the present invention further extends this dithiolane technology further into nucleosides . conjugation of dithiolane moiety to the either nucleobase or to sugar part with linker arm should generate very interesting functionalized thiol oligonucleotides . the advantage of relatively long linker arm is that it allows clean formation of the monomers on the solid surfaces and keeps the self - assembled monomers in the optimum distance from the solid support . pairs of oligonucleotide - gold nano - particle conjugates serve as unique probes for recognizing specific sequences in dna segments , as building blocks for assembling novel structures , bio diagnostics and nano technology based therapeutics . one embodiment of the invention is directed to a nucleoside , comprising : a guanine , a 2 ′- deoxyribose , a dithiolane derivative at n2 of the guanine ; and a phosphoramidite derivative at the 3 ′- o of the deoxyribose , or a solid support at the 3 ′- o of the deoxyribose , wherein the nucleoside is represented by structure 1 or structure 2 : one embodiment of the invention is directed to a nucleoside , comprising : a pyrimidine ; a ribose ; and a dithiolane derivative at c5 of the pyrimidine , wherein the nucleoside is represented by structure 3 or structure 4 : one embodiment of the invention is directed to a nucleoside , comprising : a purine ; a ribose ; and a dithiolane derivative at c8 of the purine , wherein the nucleoside is represented by structure 5 or structure 6 : one embodiment of the invention is directed to a nucleoside , comprising : a pyrimidine ; a ribose ; and a dithiolane derivative at 2 ′- o of the ribose , wherein the nucleoside is represented by structure 7 or structure 8 : one embodiment of the invention is directed to a nucleoside , comprising : a purine ; a ribose ; and a dithiolane derivative at 2 ′ o of the ribose , wherein the nucleoside is represented by structure 9 or structure 10 : one embodiment of the invention is directed to a nucleoside , comprising : a pyrimidine ; a ribose ; a dithiolane derivative at c5 of the pyrimidine ; and a phosphoramidite group at 3 ′- o of the ribose , wherein the nucleoside is represented by structure 11 or structure 12 : one embodiment of the invention is directed to a nucleoside , comprising : a purine ; a ribose ; a dithiolane derivative at c8 of the purine ; and a phosphoramidite group at 3 ′- o of the ribose , wherein the nucleoside is represented by structure 13 or structure 14 : one embodiment of the invention is directed to a nucleoside , comprising : a pyrimidine ; a ribose ; a dithiolane derivative at 2 ′- o of the ribose ; and a phosphoramidite group at 3 ′- o of the ribose , wherein the nucleoside is represented by structure 15 or structure 16 : one embodiment of the invention is directed to a nucleoside , comprising : a purine ; a ribose ; a dithiolane derivative at 2 ′- o of the ribose ; and a phosphoramidite group at 3 ′- o of the ribose , wherein the nucleoside is represented by structure 17 or structure 18 : one embodiment of the invention is directed to a nucleoside , comprising : a ribose ; a succinate group at 3 ′- o of the ribose ; and a pyrimidine or a purine , wherein the pyrimidine has a dithiolane derivative at c5 and the pyrimidine is represented by structure 19 or structure 20 , the purine has a dithiolane derive at c8 and is represented by structure 21 or structure 22 : one embodiment of the invention is directed to a nucleoside , comprising : a nucleobase ; a ribose ; a dithiolane derivative at 2 ′- o of the ribose ; and a succinate group at 3 ′- o of the ribose , wherein the