Immobilization Of Biomolecules On Nano-tips Of Optic-fibers By Sol-gels

As the combination of the near-field optics and the biosensors, nano-optical-fiber bio-probe has great prospects in the biomedical and so on. How to immobilize biological molecule on the tips of optical-fiber nano-probe and maintain its biological activity are the key issues about the fabulacation of nano-optical-fiber bio-probe. We discuss the application of sol-gels on the immobilization of bio-molecules on the tip of nano-optical-fiber to meet the requirements of nano-optical-fiber bio-sensors.Firstly the ways of chemical etching was used to fabricate the optical-fiber nano-probe and the influence of the etching time and etchant concentration on the probe quality is studied. The experimental results show that the fiber tips with the diameters less than 100nm and smooth surfaces are obtained. Then the sols doped with glucose oxidase (GOD) as the biomolecules were fabricated using tetraethoxy silane (TEOS) as precursor, and the GOD gels were immobilized on the nano-tips of the optic-fibers by the lifting method. The conditions of retaining bioactivity of immobilized GODs , forming of gel films on the nano-fibers and controlling the size of immobilized tip of nano-probe under 1μm are discussed. The results show that the immobilized films were uniformity and the diameters of the tips were less than 1μm by the scanning electron microscope (SEM) and the GODs were examined to be immobilized on the nano-tips of optic-fibers by the electron-probe microanalyzer (EPMA). As pH=6.6, R=4.5, concentration of enzyme solutions at 20mg/mL and velocity of lifting on 2cm/min, GOD is successfully immobilized on the tips of optical-fiber nano-probe, activity of GOD is retained well, gel films are intact without fractures and size of tips of nano-probe immobilized GOD is controlled under 1μm.