Lin Fengming, Li Chengcheng, Chen Zhan
State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing, China.
Department of Chemistry, University of Michigan, Ann Arbor, MI, United States.
Front Microbiol. 2018 Nov 9;9:2697. doi: 10.3389/fmicb.2018.02697. eCollection 2018.
Fluorescent dye staining combined with fluorescence microscopy or flow cytometry is becoming a routine way to monitor microorganism viability that is necessary for food safety, antibiotic development, and human health. However, the conventional live/dead assay dyes suffer from high cost, inconvenient staining steps, and high cytotoxicity, which is urgently needed to overcome. Herein, cheap carbon dots, CDs-EPS605, were reported to successfully assess microbial viability in a convenient way with neglectable cytotoxicity. The fluorescent N-doped CDs-EPS605 could be facilely prepared from bacterial amino exopolysaccharide (EPS) by one-step hydrothermal carbonization, which is cost-effective and sustainable. The negatively charged CDs-EPS605 consisted of C, H, O, N, P, and S, and featured various functional groups, including -COOH, -OH, -CONH-, and -NH. CDs-EPS605 were observed to sensitively and selectively stain dead microorganisms instead of live ones to enable discrimination of live/dead microorganisms. The labeling method with CDs-EPS605 did not require protection from light, or washing, which is convenient. Additionally, CDs-EPS605 displayed better photostability and much less cytotoxicity compared to the commercial counterpart. Altogether, CDs-EPS605 represent a simple, yet powerful staining agent for microbial viability assessment, and at the same time enrich the current applications of microbial EPS.
荧光染料染色结合荧光显微镜或流式细胞术正成为监测微生物活力的常规方法，这对于食品安全、抗生素开发和人类健康至关重要。然而，传统的活/死检测染料存在成本高、染色步骤不便和细胞毒性高的问题，迫切需要克服。在此，报道了廉价的碳点CDs-EPS605能够以方便的方式成功评估微生物活力，且细胞毒性可忽略不计。荧光N掺杂碳点CDs-EPS605可通过一步水热碳化由细菌氨基胞外多糖（EPS）轻松制备，具有成本效益且可持续。带负电荷的CDs-EPS605由C、H、O、N、P和S组成，并具有多种官能团，包括-COOH、-OH、-CONH-和-NH。观察到CDs-EPS605能灵敏且选择性地对死微生物而非活微生物进行染色，从而实现对活/死微生物的区分。用CDs-EPS605进行标记的方法不需要避光或洗涤，十分方便。此外，与市售同类产品相比，CDs-EPS605表现出更好的光稳定性和更低的细胞毒性。总之，CDs-EPS605是一种用于微生物活力评估的简单而强大的染色剂，同时丰富了微生物EPS的当前应用。
