A Study Of An Optical Biosensor Based On Porous Silicon Monolayer

Tuberculosis is still one of the biggest killers which harm people’s health all over the world and its testing method is still far from meeting the needs. New testing methods need to be developed urgently. The aim of this paper is to study a new technique that can be used for real-time detection of tuberculosis. Serological detection methods of tuberculosis have been studied for many years of history, but the practical application of the current methods are almost all in a labeled way, which brought a lot of trouble for the miniaturization of detection devices. Porous silicon is a material widely studied for its good biocompatibility and flexible surface treatment. Its raw material is crystal silicon which is full developed because of the development of integrated circuit fabrication and this make it potentially to be integrated into a circuit system. This article shows a method which combines the good merits of serological detection and our porous silicon optical biosensor which is available to provide a compact, fast, low-cost, high accuracy and label-free detection. We have made a detailed investigation on porous silicon working as biosensors. According to the survey, we chose porous silicon monolayer as our biosensor platform. By combining the theoretical and experimental analysis, we designed a porous silicon monolayer which obtained large size pore and was thin and flat enough, whose reflectance spectrum is well matched with simulated reflectance spectrum. We then oxidized our porous silicon monolayer with a proper temperature of 500℃ and successfully functionalized the layer with 3-APTES and glutaraldehyde. After that we planted anti-LAM antibody probes into the monolayer and completed the reaction experiment of anti-LAM antibody and LAM antigen. The experiment showed a good result. The sensitivity of our biosensor was 0.11nm/(μg/mL) and the detection limit was 0.45μg/mL. The detection result is a promising level and is potentially to be applied in actual detection of Tuberculosis. Our article also provided some further improvement methods of the biosensor. We can use higher concentration of anti-LAM antibody and gain a higher probe coverage rate which would achieve a higher sensitivity. We can manufacture our porous silicon platform into microarrays and use multi-platform detection which can further decrease the cost and improve the stability and accuracy.