Size-dependent light scattering of CoOOH nanoflakes for convenient and sensitive detection of alkaline phosphatase in human serum.

As a natural enzyme, alkaline phosphatase (ALP) plays an essential role in clinicopathological examinations and biomedical research, which is capable of hydrolyzing the phosphate group of L-ascorbic acid-2-phosephate (AAP) to yield L-ascorbic acid (L-AA). While L-AA could reduce 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. Hereby, the indirect detection of ALP was achieved by the reduced light scattering signal of CoOOH nanoflakes. Under the optimal conditions, the decrease in the scattering intensity was proportional to the concentration of ALP in the range of 0.1~160 U/L and the detection limit was 0.034 U/L (3σ/k). Compared with the other assays, the proposed light scattering method were more convenient and economic for ALP sensing. The method was successfully applied to ALP analysis in human serum samples, which was similar to the result obtained by the commercial kits.