Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi 221005, UP, India.
Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi 221005, UP, India.
Int J Biol Macromol. 2020 Dec 1;164:2370-2379. doi: 10.1016/j.ijbiomac.2020.07.279. Epub 2020 Aug 3.
The non-gelatinous and thermo-responsive properties were introduced in chitosan by incorporating the chain of poly(N-isopropylacrylamide) via reversible addition-fragmentation chain transfer (RAFT) polymerization. To achieve this, the reaction was carried out at 80 °C by modifying the chitosan(CS) with RAFT agent as a macroinitiator (CS-RAFT), where the amine group of CS was protected with phthalic anhydride and then reacted with 4-cyano-4-[(dodecyl sulfanyl thiocarbonyl)sulfanyl]-pentanoic acid (CDSTSP) to form CS-RAFT agent. Further, the addition of NIPAAm chains onto CS-RAFT was carried out in N,N'-dimethylformamide (DMF) solvent by using 2,2'-azobisisobutyronitrile (AIBN) as an initiator in N atmosphere. The controlled addition of NIPAAm chains on to CS was confirmed by H NMR spectroscopy, further, a kinetic study was performed to get the characteristic features of the RAFT reaction. The product was characterized by H NMR, FT-IR, UV-Visible spectroscopy, XRD, SEM, and TGA analyses. The product in aqueous solution showed LCST at 2.0 mg/mL on 33 ± 0.1 °C. Further, beads were prepared with the sodium alginate and loaded the water-soluble levofloxacin drug (60% w/w loading was achieved). The drug delivery process was studied in-vitro at 37 ± 0.1 °C & pH 7.4, which shown controlled release of drug up to 32 h and it was 71% of the loaded levofloxacin.
通过可逆加成-断裂链转移（RAFT）聚合将聚（N-异丙基丙烯酰胺）链引入壳聚糖中，从而引入非凝胶和温敏特性。为了实现这一点，在 80°C 下通过用 RAFT 试剂作为大分子引发剂（CS-RAFT）修饰壳聚糖（CS）来进行反应，其中 CS 的氨基被邻苯二甲酸酐保护，然后与 4-氰基-4-[[（十二烷基硫基硫代羰基）硫代]戊酸（CDSTSP）反应形成 CS-RAFT 试剂。此外，在 N 气氛中使用 2,2'-偶氮二异丁腈（AIBN）作为引发剂，在 N,N'-二甲基甲酰胺（DMF）溶剂中，将 NIPAAm 链添加到 CS-RAFT 上。通过 H NMR 光谱证实了 NIPAAm 链对 CS 的受控添加，进一步进行了动力学研究以获得 RAFT 反应的特征。通过 H NMR、FT-IR、UV-可见光谱、XRD、SEM 和 TGA 分析对产物进行了表征。在水溶液中的产物在 33±0.1°C 时表现出 LCST 为 2.0mg/mL。此外，用海藻酸钠制备了珠粒，并负载了水溶性左氧氟沙星药物（达到 60%w/w 的负载量）。在 37±0.1°C 和 pH 7.4 下进行了体外药物输送过程的研究，表明药物可控制释放长达 32 小时，释放的左氧氟沙星达到负载量的 71%。
