Portable intelligent paper-based sensors for rapid colorimetric and smartphone-assisted analysis of hydrogen peroxide for food, environmental and medical detection applications

One of the effective approaches to safeguard human health is the rapid and sensitive identification of food additives, environmental pollutants, and disease markers. This study developed a portable intelligent paper-based sensor for point-of-care detection of hydrogen peroxide (H2O2) and sarcosine (SA) using smartphone colorimetric analysis, supplemented by UV-Vis verification. The paper-based sensor utilizes a chemical modification of conventional filter paper by immobilizing horseradish peroxidase (HRP) from the horseradish plant, achieved through boronate affinity and metal chelation techniques. For H2O2 detection, the sensor exhibited a linear range of 2–100 µmol L−1 and a limit of detection (LOD) of 1.0 µmol L−1. Similarly, a range of 2–400 μmol L−1 for SA detection and an LOD of 1.0 μmol L−1. The sensors were successfully employed for determining the H2O2 concentration in liquor samples, environmental water, and the amount of SA in urine. Significantly, the detection ranges of these sensors surpassed those of commercially available test strips. In summary, we first proposed enzyme-immobilized paper-based sensors for immobilizing HRP from plants to detect H2O2 and SA, which are intelligent, portable, fast, green, low-cost, highly sensitive, and selective, with broad application prospects in food analysis, environmental monitoring, and medical diagnostics.