Facile enzymatic preparation of fluorescent conjugated polymers of phenols and their application in sensing

Abstract

ABSTRACTThe recognized drawback of utilizing metal catalysts for the synthesis of fluorescent conjugated polymers (CP) is the requirement for extensive purification to ensure complete removal of residual catalyst that would otherwise quench the fluorescence. In addition, typical synthesis of fluorescent CP involves multiple steps, monomers and solvents with varying levels of toxicity. This work demonstrates the possibility of utilizing oxidoreductase enzymes as the catalyst, for the one step polymerization of naturally occurring phenols to yield fluorescent conjugated polyphenols. The metal in the active site of the enzyme remains chelated during the synthesis allowing the polymers to be fluorescent as synthesized without the need for extensive purification. Three natural phenols, 4‐hydroxyphenylacetic acid, hydroxytyrosol, and chlorogenic acid were polymerized using Horseradish peroxidase as the biocatalyst. Spectroscopic techniques, UV–vis, Fourier transform infrared Spectroscopy–Attenuated Total Reflectance, and fluorescence, are used to characterize chemical structure and photoluminescence of these polymers. The polyphenols exhibit fluorescence with significant stokes shift in the range 30–100 nm rendering them useful in fluorescence quenching‐based sensors. Preliminary studies on use of these polymers, in the detection of nitro‐aromatic compounds in solution through using fluorescence‐quenching are also presented. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46496.