nucleobase is a pyrimidine as represented by structure 23 or structure 24 , or a purine as represented by structure 25 or structure 26 : one embodiment of the invention is directed to a nucleoside , comprising : a nucleobase ; a ribose ; a dithiolane derivative at 2 ′- o of the ribose ; and a solid support at 3 ′ o — of the ribose , wherein the nucleobase is a pyrimidine as represented by structure 27 or structure 28 , and a purine as represented by structure 29 or structure 30 : one embodiment of the invention is directed to a nucleoside , comprising a dithiolane derivative according to one of the above - mentioned nucleosides , wherein the nucleoside is represented by one of structure 1 through structure 30 . one embodiment of the invention is directed to a conjugate , comprising : the nucleoside mentioned above , and a solid support , wherein the solid support is gold or quantum , and the conjugate is presented in fig1 . to show this , we have successfully synthesized n2 - functionalized deoxy - guanosine amidites ( 1 , chart 1 ) and proposed the scheme for the corresponding compound with solid support ( 2 , chart 1 ). in addition to these we proposed various dithiolane functionalized dna and rna amidites and solid supports ( schemes 1 to 8 ). these monomers are useful in generating the thiol functionalities at 3 ′- or 5 ′- end of oligonucleotides . with these improvements , we strongly believe that our probes are designed to be ideally suited to application in high quality probes consisting of dithiolane moieties . the thiol modified oligonucleotides have vast number of applications in the field of nucleic acid chemistry such as it enables covalent attachment of a variety of ligands and also has an ability to form relatively stronger bond with gold surface . dna functionalized gold nanoparticles have become widely used building blocks in key nucleic acid based assembly strategies and therapeutics . even though thiol group forms relatively stronger bond with elemental gold ( about 30 - 40 k cal / mole ), it gets displaced at higher temperature , in high salt concentration buffers and in presence other thiols . for many of applications with these conjugates strong binding of the oligonucleotides to the gold nano particles is required . however to circumvent displacement of thiol , a few cyclic disulfide modifiers that can introduce multiple thiol groups have been introduced in the 15 prior art . their stability studies revealed that these multi - thiol functionalized oligonucleotides form relatively more stable sams compared to the corresponding mono - thiol derivatives . in the present application , we describe the design and efficient synthesis of n2 cyclic dithiolane functionalized phosphoramidite derivative 1 ( chart 1 ) and proposed synthesis of corresponding dithiolane succinyl cpg supports 2 ( chart 1 ). in addition to the synthesized dithiolane functionalized derivatives 1 ( chart 1 ), we envision various other functionalized derivatives compounds from schemes 1 to 8 . conjugation of dithiolane moiety to the either nucleobase or to sugar part with linker arm should generate very interesting functionalized thiol oligonucleotides . the advantage of relatively long linker arm is that it allows clean formation of the monomers on the solid surfaces and keeps the self - assembled monomers in the optimum distance from the solid support . pairs of oligonucleotide - gold nano - particle conjugates serve as unique probes for recognizing specific sequences in dna segments , as building blocks for assembling novel structures , bio diagnostics and nano technology based therapeutics . 