Novel ultrasensitive Raman assay method based on enzyme mimetics for ultra trace of H2O2

Abstract

Enzyme mimetics have been widely applied on H2O2 assay, but it is still challenging and interesting to realize the sensitive detection for ultra-trace H2O2. Here, an ultrasensitive Raman assay method based on novel WO3@IP6-Fe3+ enzyme mimetics with peroxidase-like activity was established. WO3 microspheres (MSs) were found to have weak peroxidase-like activity, and the combination of IP6-Fe3+ and WO3 can produce stronger activity. WO3@IP6-Fe3+ MSs showed polyhedron-like structure, uniform size, and smooth surface. Although WO3@IP6-Fe3+ enzyme mimetics have low catalytic efficiency and high absorbance background, the proposed Raman method can bypass the above problems. In Raman method, high concentration of WO3@IP6-Fe3+ can be used to overcome low catalytic efficiency without high absorbance background. Moreover, 3,3′,5,5′-tetramethylbenzidine oxide has prominent characteristic Raman peak at 1608 cm−1, greatly improving the sensitivity and eliminating interference of impurities. Due to the high sensitivity and low background, Raman assay showed the ultra-low limit of detection (5.49 × 10−15 M), which was 4–7 orders of magnitude lower than other detection methods. The ultrasensitive Raman assay not only provided the possibility for the enzyme mimetics-based detection of ultra-trace H2O2, but also enable the enzyme mimetics with low activity to be applied.