Construction And Properties Of Mesoporous Silicon With Polymer/Carbon Dots Hybrid Shell And Responsiveness

Nano drug carriers can improve drug solubility and stability,reduce systemic side effects,and achieve controlled release of drugs.In this paper,two nano-drug carriers were designed to study the properties of drug encapsulation,release,real-time monitoring and cytotoxicity,which are based on mesoporous silica,carbon quantum dots and temperature-sensitive polymer as a mixed shell.The addition of carbon quantum dots can endow nano carriers new properties,such as changes in fluorescence and NO delivery.The specific research content is as follows:?1?Amino-terminated poly-N-vinylcaprolactam?PNVCL-NH₂?was prepared by polymerization of the monomer N-vinylcaprolactam?NVCL?using 2-aminoethanethiol as chain transfer agents and azoisobutyronitrile?AIBN?as Initiators.The citric acid carbon quantum dots?CDs?were synthesized by citric acid and carbamide via the microwave method.The modified St?ber method was used to prepare mesoporous silica nanoparticles?MSNs?.Then PNVCL-NH₂ and CDs were connected to the surface of MSNs using Schiff base reaction,obtaining mixed shell MSNs with thermo/pH responsiveness.The structures of the carriers were characterized,and the drug loading and release were studied.In addition,using the changes of fluorescence intensity monitor the state of drug release in a real-time.The results showed that the encapsulation effect of DOX was better at normal physiological temperature?37??than that at room temperature?25??;the drug release rate increased with the decrease of pH values.The breaking of the Schiff base bond is accompanied by the change of CDs fluorescence intensity.The good linear relationship between the cumulative release rate of DOX?y?and the fluorescence intensity?x?indicated that the changes of fluorescence intensity can monitor drug delivery in real time.CDs/PNVCL@MSNs are easily internalized into cells,less toxic to cells,and capable of fluorescent imaging.?2?The arginine carbon quantum dots?CDs?were prepared by microwave method using L-arginine and ethylenediamine.CDs can be used as nitric oxide donors,which can be connected to the surface of polymer-grafted MSNs?PNVCL@MSNs?via Schiff base reaction,obtaining mixed shell MSNs?CDs/PNVCL@MSNs?.The structures of the carriers were characterized,and the drug loading and release were studied.In addition,the killing effect of CDs/PNVCL@MSNs synergistic delivery NO and DOX against the cancer cells was studied.The results showed that the drug release rate at25? was obviously faster than that at 37? under neutral condition.The drug release rate in an acidic environment?pH=5.0?is faster than that in a neutral environment?pH=7.4?.And under the action of hydrogen peroxide can produce NO.The synergistic delivery of NO and DOX produced greater cytotoxicity displayed by MTT experiments and Cell cytotoxicity experiments.