Basic Research On Microbial Detection Methods Based On Photocatalytic Materials

Rapid detection of microorganisms in the environment is of great significance to control the safety problems caused by microorganisms.However,many microbial detection methods are confronted with the problems of secondary contamination and contamination of sensitive components.The development of a multifunctional microbial detection method with bactericidal function can be a good solution for overcoming these drawbacks.In this paper,ZnO nanorod array and BiOX semiconductor were used as the basic photocatalytic materials,marine corrosive microorganism SRB and common pathogenic bacteria Escherichia coli and Staphylococcus aureus were used as the model bacteria to explore the technical means of building a microbial detection platform with photocatalytic materials.In combination with the photoelectric conversion properties of photocatalytic materials,a platform for microbial detection was constructed by modifying precious metals,in-situ generating quantum dot and bio-etching photocatalytic materials.On this basis,the bactericidal properties of noble metals or photocatalysis were further utilized to kill microorganisms,which has important guiding significance for the development of integrated multifunctional microbial detection methods with capture,removal and killing functions.The specific research content is described below:?1?A novel SRB photoelectrochemical?PEC?detection method based on biosynthesis of CdS quantum dots?QDs?sensitizing ZnO nanorod arrays was developed.ZnO nanorod arrays were synthesized on the FTO substrate via galvanic-cell-based approach and then silanized by?3-Aminopropyl?triethoxysilane?APTES?with amino groups to introduce Cd²⁺.By taking advantage of the characteristic bacterial metabolite?H₂S?reaction with Cd²⁺,CdS QDs can be biosynthesized on the surface of ZnO nanorod and significant enhancement of photocurrent due to the formation of CdS/ZnO heterostructures.The detection method can realize sensitive detection to SRB,and the detection limit is as low as 32 cfu/mL.?2?A novel SRB PEC detection method based on bio-etching sensitized photocatalytic materials was developed.BiOCl nanosheets were first synthesized by the hydrothermal method and BiOCl platform was prepared by a simplely dip-coating method.Taking advantage of the characteristic bacterial metabolite?H₂S?,BiOCl platform can be bio-etched and Bi₂S₃/BiOCl p-n heterojunction can be formed,leading to a significant enhancement photocurrent.Due to the formation of p-n heterojunction,the electron-hole recombination rate of the photoelectrochemical sensing platform can be reduced and the light absorption range can extend to the visble region,which can make the photocurrent significantly enhanced.Based on the change of the photocurrent,the detection method constructed by the bio-etching strategy can be used for sensitive to the detection of SRB with low detection limit 29 cfu/mL.?3?A multifunctional microbial electrochemical detection method consisting of vancomycin functionalized AgNPs/ZnO nanorod array was constructed.Based on the specific recognition of Van for Gram-positive bacteria,the electrochemical methods has presented high detection sensitivity to Staphylococcus aureus with a low detection limit of 330 cfu/mL and adaptable bacterial-elimination efficiency?50%?at low concentrations?1000-2000 cfu/mL?.Moreover,the platform has shown high antibacterial activity?99.99%?arising from the synergistic germicidal effect of the composited antibacterial AgNPs and Van units.?4?A integrated multifunctional PEC detection method for microorganisms with simultaneous capture,detection and killing of pathogenic bacteria was constructed.The BiOI semiconductor film is selected as photo-electricity conversion unit and visible light driven photocatalytic antibacterial unit,gold nanoparticles?AuNPs?are used as link unit and mercaptophenylboronic acid?MPBA?is chosen as antibiotic-free capture unit.Based on the reversibly binds between boronic acid group and peptidoglycan of the bacteria cell wall,the integrated PEC detection method presents excellent capture performance and high detection sensitivity to E.coli with a low detection limit of 46cfu/mL.Moreover,this multifunctional platform shows high antibacterial activity arising from the visible light driven photocatalytic effect of AuNPs/BiOI.Under visible light irradiation for 20 minutes,the 99.99%of bacteria can killed.