Research Of Microcantilever Array Biochemical Sensing Technique Based On Aptamer

Microcantilever biochemical sensing technology is a new analytical method which is derived from Atomic Force Microscope(AFM).Micro-electromechanical system(MEMS),mechanics,biology and chemistry are integrated in microcantilever sensing technology.With microcantilever,the simplest device of MEMS,we can detect the resonance frequency shift or the deflection of microcantilever for monitoring the interaction on the surface of microcantilever in a real-time manner.This method has the advantages of highly sensitive,label-free and real-time.Microcantilever array consists several cantilevers in an array.The biochemical sensing experiments with microcantilever arrays can realize the high throughput detection and decrease the noise induced by the environment.The detection based on microcantilever array has great prospect in biochemical sensing field.In this dissertation,based on the available microcantilever array sensor platforms,several biochemical detection researches of cancer biomarker and toxic substances in food security field were carried out with antibody and aptamer used as the probe molecules.The main work of the dissertation is as follows:On microcantilever array sensing platform based on optical fibers,the influence of different concentrations of methyl alcohol,ethyl alcohol and acetone to the sensing system was detected in static mode.And the influence of glycerine to the change of resonance frequency was also detected.With the sensing platform based on optical fibers,different concentrations of Hg2+ was detected and the concentrations was from 5 ng/mL to 100 ng/mL.The results showed good consistency and the capacity for quantitative detection of Hg2+.The preliminary research to directly verify the modification of aptamer to the microcantilever was carried out.Fluorescence labelled aptamer was modified to microcantilever array and observed with fluorescence microscope.The results showed that the fluorescence of microcantilever was not obvious and there were fluorescence observed on the base of microcantilever array.New observation method with enzyme labelled aptamer was suggested.The enzyme could catalyze substrate and change the color of substrate,which might be detected and then demonstrate the modification of aptamer to microcantilever.Cancer biomarker Her2 was detected with antibody used as probe molecule in both dynamic mode and static mode on microcantilever array sensing platforms.The antibody was immobilized on the surface of microcantilever array with the self-assembled mercaptan.In dynamic mode,different concentrations of Her2 were detected with monitoring the resonance frequency shift of microcantilever and the minimum detection concentration was 50 ng/mL.In static mode of the microcantilever array sensor system based on optical fibers,the deflection of microcantilever was monitored in real-time for the detection of Her2 and the minimum detection concentration was 50 ng/mL.ELISA experiments verified the activity of antibody which was modified to the surface of microcantilever.Contrast experiments in both dynamic and static modes demonstrated the responses of microcantilever arrays were caused by the specific interaction of antibody and antigen.With aptamer used as the probe molecule,the biochemical detection of profenofos and okadaic acid(OA)was carried out on the microcantilever array sensor system based on optical fibers.An aptamer-based microcantilever array sensor was operated in static mode to detect profenofos,with the advantages of label-free,highly sensitive,one-step immobilization,quantitative and real-time.The microcantilever array was functionalized with aptamer and then the specific binding of profenofos to aptamer induced a deflection of the microcantilever.The microcantilever deflection showed a positive relationship with profenofos concentration from 5 ng/mL to 1000 ng/mL and the detection limit was 1.3 ng/mL.Contrast experiments verified the selectivity of the sensor.Additionally,experiment of profenofos detection in vegetable sample solution was conducted.Aptamer functionalized microcantilever array sensor was used to detect different concentrations of OA and achieved good consistency.The average deflection of microcantilever array showed a positive relationship with OA concentration and the detection concentrations were from 5 ng/mL to 100 ng/mL.