Selective estimation of C-reactive protein in serum using polymeric formulations without antibody

A new method without employing antibody for the estimation of C-reactive protein (CRP) in serum is presented. The method centres on the variation of fluorescence intensity of pair copolymers, containing a fluorophore (Fluoreseinamine isomer 1) and O-Phosphorylethanolamine (PEA), a ligand of CRP. We found that the fluorescence of fluorophore attached copolymer was quenched in the presence of copolymer conjugated with PEA. The fluorescence emission was, however, increased when CRP was added into the solution of the copolymers. The intensity of fluorescence increased linearly up to a concentration of 250 ng/mL of CRP and then attained a constant value which remains the same with additional quantity of CRP. This observation was assigned to the saturation of the binding sites. Other proteins namely, albumin, fibrinogen and globulin did not show any interference in the measurement. The method was used for the estimation of CRP in blood serum of patients reported to the cardiology and the data compared well with the quantity of CRP in the same samples estimated using immunoassay method. Our results suggest that the polymer pick up CRP selectively from a complex milieu like serum. The method is simple, cost effective and sensitive with a detection limit of 20 ng/mL. (C) 2010 Elsevier B.V. All rights reserved.