Immobilization of Concanavalin A on iron oxide magnetic nanoparticles. Effect of Bovine Serum Albumin in the recognition interactions of the lectin

Abstract

Iron oxide magnetic nanoparticles are engaging platforms for diverse nanobiotechnological applications, such as proteins separation and glico-biosensing mediated by the surface functionalization with lectins as recognition elements. We present a new strategy for the union of the lectin Concanavalin A (ConA) at the surface of carboxylated iron oxide magnetic nanoparticles (IOMNPs-Ar-COOH). The nanoparticles were obtained by a single step synthesis in the presence of the aryl diazonium salt derived from 4-aminobenzoic acid. The spontaneous grafting allowed to obtain carboxylic acid covalently functionalized magnetite nanoparticles with the carboxylate group exposed to the solution, as was evidenced through the exhaustive characterization by XRD, FTIR, Raman spectroscopy, and TEM analysis. The nanoparticles of Fe3O4 of (6.6 ± 0.7) nm diameter exhibited good magnetic field responsiveness towards an external magnet and stability towards the environmental oxidation. The carboxylic acid groups exposed were used for the conjugation with ConA and participated in its adsorption onto the surface. The ability of ConA to recognize the glycoprotein Glucose Oxidase (GOx) was analyzed in real time by surface plasmon resonance. These results were correlated with the responses obtained by electrochemical methods (electrochemical impedance spectroscopy, and cyclic voltammetry). Considering the possible applications of this nanomaterial, we also evaluate the effect of Bovine Serum Albumin (BSA) in the recognition capability of ConA. Our work let us to conclude that although ConA does not specifically recognize BSA, this protein alters the affinity of ConA for GOx giving an interesting vision of the behaviour of this hybrid nanomaterial in physiological mediums or other matrixes with high concentration of proteins where this nanomaterial could be employed e.g., in a biosensor or the separation of a glycoprotein, among others.