O-Nitrobenzyl Ester-based Traceable Drug Carriers With Targeting And Controlled Release

The incidence of cancer is increasing,and cancer therapy faces a huge challenge,which is called the"Moon Landing Program"of the medical community.Although nano-drug carriers can reduce the side effects of chemotherapeutic drugs,they still have problems such as poor targeting and low therapeutic efficacy.Therefore,this thesis aims to give drug carriers targeting,magnetic resonance imaging（MRI）,endogenous（p H,GSH,and H2O2）and exogenous stimulation（light）multiple-responsive functions.Multifunctional drug carriers can monitor drug specifically deliver to tumor and release in tumor under stimulation,thereby reducing the damage of the drug to normal tissues and achieving tumor targeting,which improves therapeutic efficacy of anticancer drug.Using 4-bromomethyl-3-nitrobenzoic acid as raw material,a series of o-nitrobenzyl ester amphiphilic molecules（N,N-NB-DTPA）with polycarboxyl structure were synthesized through four-step reaction.UV/p H dual-responsive drug-loaded liposomes（N,N-NB-DTPA-DOX）were prepared by using N,N-NB-DTPA to encapsulate DOX·HCl.The cmc of N,N-NB-DTPA molecule was in order of 10^-6m N/m;Mutation of p H and conductivity of molecule solution,cleavage of molecule structure after UV irradiation,indicating molecule had good p H/UV sensitivity;At 250μg/m L,N,N-NB-DTPA molecule had low hemolysis and cytotoxicity;The drug encapsulation efficiency of blank liposomes was more than 70%.The drug-loaded liposomes can be stable in 10 days,and UV light significantly increased the size of liposomes;Lowering the p H and prolonging the light time made the cumulative drug release rate of the drug-loaded liposomes reach more than 60%.The in vitro cytotoxicity test indicated that UV-induced N,N-NB-DTPA-DOX liposomes enhanced the anti-cancer effect of DOX,resulting in enhanced anti-cancer activity of"0+1>1".In order to give the drug carriers with the property of MRI tracer,a series of photocleavable o-nitrobenzyl molecules（N,N-NB-DTPA-Gd）with high MRI performance were synthesized obtained by complexing N,N-NB-DTPA with Gd³⁺.When the concentration of N,N-NB-DTPA-Gd was lower than 250μg/m L,the hemolysis rate was lower than 5%.N,N-NB-DTPA-Gd was decomposed into o-nitrosobenzaldehyde derivatives and Gd-DTPA after UV irradiation;N,N-NB-DTPA-Gd had high drug encapsulation efficiency（>60%）;Increasing UV irradiation time made the size and the drug release rate of the drug-loaded liposome N,N-NB-DTPA-Gd-DOX increase significantly,indicating that the drug-loaded liposomes had UV-responsiveness.The relaxivity of N,N-NB-DTPA-Gd molecules was more than four times higher than Gd-DTPA.In contrast to Gd-DTPA,N,N-NB-DTPA-Gd exihibited high MRI performance and effectively accumulated in tumor;In contrast to DOX,the drug-loaded liposome had a higher blood drug concentration at the same time;In vivo and in vitro anti-cancer experiments showed that the low-toxic N,N-NB-DTPA-Gd encapsulated drug exhibited photo-induced enhanced anti-cancer activity under UV irradiation;Moreover,in contrast to DOX treatment,the photo-induced N,N-NB-DTPA-Gd-DOX treatment had no obvious tissue damage and basically no inflammatory,showing good in vivo biosafety.In order to give the drug carriers with the function of active targeting and dual-responsiveness,LA-modified and non-modified UV/reduction dual-responsive molecules（10,10-NB-S-S-P-LA and 10,10-NB-S-S-P-OMe）were synthesized.After UV and TCEP treatment,the MS results were consistent with the photodegradation and reduction degradation mechanism,revealing that the molecules had UV/GSH dual-responsiveness;their hemolysis rate was still less than 5%at a high concentration of 500μg/m L;Compared with the drug encapsulation efficiency,MRI performance,and active targeting of liposomes with different ratios,12,12-NB-DTPA-Gd:10,10-NB-S-S-P-LA=3:1 was determined as the appropriate ratio for preparing the targeted UV/GSH dual-responsive liposomes GNSPL with MRI performance.In addition,the drug-loaded liposomes（GNSPLD and GNSPMD）can keep stable in two weeks,and the drug cumulative release rate reached to the maximum（>70%）under dual stimulation of UV and TCEP.In vivo and in vitro targeting studies showed that,targeted drug-loaded liposomes GNSPLD exihibited good liver cancer targeting activity in contrast to non-targeted drug-loaded liposomes GNSPMD;In contrast to DOX,the targeted drug-loaded liposome GNSPLD had a higher blood drug concentration at the same time;In vivo and in vitro anti-cancer experiments showed that GNSPL had low toxicity,GNSPLD exhibited photo-induced enhanced anti-cancer activity and inhibited the growth and migration of Hep G2 cells under UV irradiation;Moreover,in contrast to DOX treatment,the treatment with GNSPLD+UV had no obvious tissue damage and basically no inflammatory,showing good in vivo biosafety.In order to achieve multi-tumor targeting of drug carriers,Anisamide-modified and non-modifiedUV/GSH-responsivemolecules（10,10-NB-S-S-P-AAand10,10-NB-S-S-P-OMe）,celecoxib-modified and non-modified UV/H2O2-responsive molecules（10,10-NB-OA-P-CE and 10,10-NB-OA-P-OMe）were synthesized.Compared with the drug encapsulation efficiency,MRI performance,and active targeting of liposomes with different ratios,6:1:1（12,12-NB-DTPA-Gd:10,10-NB-S-S-P-AA:10,10-NB-OA-P-CE）was determined as the appropriate ratio for preparing the MRI-tracing targeted UV/GSH/H2O2triple-responsive hybrid liposomes（GNSOPAC）.GNSOPAC liposomes can keep stable in one week.The liposomes presented high DEE（>60%）,low hemolysis rate（<5%）and superior MRI performance（more than six times of Gd-DTPA）.In vivo and in vitro targeting studies showed that the targeted drug-loaded liposome GNSOPACD had better multiple cancer cell targeting and tumor targeting effects in contrast to the non-targeted drug-loaded liposome GNSOPMD;Compared with DOX,the targeted drug-loaded liposome GNSOPACD had a higher blood drug concentration at the same time;In vivo and in vitro anti-cancer experiments showed that GNSOPAC had low toxicity,GNSOPACD exhibited photo-induced enhanced anti-cancer activity under UV irradiation;Moreover,in contrast to DOX treatment,the treatment with GNSOPACD+UV had no obvious tissue damage and basically no inflammatory,showing good in vivo biosafety.