based on the ideas of the invention described above , tam can be also applied for targeted prodrug design . tam can be directly conjugated to conventional drugs and guiding drugs to estrogen receptor over - expressed cells . in addition , there is no limitation for the active ingredients used here in the present invention . the preferable active ingredients are compounds , nucleic acids , proteins , peptides , deoxyribonucleotides , ribonucleotides , oligonucleotides , imaging agents , fluorescent dyes or the combination thereof . the preferable moiety capable of binding estrogen receptor is compound of formula ( ii ): the synthetic scheme of tam derivative is shown in fig1 . first , clomifene is reacted with tbuli and 2 -( 2 - bromoethyl ) dioxolane to form dioxolane - tamoxifen . then , dioxolane - tamoxifen is oxidized with 10 % oxalic acid to form aldotamoxifen . the synthesized aldotamoxifen is reacted with dspe - peg - amine in the presence of nabh 4 to form a product tam - peg - dspe of formula ( ii ): liposomes are prepared by thin film hydration method . the formula of the liposomes is indicated in table 1 . briefly , lipids ( 20 mg ) mixtures are dissolved in ethanol and evaporated to dryness under a stream of nitrogen gas . then the lipid film is hydrated with 10 % sucrose solution at 60 ° c . followed by sonication for particle size reduction . the particle sizes are determined by laser particle analyzer , and the properties of the liposomes prepared here are shown in table 1 . mcf - 7 ( receptor positive breast cancer cells ) and zr - 75 - 1 ( receptor positive breast cancer cells ) cells are seeded in 8 - well chamber slides with 5 × 10 4 cells per well 16 hr before further experiments hereafter . after overnight incubation , cells are respectively treated with various concentrations of dii containing control liposomes or tam - liposomes for 2 hours at 37 ° c ., and then washed with pbs for three times . subsequently , cells are fixed with 4 % paraformaldehyde in pbs for 15 minutes at 4 ° c . finally , cells are washed with pbs several times and are observed with the fluorescent microscopy . as a result , the fluorescence intensity of cells treated with tam - liposomes is significantly stronger than that of the cells treated with control liposomes . it indicates that tam - liposomes could enter those two er over - expressed cells much more efficiently . mcf - 7 and zr - 75 - 1 cells are seeded in 24 - well plates with 5 × 10 4 cells per well 16 hr before further experiment here . after overnight incubation , cells are respectively treated with various concentrations of dii containing control liposomes or tam - liposomes for 4 hours at 37 ° c ., and then washed with ice - cold pbs for one time . subsequently , cells are incubated with 1 % triton x - 100 in pbs for 1 hour at 37 ° c . for cell lysis . the cell lysates are taken out and the fluorescence intensity of these samples are analyzed with a fluorescence spectrometer . the result is shown in fig2 . the curves in fig2 show that the delivery efficiency of tam - liposomes is 3 - 5 times higher than that of control liposomes for those two er over - expressed cells . mcf - 7 cells are seeded in 24 - well plates with 5 × 10 4 cells per well 16 hr before the experiment . the experiment is performed after overnight incubation . two hours before further treatment here , medium of the competitive group is replaced with medium containing 100 μm estradiol ( ed ). two hours latter , cells are respectively treated with dii containing control liposomes or tam - liposomes in a concentration of 500 mole of total lipids for 4 hours at 37 ° c . in the presence or absence of 100 μm estradiol ( ed ), and then washed with ice - cooled pbs for one time . subsequently , the cells are incubated with 1 % triton x - 100 in pbs for 1 hour at 37 ° c . for cell lysis . the cell lysates are taken out and the fluorescence intensity of these samples are measured by a fluorescence spectrometer . the result is shown in fig3 . in the absence of ed , the delivery efficiency of tam - liposomes is 2 times higher than that of control liposomes for er over - expressed cells . however , in the presence of ed , there is no difference in delivery efficiency between tam - liposomes and control liposomes . there is no difference between the delivery efficiencies of control liposomes in the presence or absence of ed . as a result , tamoxifen is capable of targeting to er , guiding the liposomes to er over - expressed cells , and thus increasing the delivery efficiency . liposomes are prepared by thin film hydration method . tam - liposomes are prepared according to the ratio : dspg / dope / tam - peg - dspe = 49 / 49 / 2 ( mole ratio ). control liposomes are prepared according to the ratio : dspg / dope / dspe - peg = 49 / 49 / 2 ( mole ratio ). np can be obtained by mixing equal volume of the following solutions : fitc labeled oligonucleotide ( f - odn ) and calf thymus dna solution ( 0 . 1 mg / ml ), 1 . 1 mg / ml charged peptide or polymer ( such as polylysine , protamine ) solution , and 0 . 