Photothermal Properties And Bioimaging Of Noble Metal/Layered Double Hydroxide Composite Nanomaterials

As a material widely used in photothermal therapy photothermal agents,the photothermal conversion efficiency of gold nanomaterials can be improved by adjusting their morphology.In addition,by compounding gold nanomaterials with other materials,the photothermal conversion efficiency of the material can be improved,and the integration of diagnosis and treatment can be realized by giving it multiple functions.Therefore,in this paper,gold nanostars(Au Nano Stars,Au STs)with higher photothermal conversion efficiency are prepared by a simple method.Compared with gold nanoparticles(Au Nano Particles,Au NPs)and gold nanorods(Au Nano Rods,Au NRs)have significant tip-enhanced localized surface plasmon resonance(LSPR)properties,so they have a more excellent photothermal conversion effect.Afterwards,the effects of Au STs in photothermal therapy(PTT)and optical coherence tomography(OCT)were verified.Furthermore,in order to improve the photothermal conversion efficiency and biocompatibility of Au STs,we constructed Au STs and layered double hydroxide(LDH)composite nanomaterials Au STs@LDH.The Au STs@LDH composite nanomaterials have higher photothermal conversion efficiency,stronger photothermal treatment effect and significantly improved OCT imaging effect.The main research contents of this paper are as follows:1.First,Au STs are prepared by seed-mediated growth method.The morphology of Au STs is observed by transmission electron microscopy(TEM),and the structure of Au STs is analyzed by X-ray diffraction analyzer(XRD).The size and physical properties of Au STs are studied by near-infrared spectrophotometer and particle size analyzer.It is proved that the as-prepared Au STs are multi-spike-like structures with a length of about 30 nm grown on a 50 nm nuclei,then show an obvious Au crystal phase and a strong absorption intensity at 600-900 nm.It is beneficial to its application as a photothermal agent in photothermal therapy.2.The photothermal properties of Au STs are investigated.The application effect of Au STs as a therapeutic agent in photothermal therapy and optical coherence tomography is obtained by measuring the time-temperature curve of Au STs,thiazolyl blue colorimetry(MTT)method and OCT imaging of simulated tissue phantoms.In the study of photothermal properties,the temperature rise value of Au STs is 36.9 °C,and its photothermal conversion efficiency was 42%.And has low biological toxicity.In vitro photothermal therapy,Au STs as photothermal agents can kill human breast cancer(MCF-7)cells with a high killing efficiency of 63% after 10 min of laser irradiation.And the signal intensity in the simulated tissue optical coherence tomography was also increased by about5 times.3.A facile one-pot synthesis method is developed to construct Au STs@LDH composite nanomaterials.The morphology of Au STs@LDH is studied by transmission electron microscopy,the structure and elemental information of Au STs@LDH are analyzed by XRD,FTIR,scanning electron microscopy,and EDS studies,and then UV-Vis-NIR spectrophotometer is used to analyze the structure and element information of Au STs@LDH,Zeta potential tester to characterize the physical properties of Au STs@LDH composite nanomaterials.It is proved that Au STs and LDH are successfully prepared as Au STs@LDH composite nanomaterials,and their crystal phase structure is stable,and the absorption spectrum test shows that there is a strong absorption between 650-850 nm.4.The photothermal properties of Au STs@LDH are investigated.Due to the interaction between Au STs and LDH,the larger specific surface area has a larger absorption cross-section.At the same time,LDH limits the heated Brownian motion of Au STs,and more free electrons on the gold surface also bring stronger LSPR.effect,its photothermal conversion efficiency η=64%.In addition,the application of Au STs@LDH as a diagnostic agent in in vitro photothermal therapy and optical coherence tomography is explored,and Au STs@LDH is used as a contrast agent to realize the imaging of the eyes of crucian carp.Among them,the temperature limit of Au STs@LDH in the photothermal test is about79.4 °C,which is significantly improved compared with single Au STs,and has extremely low biological toxicity.At the same time,it has shown obvious effects in in vitro photothermal therapy and optical coherence tomography of simulated tissue.