Istanbul Technical University, Department of Chemistry, Soft Materials Research Laboratory, 34469 Maslak, Istanbul, Turkey; Present Address: Max Planck Institute of Colloids and Interfaces, Potsdam, Brandenburg, Germany.
Istanbul Technical University, Department of Chemistry, Soft Materials Research Laboratory, 34469 Maslak, Istanbul, Turkey.
Int J Biol Macromol. 2023 Dec 31;253(Pt 8):127483. doi: 10.1016/j.ijbiomac.2023.127483. Epub 2023 Oct 19.
Optimization of the synthesis of polymer microspheres and millimeter-sized gel beads has gained importance due to efficiency and design advantages in applications. A systematic study is presented to allow for a molecular-based understanding of elasticity of crosslinked-chitosan (CS) beads. Unique results were obtained examining the effect of polymerization temperature and gel-preparation form on physico-mechanical properties of CS-incorporated poly (N-isopropylacrylamide‑sodium acrylate)/polyacrylamide, PNIPA/PAAm-CS, beads. ATR-FTIR, and thermogravimetric analysis results confirmed the successful preparation and enhanced thermal stability of CS-based gel beads in the form of semi-IPN. The structural changes of semi-IPN gels were studied based on powder X-ray diffraction analysis. After being incorporated with CS, the cryopolymerization was carried out under cryo-conditions, and PNIPA/PAAm structure became much more resistant to mechanical load. Addition of CS to semi-IPN structure caused a 2-fold increase in compressive elastic modulus, while the gel preparation under cryoconditions also improved the mechanical properties considerably by lowering the polymerization temperature. The scaling parameter calculations estimated by Hertz model for PNIPA/PAAm-CS semi-IPN cryobeads are related to displacement of compression force with an exponent of 1.63 ± 0.19. As cryobead diameter increased, swelling degree tendency increased, while a decrease in modulus was observed with increasing swelling. The presence of CS in semi-IPNs improved pH-response in an acidic environment, but stiffness of CS reduced the shrinkage ability of cryobeads upon increasing swelling temperature. Based on the interaction between semi-IPN structure and salt solutions, an improvement in elastic modulus was observed in various ammonium salts and sodium tripolyphosphate solution. On-off switching of cryobeads was a reversible process that was consistent with changes in ammonium salt concentration. Qualitative comparisons with experimental results showed that the prepared cryobeads can be designed as drug release carriers by ionic strength-switching modulation.
由于在应用中具有效率和设计优势，聚合物微球和毫米级凝胶珠的合成优化得到了重视。本文系统地研究了交联壳聚糖 (CS) 珠弹性的分子基础。通过研究聚合温度和凝胶制备形式对 CS 掺入的聚（N-异丙基丙烯酰胺-丙烯酸钠）/聚丙烯酰胺，PNIPA/PAAm-CS 珠的物理力学性能的影响，得到了独特的结果。ATR-FTIR 和热重分析结果证实了 CS 基凝胶珠的成功制备和增强的热稳定性，其形式为半互穿网络 (semi-IPN)。通过粉末 X 射线衍射分析研究了半互穿网络凝胶的结构变化。在与 CS 结合后，在低温条件下进行低温聚合，PNIPA/PAAm 结构对机械载荷的抵抗力大大提高。在半互穿网络结构中加入 CS 会使压缩弹性模量增加一倍，而在低温条件下进行凝胶制备也会大大提高机械性能，降低聚合温度。Hertz 模型估算的半互穿网络冷冻珠 PNIPA/PAAm-CS 的标度参数与压缩力的位移有关，指数为 1.63±0.19。随着冷冻珠直径的增加，溶胀度趋势增加，而随着溶胀的增加，模量降低。半互穿网络中 CS 的存在改善了酸性环境中的 pH 响应，但 CS 的刚性降低了冷冻珠在增加溶胀温度时的收缩能力。基于半互穿网络结构与盐溶液之间的相互作用，观察到在各种铵盐和三聚磷酸钠溶液中弹性模量的提高。冷冻珠的开/关切换是一个可逆过程，与铵盐浓度的变化一致。与实验结果的定性比较表明，所制备的冷冻珠可以通过离子强度切换调制设计为药物释放载体。
