Colorimetric Detection Of Lead Ions Using Glutathione Stabilized Silver Nanoparticles

Heavy metal poisoning is one of the common problems that occurs due to changes in food chain, environmental conditions, etc., One of the most commonly occurring toxicities due to metal ions is lead poisoning. It causes many diseases like skin lesions, cancer, diabetes, heart and lung related problems etc., in human beings. It was widely reported that the elevated level of Pb (II) in drinking water is primarily related to human health effects such as damage of the brain and nervous system, behavioural and learning disabilities, blood pressure increase, kidney damage and anemia. Extremely low concentrations of lead in blood and urine causes reproductive disorders especially in children and high concentrations causes seizures, coma and sometimes leading to death. In this work, the silver nanoparticles is stabilized with glutathione a tripeptide, are synthesized (GSH-AgNPs) using the modified Creighton’s method and colorimetric assay of heavy metals with GSH-AgNPs was carried out. The synthesized nanoparticles were characterized by XRD, UV-Vis spectrophotometer, FTIR techniques. The sensitivity and selectivity of different metal ions such as chromium, lead, magnesium, manganese, copper, mercury, ferric and ferrous in water and blood samples were checked. Initially, the synthesized GSH-AgNPs were in pale yellow colour colloidal solution. When mixed with different concentrations of lead from 10 -3 to 10 -9 M and pH from 3 to 7, it turns from pale yellow to deep orange and remaining metal ions didn’t show any colour change. The optimisation was performed for various parameters such as concentration and pH. From the UV absorbance peak intensity, the concentration of lead ion can be obtained. This assay can be used to detect the lead ion even to the lowest concentration level of ~10 -9 M. The future work is to develop a labon-chip sensor using MEMS technique for more accurate detection of metal toxicities in various biological samples. This diagnostic study can be helpful in identifying lead poisoning at an early stage.