Nonconjugated Polyelectrolyte as Efficient Fluorescence Quencher and Their Applications as Biosensors: Polymer-Polymer Interaction

Abstract

A simple fluorescence quenching method for the quantitation in serum of an acute phase reactant, C-reactive protein (CRP), which can differentiate between viral and bacterial infections, is described, where material and reagent costs are minimal. The study harnesses a fluorescence quenching between a nonfluorescent polyelectrolyte containing a ligand (O-phosphorylethanolamine, PEA) and fluorophore (fluorescamine isomer 1) containing polyelectrolyte. The quenching was attributed due to strong polymer-polymer interaction through intermolecular hydrogen bonding. The nonlinear behaviour of Stern-Volmer plot indicates a binding induced quenching, that is, static quenching. However, fluorescence was found to increase in presence of C-reactive protein, due to the specific molecular recognition occurring between CRP and PEA, thereby excluding fluorophore containing chain. A definite correlation was found between concentration of CRP and fluorescence intensity and the method exhibited a linear relationship in the range of 40–360 ng/mL with a detection limit of 30 ± 2 ng/mL. The antibody free method was successfully applied for the analysis of CRP in human serum samples and the method showed good correlation with hospital measurements (y=1.0313x−0.1423;  n=32;  R=0.9998,  P<0.0001). Thus the fluorescence based polyelectrolyte biosensor is a potential system for rapid, and antibody free platform for CRP detection.