A colorimetric aptasensor based on two dimensional (2D) nanomaterial and gold nanoparticles for detection of toxic heavy metal ions: A review

Abstract

Food contamination by heavy metals is a growing public health problem that necessitates the development of fast and simple tools for detection in biological and environmental samples. Recently, it has been found that colorimetric detection methods have the potential to replace traditional methods due to their ease of use, rapid response, ease of manufacture, low cost, and visual visibility. It is, therefore, suitable for use in field work, especially in remote areas of the world. However, the development of colorimetric detection methods with low detection limit is a challenge that limits their wide applicability in the detection of food contaminants. To address these challenges, nanomaterial-based transduction systems are used to build colorimetric biosensors. For example, gold nanoparticles (AuNPs) attract much attention in the manufacturing of colorimetric biosensors due to the advantages of ease of synthesis, biocompatibility, advanced surface functionalization, and adjustable physics-chemical properties, in addition to localized surface plasma resonance (LSPR). Furthermore, two-dimensional (2D) nanozyme such as graphene, graphene oxide, and transition metal dichalcogenide has been used to fabricate colorimetric sensors for the rapid and efficient detection of toxic heavy metal ions. To improve the selectivity of the colorimetric biosensors, the surface plasmon resonance (SPR) changes in AuNPs and 2D nanozymes must be modified by aptamers recognition elements. In this review, two mechanisms for the colorimetric detection of heavy metal ions based on AuNPs and 2D nanozymes have been described. First, the sensors that utilize the localized surface plasmon resonance (LSPR) phenomenon of gold nanoparticles can exhibit very strong colors in the visible region, due to changes in SPR caused by the aggregation and disaggregation of AuNPs.Second, the recognition mechanism of 2D nanozymes is based on their enzymatic mimic properties and can be used in the manufacture of TMB/H2O2 reaction-based colorimetric sensors and biosensors for the detection of heavy metal ions. Therefore, this review summarizes the recent application of colorimetric aptasensors for the detection of heavy metal ions based on AuNPs and 2D nanozymes with a particular emphasis on selectivity, sensitivity, and practicality. Finally, the current key challenges and opportunities in this area are discussed.