Determination of gamma-globulin at nanogram levels by its quenching effect on the fluorescence of a red emitting conjugated polymer

Abstract

In this study, a novel fluorescence sensing strategy has been proposed for γ-globulin (γ-IgG) assay, based on the measurement of quenched fluorescence signals resulting from the interaction of a water-soluble conjugated polymer, poly[2,5-di(propyloxysulfonate)-1,4-phenylene-ethynylene-9,10-anthrylene] (referred to as PPEASO₃), with γ-IgG. The red fluorescence of PPEASO₃ at 682 nm is greatly quenched when trace amounts of γ-IgG are added. Under optimal experimental conditions, the quenched fluorescence intensity is linear with the concentration of γ-IgG in the range 5–1000 ng mL⁻¹ with a detection limit of 0.8 ng mL⁻¹. The proposed method is simple and sensitive for the detection of trace amounts of γ-IgG and used to determine the content of γ-IgG in synthetic samples with satisfactory results.