Preparation of Co3O4/crumpled graphene microsphere as peroxidase mimetic for colorimetric assay of ascorbic acid

The well-dispersed Co3O4 nanoparticles-decorated crumpled graphene microsphere (CGM) was successfully prepared by aerosol-assisted frying self-assembly and annealing process. It is found that the obtained Co3O4/CGM nanohybrid possessed enhanced intrinsic peroxidase-like activity and could catalytically oxidize 3,3',5,5'-tetramethylbenzidine by H2O2 to produce a typical blue product. But the presence of ascorbic acid could induce the reduction of oxTMB to TMB, resulting in a significant blue color fading. Therefore, a simple, sensitive and selective colorimetric method to detect ascorbic acid was established with a good linear relationship (30-140 mu M) and a low detection limit of 0.19 mu M. Meanwhile, the selectivity, stability and repeatability were acceptable. It is also a facile route to fabricate nanoparticles/CGM as high-performance enzyme mimetic for colorimetric biosensing.