Design Of PH-sensitive/charge-conversion Amphiphilic Small Molecule Prodrug Self-delivery System And Evaluation Of Its Antitumor Properties In Vitro And In Vivo

In recent years,air pollution,food safety and unhealthy living habits have led to the frequent occurrence of tumor diseases.As the preferred treatment method,chemotherapy has the advantages of a wide range of drug applications,simple and diverse drug delivery methods,and easy operation.However,chemotherapy also has many defects,such as bad water solubility,no targeting,and multidrug resistance,making the therapeutic effect greatly reduced.Nano-drug delivery system can improve the solubility and stability of drugs,reduce toxic and side effects,and increase the enrichment in tumor tissues.However,nano-drug delivery system also has some defects,such as low drug loading rate,incomplete release.The complex structure of the vector and its potential immunogenicity,Different batches differ greatly.Therefore,carrier-free self-delivery systems based on small molecule prodrugs,such as nanometer drug crystal,amphiphilic drug-drug conjugate,polypeptide-drug conjugate,have received extensive attention and research.Amphiphilic drug-drug conjugate self-assembly system has the advantages of simple structure,high drug load and complete drug release.In this paper,an amphiphilic drug-drug coupling prodrugs(DOX-NCTD)was obtained by linking Doxorubicin(DOX)and Norcantharidin(NCTD)through aβ-carboxylic acid amide bond,and this small molecule prodrugs can self-assemble in aqueous solution to obtain a nanoparticle(DOX-NCTD NPs)with both pH sensitivity and charge-conversion ability.Amphiphilic drug-drug coupling control prodrugs(DOX-CA)were obtained by amide bond coupling of Doxorubicin(DOX)and 1,2-cyclohexanedicarboxylic anhydride(CA),and control nanoparticles(DOX-CA NPs)were self-assembled.Detailed characterization of the structure,nanoparticle morphology and drug release properties,and antitumor properties of the small molecule prodrugs in this paper was carried out,with the main work including the following:(1)Amphiphilic drug-drug coupling prodrugs(DOX-NCTD)were obtained by using Doxorubicin(DOX)and Norcantharidin(NCTD)as starting reactants,which were linked byβ-carboxylic acid amide bonds.The structures of DOX-NCTD and DOX-CA were characterized using nuclear magnetic hydrogen spectroscopy(H~1 NMR),Fourier Transform Infrared(FTIR),and mass spectrometry(MS).The results showed that the structures of DOX-NCTD and DOX-CA were valid and rational.(2)DOX-NCTD and DOX-CA prodrugs were self-assembled to obtain DOX-NCTD NPS and DOX-CA NPs,respectively.DLS and TEM were used to detect the particle size and surface morphology of the two kinds of nanoparticles.DLS data showed that the size of nanoparticles is 150-200 nm.TEM images showed that the morphology of nanoparticles was spherical.DOX-NCTD NPs could effectively inhibit the growth of multicellular spheres.(3)In vitro drug release results of DOX-NCTD NPS showed that the drug was not released at pH 7.4,but theβ-carboxylic acid amide bond was broken at pH 5.0,and DOX and NCTD drugs were released at a faster rate.In vitro cytotoxicity test results of DOX-NCTD NPs and DOX-Ca NPs showed that DOX-NCTD NPs had concentration-dependent toxicity on cells.DOX-NCTD NPS can effectively inhibit the growth of multicellular spheres.(4)Anti-tumor experiments in mice showed that DOX-NCTD NPs was better than other experimental groups in inhibiting tumor growth.The results of drug distribution experiments in mice showed that DOX-NCTD NPS could prolong the blood circulation time of drugs and improve the enrichment of drugs in tumor sites.The results of histopathological section showed that DOX-NCTD NPs had no damage to the tissues and organs of mice,and the anti-tumor effect was obvious.In this paper,The doxorubicin and norcantharidin was linked throughβ-carboxylic acid amide bond,and obtained an amphiphilic small molecule prodrug structure.It has the characteristics of simple structure without other redundant chemical structure,green and environmental protection.A series of physical and chemical properties of nanoparticles were explored,including charge reversal effect,acid-sensitive stimulation response,drug release performance in vitro,cytotoxicity in vitro,anti-tumor effect in vivo and drug distribution in vivo.