Development And Application Of Photoelectrochemical Biosensor Based On Nanocomposites

The photoelectrochemical(PEC)detection is a newly developed analytical technique for the sensing platform,which fully integrates the photogenerated carriers and electrochemical signals for detecting the chemical reaction at the photoelectrode surface.Photoelectrochemical biosensor has applied in many fields,such as biological analysis,clinical detection,environmental protection,food inspection and so on.Such PEC sensors based on the nanocomposite materials have made a breakthrough in recent years.Herein,the semiconductor materials have been combined with two-dimensional nanostructure in PEC biosensors detection based on its large specific surface area,excellent electrical conductivity and higher photoelectric conversion efficiency.The applications of nanocomposite materials were carried out as follows:1.Here,a simple,effective method was used to synthesize WS2/CdS nanocomposite heterojunction for PEC detection.The WS2 nanosheets were deposited onto ITO substrate via electrophoretic method in water/ethanol solution,CdS nanoparticles were followed grown via facile successive ion layer absorption and reaction(SILAR)method.The high surface area,effective charge transfer and the heterojunction of the composite could improve PEC performance.The PEC sensor exhibited good sensitivity,selectivity and stability for detecting L-cysteine.The detection limit of L-cysteine was 5.29 nM and the linear ranged from 0.07 to 300?M.Moreover,the results also indicated a good anti-interference and acceptable accuracy in practical application,providing a rapid and sensitive detection method.2.A new,ultrasensitive photoelectrochemical aptasensor was established on the basis of GQDs/TiO2 NTs coupled with aptamers.In this proposal,chloramphenicol(CAP)was selected as an example of target analyte to show the analytical performances of the biosensor.Under visible-light irradiation,ascorbic acid was used as an efficient electron donor for scavenging photogenerated holes.In addition,the conduction band energy of GQDs is higher than that of TiO2,the band alignment of GQDs and TiO2 in electrolyte made the photocurrent response significantly enhanced.Aptamers of CAP were immobilized on GQDs/TiO2 NTs modified electrode by the ?–? stacking interaction between the surfaces of GQDs and the aptamers.Under the optimized measurement conditions,the fabricated PEC aptasensor showed a low limit of detection of 57.9 pM and a wide linear range from 0.5 nM to 100 n M for CAP detection,and it also exhibited good specificity,stability and reproducibility.The mentioned photoelectrochemical platform established a new,simple and fast strategy for fabrication of aptasensor,which might be widely applied in accurate detection of CAP in life analysis field.