“…Moreover, MnO 2 has shown a variety of excellent enzyme-like properties because of its transition metal element Mn, including a peroxidase-like property and a catalase-like property. Zhao 28 developed an efficient method for the determination of alkaline phosphatase (ALP) activity by directly using MnO 2 nanosheets as colorimetric probes or using MnO 2 and a chromogenic substrate 3,3 0 ,5,5 0 -tetramethylbenzidine (TMB) as colorimetric probes based on a oxidative TMB catalytic reduction. The first strategy has a linear range of 10-80 U L À1 and a detection limit of 3.0 U L À1 , and the second strategy has a linear range of 7-100 U L À1 and a detection limit of 0.05 U L À1 .…”