Research On Rapid Ultra-sensitive Colorimetric Methods For Detection Of Heavy Metal Hg²⁺ Based On Gold Nanoparticles

Rapid and ultrasensitive detection of trace heavy metal mercury (II) ions (Hg2+) is of significant importance due to the induced serious risks for environment and human health. This presented article reports three colorimetric methods to detect Hg2+:1. Traditional colorimetric detection of Hg2+based on aptamer and AuNPs We applied the classical identification of T-Hg2+-T mismatch as the core recognition to capture Hg2+, which maked a closer distance of AuNPs and changed surface plasmon resonance of AuNPs result of the color changing from red to purple or blue gray to visual detection of Hg2+. We optimized the sequence of recognition probe and re-suspension formulation of DNA-AuNPs conjugates. Under the optimal conditions, we obtained the visual detection limit of 0.05 nM (0.01 ppb), and a detection limit of 0.093 nM calculated by 3a method and the standard curve (R2=0.9916) established by UV-vis of AuNPs. At the same time, we demonstrated the excelent specificity against other ions. The research also had applied in the detection of real samples, and accuracy was comparable to ICP-MS.2. Signal enhanced colorimetric detection of Hg2+based on aptamer and AuNPs More aggregated AuNPs makes color changing more obvious to increase the detection sensitivity by modifying the enhanced probes on AuNPs based on the above mentioned methods of colorimetric detection. We optimized ratio of recognition and enhancement probe, size of enhancement AuNPs and sample adding order of reaction. Under the optimal conditions, we obtained the visual detection limit of 0.005 nM (0.001 ppb), and a detection limit of 0.0016 nM calculated by 3a method and the standard curve (R2=0.9921) established by UV-vis of AuNPs. At the same time, we demonstrated the excelent specificity against other ions. This method is also applied directly for real water sample monitoring and, more importantly, applied in analysis of mercury poisoned animal tissues and body fluidic samples, indicating a potential powerful and promising tool for environmental monitoring and food safety control.3. Colorimetric detection of Hg2+based on Lysine and AuNPs Detailed and careful investigation of the broad mechanism involved in the chemical initiated aggregation of gold nanoparticles (AuNPs) in the presence of mercury has demonstrated that only amine-based chemicals containing more than one amino group are effective as the "bridge molecule" for the GNPs-based sensing of mercury ions. The optimization of the solution pH at 8 and Lys concentration at 0.4μM, while enabling the achievement of detection limits as low as 8.4 pM and 0.01 nM for quantitative and qualitative analysis, respectively. At the same time, we demonstrated the excelent specificity against other ions. The research also had applied in the detection of real samples, and accuracy was comparable to ICP-MS.