Poly (acrylic acid) (PAA), an anionic polymer was used to prepare ion pair self-assembly (IPSAM) with 4-(methylthio)aniline (MTA), a hydrophobic counter ion, which is responsive to temperature and oxidation. The IPSAM was formed when the carboxylic to amino group molar ratio was 7/3-5/5. The structure of the IPSAM nanoparticle was spherical whose diameter was 30-40 nm on the TEM images. The PAA/MTA ion pair showed the upper critical solution temperature (UCST) that hiked with increasing MTA content. When the MTA of the ion pair was oxidized by H2O2, the UCST was also increased. The amphiphilic property of the ion pair was responsible for interface activity which declined upon the oxidation of the MTA. The surface tension was low for the ratio of PAA/MTA (5/5), which made the 5/5 ratio suitable for further studies. The interaction between PAA and MTA, which was ionic, and the oxidation of MTA was confirmed by FT-IR spectroscopy. The release of payload (i.e. Nile red) in IPSAM was restrained below the UCST but it was triggered above the phase transition temperature possibly due to the disintegration of the IPSAM whereas on MTA oxidation the release was shielded due to more hydrophobicity. The release was found to be higher in tumor environment temperature which could be controlled with the input concentration of H2O2 giving a stable IPSAM. The cell viability results showed that IPSAM has no significant cytotoxicity and can serve as a drug carrier for stimulus-response.

中文翻译：

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ThermOxshield 离子对自组装释放抑制释放

使用阴离子聚合物聚丙烯酸 (PAA) 与 4-(甲硫基)苯胺 (MTA)（一种对温度和氧化敏感的疏水性抗衡离子）制备离子对自组装 (IPSAM)。当羧基与氨基摩尔比为7/3-5/5时形成IPSAM。TEM图像显示IPSAM纳米粒子的结构为球形，直径为30-40 nm。PAA/MTA 离子对显示上临界溶液温度 (UCST) 随着 MTA 含量的增加而升高。当离子对的MTA被H氧化时2氧2、UCST 也增加了。离子对的两亲特性导致界面活性在 MTA 氧化时下降。PAA/MTA 比例 (5/5) 的表面张力较低，这使得 5/5 比例适合进一步研究。PAA 和 MTA 之间的相互作用（离子型）和 MTA 的氧化通过 FT-IR 光谱得到证实。IPSAM 中有效负载（即尼罗红）的释放被限制在 UCST 以下，但在相变温度以上被触发，可能是由于 IPSAM 的分解，而在 MTA 氧化时，由于疏水性更强，释放受到屏蔽。发现在肿瘤环境温度下释放较高，可以通过 H2 输入浓度进行控制2氧2给出稳定的IPSAM。细胞活力结果表明IPSAM没有明显的细胞毒性，可以作为刺激响应的药物载体。