The Application Of Mesoporous Silica Coated Gold Nanorods In Biological Detection And Photothermal Therapy

As one distinctive nanostructure of noble mental nanoparticles,Great attention iscurrently drawn towards gold nanorods（AuNRs）due to its LSPR properties and derived photothermal conversion properties.Much investigation based on AuNRs were focus on the applications in biological detection and photothermal therapy.Despite of their extraordinary merits,the direct use of AuNRs is still unrealistic due to the presence of highly toxic,poor surface and small specific surface area.Here,we improved the properties of AuNRs by coating AuNRs with biocompatible silica shell,which was used to extending the application of AuNRs in biological detection as well as cancer therapy.Combined AuNRs with mesoporous silica,this paper mainly carry out the following two works:（1）Construct LSPR sensor based on AuNRs@Si O₂ for detecting E.coli O157:H7.The AuNRs@Si O₂ with mesoporous silica was synthesized according to the traditional method,in which the Hexadecyl trimethyl ammonium Bromide（CTAB）served as template.The silica thickness was tuable via controlling the concentration of CTAB and the amounts of tetraethyl orthosilicate（TEOS）.Furthermore,the sensitivity of AuNRs@Si O₂ was optimized by sensitivity test with changing the refractive index of the environment.The results showed that the AuNRs@Si O₂ with thinner shell was more sensitive to the change of the refractive index and the highest sensitivity was up to 390 nm/RIU.Finally,the AuNRs@Si O₂ with optimizing thickness was applied in detecting E.coli O157:H7.The detection results presented that the LSPR shift of AuNRs@Si O₂ was linearly dependent on the concentration of E.coli O157:H7.What’s more,the detection limit achieved 10 CFU and was much lower than that of conventional methods,which lays the foundation for the quantification and the highly sensitive detection of E.coli O157:H7.（2）A smart tumor-targeted drug delivery nano-platform based on thermo-responsive polymer gated AuNRs@Si O₂.The block polymer of NIPAM and AAm,which enabled the AuNRs@Si O₂ thermosensitivity,was grafted on the AuNRs@Si O₂ nanostructures according to the self-initiated photo-grafted photopolymerization（SIPGP）method.The AuNRs could be employed in the photothermal therapy application due to the LSPR properties.Mesoporous silica was chosen to improve the biocompatibility and stability of AuNRs as well as increasing the drug loading.Moreover,the thermosensitive polymer endowed the system switching response properties.To investigate in depth the switching response of the thermosensitive system,the drug release properties in vitro was explored,in which doxorubicin hydrochloride（DOX）served as model drug.The drug release rate presented huge difference under different temperature and p H environment.What’s more,the drug release rate showed dramatic increase with the near infrared light irradiation.This laid foundation for the study of solving the problem of traditional controlled slow release and achieving intracellular switching responsed drug release properties.