在我们的身体里，有一种叫做8 - 氧代鸟嘌呤（o8G）的物质，它是RNA氧化修饰的一种典型代表。这种修饰和衰老、癌症以及心血管疾病等密切相关。然而，检测o8G却不是一件容易的事。o8G结构不稳定，还会因为所在序列不同产生诱变效应，这让现有的检测方法很难快速又灵敏地找到被o8G修饰的微小RNA（miRNA），而且操作起来也不便捷。为了解决这个难题，科学家们开发了一种叫做“精氨酸蛋白整合检测（AID）”的系统。这个系统把中温精氨酸蛋白（Ago）具有的序列特异性切割活性和滚环扩增（RCA）技术结合起来。Ago蛋白有一个特别的本事，当遇到被o8G修饰的miRNA时，它的切割会停下来；而对于没有被修饰的RNA，它就会进行选择性切割。这样一来，被o8G修饰的miRNA就能被保留下来，然后通过RCA技术进行信号放大。AID系统非常厉害，它能达到皮摩尔级别的灵敏度，还能分辨出单个核苷酸的差异。这个系统的反应在恒温条件下就能进行，还可以集成到便于携带到野外使用的设备中。我们用肉眼或者智能手机就能看到检测结果，在几个小时内就能检测出皮摩尔级别的被o8G修饰的RNA。这个便携式系统既保证了分子检测的特异性，操作又很简单。它不仅有可能在临床诊断中快速检测出氧化RNA生物标志物，而且不需要昂贵的设备，还能为相关疾病的表观遗传调控机制研究提供一个好用的工具。

期刊

Analytical Chemistry

标题

Quantification of the Uptake and Biodistribution of Nanoplastics in Escherichia coli

作者

Yan Gao, Quanzhi Xiao, Jie Zhang, Kena Zhang, Liping Fang, Xiao-Xia Zhou, and BingYan

摘要

Nanoplastics (NPs) are prevalent in the environment, posing risks to ecosystems and human health. While research into their effects on bacterial activity has increased, the mechanisms underlying NP-bacteria interactions─specifically whether NPs penetrate cells or adhere to the cell surface─remain poorly understood. This knowledge gap largely stems from the absence of quantitative analytical methods. Herein, we developed a novel approach combining lysozyme treatment with pyrolysis gas chromatography–mass spectrometry (Py-GC/MS) to differentiate between intracellular and cell wall-bound NPs in Escherichia coli (E. coli) quantitatively. The method involves selective removal of the bacterial cell wall using lysozyme, protein corona-induced extraction to enrich cell wall-bound NPs, and hydrogen peroxide digestion to eliminate protoplast interference before Py-GC/MS analysis. Validation with europium (Eu)-labeled NPs, quantified by inductively coupled plasma mass spectrometry (ICP-MS), confirmed the method’s accuracy and reliability. Using this approach, we found that after NP exposure, only a small fraction (9.6–10.5%) of NPs penetrated E. coli cells, while the majority (36.9–63.8%) adhered to the cell surface. Transmission electron microscopy further corroborated these findings. Consequently, this work provides a robust tool for the quantification of NP uptake and biodistribution in bacterial systems, advancing our understanding of NP–microorganism interactions and their environmental implications.

原文链接

https://pubs.acs.org/doi/10.1021/acs.analchem.5c00822

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