A Real-Time Detection Method of Hg2+ in Drinking Water via Portable Biosensor: Using a Smartphone as a Low-Cost Micro-Spectrometer to Read the Colorimetric Signals

Abstract

This paper reported a real-time detection strategy for Hg2+ inspired by the visible spectrophotometer that used a smartphone as a low-cost micro-spectrometer. In combination with the smartphone’s camera and optical accessories, the phone’s built-in software can process the received light band image and then read out the spectral data in real time. The sensor was also used to detect gold nanoparticles with an LOD of 0.14 μM, which are widely used in colorimetric biosensors. Ultimately, a gold nanoparticles-glutathione (AuNPs-GSH) conjugate was used as a probe to detect Hg2+ in water with an LOD of 1.2 nM and was applied successfully to natural mineral water, pure water, tap water, and river water samples.

Recent Advances in the Application of Bionanosensors for the Analysis of Heavy Metals in Aquatic Environments

“…AuNPs have a high affinity for biothiols, and when molecules containing thiol groups (for example, mercury, Hg 2+ has a higher sulfurophilicity [ 115 ]) are added to the AuNP solution, they quickly bind to the surface of the AuNPs [ 116 ], causing AuNP aggregation and a color change from red to blue [ 117 , 118 , 119 ]. This approach was also used to successfully recover natural mineral water, pure water, tap water, and river water, with recoveries ranging from 97.4 to 115.9% [ 120 ].…”

“… ( a ) Colorimetric biosensor system based on a smartphone and schematic illustration of Hg 2+ detection based on AuNPs-GSH. Characterization of the absorption spectra of the AuNPs−GSH solution using the proposed sensor and TEM images of the AuNPs−GSH solution before and after addition of Hg 2+ [ 120 ]. Reprinted with permission [ 120 ].…”

“…Characterization of the absorption spectra of the AuNPs−GSH solution using the proposed sensor and TEM images of the AuNPs−GSH solution before and after addition of Hg 2+ [ 120 ]. Reprinted with permission [ 120 ]. Copyright 2022, Biosensors.…”

Rapid Nondestructive Testing Technology-Based Biosensors for Food Analysis

“…When combined with a smartphone, the camera can be used to detect and quantify the color change, making it a portable and convenient method for on-site detection of various substances in food analysis. Gu et al [5] presented a real-time detection method for Hg 2+ in drinking water using a smartphone as a lowcost micro-spectrometer. The detection strategy uses a colorimetric sensor based on gold nanoparticles and glutathione conjugate, with a limit of detection (LOD) of 1.2 nM.…”