| Quantum dots are widely used in biomedical directions due to their unique optical properties and properties such as electronic transitions occurring under light irradiation at specific wavelengths.More importantly,quantum dots can produce reactive oxygen under light conditions,to achieve bacterial inhibition,inhibit tumor growth and other effects.Using this characteristic of chitosan,it was prepared with chitosan,and used to preserve the preservation of lotus root to explore the preservation effect of compound antibacterial membrane.The main results of this research were:1.Syntheticed Oil-soluble ZAISe/ZnS QDs and converted with trioglycappropylic acid(MPA)to water-soluble MPA@ZAISe/ZnS QDs.UV and fluorescence spectroscopy found that the MPA@ZAISe/ZnS QDs were substantially consistent with ZAISe/ZnS QDs,but the fluorescence intensity decreased with the radiation peak redshift to 700 nm.After turning the water phase,the quantum dots gathered slightly.Through cell viability experiments,it is found that MPA@ZAISe/ZnS QDs was basically non-toxic;the reactive oxygen species(ROS)generation content of quantum dots were determined,and the fluorescence intensity of the MPA@ZAISe/ZnS QDs group under light was the highest,and the ROS generation was the largest.Through antibacterial experiments,it was found that E.coil and S.aureus treated with light MPA@ZAISe/ZnS QDs had the best antibacterial effect;the morphology of the bacteria was observed by scanning electron microscope,and found that the shapes of E.coil and S.aureus in the lighting quantum dot group are incomplete or even broken;the staining of reactive oxygen species in the bacteria also proved that a large amount of ROS is produced in the bacteria in the lighting quantum dot group.2.Syntheticed MPA@ZAISe/ZnS quantum dot/chitosan composite membrane,,chitosan membrane as the control.The thickness,tensile strength,fracture elongation,color difference and light transmittance of the composite film all increased,and the water vapor transmittance decreased to 0.37 g·mm/(m~2·h·kPa).The addition of the quantum dots changed the intermolecular hydrogen bond of the chitosan,and the telescopic vibration peak offseted of the C-H.The thermal analysis showed comparable thermal stability of both films,with two weightlessness in 0?110?and150?300?.The antibacterial experiments showed that the diameters of the compound membrane solution to E.coil and S.aureus were 19.16 mm and 25.33 mm,respectively.While the diameters of the chitosan membrane solution to E.coil and S.aureus were only 11.33 mm and 20.17 mm,indicating that the antibacterial effect was significant.3.Fresh lotus root with MPA@ZAISe/ZnS quantum dot/Chitosan composite membrane at 1 h daily illumination,compared with the Chitosan membrane group.It was found that the total phenol content of lotus root treated with the composite film was higher,and the 5.85?g/g at day 15.The content of propylene dialdehyde,polyphenol oxidase activity and peroxidase activity were relatively low,so the browning degree of the lotus root treated by the composite film was low,inhibiting the lotus root browning and maintaining a good appearance quality.Through determination of hardness and total sugar content in lotus root storage,it found that the hardness of lotus root in composite film packaging decreased slowly,reaching11826.79 g.The decomposition of the total sugar content was suppressed,and finally there was still 5.49%,to maintain a high proportion of nutrients,to ensure the taste,nutrition and flavor of the lotus root. |
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