In this study,the poly(D-lactide)-block-poly(butylene succinate)-block-poly(D-lactide)(PDLA-b-PBS-b-PDLA)triblock copolymers with a fixed length of PBS and various lengths of PDLA are synthesized,and the crystallizati...In this study,the poly(D-lactide)-block-poly(butylene succinate)-block-poly(D-lactide)(PDLA-b-PBS-b-PDLA)triblock copolymers with a fixed length of PBS and various lengths of PDLA are synthesized,and the crystallization behaviors of the PDLA and PBS blocks are investigated.Although both the crystallization behaviors of PBS and PDLA blocks depend on composition,they exhibit different variations.For the PDLA block,its crystallization behaviors are mainly influenced by temperature and block length.The crystallization signals of PDLA block appear in the B-D 2-2 specimen,and these signals get enhanced with PDLA block length.The crystallization rates tend to decrease with increasing PDLA block lendth during crystallizing at 90 and 100°C.Crystallizing at higher temperature,the crystallization rates increase at first and then decrease with block length.The crystallization rates decrease as elevating the crystallization temperature.The melting temperatures of PDLA blocks increase with block lengths and crystallization temperatures.For the PBS block,its crystallization behaviors are mainly controlled by the nucleation and confinement from PDLA block.The crystallization and melting enthalpies as well as the crystallization and melting temperatures of PBS block reduce as a longer PDLA block has been copolymerized,while the crystallization rates of the PBS block exhibit unique component dependence,and the highest rate is observed in the B-D 2-2 specimen.The Avrami exponent of PBS crystallites is reduced as a longer PDLA block is incorporated or the sample is crystallized at higher temperature.This investigation provides a convenient route to tune the crystallization behavior of PBS and PLA.展开更多
Poly(lactic acid)(PLA)is a biodegradable and eco-friendly polymer that is increasingly being incorporated into various applications in contemporary society.However,the limited stability of PLA-based products remains a...Poly(lactic acid)(PLA)is a biodegradable and eco-friendly polymer that is increasingly being incorporated into various applications in contemporary society.However,the limited stability of PLA-based products remains a significant challenge for their broader use in various applications.In this study,poly(L-lactic acid)(PLLA)/poly(D-lactic acid)(PDLA)melt-blown nonwovens were prepared by melt spinning.The structure,thermal properties,thermal stability,biodegradability and crystalline morphology of the melt-blown nonwovens were investigated.DSC and WAXD confirmed the formation of stereocomplex(SC)crystallites in the PLLA matrix.The storage modulus(G′),loss modulus(G″),and complex viscosity(∣η^(*)∣)of the PLLA/PDLA blend increased with an increase in SC crystallite content.The thermal degradation temperatures of PLLA/PDLA melt-blown nonwovens increased with the incorporation of SC crystallites,and the maximum rate of decomposition increased to 385.5℃,thus enhancing the thermal stability.Compared with neat PLLA melt-blown nonwovens,the hydrophobicity of PLLA/PDLA melt-blown nonwovens was improved,and WCA increased to 139.7°.The SC crystallites were more resistant to degradation by proteinase K compared to neat PLLA.However,the degradation rate of PLLA/PDLA melt-blown nonwovens remained at a high level.This work provides an effective strategy to obtain high-performance PLLA melt-blown nonwovens.展开更多
The strain-induced crystallization behaviors of ultrasonic micro-injection molded poly(L-lactic acid)/poly(D-lactic acid)(PLLA/PDLA)samples from an amorphous state were investigated by stress-strain relations and in s...The strain-induced crystallization behaviors of ultrasonic micro-injection molded poly(L-lactic acid)/poly(D-lactic acid)(PLLA/PDLA)samples from an amorphous state were investigated by stress-strain relations and in situ wide angle X-ray diffraction(WAXD) measurements.The formation of direct strain-induced stereocomplex(SC) was evident.In samples molded at 50 and 80℃,this phenomenon can be attributed to the acceleration of the ordered structures due to the existence of a large number of SC nuclei.The SC nuclei are assumed to serve as the transient physical cross-links to initiate the strain-induced crystallization.The onset of strain-induced crystallization is analogous to the heating induced structural reorganization.Consequently,the observed strain-induced SC process can be considered a pseudo process,which is actually thermally induced.Upon further stretching,the actual strain-induced crystallization occurs with the exclusive formation of the homocrystallite(HC),while the preceding formed SC crystals undergo slight fragmentation during subsequent tensile deformation.At 120 ℃,due to the reduced number of SC nuclei within the sample,the occurrence of cold crystallization during stretching plays a more significant role than SC nuclei with respect to the strain-induced SC process,as demonstrated by in situ WAXD measurements upon annealing in both the static and stretched states.展开更多
