Development of Nanomaterials-fabricated Paper-based Sensors for the Analysis of Environmental and Biological Samples: A Review

Background: Currently, the environmental and biological samples, such as water, soil, vegetables, etc., are highly contaminated with metal ions, anions and pesticides. For analysis of these toxic substances from the environmental and biological samples, sophisticated and expensive instruments are being used. The present work deals with the development of a simple, faster, sensitive and economical method for the analysis of toxic substances present in different samples. Methods: The general methods for synthesis and characterization of metallic (Ag, Au, Cu and graphene) nanoparticles and conductive polymer for the development of conductive nano-ink and fabrication of paper substrate by direct deposition and laser, wax, or inkjet printing techniques, have been reported. Results: Paper-based sensors fabricated with different nanomaterials used as colorimetric, electrochemical and fluorescence-based chemical sensors for the quantitative determination of pesticides and toxic metal ions in various biological and clinical samples have been comprehensively discussed in this review. Conclusion: The low-cost, rapid, eco-friendly, flexible, portable, and paper-based sensors using nanoparticles (NPs) are in demand for on-site detection of different chemical constituents present in various environmental, biological and clinical samples.