Optical Detection Technology In Biological Analysis

Optical analysis is widely used in life analysis because of its fast response,small interference,simple design and easy operation.Electrochemiluminescence analysis(ECL)and surface plasmon(SPR)dark field imaging analysis are important detection methods in optical detection.ECL has the advantages of small background,high sensitivity,wide linear range,reproducibility,controllability and selectivity.SPR dark-field imaging biosensor has the advantages of high throughput,high sensitivity,label-free and high spatial and temporal resolution.In this paper,we mainly focus on the application of ECL and SPR dark-field imaging in biochemical detection.The main contents are as follows:1.A label-free aptasensor for Pb2+ detection based on electrochemiluminescence resonance energy transfer between carbon nitride nanofibers and Ru(phen)32+The electrochemiluminescent resonance energy transfer interaction(ECL-RET)between g-C3N4 nanofibers(CNNFs)and Ru(phen)32+was constructed for the high sensitivity detection of Pb2+.CNNFs were synthesized by simple pyrolysis combined with electrolysis,which has strong ECL signal and good stability.Carbon nanotube with Au can not only enhance the ECL signal of the material,but also improve the stability of the optical signal.The complementary DNA chains of Pb2+ adapter(cDNA)were modified on the electrode to form a double-stranded structure to embedded Ru(phen)32+.When adding the Pb2+,Ru(phen)32+will release from the double strand,the ECL-RET effect is blocked and the ECL signal of the system is attenuated.Quantitative analysis of Pb2+ in water samples was carried out by the strength of ECL.In addition,Exo I was added to amplify Pb2+ which can reduce the detection limit to 0.04 pM.This simple probe has wide application prospects in the analysis of water sample.2.Hybridization Behavior of Label-free Single Molecular MicroRNA using SPR and Dark Field Scattering ImagingThe real-time imaging of gold nanoparticles(GNPs)was recorded by self-assembled SPR combined with dark-field scattering imaging.In this work,we constructed a light-driven nano-oscillator probe for the study of hybridization kinetics of labeled-free single-molecule microRNA.We modify the gold surface with nano-oscillators to form a certain gap width between the gold spheres.Because microRNA can hybridize with complementary DNA on the gold surface to form a rigid double-stranded structure,the vibration of GNPs can be prevented.At the same time,we combine self-assembled SPR with scattering imaging to realize high sensitivity real-time monitoring of the change of gap width.We associate the state of microRNA unwinding and hybridization with the nano-oscillator amplitude in the system.It was concluded that the speed of microRNA hybridization is related to three-dimensional diffusion,the temperature and concentration of the reaction had an important influence on the hybridization and deconvolution of DNA.This imaging system is of great significance to the later research in single molecule detection and nanomechanics field.