Microwave-assisted rapid synthesis of luminescent gold nanoclusters for sensing Hg2+ in living cells using fluorescence imaging

Abstract

A microwave-assisted strategy for synthesizing dihydrolipoic acid (DHLA) capped fluorescent gold nanoclusters (AuNCs) has been developed. Irradiation with microwaves during synthesis enhanced the fluorescence quantum yield (QY) of AuNCs by about five-fold and shortened the reaction time from hours to several minutes. The as-synthesized DHLA-AuNCs possessed bright near-infrared fluorescence (QY: 2.9%), ultrasmall hydrodynamic diameter (3.3 nm), good colloidal stability over the physiologically relevant pH range of 5-10 as well as low cytotoxicity toward HeLa cells. Moreover, these DHLA-AuNCs were capable of sensing Hg(2+) through the specific interaction between Hg(2+) and Au(+) on the surface of AuNCs; the limit of detection (LOD) was 0.5 nM. A potential application in imaging intracellular Hg(2+) in HeLa cells was demonstrated by using spinning disc confocal microscopy.

Ultra-small fluorescent inorganic nanoparticles for bioimaging

“…122 In all syntheses, ligands play a crucial role in obtaining these ultra-small fluorescent metal nanoclusters. Their ability to donate electrons drastically influences the fluorescence intensity, i.e.…”

“…5 Besides these methods, microwaves and ultrasound were also used to assist the synthesis of fluorescent metal nanoclusters in recent years. 121,122 For example, Xu and Suslick adopted sonochemistry to prepare fluorescent Ag nanoclusters with a QY of 11% in the presence of PMAA. 121 Shang et al synthesized…”

Synthesis of Protein-Directed Orange/Red-Emitting Copper Nanoclusters via Hydroxylamine Hydrochloride Reduction Approach and Their Applications on Hg2+ Sensing

“…36,37 MNCs are too small to support surface plasmon resonance, and therefore signi¯cantly di®erentiate themselves from their counterpart plasmonic nanoparticles. As shown in Figs (fractional weights) of 0.4966 s (13.72%), 2.181 s (57.03%) and 6.925 s (29.25%); the average lifetime for the emission of Cu NCs at 645 nm was therefore calculated to be 3.337 s. According to the previous report, 38 we speculate that the existence of a large fraction of long lifetime components may be due to substantial contributions of Cu(I)-thiol complexes to the°uorescence Cu NCs.…”

Recent developments on nanomaterials-based optical sensors for Hg2+ detection

“…In the absence of Hg 2+ , the FAM-tagged ssDNA protected the Au NPs from salt-induced aggrega- The second frequently adopted scheme was based on the fluorescence quenching of Au NCs. Au NCs capped with lysozyme (Lys), bovine serum albumin (BSA) and dihydrolipoic acid (DHLA) have been synthesized for sensing Hg 2+ through the specific interaction between Hg 2+ (5d 10 ) and Au + (5d 10 ) on the surface of Au NCs [89][90][91][92][93]. As shown in Fig.…”