Self-assmbly Behavior And Antitumor Function Of ROS Or PH Responsive Peptide Materials

Cancer has become one of the major diseases around the world.The traditional cancer therapy,including chemotherapy and radiotherapy,shows limited therapeutic effect,which would cause serve side effects,however,due to the non-specific damage to the normal cells in a patient.The peptide nanodrugs developed in recent years has contributed a lot to overcome this problem.In the tumorigenesis,the new vessels would always be formed in an abnormal way with incomplete structure.In addition of the lack of effective lymphatic drainage,nanoparticle based on the peptide nanodrugs would possess enhanced permeability and retention effect in tumor area,which allows them to specificity accumulate in target region.Besides,the peptide nanodrugs are versatile subject to diverse design and simple synthesis.With good biocompatibility,this material can be used for delivering anti-tumor drugs which enables high therapeutic efficiency and low system toxicity at the same time.This paper mainly relies on the functionalization advantages of peptide nanomaterials to achieve deep drug delivery within tumors or solid tumors through the responsiveness and self-assembly behavior of nanomaterials to achieve a more complete tumor treatment system.Firstly,the solution to the problem of the lack of targeting and poor biocompatibility of chemotherapy drugs,we use peptide-drug conjugate to assemble nanoparticles to achieve precise drug delivery and killing effect.this research combined anticancer drug(CPT)with the bioactive mitochondrial targeting peptide(peptide sequence:KLAKLAKKLAKLAK)via a ROS responsive unit(TK).The synthesized peptide-drug conjugates were characterized by ~1H NMR and MALDI-TOF-MS.The ROS response of peptide-drug conjugates were investigated by dynamic laser scattering(DLS)and the change of the morphology with the transmission electron microscopy(TEM).Then,the kinds of ROS-overexpressing cancer cells were screened by flow cytometry,and a series of cell confocal imaging experiments were conducted to verify the targeting of materials in cells and the in situ responsive of ROS in tumor cells.Finally,the peptide-drug conjugates were evaluated the antitumor efficiency showed that the materials could lead to the elevation of ROS in cancer cells,damage mitochondria and induce apoptosis,and had better anticancer efficacy than anticancer drugs alone.In the process to the clinical use,quite a few defects of nanomaterials still exist limited its development.Among them,penetrability of the nanomaterials remains as one of the most critical issues.Solid tumor occurred always with high interstitial pressure,which set up barriers for nanodrugs to penetrate.Cancer cells located deeply in a solid tumor could always escape from the clearance of nanodrugs.It is well-known that the small particle size could contribute to high penetrability,which,in turn,would reduce its accumulation in tumor or internalization into the cancer cells.It is of great significance,therefore,to achieve high penetration of the nanodrugs and maintain the high accumulation and internalization at the same time.‘In vivo self-assembly’strategy is used to solve the problem in this work.In general,a pH-sensitive polymer-peptide conjugate was designed and synthesized,which could penetrate solid tumor deeply as a single chain.In this process,the material could respond to the mildly acidic condition and self-assemble to restore the high internalization ability and therapeutic function.The major work in this paper is listed as followed.Secondly,to address the problem of weak penetration of nanodrugs against solid tumors,we adopted a peptide polymer in vivo self-assembly strategy to achieve the deep delivery effect of solid tumors and to assemble and kill tumors inside the tumor.Aβ-thioester polymers was synthesized by condensation polymerization,and two peptides were produced by solid-phase peptide synthesis.One peptide was modified by a pH-sensitive group,cis-aconitic anhydride,before preparing the polymer-peptide conjugates by coupling the peptides with polymers through Michael Addition.The structure of the peptide-polymer was characterized by 1H NMR.The particle size and pH-sensitive porperties were investigated by the change the size with the dynamic light scattering(DLS),the change of the fluorescence intensity with the nonpolar fluorescence probe and the change of the morphology with the transmission electron microscope(TEM).Lastly,the peptide-polymer was evaluated the antitumor efficiency.First at all,the peptide-polymer was found to induce apoptosis by destroying the mitochondria at the cell level.The cytotoxicity test showed that the pH-responsive peptide-polymer affected the cell killing ability when the peptide-polymer was self-assembly.Finally,the penetration and intracellular self-assembly behavior of the peptide polymers were validated at the cellular and in vivo levels.Cellular experiments more visually demonstrate the cellular process of pH-responsive polypeptide polymers and the self-assembly behavior of the intracellular response,and in vivo experiments fully illustrate the penetrating effect of small molecules on solid tumors.In summary,in this paper we firstly designed peptide-drug nanomaterials to achieve mitochondrial targeting and induce assembly-disassembly to release drugs,and then we designed synthetic peptide polymers,which can respond and assemble under weak acid conditions;finally,we overcame the shortcoming of insufficient penetration of nanomaterials against solid tumors,and achieved deep penetration and efficient killing of nanodrugs against solid tumors through pH-responsive self-assembly behavior of peptide polymers,providing more possibilities for drug delivery design.