Colorimetric detection of Cr3+ based on gold nanoparticles functionalized with 4-mercaptobenzoic acid

Zhikun Zhang,Qingqing Liu,Runjing Liu,Xiaojie Ye,Yumin Liu

doi:10.1186/s40543-020-00209-7

Colorimetric detection of Cr3+ based on gold nanoparticles functionalized with 4-mercaptobenzoic acid

Zhikun Zhang, Qingqing Liu + Show 3 more

Open Access

https://doi.org/10.1186/s40543-020-00209-7

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Abstract

Herein, we report the construction of a colorimetric probe used to detecting Cr3+ ions in aqueous solution based on functionalized gold nanoparticles. We investigated 4-mercaptobenzoic acid, 4-nitrobenzenethiol, and a mixture of 4-mercaptobenzoic acid and 4-nitrobenzenethiol as ligands for Cr3+ ions to functionalize the gold nanoparticles, respectively. The results showed that the three probes were all aggregated in the presence of Cr3+ ions, which induces a color change from ruby to violet. Moreover, gold nanoparticles modified with 4-mercaptobenzoic acid exhibit a higher response toward Cr3+ than the two other probes, which can be detected by the naked eye and UV-vis absorption spectroscopy. The detection time was rapid (within 25 min). A linear relationship was obtained from 20 to 25 μM between the ratio of the absorbance observed at 635 nm and 520 nm (A635 nm/A520 nm) with the limit of detection was 5 × 10−6 M. This method exhibited excellent selectivity for Cr3+ ions over other tested heavy metal ions, anions, and organic molecules in the absence of another shielding reagent of metal ion. The system was successfully utilized to detect Cr3+ ions in simulated samples.

Highlights

Chromium is extensively applied in various fields, including steel works (Gomez et al 2006; Parlayici, et al 2019), electroplating, tanning industry, and chemical industries
We have investigated the single/collaborative behavior of 4-mercaptobenzoic acid (4-MBA) and 4-nitrobenzenethiol (4-NPT) for functionalizing Gold nanoparticles (AuNPs) in Cr3+ ions detection. 4-MBA and 4-NBT contained a -SH group, which interacts with AuNPs via a covalent bond
Stock solutions containing 1 × 10−4 M 4-MBA, 4-NTP, and 4-MBA/4-NTP were prepared using purified water. 1.0 mL of 10−4 M the above-mentioned solutions was added into 100 mL of the AuNPs solution, and the resulting mixture was equilibrated at the room temperature for 30 min to ensure the self-assembly of 4-MBA and 4-NBT on the surface of the AuNPs

Summary

Introduction

Chromium is extensively applied in various fields, including steel works (Gomez et al 2006; Parlayici, et al 2019), electroplating, tanning industry, and chemical industries. The -NO2 group in 4-NBT and -COOH group in 4-MBA are both modified on the surface of the AuNPs together These groups have a strong affinity to metal ions (Hemmateenejad et al 2015; Lin, et al 2002). 1.0 mL of 10−4 M the above-mentioned solutions was added into 100 mL of the AuNPs solution, and the resulting mixture was equilibrated at the room temperature for 30 min to ensure the self-assembly of 4-MBA and 4-NBT on the surface of the AuNPs. Detection of Cr3+ ions The colorimetric detection of Cr3+ was carried out using functionalized AuNPs. Typically, 300 μL of an aqueous solution of Cr3+ prepared at different concentrations was mixed with 2.7 mL of the AuNPs solution. The process of the mixture was the same as detection of Cr3+ ions

Result and discussion

Conclusions