Enhanced mimetic enzyme activity of phosphorylated porphyrin nanocomposite induced by localized surface plasmon resonance for colorimetric assay

Abstract

Plasmon-enhanced light harvesting has been of great interest to enhance the catalytic efficiency of some composites or hybrids. The enhanced peroxidase-like activity of phosphorylated iron(III) porphyrin (TPPFe(III))-based nanocomposite, induced by localized surface plasmon resonance for a colorimetric assay, was developed in this study. Firstly, a phosphate group modification strategy was adopted to synthesize water-soluble iron(III) porphyrin materials. Then, the assynthesized TPPFe(III) was covalently attached to core-shell gold nanorods (GNRs), GNR@Au2S/AuAgS, to form TPPFe(III)-GNR@Au2S/AuAgS nanocomposite, which shows greatly enhanced peroxidase-like activity compared to TPPFe(III). A mechanism for the enhanced peroxidase-like activity of TPPFe(III)-GNR@Au2S/AuAgS was proposed, which results from a synergic effect of hot electrons excited by localized surface plasmon resonance and photogenerated electrons of the TPPFe(III), verified by experiments. Furthermore, a fast colorimetric assay for the detection of H2O2 and glucose was established based on the unique property of TPPFe(III)-GNR@Au2S/AuAgS. This colorimetric assay was applied to determine practical human serum samples; satisfactory results demonstrate this method has high accuracy. The present study would not only provide some insights into the mechanism of plasmon-activated enzyme-like reactions, but also offer new strategies for improving the catalytic activity of a mimetic enzyme.