Development of a Porous Gelatin‐G‐Polyacrylamide Hydrogel Biosensor for the Rapid Colorimetric Detection of Lead, Cadmium, and Mercury in Simulated Urine

ABSTRACT The heavy metals mercury (Hg), lead (Pb), and cadmium (Cd) possess significant toxicity, and thus there is a strong demand for the rapid screening of their toxicities. However, the conventional techniques for the measurement of these heavy metals are slow and expensive, and thus they cannot be used for point‐of‐care (POC) applications. In the present work, a novel semi‐interpenetrating polymer network (IPN) hydrogel‐based sensor for the colorimetric determination of mercury, lead, and cadmium ions in urine samples is reported. This novel sensor is prepared by the free‐radical polymerization of acrylamide and gelatin. Dithizone, a strong metal‐chelating agent, is incorporated into the IPN, and the 3D network of the polymer facilitates the diffusion of the metal ions. When the novel sensor is immersed in a simulated urine sample containing the heavy metal ions, a color change is observed, and the color intensity changes linearly with the concentration of the metal ions. This novel sensor works within 1 to 6 min, and the results are validated by Fourier transform infrared spectroscopy, x‐ray diffraction, scanning electron microscopy, and thermogravimetry. Despite the presence of urine, the novel sensor works effectively, and the results are corrected by a baseline correction method.