Protein-based Nanocomposites With Redox Balance-breaking Ability For Tumor Therapy

For cancer therapy,the accuracy and efficiency of therapeutic modalities,and the biosafety of nanocarriers are the key factors that influence the clinical translation progress of nanomedicine.Redox homeostasis is vital for cell survival.Compared to normal cells,improved reactive oxygen species（ROS）level is found in tumor cells,which in this case develop a strong anti-oxidative system to eliminate the over-produced ROS to maintain the redox balance.Even though,it is easier to break this balance in tumor cells than that in normal cells.In addition,tumor cells are more sensitive to over-produced ROS,which can induce the cell death.Thus,it is an effective strategy to break the redox homeostasis inside tumor cells,which also has good specificity.Generally,this strategy includes two aspects:one is to disturb the anti-oxidative system,which can decrease the ROS elimination;the other is to increase the ROS production simultaneously,aggravating the intracellular oxidative stress.Protein-based nanomaterials have been widely explored for tumor theranostics due to their excellent biocompatibility,good drug loading capacity,abundance in functional groups and so on.Nowadays,there have been varieties of protein-based nanomaterials approved for use in clinic or clinical test,proving the great potential in clinical translation.It is very promising to endow protein-base nanomaterials with redox balance-breaking ability.Based on this,the thesis focuses on designing and preparing novel protein-based nanomaterials with redox balance breaking ability for effective tumor therapy.The main research contents are as follows:（1）Transferrin-based nanomaterials for the MR imaging of orthotopic glioblastoma and glutathione（GSH）-depletion assisted sonodynamic therapy.Mn O₂ is synthesized in situ inside holo-transferrin molecules through a modified biomineralization method,followed by the conjugation of sonosensitizer protoporphyrin IX（pp IX）to give the final material.The size is 20～30 nm,with good dispersity and stability.The structure of transferrin is well maintained during synthesis,guaranteeing its inherent blood-brain barrier traversing and glioblastoma targeting ability.Responsive T₁-weighted MR imaging of the tumor region is achieved through Mn O₂.In addition,Mn O₂-mediated GSH depletion decreases its intracellular level,disturbing the ROS elimination.Combined with O₂ generation from H₂O₂ decomposition catalyzed by Mn O₂,the sonodynamic effect is synergistically enhanced to achieve the suppression of tumor growth.（2）Albumin-based multifunctional nanoagent for GSH depletion-assisted chemo-/chemodynamic combination therapy.Copper oxide and manganese oxide are in situ grown inside bovine serum albumin（BSA）molecules,followed by the conjugation of cisplatin prodrug to give the final material.The size is 20～30 nm,with good dispersity and stability The decrease of GSH level cause by Mn O_x oxidation,on the one hand,reduce the generation of GSH-Pt adducts,favoring the improvement of cisplatin-mediated chemotherapy;on the other hand,mitigates the·OH elimination,thus enhancing the chemodynamic outcomes.Moreover,the boosting of chemotherapy in turn promotes the generation of H₂O₂,benefiting the·OH generation.Cu-based Fenton-like reaction has better reaction efficiency under weakly acidic conditions,which also benefits·OH production in the tumor microenvironment.Notably,the decrease of GSH and the generation of ROS induce the inhibited expression of glutathione peroxidase-4（GPX-4）,thus further aggravating the redox dyshomeostasis for better therapy outcomes.This work utilizes the GSH depletion more comprehensively and explore the ROS generation strategy with a highly effective and controlled manner,avoiding the uncontrolled production of ROS in sonodynamic therapy due to ultrasound-induced cavitation and other effects.（3）Albumin-based nanocomposites for GSH depletion,oxygen generation and low temperature photothermo-assisted photo-/chemodynamic combination therapy.Iron oxyhydroxide and manganese oxide are in situ grown inside human serum albumin（HSA）molecules,followed by loading with indocyanine green（ICG）to give the final material.The size is～100 nm with good dispersity and stability.On the one hand,the photothermal effect of ICG is utilized to promote the Fenton reaction;on the other hand,ICG is used as photosensitizer at the same time to produce ¹O₂ under irradiation.O₂from the decomposition of H₂O₂ catalyzed by Mn Ox further improves the photodynamic effects.Also,the GSH depletion by Mn O_x decrease its clearance towards·OH and ¹O₂,benefiting the enhancement of ROS-mediated therapies.Meanwhile,the expression of GPX-4 is inhibited during the process,aggravating the intracellular oxidative stress.Evident lipid peroxidation can be found inside cells.Collectively,satisfactory killing effect is achieved towards tumor cells.This work provides a useful perspective on preparing novel protein-based nanocomposites with good biocompatibility for effectively breaking the redox balance,achieving specific tumor therapy.