Nanoparticle-Decorated Biomimetic Extracellular Matrix for Cell Nanoencapsulation and Regulation

Cell encapsulation has been studied for various applications ranging from cell transplantation to biological production. However, current encapsulation technologies focus on cell protection rather than cell regulation that is essential to most if not all cell-based applications. Here we report a method for cell nanoencapsulation and regulation using an ultrathin biomimetic extracellular matrix as a cell nanocapsule to carry nanoparticles (CN²). This method allows high-capacity nanoparticle retention at the vicinity of cell surfaces. The encapsulated cells maintain high viability and normal metabolism. When gold nanoparticles (AuNPs) are used as a model to decorate the nanocapsule, light irradiation transiently increases the temperature, leading to the activation of the heat shock protein 70 (HSP70) promoter and the regulation of reporter gene expression. As the biomimetic nanocapsule can be decorated with any or multiple NPs, CN² is a promising platform for advancing cell-based applications.     

1,3-和1,4-环己亚硝酸二酯电子轰击解离的结构效应

烷基亚硝酸二酯是一种重要的亚硝化剂,也是大气中NO_x污染物的来源之一,近年来引起了人们的广泛关注. 烷基亚硝酸二酯中两个ONO官能团对分子反应活性的影响以及在化学反应中的作用尚不清楚. 本文用电子碰撞电离质谱研究了1,3-环己亚硝酸二酯和1,4-环己亚硝酸二酯的解离过程. 实验结果发现两种结构异构体的分解产物不同：除了亚硝酸酯的特征碎片NO⁺(m/z=30)外,对于1,3-异构体,碎片离子m/z=43和71的丰度最高;而对于1,4-异构体,电子碰撞电离质谱谱图中解离产物m/z=29、57、85和97的强度较大. 对中性分子、分子离子以及中间产物的结构和电荷计算结果显示,1,3-环己亚硝酸二酯的分解清楚地显示出两步解离机制,即母体阳离子M⁺首先失去一个NO,然后中间离子(M-NO)⁺通过两个αC-βC键的断裂打开六元碳环;对于1,4-环己亚硝酸二酯,除了两步分解机制之外,还可以直接从母体阳离子M⁺发生αC-βC键的裂解. 研究结果有助于理解在大气反应及亚硝化合成反应中烷基亚硝酸二酯的分子结构对反应历程的影响.