While deployment of intracoronary stents has been shown to reduce restenosis, stenting can also damage the endothelial monolayer lining the vessel wall, leading to possible in-stent thrombosis. Local drug delivery fro...While deployment of intracoronary stents has been shown to reduce restenosis, stenting can also damage the endothelial monolayer lining the vessel wall, leading to possible in-stent thrombosis. Local drug delivery from stent surfaces represents a means of delivering therapeutic doses of drug directly to the target site. The aim of this study was to elute fluvastatin, which can inhibit vascular smooth muscle cell proliferation, and xemilofiban, which prevents platelet adhesion and aggregation, together in bioactive concentrations from the same copolymer system. Combined elution from thermoresponsive N-isopropylacrylamide (NiPAAm)/N-tert-butylacrylamide (NtBAAm)-derived copolymer systems was achieved using microgels (NiPAAm/NtBAAm 65/35 wt/wt) randomly dispersed in 85/15 matrices. Fluvastatin elution from 5 mm films over a 14-day period showed initial burst release, which leveled off. Of the total incorporated (8.33 ± 0.21 nmol, n=4), 68.5 % was eluted during this period. Xemilofiban release was measured in terms of its ability to inhibit platelet adhesion, using a microfluidic system. To investigate the influence of location and hydrophobicity on elution of bioactivity, three separate systems were employed. While elution of anti-adhesive activity from the system containing xemilofiban-loaded matrices was more dramatic in the short term, a more sustained level of inhibition was achieved when xemilofiban had been incorporated into microgels. All samples investigated for anti-adhesive activity also decreased human coronary artery smooth muscle cell proliferation. Therefore xemilofiban has potential as an agent for preventing in-stent thrombosis. Our study has demonstrated the feasibility of using this novel matrix/microgel system to regulate simultaneous release of both agents in bioactive concentrations.展开更多
Thermosensetive poly(N-isopropylacrylamide)-based magnetic nanoparticles were synthesized by free radical polymerization of N-isopropylacrylamide (NIPPAMs), methacrylic acid (MAA), and vinyl pyrrolidone (VP) in the pr...Thermosensetive poly(N-isopropylacrylamide)-based magnetic nanoparticles were synthesized by free radical polymerization of N-isopropylacrylamide (NIPPAMs), methacrylic acid (MAA), and vinyl pyrrolidone (VP) in the presence of methylene-bis-acrylamide as cross linking agent. The Fe3O4 magnetic nanoparticls were prepared by chemical precipitation of Fe salts in the ratio of 1:2 under alkaline and inert condition. Thermosensitive crosslinked P (NI-PAAM-MAA-VP) copolymers were characterized by FT-IR and H-NMR. The pH and thermosensitive copolymer was used for preparation of drug loaded magnetic nanoparticles, and doxorubicin (DOX) was used as a typical anticancer drug. The amount of the loaded drug and drug release amount were determined by UV measurements. Scanning electron microscopy (SEM) and lower critical solution temperature (LCST) were used to determine the particle surface morphology and the phase transition temperature of the nanoparticles respectively. The release behavior of DOX at pH = 7.4 and 37°C was studied. The result indicated that this thermosensetive magnetic nanoparticle has a high drug loading capacity and favorable linear release property for DOX without initial burst release. Thus this system is promising for the application in targeted smart anticancer drug delivery.展开更多
以聚偏氟乙烯(PVDF)为基材,分别采用直接引发原子转移自由基聚合(ATRP)和碱处理后自由基聚合的方法接枝N-异丙基丙烯酰胺(NIPAAm),合成出不同接枝率的PVDF-g-PNIPAAm共聚物,然后用相转化法制备出PVDF-g-PNIPAAm共聚温敏膜。用核磁共振(1...以聚偏氟乙烯(PVDF)为基材,分别采用直接引发原子转移自由基聚合(ATRP)和碱处理后自由基聚合的方法接枝N-异丙基丙烯酰胺(NIPAAm),合成出不同接枝率的PVDF-g-PNIPAAm共聚物,然后用相转化法制备出PVDF-g-PNIPAAm共聚温敏膜。用核磁共振(1 H NMR)和X射线光电子能谱(XPS)分别对共聚物和共聚膜的化学组成进行了表征,用压汞仪测试了膜的孔结构。结果表明,与ATRP法相比,碱处理法能得到更高接枝率的产物。通过不同温度下牛血清蛋白(BSA)截留率研究膜的温度敏感行为,发现共聚膜的温敏行为受PNIPAAm接枝率影响,AT-RP法和碱处理法制备的共聚膜的温敏行为相反。展开更多
A kind of novel copolymer hydrogel of poly（N, N-dimethylaminoethyl methacrylate-co-N-isopropylacrylamide） （poly[DMAEMA/NIPAAm]） was synthesized by the initiation of K2S2O8, N, N＇-methylene-bis（acrylamide） （Bis...A kind of novel copolymer hydrogel of poly（N, N-dimethylaminoethyl methacrylate-co-N-isopropylacrylamide） （poly[DMAEMA/NIPAAm]） was synthesized by the initiation of K2S2O8, N, N＇-methylene-bis（acrylamide） （Bis） was used as the crosslinker. The effects of monomer content, pH and temperature on swelling ratio of the hydrogel were investigated; the thermo-sensitivity in deionized water and in physiological saline was determined. It showed that the swelling ratio of the hydrogel could be changed by changing the temperature or pH alternately. Both swelling ratio and LCST （Lower Critical Solution Temperature） of the hydrogel decreased with the increase of NIPAAm in the co-polymer content.展开更多
