Use of chemically modified thermoresponsive copolymers for the detection of C-reactive protein

Fluorescence intensity of N-isopropylacrylamide-glycidyl methacrylate (NIPAAm-GMA) copolymer conjugated with fluoreseinamine isomer1 was found to decrease considerably in the presence of NIPAAm-GMA copolymer containing O-phosphorylethanolamine (PEA), the specific ligand of C-reactive protein (CRP). The decrease in the emission intensity was reasoned due to the quenching of the fluorescence through the interaction of the polymer chains. The emission intensity was, however, found to increase rapidly when CRP was added in to the solution containing the polymers. The intensity of fluorescence emission was increased by five-fold in the presence of CRP as low as 20 ng mL(-1). Albumin, the major blood protein, did not show any interference in the emission. The presence of a low molecular protein, cytochrome c, on the fluorescence spectra was also studied and this protein also found not have any influence in binding of CRP onto the ligand indicating that other proteins irrespective of their molecular weights did not influence the measurement. A definite correlation was found between the concentration of CRP and the fluorescence intensity. The method appears to be very sensitive and easy to perform. The study reflects, for the first time, the scope of using copolymeric combinations for the measurement of CRP without the use of antibody.