When consumed in excessive amounts, histamine (HIS), a naturally occurring component in seafood, is known to produce an unpleasant inflammatory reaction. Hence, proper histamine measurement and detection in seafood are of utmost importance. Herein, a histamine electrochemical biosensor based on a molecularly imprinted polymer (MIP) was fabricated using a gold (Au) inverse opal (IO) electrode. Prior to the MIP synthesis, the scaffold of Au IO was modified by electropolymerizing 3,4-ethylenedioxythiophene (EDOT), providing a substrate with improved electrical characteristics. The fabrication of the MIP film was achieved by electropolymerizing aniline in circumstances that preserved the chemical structure of HIS. The electron transport properties of a standard redox probe [Fe(CN) 6 ] 3−/4− were evaluated by making use of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). We describe a synergistic strategy for constructing a hierarchical recognition material using an electrochemical approach that successfully integrates three independent approaches, including semicovalent, molecular imprinting, and inverse opal structure, to enhance selectivity and sensitivity. The fabricated HIS electrochemical biosensor exhibited a linear response from 50 nM to 500 μM, a detection limit of 1.07 nM, and was selective against different analytes as well. Moreover, the fabricated HIS electrochemical biosensor outperforms its contemporary counterparts as it also exhibited low error, high accuracy, specificity, stability, and good relative standard deviation % (RSD %).

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In this work, porous silicon (P-Si) structures were fabricated by anodizing n-type monocrystalline Si into an ethanoic-HF solution. Anisotropic electrochemical etching with constant time and current density was carried out to fabricate pores and their average diameter was found to be ~700 nm. Raman spectra exhibited widened peaks for red, blue, and green wavelengths. The widened photoluminescence (PL) spectrum was blue-shifted owing to the quantum confinement effect. The P-Si exhibited an energy gap of 1.80 eV and manifested a direct bandgap. The photoresponse of the fabricated P-Si based device was studied at different laser irradiation wavelengths in the range of 400-1100 nm. The best photoresponse was observed for 785 nm wavelength and the corresponding sensitivity was determined to be 9.4%. Hence, the P-Si can potentially be used for visible range photodetectors.

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