Co-delivery of anti-cancer drugs is promising to improve the efficacy of cancer treatment.This study was aiming to investigate the potential of concurrent delivery of resveratrol(RES)and docetaxel(DTX)via polymeric na...Co-delivery of anti-cancer drugs is promising to improve the efficacy of cancer treatment.This study was aiming to investigate the potential of concurrent delivery of resveratrol(RES)and docetaxel(DTX)via polymeric nanocarriers to treat breast cancer.To this end,methoxyl poly(ethylene glycol)-poly(D,L-lactide)copolymer(mPEG-PDLA)was prepared and characterized using FTIR and 1H NMR,and their molecular weights were determined by GPC.Isobologram analysis and combination index calculation were performed to find the optimal ratio between RES and DTX to against human breast adenocarcinoma cell line(MCF-7 cells).Subsequently,RES and DTX were loaded in the mPEG-PDLA micelles simultaneously,and the morphology,particle size distribution,in vitro release,pharmacokinetic profiles,as well as cytotoxicity to the MCF-7 cells were characterized.IC50 of RES and DTX in MCF-7 cells were determined to be 23.0μg/ml and 10.4μg/ml,respectively,while a lower IC50 of 4.8μg/ml of the combination of RES and DTX was obtained.The combination of RES and DTX at a ratio of 1:1(w/w)generated stronger synergistic effect than other ratios in the MCF-7 cells.RES and DTX loaded mPEG-PDLA micelles exhibited prolonged release profiles,and enhanced cytotoxicity in vitro against MCF-7 cells.The AUC(0→t)of DTX and RES in mPEG-PDLA micelles after i.v.administration to rats were 3.0-fold and 1.6-fold higher than that of i.v.injections of the individual drugs.These findings indicated that the co-delivery of RES and DTX using mPEG-PDLA micelles could have better treatment of tumors.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos. 51403089, 51373169, 21574060, and 21374044)the Major Special Projects of Jiangxi Provincial Department of Science and Technology (No. 20114ABF05100)+3 种基金the Project of Jiangxi Provincial Department of Education (No. GJJ170229)the Technology Plan Landing Project of Jiangxi Provincial Department of Education (No. GCJ2011-243)the Outstanding Youth Foundation of Jiangxi Normal University, China Postdoctoral Science Foundation (No. 2019M652282)Postdoctoral Science Foundation of Jiangxi Province (No. 2018KY37)
文摘In this study,the poly(D-lactide)-block-poly(butylene succinate)-block-poly(D-lactide)(PDLA-b-PBS-b-PDLA)triblock copolymers with a fixed length of PBS and various lengths of PDLA are synthesized,and the crystallization behaviors of the PDLA and PBS blocks are investigated.Although both the crystallization behaviors of PBS and PDLA blocks depend on composition,they exhibit different variations.For the PDLA block,its crystallization behaviors are mainly influenced by temperature and block length.The crystallization signals of PDLA block appear in the B-D 2-2 specimen,and these signals get enhanced with PDLA block length.The crystallization rates tend to decrease with increasing PDLA block lendth during crystallizing at 90 and 100°C.Crystallizing at higher temperature,the crystallization rates increase at first and then decrease with block length.The crystallization rates decrease as elevating the crystallization temperature.The melting temperatures of PDLA blocks increase with block lengths and crystallization temperatures.For the PBS block,its crystallization behaviors are mainly controlled by the nucleation and confinement from PDLA block.The crystallization and melting enthalpies as well as the crystallization and melting temperatures of PBS block reduce as a longer PDLA block has been copolymerized,while the crystallization rates of the PBS block exhibit unique component dependence,and the highest rate is observed in the B-D 2-2 specimen.The Avrami exponent of PBS crystallites is reduced as a longer PDLA block is incorporated or the sample is crystallized at higher temperature.This investigation provides a convenient route to tune the crystallization behavior of PBS and PLA.
基金financially supported by the fund of the Science and Technology Development Plan Project of Jilin Province of China(No.20240304161SF)the Science and Technology Development Plan Project of Jilin Province of China(No.20220203019SF)+1 种基金the Science and Technology Bureau of Changchun City of China(Nos.23SH11,23SH08)the Chinese Science Academy(Changchun Branch)(No.2024SYHZ0038).
