DOPA-Mediated Reduction Allows the Facile Synthesis of Fluorescent Gold Nanoclusters for Use as Sensing Probes for Ferric Ions

Abstract

In this paper, we describe a simple one-pot method, employing l-3,4-dihydroxyphenylalanine (L-DOPA) as a reducing/capping reagent, for the synthesis of fluorescent gold nanoclusters (AuNCs). Within a short reaction time of 15 min (excluding the time required for purification), this strategy allows the fabrication of homogeneous AuNCs having the capability to sense ferric ions (Fe(3+)). The as-prepared AuNCs exhibited a fluorescence emission at 525 nm and a quantum yield of 1.7%. On the basis of an aggregation-induced fluorescence quenching mechanism, these fluorescent AuNCs offer acceptable sensitivity, high selectivity, and a limit of detection of 3.5 μM for the determination of Fe(3+) ions, which is lower than the maximum level (0.3 mg L(-1), equivalent to 5.4 μM) of Fe(3+) permitted in drinking water by the U.S. Environmental Protection Agency.

Noble Metal Clusters: Applications in Energy, Environment, and Biology

“…As yet another strategy, aggregation‐induced fluorescence quenching mechanism of clusters was utilized to detect ions such as Hg 2+ , Fe 3+ , Pb 2+ , Cu 2+ etc. Mercury ions can form chelation complexes with free carboxylic acid groups of the ligands such as dihydrolipoic acid (DHLA), GSH, etc.…”

Fluorescent nanoprobes for sensing and imaging of metal ions: Recent advances and future perspectives

“…In addition, an aggregation-induced fluorescence quenching strategy based on coordination of ferric ions and dihydroxyphenylalanine-capped AuNCs has also been applied to the detection of Fe 3+ , with a LOD of 3.5 μM that is close to the MCL (5.4 μM) of Fe 3+ permitted in drinking water by the U.S. EPA. Similarly, other metal ions, such as Ag + [129,130], Pd 2+ [129], Co 2+ [131], Fe 3+ [132], Al 3+ [133], Cr 3+ [134], Cr 6+ [134], have also been successfully detected using metal NCs in the past five years.…”

Gold and Silver Nanomaterial‐Based Optical Sensing Systems

“…The practicability was verified by detecting Hg 2+ in fish samples. Strategies based on analyte‐induced PL quenching of Au NCs were designed to analyze different metal ions such as Pb 2+ , Cu 2+ , Fe 3+ , Cr 3+ by varying protected ligands of Au NCs or addition of different masking agents . For example, instead of using 11‐MUA, dihydrolipoic acid–Au NCs were used for monitoring Hg 2+ (10 × 10 −6 m ) in living cells through PL quenching .…”

“…For example, instead of using 11‐MUA, dihydrolipoic acid–Au NCs were used for monitoring Hg 2+ (10 × 10 −6 m ) in living cells through PL quenching . In addition, L‐3,4‐dihydroxyphenylalanine and GSH were used to prepare L‐3,4‐dihydroxyphenylalanine‐, and GSH–Au NCs for the detection of Fe 3+ and Cr 3+ , with LODs of 3.5 × 10 −6 and 40 × 10 −9 m , respectively …”