Fabrication of protein chips based on 3-aminopropyltriethoxysilane as a monolayer

Although 3-aminopropyltriethoxysilane (APTES) is widely adopted as a monolayer in biosensors, experimental silanization takes at least 1 h at high temperature. Therefore, the feasibility of the silanization with APTES in a short reaction time and at room temperature was investigated. The surface modification of glass slides using a self-assembled monolayer of APTES with a concentration of 10% was studied by immobilizing FITC. APTES was successfully immobilized on the glass slide. The effect of reaction temperature and time of silanization were investigated. Various silanization conditions of APTES were examined by contact angle measurement and fluorescence microscopy. The surface of glass patterns with a gold thin film as background was characterized by determining the fluorescent intensities following the immobilization of fluorescein isothiocyanate (FITC), protein A-FITC, antimouse IgG-FITC and sheep anti-bovine albumin-FITC. The normalized fluorescent intensity indicated that a short period (4 min) of silanization at 25°C suffices to form an APTES thin film by the immobilization of protein A on a glass surface. Such a condition does not require microheaters and temperature sensors in a microfluidic system, which will significantly reduce the manufacturing process, cost, and reaction time in the future.