文摘Poly(lactic acid)(PLA)is a biodegradable and eco-friendly polymer that is increasingly being incorporated into various applications in contemporary society.However,the limited stability of PLA-based products remains a significant challenge for their broader use in various applications.In this study,poly(L-lactic acid)(PLLA)/poly(D-lactic acid)(PDLA)melt-blown nonwovens were prepared by melt spinning.The structure,thermal properties,thermal stability,biodegradability and crystalline morphology of the melt-blown nonwovens were investigated.DSC and WAXD confirmed the formation of stereocomplex(SC)crystallites in the PLLA matrix.The storage modulus(G′),loss modulus(G″),and complex viscosity(∣η^(*)∣)of the PLLA/PDLA blend increased with an increase in SC crystallite content.The thermal degradation temperatures of PLLA/PDLA melt-blown nonwovens increased with the incorporation of SC crystallites,and the maximum rate of decomposition increased to 385.5℃,thus enhancing the thermal stability.Compared with neat PLLA melt-blown nonwovens,the hydrophobicity of PLLA/PDLA melt-blown nonwovens was improved,and WCA increased to 139.7°.The SC crystallites were more resistant to degradation by proteinase K compared to neat PLLA.However,the degradation rate of PLLA/PDLA melt-blown nonwovens remained at a high level.This work provides an effective strategy to obtain high-performance PLLA melt-blown nonwovens.
基金finicially supported by the National Natural Science Foundation of China (No. 52103047)。
文摘The strain-induced crystallization behaviors of ultrasonic micro-injection molded poly(L-lactic acid)/poly(D-lactic acid)(PLLA/PDLA)samples from an amorphous state were investigated by stress-strain relations and in situ wide angle X-ray diffraction(WAXD) measurements.The formation of direct strain-induced stereocomplex(SC) was evident.In samples molded at 50 and 80℃,this phenomenon can be attributed to the acceleration of the ordered structures due to the existence of a large number of SC nuclei.The SC nuclei are assumed to serve as the transient physical cross-links to initiate the strain-induced crystallization.The onset of strain-induced crystallization is analogous to the heating induced structural reorganization.Consequently,the observed strain-induced SC process can be considered a pseudo process,which is actually thermally induced.Upon further stretching,the actual strain-induced crystallization occurs with the exclusive formation of the homocrystallite(HC),while the preceding formed SC crystals undergo slight fragmentation during subsequent tensile deformation.At 120 ℃,due to the reduced number of SC nuclei within the sample,the occurrence of cold crystallization during stretching plays a more significant role than SC nuclei with respect to the strain-induced SC process,as demonstrated by in situ WAXD measurements upon annealing in both the static and stretched states.
基金the Liaoning Province Pan Deng Xue Zhe Grant(M.Yang)Liaoning Provincial Education officer’s Excellent Talents Supporting Plan(D.Cun)National Natural Science Foundation of China(No.81302720 and 81573380)for financial support。
文摘Co-delivery of anti-cancer drugs is promising to improve the efficacy of cancer treatment.This study was aiming to investigate the potential of concurrent delivery of resveratrol(RES)and docetaxel(DTX)via polymeric nanocarriers to treat breast cancer.To this end,methoxyl poly(ethylene glycol)-poly(D,L-lactide)copolymer(mPEG-PDLA)was prepared and characterized using FTIR and 1H NMR,and their molecular weights were determined by GPC.Isobologram analysis and combination index calculation were performed to find the optimal ratio between RES and DTX to against human breast adenocarcinoma cell line(MCF-7 cells).Subsequently,RES and DTX were loaded in the mPEG-PDLA micelles simultaneously,and the morphology,particle size distribution,in vitro release,pharmacokinetic profiles,as well as cytotoxicity to the MCF-7 cells were characterized.IC50 of RES and DTX in MCF-7 cells were determined to be 23.0μg/ml and 10.4μg/ml,respectively,while a lower IC50 of 4.8μg/ml of the combination of RES and DTX was obtained.The combination of RES and DTX at a ratio of 1:1(w/w)generated stronger synergistic effect than other ratios in the MCF-7 cells.RES and DTX loaded mPEG-PDLA micelles exhibited prolonged release profiles,and enhanced cytotoxicity in vitro against MCF-7 cells.The AUC(0→t)of DTX and RES in mPEG-PDLA micelles after i.v.administration to rats were 3.0-fold and 1.6-fold higher than that of i.v.injections of the individual drugs.These findings indicated that the co-delivery of RES and DTX using mPEG-PDLA micelles could have better treatment of tumors.
