Transformable Stapled Peptide-croconaine Conjugate For Tumor Deep Penetration And Therapy

Due to the abnormal intratumoral interstitial pressure in tumor tissue,the penetration of nanomaterials in tumor tissue is blocked,thereby reducing the delivery efficiency of nanomaterials and drugs into the tumor.Stapled peptides are a class of materials with stable?-helical structure obtained by cross-linking the side chains of linear peptides.Compared with their linear counterpart,the stapled peptides can not only improve the uptake capacity of cells,but also have good resistance to protease hydrolysis.The photothermal treatment of tumors has characteristics of time-spatial controllable.By applying near-infrared laser to tumors,the photothermal heating effect of the photothermal conversion agent can be used to kill tumor cells.In order to improve the penetration of nanomaterials in tumors,a stapled peptide-dye conjugate nanoparticle that can undergo morphology transformation is prepared in this work,which is designed to realize the synergestic penetration and treatment of photothermal heatng and the stapled peptide.The construction of stapled peptide-dye conjugate nanoparticles.The required linear peptide KLC(KLVFFGFLG-Ahx-(KLCKLCK)₂)was prepared based on the peptide solid-phase synthesis,after which 4,4'-bis(bromomethyl)biphenyl was used to cross-link the side chains of KLC.After the preparation of croconaine dye,the mentioned two chemicals were coupled.Mass spectrometry,ultraviolet-visible light spectrophotometry and circular dichroism were employed to characterize the primary and secondary structure of the conjugate,after which the nanoparticles of the conjugate was prepared and through negatively modified to construct stapled peptide-dye conjugate nanoparticles with negatively charged surface CRs KC.Dynamic light scattering,transmission electron microscopy,Zeta potential meter were employed to characterize the morphology and potential of CRs KC.Then by applying808 nm near-infrared laser to the nanoparticles,the photothermal performance of CRs KC was investigated before and after morphology transformation.The internalization of CRs KC nanoparticles was investigated by fluorescence microscopy and flow cytometry in vitro.Multicellular spheroids model was employed to evaluate the penetration ability of CRs KC,as well as to verify the synergistic penetration effect of photothermal and stapled peptides.After co-cultured CRs KC nanoparticles with 4T1 cells,the depolarization and disturbance of mitochondrial membranes of 4T1 cells were investigated by JC-1 staining and TEM respectively.Further,the toxic effect of CRs KC nanoparticles to4T1 cells was assayed by Alarm-blue staining.In situ 4T1 breast cancer models of BALB/c mice were established to investigate the efficiency of photothermal treatment as well as the therapeutic effect of CRs KC nanoparticles in vivo.The tumor growth inhibiton value of CRs KC+Laser group achieved 86.6%,which was optimal among all groups.Furthermore,the body weight curves,histological analysis and hematology tests of tumor-bearing mice elucidated good biocompatibility of CRs KC namoparticles.