Synthesis and intrinsic enzyme-like activity of β-MnOOH nanoplates

Single phase beta-MnOOH with high crystallinity was successfully synthesized by a method combining controlled hydrothermal synthesis and subsequently air oxidation. The results of X-ray diffraction, scanning electron microscopy, transmission electron microscopy showed that the as-prepared beta-MnOOH had a thin hexagonal layered structure, uniform particle size distribution, and good dispersion. The presence of hydrazine and suitable hydrothermal temperature (140 degrees C) are of the two key factors to synthesize pure phase,beta-MnOOH. The synthesized beta-MnOOH nanoplates could catalyze the oxidation reaction of peroxidase substrate 3,3',5,5'-tetramethylbenzidine in the absence of H2O2 to produce a blue color change, indicating an intrinsic enzyme-like activity. Furthermore, as an inorganic enzyme mimic, beta-MnOOH also showed high stability, which facilitates its potential applications as enzyme mimics in biosensor, biotechnology, and biomedicine. (C) 2015 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.