicted in fig5 . the ic 50 &# 39 ; s of cyclodextrin - grafted 1pei and bpei polymers in pc3 cells were determined by mtt assay . as a comparison , the ic 50 of mannosylated - pei ( man - jet - pei ) along with the parent pei ( jet - pei ), purchased from polyplus transfections ( illkirch , france ), was determined for comparison . the ic 50 values were determined as follows : pc3 cells were plated at 60 , 000 cells / ml in 96 - well plates for 24 hours ( 0 . 1 ml per well ). polymers were added to the third column in complete and diluted serially across the rows . after 24 hours , the cells were washed with pbs and 50 μl of mtt ( 2 mg / ml in pbs ) was added per well followed by 150 μl of complete media . the media was removed after 4 hour incubation and 150 μl of dmso was added . adsorbance was read at 540 nm . the ic 50 values are shown in the chart below . polymers are shown grouped in pairs ( parent polymer and modified polymer ) in the first column . the ic 50 value for each polymer is listed in the second column in μg / ml . the third column lists the decrease in toxicity by saccharide grafted , as calculated by the modified pei ic 50 value divided by the parents pei ic 50 value . the cyclodextrin - grafted peis have ic 50 values that are over forty times those of mannosylated pei from polyplus . in addition , modification with high grafting density results in a much higher increase in tolerability ( 90 - fold vs . 20 fold ) over parent polymers . polymer ic 50 ( μg / ml ) fold increase b - pei25000 7 . 5 b - pei25000 - cd 1000 133 l - pei25000 11 l - pei25000 - cd 1000 90 jet - pei 1 . 1 man - jet - pei 23 20 balb - c mice were injected with pegylated cd - pei polyplexes containing 200 μg of pgl3 - cv ( 15 : 5 : 1 ad - peg : cd - pei : pgl3 - cv by weight ) by portal vein injection . mice were anesthesized , injected with luciferin , and imaged using a xenogen camera 4 . 5 hours after injection . luciferase expression was observed in the liver , as indicated by light emission as shown in fig6 . cd - pei based polyplexes ( containing the α - luciferase plasmid ) were modified by peg - galactose and peg by adding in ad - peg 5000 - galactose ( adamantane - polyethylene glycol - galactose ) or ad - peg 5000 during polyplex formulation ( for more information on adamantane conjugates and inclusion complexes thereof , see pct publication wo 02 / 49676 ). the adamantane from ad - peg 5000 - galactose or ad - peg 5000 forms inclusion complexes with the cyclodextrin and modifies the surface of the particles with peg - galactose or peg , respectively . these polyplexes were exposed to hepg2 cells , hepatoma cells expressing the asialoglycoprotein receptor . polyplexes modified by galactose yielded a 10 - fold increase in luciferase expression as shown in fig7 indicating increased transfection by galactose - mediated uptake . pc3 cells were plated at 50 , 000 cells / well in 24 - well plates 24 hours before transfection . immediately prior to transfection , cells in each well were rinsed once with pbs before the addition of 200 μl of optimem ( invitrogen ) containing polyplexes ( 1 μg of dna complexed with polycation synthesized as described in example 1 at 10 n / p ). after 4 hours , transfection media was aspirated and replaced with 1 ml of complete media . after another 24 hours , cells were washed with pbs and lysed by the addition of 100 μl of cell culture lysis buffer ( promega , madison , wis .). cell lysates were analyzed for luciferase activity with promega &# 39 ; s luciferase assay reagent . light units were integrated over 10 s with a luminometer ( monolight 3010c , becton dickinson ). high transfection was observed with pei : cd ratios greater than 10 ( see fig8 ). pc3 cells were plated in 96 - well plates at 5 , 000 cells / well for 24 hours . polymers were added to the third column and diluted serially across the rows . after another 24 hours , cells were washed with pbs and 50 μl of mtt ( 2 mg / ml in pbs ) was added per well followed by 150 μl of complete media . media was removed after 4 hours incubation at 37 ° c . and 150 μl of dmso was added to dissolve the formazan crystals . absorbance was read 540 nm to determine cell survival . all experiments were conducted in triplicate and averaged . average absorbance was plotted versus polymer concentration and ic 50 values were determined by interpolation within the linear absorbance region . the tolerability of the polymers increases as more cd is grafted onto bpei ( see fig9 ). the ic 50 of the cd - 1pei polymer to pc3 cells ( with 8 . 