Development of a surface-modified paper-based colorimetric sensor using synthesized Ag NPs-alginate composite.

There has been an increase in the discovery and usage of sensors for the detection of chemical compounds in the field of analytical chemistry since the last several years. This has led to progressive research in nanotechnology for developing efficient nanomaterials for bio-chemical sensing applications. Thereby, a deft synthesis of silver nanoparticles (Ag NPs) under microwave irradiation was achieved using sodium alginate as a reducing and capping agent in a fast and cost-effective approach. As per the X-ray diffraction analysis, the average particle size of Ag NPs was found to be 10 nm. X-ray photoelectron spectroscpopy analysis showed characteristic peaks at binding energies of 368.10 and 374.11 eV indicating the formation of Ag NPs. The synthesized Ag NPs-alginate composite was further used to develop a paper-based sensor for the detection of HO. Detection of HO is based on the discolouration of the Ag NPs-alginate composite modified paper sensor as a function of HO concentration. The analysis of the decoloured paper strips was done by a smartphone camera and an RGB Colour Reader application (app) to measure colour intensity. The sensing characteristics were found in the range of 0.1-10 mM. The colour analysis revealed piecewise linear relationship of intensity of RGB to HO concentration in the range of 0.1-1.5 and 2-10 mM with values of 0.97 and 0.9778, respectively. Owing to the high sensitivity, selectivity, and cost-effectiveness, the developed paper sensor can be a potential tool for real-time analysis of HO.