title: Scleroglucan-borax hydrogel: a flexible tool for redox protein immobilization.
abstract: A highly stable biological film was prepared by casting an aqueous dispersion of protein and composite hydrogel obtained from the polysaccharide Scleroglucan (Sclg) and borax as a cross-linking agent. Heme proteins, such as hemoglobin (Hb), myoglobin (Mb), and horseradish peroxidase (HRP), were chosen as model proteins to investigate the immobilized system. A pair of well-defined quasi-reversible redox peaks, characteristics of the protein heme FeII/FeIII redox couples, were obtained at the Sclg-borax/proteins films on pyrolytic graphite (PG) electrodes, as a consequence of the direct electron transfer between the protein and the PG electrode. A full characterization of the electron transfer kinetic was performed by opportunely modeling data obtained from cyclic voltammetry and square wave voltammetry experiments. The efficiency of our cross-linking approach was investigated by studying the influence of different borax groups percentage in the Sclg matrix, revealing the versatility of this hydrogel in the immobilization of redox proteins. The native conformation of the three heme proteins entrapped in the hydrogel films were proved to be unchanged, reflected by the unaltered Soret adsorption band and by the catalytic activity toward hydrogen peroxide (H2O2). The main kinetic parameters, such as the apparent Michaelis-Menten constant, for the electrocatalytic reaction were also evaluated. The peculiar characteristics of Sclg-borax matrix make it possible to find wide opportunities as proteins immobilizing agent for studies of direct electrochemistry and biosensors development.
authors.affiliation: Department of Chemistry and Drug Technologies, Sapienza University of Rome, P.le Aldo Moro, 5 00185 Rome, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Frasconi
authors.forename: Sara
authors.initials: S
authors.lastname: Rea
authors.forename: Pietro
authors.initials: P
authors.lastname: Matricardi
authors.forename: Gabriele
authors.initials: G
authors.lastname: Favero
authors.forename: Franco
authors.initials: F
authors.lastname: Mazzei
mesh_terms: D001881:Borates / Q000737:chemistry*; D003432:Cross-Linking Reagents / Q000737:chemistry; D004563:Electrochemistry; D004566:Electrodes; D005936:Glucans / Q000737:chemistry* / Q000648:ultrastructure; D006454:Hemoglobins / Q000737:chemistry; D006735:Horseradish Peroxidase / Q000737:chemistry; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D055767:Immobilized Proteins / Q000737:chemistry* / Q000648:ultrastructure; D007700:Kinetics; D009211:Myoglobin / Q000737:chemistry; D010084:Oxidation-Reduction; D013053:Spectrophotometry
chemical_list: D001881:Borates; D003432:Cross-Linking Reagents; D005936:Glucans; D006454:Hemoglobins; D055767:Immobilized Proteins; D009211:Myoglobin; C018851:borax; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; C045938:scleroglucan; D006861:Hydrogen Peroxide; D006735:Horseradish Peroxidase