Synthesis And Properties Of GNR@Fe₃O₄ Composite Nanomaterials For Integrated Cancer Diagnosis And Treatment

At present,cancer with extremely high morbidity and mortality has become a very serious public health problem worldwide.As a new treatment method for cancer,photothermal therapy(PTT)has the advantages of simple and effective operation,light pain,and rapid recovery,Showing the potential to replace traditional resection methods such as surgical resection,chemotherapy,and radiotherapy.In the past ten years,the synthesis and biomedicine of functional nanomaterials have attracted more and more attention of scientists,and the assembly of GNRs with excellent photothermal properties and Fe₃O₄MNPs with superparamagnetism,with the potential of magnetic resonance(MRI)imaging-guided tumor photothermal therapy.Therefore,based on previous studies,GNRs,Fe₃O₄MNPs,and GNRs@Fe₃O₄magnetic nanocomposites have been designed and synthesized in order to build a nano-medical platform that combines MRI diagnosis of tumors,photothermal treatment,and high biocompatibility.The research contents are as follows:(1)Firstly,GNRs with monodispersity and appropriate size in water were synthesized by seed growth method.The effects of adjusting the concentration of cetyltrimethylammonium bromide(CTAB),gold seeds and ascorbic acid(AA)were investigated.The effect of the content on the size,shape and photothermal properties of GNRs.The results show that the concentration of CTAB achieves the switching of the shape of gold nanoparticles.At high concentrations,the spherical shape is dominant,and at low concentrations,the yield of rods is higher.The fine adjustment of gold seeds and AA content can achieve the wide range tuning of GNRs and LSPR.The change value is170 nm;in addition,when the AA content is too large,the rod shape can be turned into a"toast"shape and a"dog bone"shape.The aqueous solution of GNRs could be rapidly heated after 808 nm near-infrared laser irradiation,which verified the photothermal conversion ability.(2)The thermal stability of GNRs under high temperature was simulated and investigated.The results showed that GNRs still maintained good morphology and excellent photothermal properties after being held at a temperature below 110?for 24 h.In addition,heat treatment can achieve gold The blue shift of the nanorod LSPR and its drastic reduction in FWHM correspond to the reduction in length and narrower particle size distribution of GNRs after heat treatment,respectively.(3)Spherical Fe₃O₄MNPs with monodispersity in non-polar solvent cyclohexane were successfully synthesized by liquid-solid-solution(LSS)method.The effect of NaOH content on the product was explored.The results showed that the product was Fe OOH when the alkalinity was too low,and Fe₃O₄when the alkalinity was high.Too high alkalinity would bring a certain degree of agglomeration.The particle size and narrow size distribution of Fe₃O₄MNPs are favorable for assembly with GNRs.Its superparamagnetism proves that it has MRI imaging capabilities.(4)The oil phase to water phase operation of Fe₃O₄MNPs realized by the PVP reverse micelle oleic acid oxidation method,and to explore the changes in particle size,dispersibility and magnetic properties after phase transfer.The characterization results show that the shape and particle size of Fe₃O₄MNPs are almost unchanged before and after phase transfer,they are still monodisperse in water,and their magnetic properties are slightly enhanced.The carboxyl groups at the surface ends of Fe₃O₄MNPs after phase transfer are beneficial for subsequent assembly with GNRs.(5)SH-PEG-NH₂modified gold nanorods were used to replace CTAB with cytotoxicity,while improving the biocompatibility and aminating the surface end of GNRs,and characterizing that the shape,size and optical properties did not change The work lays the foundation for the assembly with Fe₃O₄superparamagnetic nanoparticles.(6)Synthesis of GNR@Fe₃O₄composite nanomaterials was achieved by the condensation reaction of amino and carboxyl groups,and its light-to-heat conversion ability was evaluated by means of a 808 nm laser.It was found that its chemical composition,phase structure,macro color,and optical properties are the superposition of two monomers.The maximum temperature rise of the composite under irradiation of a808 nm laser with a laser power density of 1.91 W/cm²for 10 min can reach 25?.It can be considered that GNR@Fe₃O₄NCPs,which has the respective advantages of GNRs and Fe₃O₄MNPs,has good application prospects in the fields of MRI imaging diagnosis and photothermal therapy.