Colorimetric determination using digital image processing of sensor based on polymer-stabilized silver nanoparticles: monitoring of glucose in saliva.

We propose transparent colorimetric sensor systems based on silver nanoparticles embedded within a polymethacrylate matrix for the determination of glucose and other substances capable of entering into redox reactions. We chose to use stabilized nAg in the form of colloids embedded in PMM to determine glucose using the glucose oxidase method. The PMM-Ag plates are immersed in the sample solution and changes in their optical characteristics are registered. We demonstrated the potential of smartphone-based two-mode spectrophotometric and colorimetric registration of the PMM-Ag signal for the quantitative determination of glucose. Dual-signal spectrophotometric and colorimetric approaches can be used for the determination of glucose in the ranges 0.2-4.4 mM and 0.1-0.8 mM with corresponding detection limits of 0.1 mM and 0.05 mM. We studied the conditions of interaction between the silver nanoparticles and matrix components, glucose and some other substances by evaluating the influence of such factors as solution pH, amount of nanoparticles within the polymer matrix, contact time, and analyte concentration upon the analytical signal.