2 - fluoro of the nucleoside 53 [ cao , h ., yong , j ., yinsheng w . jour . of the am . chem . soc . 2007 , 129 , 12123 - 12130 ] was displaced by the 1 , 12 - diaminododecane to afford amino nucleoside 54 in 79 % yield . nucleoside 54 was coupled to thioctic acid using edc . hcl to get n2 - dithiolane coupled product 55 . finally , compound 55 was converted to target amidite 1 using n , n ′-( diisopropyl ) phosphoramidochloridite reagent and n , n ′- diisopropylethylamine in anhydrous thf in 67 % yield ( scheme 9 ). compound 55 can also be converted to corresponding succinate 57 ( scheme 10 ) followed by coupling to the suitable solid support to get compound 2 ( scheme 10 ). these target compounds 1 and 2 can be incorporated into the oligonucleotide sequence to get the dithiolane modification at the either 3 ′- or 5 ′- end of the oligonucleotide sequence as depicted in schemes 9 and 10 . the proposed scheme 1 outlines synthesis of uridine c - 5 spacer moiety , at the terminal of which dithiolane function is attached . other modification of solid chain at c - 5 can be envisioned such as introduction of alkyl carboxy function for further elongation of c - 5 and eventually attaching dithiolane function . besides 2 ′- deoxy nucleosides 2 ′- modified nucleosides are also envisioned , such as 2 ′- f , 2 ′- omethyl , 2 ′- o alkyl , 2 ′- o - amino ( protected ). various chromophores can be attached to this nucleoside as well as tho oligonucleotide chain for better and diverse detection applications . phosphoramidites and succinates are envisioned . the later function can be utilized to attach the compound ( 9 ) to various solid support . the proposed scheme 2 outlines synthesis of cytidine c - 5 spacer moiety , at the terminal of which dithiolane function is attached . other modification of solid chain at c - 5 can be envisioned such as introduction of alkyl carboxy function for further elongation of c - 5 and eventually attaching dithiolane function . besides 2 ′- deoxy nucleosides 2 ′- modified nucleosides are also envisioned , such as 2 ′- f , 2 ′- omethyl , 2 ′- o alkyl , 2 ′- o - amino ( protected ). various chromophores can be attached to this nucleoside as well as to oligonucleotide chain for better and diverse detection applications . phosphoramidites and succinates are envisioned . the later function can be utilized to attach the compound ( 15 ) to various solid support the proposed scheme 3 outlines synthesis of deoxy adenosine c - 8 spacer moiety , at the terminal of which dithiolane function is attached . other modification of solid chain at c - 8 can be envisioned such as introduction of c - 8 - o - alkyl function for further elongation of c - 8 and eventually attaching dithiolane function . besides 2 ′- deoxy nucleosides 2 ′- modified nucleosides are also envisioned , such as 2 ′- f , 2 ′- omethyl , 2 ′- o alkyl , 2 ′- o - amino ( protected ). various chromophores can be attached to this nucleoside as well as to oligonucleotide chain for better and diverse detection applications . phosphoramidites and succinates are envisioned . the later function can be utilized to attach the compound ( 21 ) to various solid support . the proposed scheme 4 outlines synthesis of guanosine c - 8 spacer moiety , at the terminal of which dithiolane function is attached . other modification of solid chain at c - 8 can be envisioned such as introduction of 8 - o - alkyl function for further elongation of c - 8 and eventually attaching dithiolane function . besides 2 ′- deoxy nucleosides , 2 ′- modified nucleosides are also envisioned , such as 2 ′- f , 2 ′- omethyl , 2 ′- o alkyl , 2 ′- o - amino ( protected ). various chromophores can be attached to this nucleoside as well as to oligonucleotide chain for better and diverse detection applications . phosphoramidites and succinates are envisioned . the later function can be utilized to attach the compound ( 27 ) to various solid support . in the proposed scheme 4 , o6 has been protected with a protecting group , which can be removed under mild conditions to generate free o6 carbonyl function of guanosine . the proposed scheme 5 outlines synthesis of uridine 2 ′- o - alkyl spacer moiety , at the terminal of which dithiolane function is attached . other modification of solid chain at 2 ′- o — can be envisioned such as introduction of alkyl carboxy function for further elongation of o - 2 ′- and eventually attaching dithiolane function . various chromophores can be attached to this nucleoside to synthesize oligonucleotide chains for better and diverse detection applications . phosphoramidites and succinates are envisioned . the later function can be utilized to attach the compound ( 33 ) to various solid support . the proposed scheme 6 outlines synthesis of cytidine 2 ′- o - alkyl spacer moiety , at the terminal of which dithiolane function is attached . other modification of side chain at 2 ′- o — can be envisioned such as introduction of 2 ′- o - alkyl carboxy function for further elongation of o - 2 ′- and eventually attaching dithiolane function . various chromophores can be attached to this nucleoside to synthesize oligonucleotide chains for better and diverse detection applications . phosphoramidites and succinates are envisioned . the later function can be utilized to attach the compound ( 39 ) to various solid support . the proposed scheme 7 outlines synthesis of adenosine 2 ′- o - alkyl spacer moiety , at the terminal of which dithiolane function is attached . other modification of side chain at 2 ′- o — can be envisioned such as introduction of 2 ′- o - alkyl carboxy function for further elongation of o - 2 ′- and eventually attaching dithiolane function . various chromophores can be attached to this nucleoside to synthesize oligonucleotide chains for better and diverse detection applications . phosphoramidites and succinates are envisioned . the later function can be utilized to attach the compound ( 45 ) to various solid support . the proposed scheme 8 outlines synthesis of guanosine 2 ′- o - alkyl spacer moiety , at the terminal of which dithiolane function is attached . other modification of side chain at 2 ′- o — can be envisioned such as introduction of 2 ′- o - alkyl carboxy function for further elongation of o - 2 ′- and eventually attaching dithiolane function . various chromophores can be attached to this nucleoside to synthesize oligonucleotide chains for better and diverse detection applications . phosphoramidites and succinates are envisioned . the later function can be utilized to attach the compound ( 51 ) to various solid support . in the proposed scheme 8 , o6 has been protected with a protecting group , which can be removed under mild conditions to generate free o6 carbonyl function of guanosine . oligonucleotides such as 56 and 58 can be synthesized having different nucleosides of interest within sequence . b can be natural or modified nucleosides , purine or pyrimidine modifications , such as but not limited to , 5 - fluoro - u , 5 - fluoro du , 5 - fluoro - dc , 5 - fluro - rc , pseudouridine , 5 - methyl - du , 5 - methyl - ru , 5 - methyl - dc , 5 - methyl - rc , 5 - bromo - du , 5 - bromo - ru , 5 - bromo - dc , 5 - bromo - rc , 5 - iodo - du , 5 - iodo - ru , 5 - vinyl - du , 5 - vinyl - ru , 5 - vinyl thymidine , n - 3 methyldeoxy uridine , n - 3 methyl - ribouridine , n - 3 methyl thymidine , 4 - thio uridine , 4 - thio - 2 ′- deoxyuridine , 2 , 6 - diaminopurine deoxy riboside , n - 3 methyl ribothymidine , 2 , 6 - diaminopurine riboside , 8 - bromo 2 ′- deoxy adenosine , 8 - bromo - r - adenosine , 8 - oxo - deoxy adenosine , 8 - oxo - riboadenosine , 8 - oxo - 2 ′- deoxy - adenosine , 8 - oxo - riboadenosine , 8 - oxo - deoxy inosine , 8 - oxo - ribo inosine , 8 - bromo - deoxy inosine , 8 - bromo - ribo - inosine , n - 1 methyl - riboadenosine , n - 1 methyl - 2 ′- deoxy adenosine , n - 1 methyl 2 ′- deoxy inosine , n - 1 methyl riboadenosine , n - 1 methyldeoxy guanosine , n - 1 - methyl - riboguanosine , etheno adenosine , etheno 2 ′- deoxy adenosine , purine 2 ′- deoxy riboside , purine - ribonucleoside , 2 - aminopurine - 2 ′- deoxyriboside , 2 - aminopurine - ribonucleoside . labelling of internal positions of a dna synthesized by this method is achievable with chromophores such as , but not limited to fluoroscein - c - 5 dt , dabcyl - c - 5 thymidine , internal carboxyl group 5 - du - methylacrylate , biotin dt ( biotin attached via spacer to c - 5 of du ), amino - dt ( terminal amino attached via c - 6 spacer to c - 5 du ). the sugar modification of modified nucleosides could consist of 2 ′- deoxy - 2 ′- fluoro ribo nucleosides ( 2 ′- f - anas ) such as a , c , g , u , inosine and modified nucleosides containing 2 ′- fluoro , in one or more positions of an rna or dna sequence synthesized by the method of this invention . the sugar modification of modified nucleosides could consist of 2 ′- deoxy - 2 ′- methoxy ribo nucleosides ( 2 ′- ome -) such as a , c , g , u , inosine and modified nucleosides containing 2 ′- methoxy , in one or more positions of an rna or dna sequence synthesized by this method . the sugar modification of modified nucleosides could consist of 2 ′- deoxy - 2 ′- amino ribo nucleosides ( 2 ′- nh2 ) such as a , c , g , u , inosine and modified nucleosides containing 2 ′- amino , in one or more positions of an rna or dna sequence synthesized by this method . the sugar modification of modified nucleosides could consist of 2 ′- deoxy - 2 ′- terminal amino ribo nucleosides ( 2 ′- terminal nh2 ), attached via spacer from 2 - 10 atoms on nucleosides such as a , c , g , u , inosine and modified nucleosides containing 2 ′- terminal amino , in one or more positions of an rna or dna sequence synthesized by this method . the sugar modification of modified nucleosides could consist of 2 ′- deoxy - 2 ′- methoxy ethoxy ribo nucleosides ( 2 ′- moe ), such as a , c , g , u , inosine and modified nucleosides containing 2 ′- moe , in one or more positions of an rna or dna sequence synthesized by this method . the sugar modification of modified nucleosides could consist of other 2 ′- o - alkyl groups , such as 2 ′- deoxy - 2 ′- ethoxy , propargyl , butyne ribo nucleosides ( 2 ′- oet , o - propargyl , 2 ′- o - butyne ), such as a , c , g , u , inosine and modified nucleosides containing 2 ′- 2 ′- oet , o - propargyl , 2 ′- o - butyne , in one or more positions of an rna or dna sequence synthesized by this method . 2 - fluoro - 2 ′- deoxy guanosine nucleoside ( 5 g , 7 . 9 mmol ) was dissolved in freshly prepared 1 , 12 - diaminododecane in meoh ( 79 mmol , 10 : 90 , v / v ). after stirring the reaction mixture at 40 ° c . for 18 hr it was evaporated to dryness and purified by silica gel column chromatography using chcl 3 : triethylamine : meoh ( 95 : 5 : 0 to 91 : 5 : 4 , v / v / v ) to afford the compound 54 ( 5 gr , 79 %) as white solid material r f = 0 . 