Blood Compatibility of Amphiphilic Poly(N-α-acrylamide-L-lysine-<i>b</i>-dimethylsiloxane) Block Copolymers

Amphiphilic block copolymers poly(LysAA-b-DMS) consisting of a hydrophilic poly(N-α-acrylamide-L-lysine) [poly(LysAA)] segment with different molecular weights and a hydrophobic polydimethylsiloxane (PDMS) segment were prepared as follows. The precursor copolymer poly(Boc-LysAA-OtBu-b-PDMS) was obtained from radical polymerization of N-α-acrylamide-N-ε-tert-butoxycarbonyl-L-lysine-tert-butylester (Boc-LysAA-OtBu) initiated with 4,4’-azobis(polydimethylsiloxane 4-cyanopentanoate) (azo-PDMS) with the molecular weight of PDMS Mw = 4.3 × 103 in the presence of 2-mercaptoethanol (2-ME) as a chain-transfer agent. Removal of the protecting groups of the precursor copolymer was carried out in 80% trifluoroacetic acid aqueous solution to give poly(LysAA-b-DMS)-1-3. The weight average molecular weight of poly(LysAA-b-DMS)-1-3 was Mw = 1.02 × 104 – 2.52 × 104. From the 1H-NMR and fluorescence spectra measurements, poly(LysAA-b-DMS)-1-3 was determined to self-organize and form core-shell micelles in water. The critical micelle concentration (CMC) increased to 1000 - 4000 mg·L–1 with increasing molar ratio of the poly(LysAA) segment from 0.42 to 0.65. From morphological analysis with a scanning probe microscope (SPM), poly(LysAA-b-DMS) has microphase-separated structures made up of hydrophilic and hydrophobic regions with the domain size ranging from several tens to several hundreds of nanometers. Inhibition of thrombin activity of poly(LysAA-b-DMS) was evaluated from the Michaelis constant (KM) and catalytic activity (kcat) for the enzymatic reaction of thrombin and synthetic substrate S-2238 in the presence of poly(LysAA-b-DMS). The KM and kcat were 0.10 - 0.11 mM and 4.04 × 105 – 4.26 × 105 min–1, respectively. Fibrinolytic activity was also verified from the transformation of plasminogen to plasmin by tissue plasminogen activator (t-PA) using synthetic substrate S-2251 in the presence of poly(LysAA-b-DMS). The KM and kcat were 0.07 mM and 5.73 × 106 –5.95 × 106 min–1, respectively.

含环糊精的聚乙烯亚胺-g-聚(N-异丙基丙烯酰胺)的合成与表征

以支化聚乙烯亚胺(BPEI)为骨架,将β-环糊精(β-CD)和聚(N-异丙基丙烯酰胺)(PNIPAm)引入到BPEI上,合成出了接枝共聚物(BPEI-CD)-g-PNIPAm。用FTIR、SEC/MALLS和1H NMR进行了表征。结果表明,聚合物具有温度敏感性和超分子包合性能。

Comb-like Poly(N-(2-hydroxypropyl) methacrylamide) Doxorubicin Conjugates: The Influence of Polymer Architecture and Composition on the Biological Properties

The synthesis and structure-property correlation of poly（N-（2-hydroxypropyl） methacrylamide） （PHPMA） conjugates with various architectures including random, block, branched or star-like structures and compositions have been thoroughly explored. However, related synthesis and structure-property data are still lacking for comb-like PHPMA. In this work, we report the synthesis of comb-like PHPMA copolymer-doxorubicin （DOX） conjugates with different backbone/side-chain lengths and location of drug moieties. Well-defined comb-like PHPMA-DOX conjugates are obtained via the combination of controlled radical polymerization and fractional precipitation techniques. The influences of structural factors on the biological properties such as cellular uptake, blood circulation and tumor accumulation have been investigated. Long blood circulation and efficient tumor accumulation can be achieved by proper control of the comb number, length and location of drug moieties. These facile comb-like structures possess great potentials in future theranostics for brachytherapy or surgical navigation.

Electrosynthesis of Chirality Conducting Poly[N-（9-fluorenylmethoxycarbonyl）-L-phenylalanine] with Good Blue Light-Emitting Properties

Poly[N-（9-fluorenylmethoxycarbonyl）-L-phenylalanine] （PN9FPA） films with good fluorescence properties and chirality were prepared electrochemically by direct anodic oxidation of N-（9-fluorenylmethoxycarbonyl）- L-phenylalanine （N9FPA） in boron trifluoride diethyletherate （BFEE）. Fourier transform infrared spectroscopy measurement showed that the polymerization of N9FPA occurred mainly at the C（2） and C（7） positions. The fluo- rescence spectra indicated that PN9FPA films were blue-light emitters. In addition, the structures and properties of the monomer and the polymers were characterized and evaluated with CV, UV, TGA and SEM.

In vitro Studies on Binding and Release of Vascular Endothelial Growth Factor in Heparinized Bovine Pericardiums

Objective： To investigate binding and release of vascular endothelial growth factor （VEGF） and its effect on adhesion and proliferation of endothelial cells （ECs） in acellular fresh specimens of bovine pericardiums, which were modified by heparinization. Methods： Cross-linked aeellular fresh specimens of bovine perieardiums were heparinized by three methods： （1） heparinizcd N-（3-diinethylaminopropyl）-N＇-ethylcarbodiimide hydrochloride （EDC） treated acellular tissue samples; （2） heparinized poly（ethyleneimine） （PEI） treated acellular tissue samples; （3） heparinized EDC-PEI treated aeellular tissue samples. Controlled release of VEGF and its effect on adhesion and proliferation of ECs was evaluated. Results： In the present study, binding and release of VEGF had better performance in heparinized EDC-PEI treated group, compared with heparinized EDC-alone treated group and heparinized PEI -alone group. We could observe enhanced ability to adhesion and proliferation via modest moisture and effective controlled binding and release of VEGF. Conclusion： Binding of VEGF in heparinized EDC treated group was stable, while reiease of VEGF in heparinized treated group was adjusted freely. Interestingly, controlled binding and release of VEGF could exert beneficial effect on adhesion and proliferation of ECs in heparinized EDC-PEI treated group.