Research On Synthesis Mechanism And Drug-Carrying Of Multimorphology Mesoporous Carbon@Silicon Composite Nanoparticles

The design and synthesis of nanostructured mesoporous materials have attracted much attention in basic research and practical applications.Compared with traditional solid nanoparticles,non-solid particles have the advantages of low density,large specific surface area and high loading capacity.The permeable hollow structure can not only provide the reaction microenvironment,but also effectively separate the substance,reflecting the characteristics of high activity and strong selectivity of nanomaterial,which make it broad application prospects in the fields such as catalysis,energy cycle,drug storage and electrochemistry.In addition to the internal structure,the asymmetry of the external morphology of nanomaterials has always been a research hotspot,because anisotropic particles have highly sophisticated morphologies and special properties which are expected to become the nextgeneration new building blocks of advanced materials.However,there is currently no report on the synthesis method that can simultaneously adjust the internal structure and external morphology of nanoparticles.Apart from structural research,the research on the composition of nanostructured mesoporous materials is also a hot topic.Common mesoporous materials mainly include mesoporous silica and mesoporous carbon materials.The good dispersibility of mesoporous silica nanoparticles(MSNs)can improve the dissolution and release of poorly water-soluble drugs.Mesoporous carbon nanoparticles(MCNs),as three-dimensional carbon materials,have become a new type of cancer therapy drug carrier owing to their clear mesopores,large specific surface area and tunable particle size.In order to combine the advantages of MSNs and MCNs into a same drug carrier,mesoporous carbon@silicon composite materials can be prepared.This article has carried on the thorough and specific explorations of the synthesis and application of nanostructured mesoporous materials based on the problems mentioned above.The main research contents are as follows:(1): Multi-morphology mesoporous carbon@mesoporous silicon nanoparticles(MC@MSs),such as hollow structure MC@MSs(HMC@MSs),multi-cavity structure MC@MSs(MMC@MSs),and hollow bowl-shaped MC@MSs(HBMC@MSs)with adjustable concave degrees and surface roughness are firstly synthesized by emulsion-induced interface self-assembly method in the same system.The synthesis is carried out by employing glyceryl trioleate(GTO)and Pluronic F127 as co-template,phloroglucinol-formaldehyde(PF)as carbon precursor,ethylenediamine(EDA)as both base catalyst and nitrogen precursor,TEOS as silica source and CTAB as structure directing agent for silicon.The obtained MC@MSs has hydrophilic outer shell and hydrophobic inner core.By adjusting the reaction parameters,such as changing the amount of GTO,the cavity size of HMC@MSs can be adjusted;changing the ethanol concentration in the primary emulsion can modulate the internal structure of the nanoparticles;changing the ratio of ethanol/water can adjust the degree of depression of HBMC@MSs;changing the amount of CTAB can modulate the surface roughness of HBMC@MSs.And the swelling-double penetration mechanism is proposed to explain the formation process of multimorphology MC@MSs for the first time.(2)The results of hemolysis experiments show that MC@MSs have good biocompatibility and meet the basic requirements as drug carrier.Cell uptake experiments demonstrate that HMC@MSs,MMC@MSs and HBMC@MSs can enter cells through endocytosis,and among them HBMC@MSs enter cells the fastest.The high specific surface area of MC@MSs is conducive to the adsorption of drugs.Hydrophobic drug 5-fluorouracil(5-FU)is selected as the model drug to prepare the drugcarrying material 5-FU-MC@MSs.Comparing the drug release behaviors of different drug-loading materials in divergent dissolution media,the results indicate that the drug-releasing behaviors are p H-responsive.The lower the p H of the dissolution medium,the faster the drug dissolution rate.The drug release behaviors of different morphologies of drug-loading materials are different in the same dissolution environment,and the singlecavity structure of MC@MSs have the fastest drug release rate.(3)It is the first time to synthesize nitrogen-doped multi-cavity structure MC@MSs by local pyrolysis method with simpler experimental operation and reduced the use of raw materials,which is the improvement to the emulsion method.The internal structure of the product is adjusted by changing the amount of formaldehyde during the synthesis process.Hemolysis experiments show that the material has good biocompatibility,and is used as drug carrier.The hydrophilic drug cyclophosphamide(CTX)and the hydrophobic drug 5-FU are selected as model drugs,and the drug loading of CTX is 87%,the drug loading of 5-FU is 34%.The results of drug dissolution show that the dissolution rate of CTX-MC@MSs is greater than that of 5-FU-MC@MSs in the same dissolution medium,indicating the material has obvious differences in loading and dissolution of drugs with different properties,and it can be selected according to actual needs.