Biomacromolecules. 2018 Mar 12;19(3):860-871. doi: 10.1021/acs.biomac.7b01659. Epub 2018 Feb 8.
Here, we have exploited the heightened extracellular concentration of matrix metalloproteinase-9 (MMP-9) to induce surface-conversional properties of nanogels with the aim of tumor-specific enhanced cellular uptake. A modular polymeric nanogel platform was designed and synthesized for facile formulation and validation of MMP-9-mediated dePEGylation and generation of polyamine-type surface characteristics through peptide N-termini. Nanogels containing MMP-9-cleavable motifs and different poly(ethylene glycol) corona lengths (350 and 750 g/mol) were prepared, and enzymatic surface conversional properties were validated by MALDI characterization of cleaved byproducts, fluorescamine assay amine quantification, and zeta potential. The nanogel with a shorter PEG length, mPEG350-NG, exhibited superior surface conversion in response to extracellular concentrations of MMP-9 compared to that of the longer PEG length, mPEG750-NG. Confocal microscopy images of HeLa cells incubated with both fluorescein-labeled nanogels and DiI-encapsulated nanogels demonstrated greater uptake following MMP-9 "activation" for mPEG350-NG compared to its nontreated "passive" mPEG350-NG parent, demonstrating the versatility of such systems to achieve stimuli-responsive uptake in response to cancer-relevant proteases.
在这里，我们利用细胞外基质金属蛋白酶-9 (MMP-9) 的浓度升高，诱导纳米凝胶的表面转化特性，旨在实现肿瘤特异性增强的细胞摄取。设计并合成了一种模块化的聚合物纳米凝胶平台，用于通过肽 N 末端轻松制定和验证 MMP-9 介导的去 PEG 化和多胺型表面特性的产生。制备了含有 MMP-9 可切割基序和不同聚(乙二醇)冠长度（350 和 750 g/mol）的纳米凝胶，并通过 MALDI 分析切割副产物、荧光胺测定胺定量和zeta 电位验证了酶促表面转化特性。与较长 PEG 长度的 mPEG750-NG 相比，较短 PEG 长度的 mPEG350-NG 在响应细胞外 MMP-9 浓度时表现出更好的表面转化。用荧光素标记的纳米凝胶和 DiI 包封的纳米凝胶孵育的 HeLa 细胞的共焦显微镜图像表明，mPEG350-NG 的 MMP-9“激活”后摄取量大于未经处理的“被动”mPEG350-NG 母体，证明了此类系统能够实现对癌症相关蛋白酶的刺激响应性摄取的多功能性。
