Opticall Detection Of Biomolecules Based On Microfluidics And Nanoparticles

In the detection of biomolecules related to diseases, the requirements in technologies with high through put, high sensitivity and easily handling significantly increase. For instance, the detection of nucleic aicd with traditional methods such as PCR could not afford the capability of high throughput and miniaturization; and in the measurement of tumor markers for diagnostics of cancer, the concentration of tumor markers are usually at very low concentration, though some approaches such as radio immunoassays (RIA) can perform the mission, the use of radioactive isotope is harmful to human body and environment, and the way is not easy to handle; glucose is related to many dieases, but traditional ways for monitoring glucose are mostly based on enzyme, electrochemical and fluorescencent methods. Enzyme could be easily denatured, and electrochemical and fluorescencent methods often need complex facilities, thus the application and popularization of the ways for detection of glucose based on these traditional methods are always confined. The developments of nanotechnology in recent years encourage us to solve above problems of detection of biomolecules by using these new tools. In the paper, we developed three optical detection approaches for nuleic acid, tumor marker and glucose.Parallel micro channels were fabricated by using Polydimethylsiloxane (PDMS). We analyzed the specific target sequence of flu H1NA by combing microchannels with loop mediated isothermal amplification (LAMP). When target sequence exsited, they would be amplified and the by-product white precipitate of magnesium pyrophosphate formed. Naked eye could be used to distinguish the positive samples or negative ones. Moreover, we designed a channel integrated with optical fibre sensor to monitor the change of turbidity in solution for real time measurement of LAMP process. Compared with traditional methods in PCR tubes, the method was high throughput and easy to read out. CdTe quantum dots with characteristic of electrochemiluminescence were used to label the secondary antibodies. And the ITO electrode was modified by the antibodies recognizing another epitope of AFP antigens. When AFP was in present, immobilized antibodies, antigens and CdTe quantum dots labeled secondary antibodies would form sandwich immuno complex on the surface of electrode. Then potential was applied, the electrochemiluminescence signal would generate. The intensity of the signal was related to the concentration of antigens. The lowest concentration of antigens could be detected was 10 ng/mL. We also evaluated the efficiency of crosslink reaction with different concentrations of EDC/NHS by high performance liquid chromatography (HPLC).In this paper, a new way for detecting glucose based on gold nanoparticles assisted silver mirror reaction was reported. When glucose exsited in the system, the silver ion would be reduce by glucose to sliver shell around the Au NPs, thus characteristic adsorption of Au NPs at 520 nm disappeared, and the characteristic adsorption of silver at 410 nm increased. The absorbance at 410 nm is proportional to the glucose concentration within the range of 0.04 mM to 1 mM, and the lowest concentration that can be distinguished by the naked eye is 10 nM. The interferences of the system from many aspects were investigated, and there was a good signal response when we applied the method to measure different concentrations of glucose in serum.