In this paper, a kind of thermally linear polymer, poly N isopropylacrylamide(PNIPA) was packed into capillary electrophoresis, which can be used to separate bound and free estradiol antigen. A useful method for deter...In this paper, a kind of thermally linear polymer, poly N isopropylacrylamide(PNIPA) was packed into capillary electrophoresis, which can be used to separate bound and free estradiol antigen. A useful method for determination of estradiol in serum by hydrogel capillary electrophoretic immunoassay(CEIA) was developed. The influence of concentration and pH of buffer, concentration of hydrogel, applied voltage, temperature etc has been studied. The limit of detection and the linear range of estrodiol were 30 pg/mL and 0 1—10 ng/mL. [WT5HZ]展开更多
文摘While deployment of intracoronary stents has been shown to reduce restenosis, stenting can also damage the endothelial monolayer lining the vessel wall, leading to possible in-stent thrombosis. Local drug delivery from stent surfaces represents a means of delivering therapeutic doses of drug directly to the target site. The aim of this study was to elute fluvastatin, which can inhibit vascular smooth muscle cell proliferation, and xemilofiban, which prevents platelet adhesion and aggregation, together in bioactive concentrations from the same copolymer system. Combined elution from thermoresponsive N-isopropylacrylamide (NiPAAm)/N-tert-butylacrylamide (NtBAAm)-derived copolymer systems was achieved using microgels (NiPAAm/NtBAAm 65/35 wt/wt) randomly dispersed in 85/15 matrices. Fluvastatin elution from 5 mm films over a 14-day period showed initial burst release, which leveled off. Of the total incorporated (8.33 ± 0.21 nmol, n=4), 68.5 % was eluted during this period. Xemilofiban release was measured in terms of its ability to inhibit platelet adhesion, using a microfluidic system. To investigate the influence of location and hydrophobicity on elution of bioactivity, three separate systems were employed. While elution of anti-adhesive activity from the system containing xemilofiban-loaded matrices was more dramatic in the short term, a more sustained level of inhibition was achieved when xemilofiban had been incorporated into microgels. All samples investigated for anti-adhesive activity also decreased human coronary artery smooth muscle cell proliferation. Therefore xemilofiban has potential as an agent for preventing in-stent thrombosis. Our study has demonstrated the feasibility of using this novel matrix/microgel system to regulate simultaneous release of both agents in bioactive concentrations.
文摘Thermosensetive poly(N-isopropylacrylamide)-based magnetic nanoparticles were synthesized by free radical polymerization of N-isopropylacrylamide (NIPPAMs), methacrylic acid (MAA), and vinyl pyrrolidone (VP) in the presence of methylene-bis-acrylamide as cross linking agent. The Fe3O4 magnetic nanoparticls were prepared by chemical precipitation of Fe salts in the ratio of 1:2 under alkaline and inert condition. Thermosensitive crosslinked P (NI-PAAM-MAA-VP) copolymers were characterized by FT-IR and H-NMR. The pH and thermosensitive copolymer was used for preparation of drug loaded magnetic nanoparticles, and doxorubicin (DOX) was used as a typical anticancer drug. The amount of the loaded drug and drug release amount were determined by UV measurements. Scanning electron microscopy (SEM) and lower critical solution temperature (LCST) were used to determine the particle surface morphology and the phase transition temperature of the nanoparticles respectively. The release behavior of DOX at pH = 7.4 and 37°C was studied. The result indicated that this thermosensetive magnetic nanoparticle has a high drug loading capacity and favorable linear release property for DOX without initial burst release. Thus this system is promising for the application in targeted smart anticancer drug delivery.
文摘以聚偏氟乙烯(PVDF)为基材,分别采用直接引发原子转移自由基聚合(ATRP)和碱处理后自由基聚合的方法接枝N-异丙基丙烯酰胺(NIPAAm),合成出不同接枝率的PVDF-g-PNIPAAm共聚物,然后用相转化法制备出PVDF-g-PNIPAAm共聚温敏膜。用核磁共振(1 H NMR)和X射线光电子能谱(XPS)分别对共聚物和共聚膜的化学组成进行了表征,用压汞仪测试了膜的孔结构。结果表明,与ATRP法相比,碱处理法能得到更高接枝率的产物。通过不同温度下牛血清蛋白(BSA)截留率研究膜的温度敏感行为,发现共聚膜的温敏行为受PNIPAAm接枝率影响,AT-RP法和碱处理法制备的共聚膜的温敏行为相反。
文摘A kind of novel copolymer hydrogel of poly（N, N-dimethylaminoethyl methacrylate-co-N-isopropylacrylamide） （poly[DMAEMA/NIPAAm]） was synthesized by the initiation of K2S2O8, N, N＇-methylene-bis（acrylamide） （Bis） was used as the crosslinker. The effects of monomer content, pH and temperature on swelling ratio of the hydrogel were investigated; the thermo-sensitivity in deionized water and in physiological saline was determined. It showed that the swelling ratio of the hydrogel could be changed by changing the temperature or pH alternately. Both swelling ratio and LCST （Lower Critical Solution Temperature） of the hydrogel decreased with the increase of NIPAAm in the co-polymer content.
文摘In this paper, a kind of thermally linear polymer, poly N isopropylacrylamide(PNIPA) was packed into capillary electrophoresis, which can be used to separate bound and free estradiol antigen. A useful method for determination of estradiol in serum by hydrogel capillary electrophoretic immunoassay(CEIA) was developed. The influence of concentration and pH of buffer, concentration of hydrogel, applied voltage, temperature etc has been studied. The limit of detection and the linear range of estrodiol were 30 pg/mL and 0 1—10 ng/mL. [WT5HZ]
