Surface modification of aluminum oxide for biosensing application

The surface modification for immobilization of antibodies on the aluminum oxide surface was developed for biosensing application. The aluminum oxide has been received much attention since it has various advantages including low cost, hardness, resistance to organic solvents, and high capacitance. In addition, the aluminum oxide can prevent the leakage current in the electrical detection. For development of the protein anchorable surface, the aluminum oxide chip was treated with oxygen plasma and directly immersed in ethanol and toluene solution of 3-aminopropyltriethoxysilane (APTES). Next, this amine modified chip was immersed in the glutaraldehyde solution that contained sodium cyanoborohydride. Finally, the fluorescent materials, the Alexa 488, and the FITC conjugated anti-IgG were reacted to the aldehyde-modified surface. To verify the modified surface, the intensity of the fluorescence was measured and compared. The higher intensity of the fluorescence was observed when the APTES was dissolved in toluene rather than in ethanol. From the highest intensity of the fluorescence observed, the FITC conjugated anti-IgG was well immobilized on the modified surface of the aluminum oxide with APTES and glutaraldehyde. Thus, the proposed surface modification method can immobilize the proteins including antibodies, and can be applied for the various biological researches including biosensors and biochips.