The light modulation of the interaction of L-cysteine with porphyrins coated ZnO nanorods

The photoenhancement properties of metalloporphyrins coated ZnO nanostructures have been demon-strated for both gas and liquid sensing. In gas sensing the light favours the electron transfer from theadsorbed analyte and the porphyrin, while in solution the increased catalytic effects of metalloporphyrinsshould also be considered.In this paper we report the sensing properties of copper and manganese porphyrins coated ZnOnanorods with respect to a thiolated biomolecule such as the l-cysteine. A one-pot hydrothermal growthmethod has been used to prepare the functionalized nanostructures onto an ITO substrate. The ensembleITO–ZnO–porphyrin has been used as the working electrode in a three-electrodes amperometric setup.I/V curves have been measured at different concentrations of l-cysteine and interfering compounds. TheI/V curves have been analyzed by principal component analysis, and the first principal component hasbeen used as the sensor feature.The results show that illumination enhances the sensitivity to l-cysteine and the selectivity towards aset of non-thiolated aminoacids and organic acid