3 mg / ml liposome suspension . then the np solution is kept at room temperature for 10 minutes before use . the particle size of np is ranging between 150 to 200 nm , and the encapsulation efficiency for odn is 100 %. mcf - 7 cells are seeded in 8 - well chamber slides with 2 × 10 4 cells per well 16 hr before further experiment here . after overnight incubation , cells are treated with p - odn containing control np or tam - np for 4 hours at 37 ° c ., and then washed with pbs for three times . subsequently , cells are fixed with meoh for 1 minute and observed under a fluorescence microscope . as a result , the fluorescence intensity of cells treated with tam - np is significantly higher than that of the cells treated with control np . it is indicated that tam - np could deliver more odn into er over - expressed cells . mcf - 7 and huvec ( human umbilical vein epithelia cell ; receptor positive cells ) cells are seeded in 24 - well plates with 5 × 10 4 cells per well 16 hr before the experiment hereafter . after overnight incubation , cells are treated with various concentrations of f - odn containing control np or tam - np for 4 hours at 37 ° c ., and then washed with ice - cold pbs for one time . subsequently , the cells are incubated with 1 % triton x - 100 in pbs for 1 hour at 37 ° c . for cell lysis . the cell lysates are taken out and the fluorescence intensities are analyzed with a fluorescence spectrometer . the result is shown in fig4 . the curves in fig4 indicate that the delivery efficiency of tam - np is 2 times higher than that of control np for er over - expressed cells . mcf - 7 and hs 578t ( human breast cancer cell line ; receptor negative cells ) cells are seeded in 24 - well plates with 5 × 10 4 cells per well 16 hr before the experiment hereafter . the experiment is performed after overnight incubation . two hours before treatment , medium of the competitive group is replaced 100 μm estradiol ( ed ) containing medium . two hours later , cells are respectively treated with f - odn containing control np and tam - np for 4 hours at 37 ° c . in the presence or absence of 100 μm ed , and then washed with ice - cold pbs for one time . subsequently , the cells are incubated with 1 % triton x - 100 in pbs for 1 hour at 37 ° c . for cell lysis . the cell lysates are taken out and the fluorescence intensity of these samples are analyzed with a fluorescence spectrometer . the result is shown in fig5 . in the absence of ed , the delivery efficiency of tam - np is 2 times higher than that of control np for er over - expressed cells . however , in the presence of ed , the delivery efficiency of tam - np is inhibited to the same level as control np . there is no difference between the delivery efficiencies of control np and tam - np for the er negative cells . as a result , tamoxifen is capable of specifically targeting to er , guiding the np to er over - expressed cells , and thus increasing the delivery efficiency . similar to the method mentioned above , potential asntisense oligonucleotide ( as - odn ) are formulated into np for the ex vivo experiment . the as - odn applied here is isis g3139 ( against bcl - 2 ). mcf - 7 cells are seeded in 24 - well plates with 5 × 10 4 cells in each well 16 hr before further performing of the experiment here . after overnight incubation , cells are respectively treated with free as - odn , as - odn containing np or tam - np for 4 hours at 37 ° c . the media are replaced with fresh media followed by incubation for another 72 hours . then the survival cells are counted by trypan blue exclusion method . the result is shown in fig6 . according to the blocks shown in fig6 , tam - np could inhibit 90 % of cell growth . np alone inhibits 65 % of cell growth . no inhibitory effect of free as - odn is observed . it indicates that tam - np could deliver more as - odn into er over - expressed cells and exert stronger killing effect . according to the embodiment illustrated above , the nanoparticles of the present invention certainly are capable of targeting the estrogen receptor over - expressed cells . moreover , the nanoparticles of the present invention , which containing active ingredients can efficiently enter the cells through estrogen receptor - mediated endocytosis . although the present invention has been explained in relation to its preferred embodiment , it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed .
a vector for targeted delivery of drugs into estrogen receptors over - expressed cells is disclosed . the vector of the present invention is mainly about an active targeting delivery carrier which consists of a plurality of nanoparticles including : a plurality of targeted moiety conjugated to the outer surface of the nanoparticles , the moiety being capable of binding with the estrogen receptor of a target cell , and bioactive agents encapsulated in the nanoparticles or forming complex with the nanoparticles . the targeted moiety of the present invention can also be conjugated to parent drugs for prodrug design .