Cationic antibacterial metal nanoclusters with traceable capability for fluorescent imaging the nano–bio interactions

A thorough understanding of antimicrobial mechanism is of great importance for developing novel,efficient antibacterial agents.While cationic nanoparticles,such as metal nanoclusters(NCs),represent an attractive type of antibacterial nanoagents,their interactions with bacteria remains largely un-elucidated.Herein,we report the synthesis of cationic bovine serum albuminprotected AuAgNCs(cBSA-AuAgNCs),which exhibit both near-infrared(NIR)fluorescence properties and significant antimicrobial effects.With E.coli and S.aureus as the representative bacteria,we investigated the antimicrobial process of cBSAAuAgNCs in real-time based on their intrinsic fluorescence properties via fluorescence imaging.Our results showed that these cBSA-AuAgNCs exert their antimicrobial effects primarily by attaching on the outer membrane of bacteria without obvious internalization,which is significantly different from the antibacterial process of negatively-charged metal NCs.Further mechanistic investigation showed that these cationic NCs will cause serious disruption to the bacterial membrane due to strong electrostatic interactions,which then leads to over accumulation of reactive oxygen species(ROS)that finally causes the bactericidal action.This study demonstrates the great potential of cationic luminescent metal NCs as novel,traceable antimicrobial agents,which also provides new tools for further understanding microbial interactions of nanomedicines.

Site-specific fabrication of gold nanocluster-based fluorescence photoswitch enabled by the dual roles of albumin proteins

Fluorescence photoswitch is becoming increasingly desirable for many applications,but its controllable fabrication still remains challenging yet.In this paper,a new strategy is proposed to fabricate fluorescence photoswitch by harnessing dual roles of albumin proteins as both photochrome carriers and biotemplates of fluorophore.As an example,we demonstrated the successful fabrication of a fluorescence photoswitch by incorporating both the photochromic diarylethene dye(CMTE)and red-emitting fluorescent gold nanoclusters(AuNCs)into the specific domains of bovine serum albumin(BSA)in a highly controllable manner.Detailed spectral and photophysical characterisation showed that CMTE well-retains the photochromic properties within the CMTE–BSA–AuNC construct,although its photoconversion rate is slightly retarded.Different from previously reported photoswitches,the fluorescence of the present system is mainly modulated via the inner filter effect(IFE)mechanism,which exhibits high switching efficiency with an on-off ratio up to 90%,reversible fluorescence response and good antifatigue performance.This work provides a new,generable albumin protein-assisted strategy of fabricating advanced fluorescence photoswitch,which can find wide applications in biological,optical and information fields.

手性NIR-Ⅱ荧光Ag_(2)S量子点的生物相互作用及其肿瘤靶向特性

手性配体不仅可以赋予纳米探针独特的物化性质,而且会影响其生物学行为.因此,明确手性在纳米-生物界面的独特作用对其生物医学应用具有重要的科学意义.本文首次合成了手性的近红外二区荧光Ag_(2)S量子点,并结合多种分析技术系统探究了其生物学效应.研究结果表明,Ag_(2)S量子点与蛋白质和细胞的相互作用以及活体水平的代谢行为均表现出显著的手性依赖性,而且D-Ag_(2)S量子点还呈现出对肾肿瘤的靶向富集的特性.本文的研究结果有助于进一步理解纳米-生物界面的手性效应,并为发展新型肿瘤靶向探针提供了新颖的设计思路.

荧光硫化银量子点的生物学行为的手性效应

手性是一种在自然界中从微观到宏观都普遍存在的现象,大到浩渺星系的旋涡结构,小到微末电子的自旋方式.手性也贯穿生命的始终,几乎所有重要的生物物种都是手性的,包括氨基酸、蛋白质、酶、核酸、糖和药物等.随着纳米科技的发展,许多具有光学活性的手性纳米材料出现在生物医学的研究中[1].