Construction And Applications Of Bacterial Analysis And Antibacterial Platform Based On CuInSe₂ Quantum Dots

Bacterial infectious diseases pose a serious threat to the safety of human life.The abuse of antibiotics not only leads to the emergence of drug-resistant bacteria,resulting in a sharp increase of the morbidity and mortality of the bacterial infection,but also the residues of antibiotics in the environment and food also pose a great threat to human health.Traditional analysis technology of bacterial and antibiotic has disadvantages such as time consuming,requiring professional operation,low sterilization efficiency and major side effects.Therefore,it is urgent to development a simple,rapid,efficient and safe bacterial and antibiotic analysis technology.As an environment-friendly inorganic semiconductor fluorescent nanomaterial,CuInSe₂quantum dots have the advantages of good biocompatibility,small size,adjustable emission wavelength,photobleaching resistance and easy surface functionalization,it’s an ideal probe for bacterial and antibiotic analysis.Therefore,this work is based on the CuInSe₂quantum dots,improve the luminous efficiency through doped zinc element and coating Zn S,build a series of efficient fluorescent probes and composite photoelectrode,realize the rapid and quantitative detection of the bacteria and antibiotics,effective ablation in vitro bacteria,and effective monitoring and treatment of bacterial infectious diseases in the body.The main research contents are as follows:（1）An environment-friendly CuInSe₂quantum dots nano fluorescent probe was synthesized by hot-injection.The luminous efficiency of CuInSe₂quantum dots are improved by doping Zn elements.The emission peak can be tuned from 566 to 710 nm through manipulating the amount of Zn elements.The hydrophilic and biocompatibility of the Zn-CuInSe₂QDs was achieved through an efficient ligand exchange strategy.Based on the different surface structure and composition of Gram-positive bacteria and Gram-negative bacteria,Zn-CuInSe₂quantum dots can specifically bind Gram-positive bacteria,especially Staphylococcus aureus,in comparison with Gram-negative bacteria,so as to distinguish Gram-positive bacteria from negative bacteria.Different concentrations of Staphylococcus aureus combined with different amounts of Zn-CuInSe₂quantum dots,the fluorescence intensity also changed gradually,so as to realize the quantitative detection of Staphylococcus aureus.The linear detection range of the Zn-CuInSe₂quantum dots for Staphylococcus aureus is from 1×10³to 1×10¹¹CFU/m L,and the detection limit is as low as 1×10³CFU/m L.At the same time,Zn-CuInSe₂quantum dots has been applied to imaging bacteria,cells and mice in vivo,and achieved good results.The experimental results show that Zn-CuInSe₂quantum dots have broad application prospects in biological field.（2）One-dimensional TiO₂ nanowire arrays were prepared by hydrothermal method.The light absorption range of TiO₂nanowire was extended to visible region by loading Au nanoparticles and Zn-CuInSe₂quantum dots,the Zn-CuInSe₂/Au/TiO₂nanowire composite electrode with Sandwich sandwich was constructed.The photocurrent density reaches 2.2 m A/cm²,which is 7 times that of pure TiO₂nanowire.Zn-CuInSe₂/Au/TiO₂nanowire composite electrode was used as the substrate to modify the specific adapter of kanamycin with sulfhydryl group,and a labeled free photochemical adapter sensor was constructed for quantitative detection of kanamycin.In the presence of kanamycin,the aptamer could specifically capture kanamycin that are oxidized by the photogenerated holes.The recombination rate of photogenerated electron-hole pairs are inhibited,which lead to a amplified in photocurrent density response.The experimental results show that the sensor has a good linear response to kanamycin in the range of 0.2-250 n M,and the detection limit is as low as 0.2 n M.Meanwhile,the sensor has good selectivity,reproducibility and stability.By changing the aptamer type,the sensor can be used to detect other biomolecules.（3）In order to increase the photocurrent density and light absorption range of TiO₂electrode,CuInS₂quantum dots with good optical properties were synthesized by one-step method.Then,the TiO₂nanowires were loaded with CuInS₂,Zn-CuInSe₂quantum dots and Mn doped Cd S nanoparticles by immersion method and successive ioniclayeradsorptionandreactionrespectively,the Mn-Cd S/Zn-CuInSe₂/CuInS₂/TiO₂nanowire composite photoelectrode was obtained.Under the irradiation of simulated sunlight,the photocurrent density reaches 12.5m A/cm²,which is 40 times that of pure TiO₂nanowire.The three electrode system was used to study the sterilization of Escherichia coli suspension.Within 50 min,the sterilization rate of Mn-Cd S/Zn-CuInSe₂/CuInS₂/TiO₂composite electrode reached96%（50 m L,1×10⁵CFU/m L）.At the same time,the mechanism of photocatalysis sterilization was studied by adding capture agent.The results showed that the generation of photogenerated holes played a key role in the sterilization process.（4）CuInSe₂ quantum dots with near infrared second region（1000-1700 nm）were synthesized by hot injection.A thin Zn S shell was coated on the CuInSe₂quantum dots to suppress surface point defects,the luminescence intensity and stability of CuInSe₂quantum dots are increased by 4 times and 7 times,respectively.Upon 808nm excitation,CuInSe₂/Zn S quantum dots have obvious emission peak at 1020 nm.Vancomycin was modified on the water transferred CuInSe₂/Zn S quantum dots to obtain a fluorescent nano biological probe（Van-CuInSe₂/Zn S）that can target Staphylococcus aureus,which was used to monitor the bacterial infection process in vivo in real time.Meanwhile,using the photothermal effect and good biocompatibility of CuInSe₂/Zn S quantum dots,we carried out the ablation experiment of Staphylococcus aureus in vitro and in vivo in mice.The results showed that under 808nm laser irradiation,Van-CuInSe₂/Zn S quantum dots could effectively cure subcutaneous bacterial infection and wound bacterial infection in mice.It shows great potential in the treatment of bacterial infectious diseases.