Khosro Mohammadi

The widespread release of heavy metals into natural water bodies and accumulation in the human body interfere with the transport of human proteins and enzymes, causing physiological toxicity. The presence of heavy metals in the air, water, soil, and food is becoming a severe threat to both humans and the environment. Metal ions are prominent entities that can cause a variety of hazardous health risks due to their prolonged half-life, potential accumulation in various parts of the body, and non-biodegradability. Thus, numerous nanotechnology methods for detecting heavy/toxic metals have been developed that are significant for human health assurance. Localized surface plasmon resonance (LSPR) is one of the most prominent features of metal nanoparticles which provide unique optoelectronic characteristics in the visible region of the electromagnetic spectrum. Metal nanoparticles especially gold and silver have very high extinction coefficients, therefore a well-suited electrochemical interaction between target analytes and nanoparticles surfaces cause aggregation, which leads to a colorimetric response. Modification and functionalization of nanoparticles with other ligands enhances the sensitivity and selectivity of colorimetric assays. In this work, we report an extremely sensitive, very simple and very selective AgNPs-Lcystein colorimetic sensor for Pb2+ detection. The result reveals that modified AgNPs colorimetric sensor exhibited excellent performance towards Pb2+ ions and the absorbance is proportional to the target concentration in the range from 3 to 9.0 ×104 nM with a detection limit and quantitation limit values of 1.47 μM and 4.69 nM, respectively. Besides, the fabricated sensor showed strong selectivity compared to other metal ions.