Thermoresponsive phospholipid–poly(N-isopropylacrylamide) (PL-PNIPAM) conjugates were synthesized via reversible addition fragmentation chain transfer polymerization mediated by a phospholipid-modified trithiocarbonate. Temperature triggered the micellization of the PL-PNIPAM conjugate to form phosphate group-decorated micelles in the aqueous solution. Driven by the chelation of phospholipids and Ca²⁺, the PL-PNIPAM conjugate and Ca²⁺ ions formed size-tunable nanoclusters at a temperature beyond the lower critical solution temperature. To fabricate cross-linked nanogels, NIPAM was copolymerized with N-succinimidyl acrylate (NSA) to obtain the PL-P(NIPAM-co-NSA) conjugate bearing pendent cross-linkable functionalities. Subsequently, the size-controllable nanogels containing disulfide linkages were generated at 37 °C by cross-linking the PL-P(NIPAM-co-NSA)/Ca²⁺ nanoclusters with cystamine through modulation of Ca²⁺ concentrations. These negatively charged nanogels demonstrate temperature/pH/reduction triple responsiveness. The nanogels can be efficiently loaded with doxorubicin (DOX) and proteins with various isoelectric points. The DOX-loaded nanogels exhibited a temperature/pH/reduction triple-responsive release profile. The immobilized RNase A, BSA, and GOx retained the protein bioactivity. The release of RNase A-loaded nanogels possesses a temperature-responsive profile. The immobilization of Lys and cytochrome C in nanogels inhibited protein bioactivity. However, the addition of NaCl triggered the recovery of bioactivity. These multistimuli-responsive nanogels can provide a versatile platform applicable in biotechnology and drug/protein delivery.

中文翻译：

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Ca2+-螯合诱导的磷脂-聚合物偶联物多刺激响应带电纳米凝胶的制备及其用于药物/蛋白质负载的应用

通过由磷脂修饰的三硫代碳酸酯介导的可逆加成断裂链转移聚合合成热响应性磷脂-聚（N-异丙基丙烯酰胺）（PL-PNIPAM）共轭物。温度触发了 PL-PNIPAM 偶联物的胶束化，从而在水溶液中形成磷酸基修饰的胶束。^{在磷脂和 Ca 2+}螯合的驱动下，PL-PNIPAM 共轭物和 Ca ²⁺离子在超过较低临界溶液温度的温度下形成尺寸可调的纳米团簇。为了制备交联纳米凝胶，NIPAM 与丙烯酸 N-琥珀酰亚胺酯 (NSA) 共聚以获得 PL-P(NIPAM- co-NSA) 缀合物具有悬垂的可交联功能。随后，通过调节 Ca ^{2+使 PL-P(NIPAM-} co - NSA)/Ca ²⁺纳米团簇与胱胺交联，在 37 °C 生成了尺寸可控的含有二硫键的纳米凝胶。浓度。这些带负电荷的纳米凝胶表现出温度/pH/还原三重响应性。纳米凝胶可以有效地装载多柔比星 (DOX) 和具有各种等电点的蛋白质。负载 DOX 的纳米凝胶表现出温度/pH/还原三重响应释放曲线。固定化的 RNase A、BSA 和 GOx 保留了蛋白质的生物活性。载有 RNase A 的纳米凝胶的释放具有温度响应特性。Lys 和细胞色素 C 在纳米凝胶中的固定抑制了蛋白质的生物活性。然而，氯化钠的添加引发了生物活性的恢复。这些多刺激响应纳米凝胶可以提供适用于生物技术和药物/蛋白质递送的多功能平台。