Electrochemical Biosensor Detection Of MicroRNA And Flow Injection Chemiluminescence Detection Of Cefsulodin Sodium

MicroRNAs(miRNAs) play vital roles in regulating gene expression and cellular processes. Dysregulation of miRNAs has been associated with a variety of diseases, which make them promising biomarkers. Electrochemical biosensor is of great advantages such as low-cost, small-size, simplicity of instrumentation, ease to operate, short reaction time, high sensitivity and good selectivity. It has been widely used in clinical diagnosis and environmental monitoring in recent years. Hybridization chain reaction(HCR) is an enzyme-free, isothermal technology for the amplification of DNA sequences,In this work, a simple and ultrasensitive electrochemical biosensor was developed for detection of target miRNA using DNA-based hybridization chain reaction(HCR) and biotin-strepavidin based amplification. In the presence of target mi RNA, the hairpin DNA capture probes immobilized on gold electrode surface were opened. Then DNA initiator strands hybridized with the opened capture probes and triggered HCR, finally, a long nicked double-helix DNA structure was developed. Streptavidin is employed for signal amplification via binding with biotin labeled on the two hairpin DNA probes which take part in the HCR. The proposed biosensor presented a high sensitivity for determination of target miRNA down to 0.56 fM with a linear range from 1 fM to 100 pM and high specificity that discriminates target miRNA from mismatched miRNAs. The method was successfully applied to the determination of miRNA spiked into human total RNA samples. Therefore, the biosensor might have potential clinical application for miRNA detection in biomedical research and clinical diagnosis.Cefsulodine Sodium(CFS) belongs to the third generation cephalosporin and have good resistance to the pseudomonas aeruginosa. CFS also has good effect for the drug resistance pseudomonas aeruginosa. Flow injection analysis has some advantages such as high sensitivity, good stability and low cost. In recent years, it often coupled with chemiluminescence detection to construct a flow injection chemiluminescence assay and has been widely used in biomedicine, environmental monitoring, food analysis and other fields.In this study, cefsulodine sodium was found to enhance the chemiluminescence of the luminol-potassium ferricyanide reaction system in alkaline condition. According to this fact, a new flow injection chemiluminescence method for the detection of cefsulodine sodium was developed. The linear range for cefsulodine sodium was 5.0�10-7~2.0�10-5 g/m L, and the limit of detection was 3.2�10-7 g/m L. The relative standard deviation was 2.25% for the determination of 4.0�10-6 g/m L cefsulodine sodium(n=11). The method has been applied to the determination of cefsulodine sodium powdery reagent and the results were in satisfactory.