The Preliminary Study As Drug Carriers Of Biomass-derived Multimorphology Mesoporous Carbon Nanospheres And Hollow Nanocapsules

Recently,mesoporous carbon nanospheres(MCNs)derived from polymer colloidal nanospheres have drawn lots of attentions.Benefited from their stable physical chemistry properties,symmetrical geometric morphology,excellent biocompatibility and unique mesoporous channels,MCNs have integrated spherical morphology and carbon materials into the nanoplatform.Therefore,MCNs are widely used in the fields of electrochemical catalysis,adsorption and biomedicine.Multimorphology mesoporous carbon nanospheres(MMCNs)that can be transformed from hollow structure to multicavity structure are becoming a research hotspot undoubtedly.However,there are few literatures about biomass-based MMCNs,and few studies on the application of biomass derived MMCNs in the field of biomedicine are reported.Taking above view into consideration,two excellent biomass precursors tannic acid(TA)and phytic acid(PA)were selected in this study,and then,they were integrated into the same system innovatively.We skillfully made use of the natural characteristics of the two types of biomasses,completed the self-assembly process mediated by hydrogen bond force and metal chelation force,and successfully fabricated hollow polymer nanocapsules and phosphorus metal codoped multimorphology mesoporous carbon nanospheres(P-Metal-MMCNs).Surprisingly,“hub-like”multicavity mesoporous carbon nanospheres and hollow mesoporous carbon nanospheres were successfully prepared in this study.The formation mechanism of the two kinds of nanoparticles were explored by various characterization.The main research contents are as follows:1.Formation of hollow polymer nanocapsules based on biomass tannic acid and phytic acid.Firstly,the emulsion was prepared by tannic acid,phytic acid and F127 driven by hydrogen bond force,and the influence of phytic acid dosage and p H value on the polymerization and stability of the emulsion were explored.Then,metal ions are introduced into the emulsion system,based on the characteristics that both kinds of biomass can chelate with metal ions,and their chelation cooperation is used to drive the selfassembly of hollow polymer nanocapsules.The prepared hollow polymer nanocapsules is a necessary intermediate of the synthesis route.This study demonstrates a simple and efficient synthetic method of polymer nanocapsules,and lays a foundation for the synthesis of multimorphology mesoporous carbon nanospheres.2.The Preliminary Study of hollow polymer nanocapsules which are known as the intermediate of this synthesis route,was investigated.Firstly,in order to obtain the drug loaded hollow polymer nanocapsules the preparation of hollow polymer nanocapsules was carried out in the solution containing model drug(indomethacin).After testing,the hollow polymer nanocapsules have shown excellent p H response ability.It can depolymerize the polymer shell in the environment of high acidity(such as p H = 1.2),and then release the drugs in the hollow cavity.On the contrary,in the neutral environment(such as p H = 6.8),the polymer shells remain completely,which play an important role in protecting the guest molecules.The drug release experiment was carried out in the in vitro environment simulating the human gastrointestinal tract.A variety of mathematical models were used to fit the drug release curve,and the drug release mechanism was preliminarily explored.The results show that the p H-responsive hollow polymer nanocapsules has good drug delivery capacity.3.Finally,the synthesis of multimorphology mesoporous carbon nanospheres codoped with phosphorus and metal was completed.TA is the main source of carbon material skeleton,PA is the phosphorus source,and metal ions are the skeleton connecting unit.The mesoporous carbon spheres with hollow structure and hub-like multicavity mesoporous carbon nanospheres were observed by TEM.The influence of metal ions on the morphology of the spheres was explored by various characterizations,and the optimal amount of metal ions was determined.Combined with the selfassembly mechanism of hollow polymer nanospheres,the formation mechanism of two kinds of mesoporous carbon spheres with unique morphology was expanded.Specifically,there is a difference in the synthesis rate of hollow nanocapsules in the self-assembly process.This difference resulting in small polymer spheres formed in advance were coated in large nanocapsules,which were transformed into multicavity mesoporous carbon spheres after pyrolysis.Hollow mesoporous carbon spheres were derived from those nanocapsules which didn’t capture small polymer spheres.Indomethacin was used as a model drug to investigate its drug release performance,and its biocompatibility was investigated by hemolysis test and cytotoxicity test.The results show that phosphorus and metal codoped multimorphology mesoporous carbon nanospheres have great application potential in the field of drug delivery.