4 pei : cd , synthesis described in example 3 ) was determined according to the procedure in example 9 and compared with the ic 50 of the parent 1pei polymer . the ic 50 of cd - 1pei ( 220 μg / ml ) was 15 times greater than the ic 50 of 1pei ( 15 μg / ml ). pc3 cells were plated at 250 , 000 cells / well in 6 - well plates . after 24 hours , the cells were transfected with 5 μg of pegfp - luc plasmid assembled with polymer at n / p in 1 ml of optimem ( for some samples , optimem containing 200 μm chloroquine was added ). four hours after transfection , media was removed and replaced with 5 ml of complete media . cells were washed with pbs , trypsinized , and analyzed by flow cytometry for egfp expression 48 hours after transfection . grafting of cyclodextrin onto 1pei at 8 . 4 pei : cd does not affect transfection efficiency . results are presented in fig1 . an equal volume of polycation ( dissolved in water or d5w ) is added to dna ( 0 . 1 mg / ml in water ). the polymer nitrogen to dna phosphate ratio ( n / p ) is varied by changing the concentration of the polycation solution . polyplexes were formulated using cd - bpei ( 12 . 6 pei : cd ratio ) at 10 n / p as described above . 5 μl of polyplexes were applied to 400 - mesh carbon - coated copper grids for 45 seconds , after which excess liquid was removed by blotting with filter . samples were negatively stained with 2 % uranyl acetate for 45 seconds before blotting . the 400 - mesh carbon - coated copper grids were glow - discharged immediately prior to sample loading . images , as depicted in fig1 , were recorded using a philips 201 electron microscope operated at 80 kv . particles were formulated using cd - bpei ( 12 . 6 pei : cd ratio ) at 10 n / p as described above and then diluted by the addition of 1 . 2 ml of water . particle size was measured using a zetapals dynamic light scattering detector ( brookhaven instrument corporation ). three measurements were taken for each sample and data reported as average size . average particle diameter standard deviation polymer ( nm ) ( nm ) bpei 290 3 lpei 115 2 cd - bpei 96 1 cd - lpei 93 1 salt stabilization of cd - bpei and cd - 1pei particles by the addition of ad - peg particles were formulated as described above and then diluted by the addition of 1 . 2 ml pbs . particle size was monitored using a zetapals dynamic light scattering detector every minute for 10 minutes . samples were run in triplicate and data reported as average size at each time point . the addition of ad - peg helps to stabilization cd - bpei and cd - 1pei particles against salt - induced aggregation . addition of ad - peg to bpei and 1pei particles has no affect on salt - induced aggregation . results are presented in fig1 . pc3 cells were plated at 2 , 000 , 000 cells / well in 6 - well plates . after 24 hours , the cells were transfected with 5 μg of fluorescently - labeled oligonucleotide complexed with polycation at 10 n / p . after 15 minutes , cells were washed with pbs , cell scrub buffer , and trypsinized and analyzed by flow cytometry for uptake of the polyplexes . cd - bpei ( 12 . 6 pei : cd ) and cd - 1pei ( 8 . 4 pei : cd ) are efficient at delivering oligos to cultured cells . results are depicted in fig1 . female , balb / c mice were injected intravenously with cd - 1pei - and cd - bpei - based polyplexes using a volume of 0 . 4 ml ( d5w based solution ) and injection speed of ˜ 0 . 2 ml / 15 sec . animals were sacrificed 24 hours after injection and blood collected for transaminase , creatinine , platelet and white blood cell analysis . groups : 1 . control 2 . cd - bpei 10 n / p 0 . 1 mg dna / ml 3 . cd - bpei 10 n / p 0 . 2 mg dna / ml 4 . cd - bpei 10 n / p 0 . 3 mg dna / ml 5 . cd - lpei 10 n / p 0 . 1 mg dna / ml 6 . cd - lpei 10 n / p 0 . 2 mg dna / ml 7 . cd - lpei 10 n / p 0 . 3 mg dna / ml the maximum tolerable dose of cd - bpei was determined to be 9 mg / kg ( assuming 20 g mice , 0 . 1 mg dna / ml dose ). at the 0 . 2 mg dna / ml dose , all animals survived but with depressed platelet counts . the maximum tolerable dose of cd - 1pei was determined to be at least 36 mg / kg ( assuming 20 g mice , 0 . 