5 ( chloroform : methanol : tea ; 90 : 05 : 05 ) ms m / z ([ m + h ] + 854 . 2 , calcd 853 . 18 ), ms m / z ( c 48 h 68 n 6 o 6 si ) [ m − h ] − 852 . 4 , calcd 853 . 18 ); 1 h nmr ( dmso , d 6 ) 7 . 91 ( s , 1h ), 7 . 32 - 7031 ( d , 2h ), 7 . 22 - 7 . 15 ( m , 7h ), 6 . 80 - 6 . 74 ( m , 5h ), 6 . 25 - 6 . 22 ( t , 1h ), 4 . 51 ( s , 2h ), 4 . 42 ( s , 1h ), 3 . 94 - 3 . 91 ( q , 1h ), 3 . 71 - 3 . 70 ( d , 6h ), 3 . 28 - 2 . 83 ( m , 13h ), 2 . 42 - 2 . 39 ( q , 1h ), 2 . 29 - 2 . 26 ( q , 1h ), 1 . 46 ( s , 2h ), 1 . 31 - 0 . 91 ( m , 23h ), hplc analysis single peak at 11 . 257 min ( 65 to 98 % acetonitrile in 0 . 1m teaa buffer ) and purity is 98 . 54 %. the compound 54 ( 2 . 5 g , 2 . 93 mmol ) was dissolved in anhydrous n , n ′- dimethylformamide ( 25 ml ) and edc . hcl ( 3 . 1 g , 16 . 11 mmol ) was added to this . after stirring the reaction for 30 min , thioctic acid ( 3 . 02 g , 14 . 65 mmol ) was added at room temperature . after stirring the reaction for 16 h at room temperature , it was evaporated to dryness and purified by silica gel column chromatography ( chcl 3 : hexane : acetone : triethylamine : meoh , 47 : 30 : 20 : 1 : 2 , v / v / v / v / v ) to afford the compound 55 ( 2 . 4 g , 67 %) as white solid material . r f = 0 . 6 ( chcl 3 : hexane : acetone : triethylamine : meoh , 47 : 30 : 20 : 1 : 2 , v / v / v / v / v ); ms m / z c 56 h 80 n 6 o 7 s 2 si ([ m + h ] − 1042 . 2 , calcd 1041 . 18 ) [ m − h ] − 1040 . 3 , calcd 1041 . 18 ); 1 h nmr ( dmso - d6 / d 2 o ) 8 . 23 ( s , 1h ), 7 . 92 ( s , 1h ), 7 . 92 ( s , 1h ), 7 . 73 - 7 . 75 ( t , 1h ), 7 . 28 - 7 . 29 ( t , 2h ), 7 . 13 - 7 . 19 ( m , 7h ), 6 . 71 - 6 . 77 ( dd , 4h ), 6 . 21 - 6 . 23 ( t , 1h ), 4 . 43 - 4 . 49 ( q , 3h ), 3 . 92 - 3 . 93 ( d , 1h ), 3 . 68 - 3 . 69 ( d , 6h ), 3 . 52 - 3 . 56 ( q , 8h ), 2 . 96 - 3 . 16 ( m , 8h ), 2 . 87 ( s , 12h ), 2 . 71 ( s , 11h ), 2 . 26 - 2 . 36 ( m , 1h ), 2 . 01 - 2 . 06 ( m 1h ), 2 . 01 - 2 . 04 ( t , 2h ), 1 . 80 - 1 . 82 ( m 1h ), 1 . 46 - 1 . 48 ( m , 5h ), 1 . 10 - 1 . 48 ( m 23h ). hplc analysis single peak at 6 . 527 min ( 0 to 50 % acetonitrile in 0 . 1m teaa buffer ) and purity is 97 . 21 % dmt - dithiolane coupled nucleoside 55 ( 2 . 4 g , 2 . 3 mmol ) was dried by coevaporation with anhydrous ch 3 cn ( 1 × 25 ml ) and dried over - night on high vacuum pump then dissolved in anhydrous thf ( 25 ml ). to this was added n , n ′- diisopropylethylamine ( 1 . 2 ml , 6 . 9 mmol ) and cooled in an ice cold water bath . after bubbling the argon for 25 min , 2 - cyanoethyl n , n ′-( diisopropyl ) phosphoramidochloridite ( 0 . 565 ml , 2 . 53 mmol ) was added under complete argon atmosphere and the reaction mixture was stirred in ice - cold water bath for 1 h , whereupon it was diluted with etoac ( 100 ml ). the organic phase was washed with saturated aqueous nahco 3 ( 100 ml ), and saturated aqueous nacl ( 100 ml ). the combine aqueous phase was back - extracted with etoac ( 250 ml ). the combined organic phase was evaporated to dryness , and the resulting residue was purified by silica gel column chromatography ( 29 : 70 : 01 heane : etoac : triethylamine , v / v / v ) to afford target amidite 1 ( 1 . 5 g , 66 %) as an colorless oil . r f = 0 . 5 ( etoac : hexane : triethylamine , 70 : 29 : 01 , v / v / v ). ms m / z c 65 h 97 n 8 o 8 ps 2 si ([ m + h ] + 1242 . 3 , calcd 1241 . 58 ). 31p nmr ( cdcl 3 ) 149 . 527 and 149 . 196 ppm . hplc analysis double peak at 14 . 924 and 16 . 271 min ( 0 - 30 % acetoinitrile in 0 . 1m teaa buffer ) and purity is 99 . 33 %.