Research On Optical Biosensor Based On Nucleic Acid Amplification Technique And SERS Technology

The biosensor has been greatly developed in recent years, which can been used to detect various chemical substances and biological molecules, such as DNA, polypeptide, protein, enzyme with high specificity and high sensitivity.The biosensor can be used for clinical medicine, pharmaceutical analysis, molecular analysis, environmental monitoring and so on. The mainly contents are described as follows:The gold nanoparticles have excellent optical, electrical, and chemical properties, have been extensively used in the field of biology and nanotechnology. Gold nanoparticles can be used for surface enhanced Raman scattering, The Raman-active Au NPs having the advantages of ultra sensitivity, stability, low toxicity. When gold nanoparticles come in close proximity, interparticle coupling interactions result in a red shift of the surface plasmon absorption. In chapter 2, we used 30 nm gold particles to augment the surface enhanced Raman scattering signals, Raman dyes was adsorbed citrate-stabilized Au NP and Then we successfully encapsulated Raman-active Au NPs with thiol containing Phospholipid In order to increase biocompatibility and stability. Ganglioside GM1 can spontaneously insert into the lipid bilayer structure due to containing the hydrophobic ceramide. Then GM1 have been implicated as receptors for cholera toxin CTB. Due to the high affinity between ganglioside GM1 and cholera toxin CTB, gold nanoparticles come in close proximity, interparticle coupling interactions enhanced local electromagnetic field, which causing the enhancement of SERS signal.The limit of detection(LOD) of CTB was found to be 0.4 pg/mL with a wide dynamic range, from 1 pg/mL to 5 ng/mL. So the assay developed for CTB detection is rapid and sensitive.MicroRNAs(miRNAs) are a class of non-coding RNA molecules with 19-25 nucleotides, containing about 1925 bases. MicroRNAs(miRNAs) play an important role in the regulation of gene expression in various physiological processes of animal, plant and so on. The abnormal expression of miRNA in vivo are closely related to various diseases, including cancer, diabetes, cardiovascular disease, neurological diseases, autoimmune diseases and so on. These results show that miRNAs can be used as a new class of biomarkers for clinical diagnosis, drug development and disease diagnosis. In chapter 3, we used a new isothermal nucleic acid amplification technology to detect miRNA. This method employed nucleic acid cleavage enzyme and DNA polymerase for miRNA detection, with high amplification efficiency, good reproducibility, efficient inhibition for the non-specific amplification. The limit of detection(LOD) of miRNA in the assay was found to be 0.1 f M. The assay showed promising result as an a new, efficient, sensitive platform for miRNA detection...