3 mg dna / ml dose ). no platelet depression or elevated liver enzyme levels was observed . in addition , all animals survived at the highest dose injected . as a comparison , the ld 50 of 1pei was determined to be ˜ 3 - 4 mg / kg ( 50 % balb / c mice died with an injection of 50 μg of dna complexed with 1pei at 10 n / p ; chollet et al . j gene medicine v4 : 84 - 91 ( 2002 ). cd - 1pei particles were injected into tumors of neuro2a tumor - bearing mice ( 120 μg dna complexed with cd - 1pei at 10 n / p per mouse ). after 48 hours , tumors were excised , homogenized and analyzed for luciferase expression . average expression was determined to be : 2500 rlu / mg tissue . p - toluenesulfonylchloride ( 5 . 8 g , 30 . 5 mmol , acros ) in anhydrous pyridine ( 10 ml ) was added dropwise to a solution of d - galactose ( 5 g , 27 . 8 mmol , aldrich ) in anhydrous pyridine ( 50 ml ) at 0 ° c . the solution was stirred for 4 h at room temperature . the reaction mixture was then quenched with meoh ( 2 ml ), diluted with 75 ml of chcl 3 , and washed twice with ice - cold water ( 50 ml ). the organic phase was dried under reduced pressure . the residue was subjected to c8 reversed - phase column chromatography using a gradient elution of 0 - 50 % acetonitrile in water . fractions were analyzed on a beckman coulter system gold hplc system equipped with a uv 168 detector , an evaporative light scattering ( els ) detector and a c18 reversed - phase column ( alltech ) using an acetonitrile / h 2 o gradient as eluant at 0 . 7 ml / min flow rate . the appropriate fractions were combined and evaporated to dryness . this procedure gave the tosyl - galactose as confirmed by mass spectroscopy : electrospray ionization : 357 . 1 [ m + na ] + , 690 . 7 [ 2m + na ] + . low loading : branched pei 25 , 000 ( 64 . 9 mg , 0 . 0026 mmol , aldrich , mw 25 , 000 ) and tosyl - galactose ( 13 mg , 0 . 039 mmol ) was dissolved in 22 ml of h 2 o / dmso ( 5 / 95 ). the solution was stirred at 70 ° c . for 3 days . the solution was then transferred to a spectra / por mwco 10 , 000 membrane and dialyzed against water for 6 days . water was then removed by lyophilization to afford a slightly colored solid . galactose / pei ratio was calculated based on the proton integration of 1 h - nmr ( varian 300 mhz , d 2 o ). high loading : branched pei 25 , 000 ( 64 . 9 mg , 0 . 0026 mmol , aldrich , mw 25 , 000 ) and tosyl - galactose ( 130 mg , 0 . 39 mmol ) was dissolved in 22 ml of h 2 o / dmso ( 5 / 95 ). the solution was stirred at 70 ° c . for 3 days . the solution was then transferred to a spectra / por mwco 10 , 000 membrane and dialyzed against water for 6 days . water was then removed by lyophilization to afford a slightly colored solid . galactose / pei ratio was calculated based on the proton integration of 1 h nmr ( varian 300 mhz , d 2 o ). low loading : linear pei 25 , 000 ( 100 mg , 0 . 004 mmol , polyscience , mw 25 , 000 ) and tosyl - galactose ( 20 mg , 0 . 06 mmol ) were dissolved in 7 . 2 ml of dmso . the solution was stirred at 70 ° c . for 6 days . the solution was then transferred to a spectra / por mwco 10 , 000 membrane and dialyzed against water for 6 days . water was then removed by lyophilization to afford a slightly colored solid . galactose / pei ratio was calculated based on the proton integration of 1 h nmr ( varian 300 mhz , d 2 o ). high loading : linear pei 25 , 000 ( 100 mg , 0 . 004 rnmol , polyscience , mw 25 , 000 ) and tosyl - galactose ( 200 mg , 0 . 6 mmol ) was dissolved in 7 . 2 ml of dmso . the solution was stirred at 70 ° c . for 6 days . the solution was then transferred to a spectra / por mwco 10 , 000 membrane and dialyzed against water for 6 days . water was then removed by lyophilization to afford a slightly colored solid . galactose / pei ratio was calculated based on the proton integration of 1 h nmr ( varian 300 mhz , d 2 o ). all of the above - cited references and publications are hereby incorporated by reference . those skilled in the art will recognize , or be able to ascertain using no more than routine experimentation , many equivalents to the specific embodiments of the invention described herein . such equivalents are intended to be encompassed by the following claims .
this application discloses compositions of carbohydrate - modified polymers , such as polyethylenimine modified with cyclodextrin moieties , for carrying drugs and other active agents , such as nucleic acids . compositions are also disclosed of carbohydrate - modified polymer carriers that release such agents under controlled conditions . the invention also discloses compositions of carbohydrate - modified polymer carriers that are coupled to biorecognition molecules for targeting the delivery of drugs to their site of action .