Organic-inorganic Hybrid Biomimetic Nanomedicine For Cancer Therapy

Cancer is a serious disease that threatens human health.In recent years,nanomedicine has become an important method for cancer therapy.Organic nanoparticles possess good biocompatibility,biodegradability and designability,while inorganic nanoparticles have distinctive physiochemical properties and the variety of functions.Developing the organic-inorganic hybrid nanomedicine will provide new multi-functional nanomedicine for cancer diagnosis and therapy.Synergistic photothermal-chemotherapy has gained much attention due to its complementary functions,good antitumor effects and low side effects.Gold nanocages(AuNCs)have been used as photothermal conversion agents for photothermal therapy due to their good biosafety,high photothermal conversion efficiency and photothermal stability.Loading chemotherapeutic drugs into AuNCs by passive drug loading method resulted in low drug loading efficiency and drug leakage,generating unsatisfactory photothermal-chemotherapeutical outcomes.Therefore,it remains a big challenge to develop AuNCs-based drug delivery systems with high loading efficiency,reduced drug leakage and increased tumor targeting to achieve spatial-temporal synchronization of photothermal-chemotherapy.High concentration of glutathione(GSH),as well as hypoxia are the hallmarks of tumor microenvironment.Sonodynamic therapy(SDT),which activates the sonosensitizer to produce reactive oxygen species(ROS)to kill cancer cells by ultrasound(US)irradiation,is a promising noninvasive cancer therapeutic approach,breaking through the barriers of low tissue penetrating depth of photodynamic therapy(PDT).However,the tumor microenvironment,such as hypoxia and high GSH,severely influences the therapeutic effects of SDT.Manganese porphyrins are the most widely used sonosensitizers in SDT.However,the hydrophobic nature,insufficient tumor localization and fast metabolism of manganese porphyrins restrict the SDT efficacy.Therefore,it is highly desirable to develop a suitable manganese porphyrins-based sonosensitizer with the self-sufficiency of O₂ and decreasing GSH capacity to synergistically increase ROS levels,improving the therapeutic effects of SDT.The main contents and results are as follows:(1)Preparation and characterization of cancer cell membranes coated AuNCs loading doxorubicin(DOX@CAuNCs).Gold nanocages(AuNCs)were synthesized via a simple galvanic replacement reaction between silver nanocubes and chloroauric acid in an aqueous solution.AuNCs were physically extruded with cancer cell membranes from murine hepatocellular carcinoma H22 cells to obtain CAuNCs.Finally,DOX@CAuNCs were constructed by actively encapsulating DOX into CAuNCs using transmembrane ammonium sulfate gradient method.DOX loading capacity and encapsulation efficiency of DOX@CAuNCs could be facilly modulated by changing the initial DOX input.The hydrodynamic diameter of DOX@CAuNCs was 105.8 nm and Zeta potential was-30.5m V by dynamic light scattering(DLS)analysis.Transmission electron microscopy(TEM)images clearly demonstrated that a thickness of about 9 nm was coated on AuNCs in DOX@CAuNCs.SDS-PAGE gel electrophoresis and western blotting analysis confirmed the maintenance of the membrane proteins in DOX@CAuNCs.The cancer cell membrane coating and DOX loading did not affect the photothermal effects and photothermal stability of AuNCs in DOX@CAuNCs.Furthermore,in vitro DOX release kinetics from DOX@CAuNCs demonstrated the slow DOX release of DOX@CAuNCs under physiological condition and the accelerated on-demand DOX release from DOX@CAuNCs upon 808 nm laser irradiation.(2)The synergistic photothermal-chemotherapeutic anticancer activity of DOX@CAuNCs.DOX@CAuNCs showed significantly decreased protein adsorption and excellent immune evasion ability in vitro.DOX@CAuNCs significantly prolonged the circulating half-life in SD rats.DOX@CAuNCs exhibited excellent tumor targeting ability in vitro and in vivo.DOX was released from DOX@CAuNCs upon 808 nm laser irradiation and entered the nucleus in H22 cells.In vivo experiments in H22 tumor-bearing mice also confirmed that laser-irradiation DOX release form DOX@CAuNCs.DOX@CAuNCs exhibited strong cytotoxicity against H22 cells via synergistic photothermal-chemotherapy.DOX@CAuNCs induced a significant temperature rise in tumor tissues of H22 tumor-bearing mice upon 808 nm laser irradiation at tumor sites.DOX@CAuNCs displayed an excellent photothermal-chemotherapeutic anticancer activity in H22 tumor-bearing mice,resulting in a complete tumor eradiation and a prolonged survival time upon 808 nm laser irradiation.DOX@CAuNCs showed good biocompatibility and a decreased inflammatory reaction.(3)Preparation and characterization of manganese porphyrin-based nanometal-organic framework(NMn-MOF)for biomimetic catalase.NMn-MOF was constructed by solvothermal reaction between zirconyl chloride octahydrate(Zr OCl₂·8H₂O)and manganese porphyrin.The hydrodynamic diameter of NMn-MOF was70.0 nm.TEM images clearly demonstrated that NMn-MOF was spherical with uniform size and pore size of about 1.2 nm.The BET surface area,pore volume and average pore diameter of NMn-MOF as measured by nitrogen adsorption analysis were 292.1 m²/g,0.605 cm³/g and 1.1 nm,respectively.Mn existed in the valence of Mn²⁺,Mn³⁺and Mn⁴⁺in NMn-MOF by X-ray photoelectron spectroscopy(XPS)analysis.Cyclic voltammetric analysis and stopped-flow spectroscopy showed the dynamic conversion of Mn³⁺/Mn⁴⁺in NMn-MOF after reaction with H₂O₂,suggesting a catalase-like activity of MNn-MOF.NMn-MOF could persistently catalyze H₂O₂ to generate O₂.Meanwhile,NMn-MOF could efficiently decrease GSH concentration.Thus,US irradiation treatment significantly increased ROS production induced by NMn-MOF after addition of H₂O₂,even under hypoxic condition.In addition,NMn-MOF revealed a significant T₁-weighted magnetic resonance(MR)imaging capacity.(4)The SDT antitumor effect of NMn-MOF in vitro and in vivo.NMn-MOF was more readily to be taken up by tumor cells and colocalized with lysosomes by confocal microscopy and flow cytometry.NMn-MOF significantly decreased intracellular GSH content in tumor cells.US irradiation significantly increased the intracellular ROS generation induced by NMn-MOF under normoxic and hypoxic condition.NMn-MOF did not significantly affect the cell viability of tumor cells under both hypoxia and normoxia,revealing good biocompatibility.However,NMn-MOF exhibited the strong cytotoxicity against tumor cells under both normoxia and hypoxia upon US irradiation,displaying excellent SDT effects.The excellent SDT efficacy of NMn-MOF was further confirmed in H22 and 4T1tumor-bearing mice.NMn-MOF significantly halted the development and progression of the tumor mass and prolonged the survival time of H22 and 4T1 tumor-bearing mice upon US irradiation.Meanwhile,SDT treatment of NMn-MOF significantly decreased lung metastasis of 4T1 tumor-bearing mice.Immunofluorescence staining of CD31,VEGF and HIF-1?in tumors after treatment indicated that NMn-MOF effectively destroyed the tumor blood vessels,inhibited the angiogenesis of tumors and reversed the hypoxia of tumors upon US irradiation.Hematoxylin and eosin(H&E)staining and serological analysis showed that NMn-MOF was biocompatible with no side effects.The good T₁-weighted MR imaging capacity of NMn-MOF was confirmed in H22 tumor-bearing mice,providing an efficient MRI contrast to monitor SDT effects.