The study of bio-platform based on C-Au film

• Main Authors: You-Jiun Chen, 陳宥竣
• Other Authors: Hsiung Chou
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/f5d3bp

碩士 === 國立中山大學 === 物理學系研究所 === 106 === Bio-sensor is one of most important development today for its importance to human health. For example, the blood glucose meter is a successful commercial biosensor. Its working principle is based on the reaction between the glucose oxidase, which can detect concentration of glucose in blood by reduction-oxidation reaction, with glucose, to bring glucose return to oxidation state, by chemical mediator and generate current on electrode making the blood glucose meter to detect glucose reliably. But most of biosensor can only detect one kind of biomolecules, to make a bio-platform that can transfer to various kind of bio-sensor by bonding with different antibodies is very important for future bio-sensor developement. This subject is to develop a biosensor platform that based on detecting the change in electrical properties when absorbs the biomolecules. Gold play the crucial role of the transducer of biosensor based on its capability to bond with antibodies and modify amorphous carbon film that surrounds it, in such a way to promote a variable range hopping(VRH) transmission. The sp3 orbital in an insulating amorphous carbon film can be partially modified into a sp2 orbital similar to graphene structure by the interface effect with nano-gold particles. When the density of the modified region exceeds a percolation threshold, there will be a chance to generate a path for the electrons to conduct between the regions bu a variable range hopping electrical transmission mechanism. Since the electrical conductivity is inversely proportional to the twelfth power of the electron average hopping distance the electrical measurement can detect tiny changes in the average hopping distance. Any bonding of antibody with antigen will change the carbon modified area and indirectly the change of hopping conduction, therefore it is possible to develop Au embed Carbon film as a platform of the biosensor with extremely high sensitivity. The first step of the experimental process is to spray Au nanoparticles on the quartz substrate. This part is supported and produced by the laboratory of Professor Yang Hung-Wei of Sun Yat-Sen University department of Medical Science & Technology . Secondly, we use DC sputtering to deposit carbon film on top of the gold nano-particles. In order to prevent the gold particles from being completely covered by the carbon film, an sputtering with an non-perpendicular direction to the substrate is used. The shadow effect by Au nanoparticles will produce inhomogeneous thickness of Carbon along Au particles, and the RTA process may enhance the interface effect between Au and amorphous C film. The Conductivity Atomic Force Microscope (CAFM) is used to measure the conductivity to detect whether the gold is exposed and how the amorphous Carbo is modified. Atomic Force Microscope (AFM) tapping mode and Transmission Electron Microscope (TEM) were used to observe the concentration of gold and the deposition of carbon film. Image show Au nanoparticles are quite dense, and the carbon film is indeed affected by the gold particles to create a shadow and the modification effects. TEM observed that the interface between carbon film and gold is modified. The CAFM shows that the resistance around the particles is smaller than center which could be due to the inhomogeneous deposition and the modification effect. The electrical measurement as a function of temperature shows clear variable range hopping transmission mechanism above 100K. Based on these results, the present experiment has reached the initial goal of this research. Future work is to cooperate with the laboratory of Professor Hung-Wei Yang to attach antibodies on gold to observe whether the distance of hopping has be changed by the charge transfer.