In the presence of uricase, uric acid generated H2O2, which further decomposed CoOOH nanoflakes to release Co2+, resulting in smaller nanoparticles with lower light scattering. Based on the relationship between the reduced light scattering and uric acid concentration, the simple strategy was applicable to uric acid sensing in human serum samples.

As a natural enzyme, alkaline phosphatase (ALP) plays an essential role in clinicopathological examinations and biomedical research, and is capable of hydrolyzing the phosphate group of l‐ascorbic acid‐2‐phosphate (AAP) to yield l‐ascorbic acid (L‐AA). L‐AA reduced cobalt oxyhydroxide (CoOOH) nanoflakes to Co2+, leading to a smaller size and weaker light scattering, which could be monitored by electron microscopic images and optical spectra. The indirect detection of ALP was achieved by the reduced light scattering signal of CoOOH nanoflakes. Under optimal conditions, the decrease in scattering intensity was proportional to the ALP concentration over the range 0.1–160 U/L and the detection limit was 0.034 U/L (3σ/k). Compared with other assays, this proposed light scattering method was more convenient and economic for ALP sensing. The method was successfully applied to ALP analysis in human serum samples, and was similar to the results obtained by commercial kits.