Engineering On Hepatitis B Core Protein Virus-like Nanoparticles For Theranostic Probes Development

With the continuous development of nanotechnology,a series of emerging nanotheranostics have provided new ideas and hopes for cancer treatment.Virus-like particles(VLPs)are wildely used due to their superb biocompatibility,biodegradability and modification flexibility.The development of VLP-based theranositics has a huge potential for application or clinical translation.In this thesis,we have developed several kinds of functional HBc VLPs and explored their potential application in nanomedicine.The main research are as follows:To improve the efficacy of chemotherapy drugs,we designed a nano-drug carrier system for chemotherapy based on hepatitis B virus core protein virus-like particles.Several modularized peptides(lipophilic NS5A peptide,6xHis tag,and tumor-targeting peptide RGD)were genetically inserted into the C-terminus and the major immunodominant loop region(MIR)of hepatitis B core protein(HBc),respectively.This study demonstrated that the recombinant HBc-based VLPs could participate in self-assembly of monodisperse nanoparticles(33.6 ± 3.5 nm)with well-defined morphology,and DOX can be packaged into VLNPs without any chemical modification.Moreover,the HBc-based VLPs could specifically target to cancer cells via the interaction with overexpressed integrin αvβ3.The treatment with DOX-loaded HBc-based VLPs show a significant inhibition of tumor growth(90.7%TGI)and less cardiotoxicity in B16F10 tumor-bearing mice models than that with the free DOX.Importantly,the results may offer an easy way to give a variety of ideal functional modulations for VLPs,thereby extending its potential biomedicine applications.To develop a nanotheranotic for treatment of tumors,a tumor-targeting RGD-HBc VLPs was fabricated through genetic engineering.For image-guided cancer phototherapy,indocyanine green(ICG)was high-efficiently loaded into RGD-HBc VLPs via disassembly/reassembly pathway and electrostatic attraction.We demonstrate that the self-assembled RGD-HBc VLPs improves poor aqueous stability,target specificity,and body retention of ICG.Meanwhile,the targeted RGD-HBc/ICG VLP could provide an accurate and sensitive detection of U87MG tumor through dual fluorescence and photoacoustic imaging.This complex has excellent photothermal and photodynamic properties,which thus significantly inhibits tumor growth without side effects in vivo after single laser irradiation.To increase the immunogenicity of tumor antigens,we have inserted the model antigen peptide OVA257-264 to the MIR(major immunodominant region)of HBc VLPs.We have confirmed that OVA-HBc proteins could self-assemble into particles with a diameter of 34.3 ± 1.6 nm.The results indicated that OVA-HBc VLPs could significantly induce BMDC(Bone marrow derived dendritic cells)maturation.OVA-HBc VLPs can be enriched in the draining lymph nodes,effectively induce the proliferation of OT-I cells and high secretion of IFN-y after subcutaneous immunization of mice.Naive C57BL/6 mice immunized with OVA-HBc VLPs were able to trigger strong cytotoxic T lymphocyte responses.Moreover,in preventive experiments,the results showed that OVA-HBc VLPs as an effective tumor vaccine could significantly delay tumor growth.Vaccination with OVA-HBc VLPs led to boosting the tumor-infiltrating T lymphocytes in tumor-bearing mice.OVA-HBc VLPs could efficiently induce preventive antitumor immunity in B 16-OVA tumor bearing mice.