Colorimetric determination of nine metal ions based on the de-aggregation of papain-functionalized gold nanoparticles and using three chelating agents

Gold Nanoparticles-Based Colorimetric Assays for Environmental Monitoring and Food Safety Evaluation

Recent years have witnessed an exponential increase in the research on gold nanoparticles (AuNPs)-based colorimetric sensors to revolutionize point-of-use sensing devices. Hence, this review is compiled focused on current progress in the design and performance parameters of AuNPs-based sensors. The review begins with the characteristics of AuNPs, followed by a brief explanation of synthesis and functionalization methods. Then, the mechanisms of AuNPs-based sensors are comprehensively explained in two broad categories based on the surface plasmon resonance (SPR) characteristics of AuNPs and their peroxidase-like catalytic properties (nanozyme). SPR-based colorimetric sensors further categorize into aggregation, anti-aggregation, etching, growth-mediated, and accumulation-based methods depending on their sensing mechanisms. On the other hand, peroxidase activity-based colorimetric sensors are divided into two methods based on the expression or inhibition of peroxidase-like activity. Next, the analytes in environmental and food samples are classified as inorganic, organic, and biological pollutants, and recent progress in detection of these analytes are reviewed in detail. Finally, conclusions are provided, and future directions are highlighted. Improving the sensitivity, reproducibility, multiplexing capabilities, and cost-effectiveness for colorimetric detection of various analytes in environment and food matrices will have significant impact on fast testing of hazardous substances, hence reducing the pollution load in environment as well as rendering food contamination to ensure food safety.

Fluorescent pattern recognition of metal ions by nanoparticles of bovine serum albumin as a chemical nose/tongue

A sensor array mimicking a chemical nose/tongue based on bovine serum albumin nanoparticles (BSANsn) has been developed for the fluorescence pattern recognition of metal ions in biofluids. Three types of BSANsn (BSANs10, BSANs20, and BSANs40) show the same excitation/emission peak at 478/526 nm. According to the differential fluorescence variation, the sensor array shows particular fluorescence response patterns depending upon metal ions. Upon principal component analysis (PCA), it was found that the sensor array can distinguish 18 metal ions clearly at a concentration of as low as 10 μM. Moreover, different concentrations of metal ions and mixed metal ions of diverse kinds or valence states can be differentiated by the sensor in biofluids. In addition, the results were well consistent with those obtained with the traditional ICP-AES method.