Department of Developmental BioEngineering, Faculty of Science and Technology, Tech Med Centre, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
Consiglio Nazionale delle Ricerche-Istituto per i Processi Chimico-Fisici, CNR-IPCF, Area della Ricerca di Pisa, Via Moruzzi 1, 56124 Pisa, Italy.
Int J Mol Sci. 2023 Feb 7;24(4):3327. doi: 10.3390/ijms24043327.
Poly(lactide) (PLA) and poly(ethylene glycol) (PEG)-based hydrogels were prepared by mixing phosphate buffer saline (PBS, pH 7.4) solutions of four-arm (PEG-PLA)-R-(PLA-PEG) enantiomerically pure copolymers having the opposite chirality of the poly(lactide) blocks. Dynamic Light Scattering, rheology measurements, and fluorescence spectroscopy suggested that, depending on the nature of the linker R, the gelation process followed rather different mechanisms. In all cases, mixing of equimolar amounts of the enantiomeric copolymers led to micellar aggregates with a stereocomplexed PLA core and a hydrophilic PEG corona. Yet, when R was an aliphatic heptamethylene unit, temperature-dependent reversible gelation was mainly induced by entanglements of PEG chains at concentrations higher than 5 wt.%. When R was a linker containing cationic amine groups, thermo-irreversible hydrogels were promptly generated at concentrations higher than 20 wt.%. In the latter case, stereocomplexation of the PLA blocks randomly distributed in micellar aggregates is proposed as the major determinant of the gelation process.
聚（丙交酯）（PLA）和聚（乙二醇）（PEG）基水凝胶是通过混合磷酸盐缓冲盐水（PBS，pH 7.4）溶液制备的，该溶液含有具有相反手性的 PLA 嵌段的四臂（PEG-PLA）-R-（PLA-PEG）对映纯共聚物。动态光散射、流变学测量和荧光光谱表明，取决于连接子 R 的性质，凝胶化过程遵循不同的机制。在所有情况下，等摩尔量的对映共聚物的混合导致具有立体复合物 PLA 核和亲水性 PEG 冠的胶束聚集。然而，当 R 是脂肪族庚亚甲基单元时，温度依赖性的可逆凝胶化主要是由于高于 5wt.%浓度的 PEG 链缠结引起的。当 R 是含有阳离子胺基团的连接子时，高于 20wt.%浓度时会迅速生成热不可逆水凝胶。在后一种情况下，胶束聚集物中随机分布的 PLA 嵌段的立体复合物被认为是凝胶化过程的主要决定因素。
