Langmuir Aggregation of Eosin-Y in Protein and its Application

Abstract

The microsurface adsorption–spectral correction (MSASC) technique is described and applied to the investigation of the interaction of eosin-Y (EOY) with proteins at pH 3.8. The microelectrostatic fields in proteins cause the aggregation of EOY and it obeys Langmuir isothermal adsorption. Results have shown that the binding ratio of EOY to bovine serum albumin (BSA), ovalbumin (OVA), concanavalin A (ConA), and human γ-globulin (γ-G) are 77 : 1, 23 : 1, 4 : 1, and 83 : 1, the adsorption constants of the complexes were calculated to be 2.82×10⁶, 1.70×10⁵, 1.80×10⁵, and 2.49×10⁴ M^–1, and their molar absorptivities 3.20×10⁶, 1.21×10⁶, 1.35×10⁵, and 5.27×10⁶ L mol^–1 cm^–1 at 540 nm. The adsorption reaction has been applied to the quantitative detection of proteins in samples with satisfactory results.