Biochemical Molecules Detection Technology Based On Nano-gold Photothermal Effect And Laser Backscattering Interference

In recent years,water safety and quality has increasingly become the key health concern,and the corresponding testing methods have also been gradually developed.Now,the traditional detection methods,such as atomic absorption spectrometry(AAS)and high-performance liquid chromatography(HPLC),always require large-scale instruments.Although these methods have good reliability,they had the disadvantages of long cycle and high cost.Therefore,researchers have been constantly studied new methods.Owing to its great monochromaticity and coherence,laser technology is widely used in various fields of detection.Because of its high sensitivity and other ments,laser back-scattering interferometry(BSI)technology has attracted many attentions.In this work,a gold-aptamer structure detection system with photothermal effect laser back-scattering interferometry(PT-BSI)is developed to detect As(Ⅲ)and SDM in water.The main research contents include the following:1.The main principle of the PT-BSI is that a laser beam emitted from one laser device and passed through the mirror to vertically irradiate the detection area of the capillary.The laser then reflected and refracted at multiple angles inside the inner and outer walls of the capillary.The reflected light will interfere with the refracted light around the capillary center within 360° to produce interference fringes.After the increasing of the solution temperature due to the photothermal effect,the refractive index of the solution would change,then the position of the interference striped moved.The distance of movement is related with the change of refractive index of solution.In order to avoid the influence of the ambient temperature,the PID temperature control system was used to fix the temperature of the detection system at 25± 0.007℃.2.Synthesis and calibration of nanogold particles: Nanogold particles with a diameter of 10 nm were prepared by sodium citrate reduction of chloroauric acid.The dispersed nano-gold solution was rad and the nano-gold particles were weakly negative.When the aptamer solution was added to the nanogold solution,the aptamer was conjugated with the dispersed nano-gold particles,forming a protective film.Thus the nano-gold particles were approximately electrically neutral,forming a nano-gold-aptamer-structure detection probe.3.This developed device was used for the detection of As(Ⅲ)and SDM in water.Based on goldaptamer structure and PT-BSI,the detection limit was 127μg/L for As(Ⅲ),255.6 μg/L for SDM.Finally,the selectivity of As(Ⅲ)detection was evaluated with other irons(Fe(Ⅲ),Cu(Ⅱ),Ca(Ⅱ),Ni(Ⅰ),Na(Ⅰ),Cr(Ⅲ)),the selectivity of SDM detection was evaluated with other antibiotic(chloramphenicol,oxytetracycline,roxithromycin,ofloxacin,ciprofloxacin,cephalosporin,amoxicillin).The obvious advantages of reliability and sensitivity confirm that the goldaptamer structure and PT-BSI system holds promise for food,environment,and medical detection.