A sensitive triple colorimetric sensor based on plasmonic response quenching of green synthesized silver nanoparticles for determination of Fe 2+ , hydrogen peroxide, and glucose

A new strategy based on Fenton reaction coupled by silver nanoparticles (AgNPs) was designed to establish a multi-functional platform for highly sensitive colorimetric determination of Fe2+, H2O2 and glucose. For this purpose, AgNPs were synthesized in a green manner using agar and ascorbic acid and then utilized as a colorimetric sensor. The UV–vis spectroscopy, DLS, FTIR, EDX, XRD and TEM were used to characterize the green synthesized AgNPs. Addition of H2O2 to the mixture of Fe2+ and AgNPs caused the production of hydroxyl radical (OH), oxidation of AgNPs and discoloration of the solution. Changing the amount of Fe2+ affected on discoloration of the solution, while other metallic ions did not show such this effect. So, a selective colorimetric sensor with a detection limit of 0.54 μM was provided for Fe2+ measuring. On the other hand, the concentration of H2O2 affected both on the oxidation of AgNPs and discoloration of the solution. These conditions was used to measure H2O2 with a LOD as low as 0.032 μM. Owing to the fact that glucose oxidase produces H2O2 from glucose, this system was also applied for determination of glucose. LOD of the method for glucose detection was 0.29 μM. Glucose determination in human blood serum sample was performed using the fabricated sensing system.