Synergistic co-assembly of artificial carbon nanozyme and natural peroxidase to design dual active molecularly imprinted interface for endocrine disruptor's detection in industrial effluent.

Molecular imprinting of artificial multi-walled carbon nanotubes (MWCNTs) nanozyme and natural horseradish peroxidase (HRP) enzyme on portable cellulose paper under UV light is reported to create a UV-cured HRP@MWCNTs sensing interface. The HRP@MWCNTs interface, having a target-specific site for phenols, catalyzed the oxidation of the colorless 3,3',5,5'-tetramethylbenzidine (TMB) to generate the oxidized TMB with visible blue color in the presence of exogenous hydrogen peroxide (HO). The binding of endocrine disruptors on the HRP@MWCNT surface inhibited the enzyme's active site for substrate oxidation, and subsequently color intensity was decreased. The MWCNTs nanozyme was characterized through X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, micro-Raman spectroscopy and UV-visible (UV-Vis) analysis, while each step of the HRP@MWCNTs interface was investigated via a field emission scanning electron microscope (FE-SEM), static water contact angle measurements and an optical microscope. The HRP@MWCNTs sensor was further employed to monitor three endocrine disrupter phenolic compounds including resorcinol (RE), hydroquinone (HQ) and 4-phenylphenol (4-PP). The HRP@MWCNTs sensor showed a broad linear range of 0.1 to 1000 ng/mL, with limits of detection of 0.096, 0.098 and 0.085 ng/mL for HQ, RE and 4-PP, respectively. The sensor was applied to samples from local industrial effluents provided by Gourmet Foods Industry and Malmo Foods Pvt. Limited. The innovative approach demonstrated that integrating natural enzymes' selectivity with high stability of nanozyme and subsequent molecular imprinting on the cellulose paper surface serve as a potential catalyst for the highly selective detection of phenolic compounds.