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

Enzyme mimetics have been widely applied on H 2 O 2 assay, but it is still challenging and interesting to realize the sensitive detection for ultra-trace H 2 O 2 . Here, an ultrasensitive Raman assay method based on novel WO 3 @IP6-Fe 3+ enzyme mimetics with peroxidase-like activity was established. WO 3 microspheres (MSs) were found to have weak peroxidase-like activity, and the combination of IP6-Fe 3+ and WO 3 can produce stronger activity. WO 3 @IP6-Fe 3+ MSs showed polyhedron-like structure, uniform size, and smooth surface. Although WO 3 @IP6-Fe 3+ 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 WO 3 @IP6-Fe 3+ 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 H 2 O 2 , but also enable the enzyme mimetics with low activity to be applied.