Construction Of Chiral Quantum Structure And Application In Chiral Selective Therapy Of Glioma

Objective : Glioma is the most common malignant tumor of the central nervous system,with poor prognosis,high recurrence,and mortality,characterized by crabclaw growth and unclear malignant boundaries.The current clinical treatment of glioma includes surgery,radiotherapy,and chemotherapy.However,due to the aggressive nature of gliomas,they cannot be completely removed by surgery.Even after the glioma is removed,the glioma can recur locally within a few centimeters of the margin of excision.Temozolomide and other glioma chemotherapy drugs are prone to drug resistance.As for radiotherapy,patients often need to choose carefully due to the possibility of serious or even irreversible damage to the central nervous system.Therefore,it is of great significance to explore new technical strategies for diagnosing and treating glioma.Diagnosis and treatment based on nanotechnology are possible ways to solve these difficulties.The representative of photoactive semiconductor elements,cadmium(Cd)-based quantum dots are widely considered to have excellent application prospects due to their simple synthesis method,physicochemical stability,and adjustable chiral optical absorption/emission characteristics.However,due to Cd’s high cellular and biological toxicity,the application of Cd-based quantum dots in the biological field is still scarce,especially in the field of drug delivery in vivo at the animal level.Currently,surface coating and modification of quantum dots are the most commonly used strategies to improve the biocompatibility of Cd-based quantum dots.Common ligand molecules include bovine serum albumin,polyethylene glycol,chitosan,chiral cysteine(Cys),and mercaptopropionic acid(MPA).We hypothesized that CdSe/CdS core-shell(Cd Se as the core,Cd S as the shell)quantum dots coupled with chiral ligands of intrinsic geometric asymmetry,would be ideal candidates for glioma fluorescence image-guided tumor phototherapy with good biocompatibility.We use different modified molecules to prepare chiral and achiral CdSe/CdS dot-in-rods(DRs)and spherical quantum dots(QDs were used to represent spherical quantum dots)with different shell thicknesses.Through optical activity characterization of materials,in vitro and in vivo bioimaging-guided phototherapy analysis,the most suitable chiral CdSe/CdS quantum dots for glioma optical diagnosis and treatment are screened to provide a new choice for therapy of glioma in the future.Methods:Chiral and achiral CdSe/CdS DRs and QDs were prepared by chiral Cys or achiral MPA ligand exchange method.The shell thickness and particle size were adjusted by controlling the experimental temperature and reaction time.DRs were D-/L-DR-1,D-/L-DR-2,and D-/L-DR-3,respectively;Morphology and size,UV-visible absorption and photoluminescence spectra of chiral and achiral CdSe/CdS DRs and QDs were measured by(high resolution)transmission electron microscopy,UV-visNIR spectrometers and fluoro SENS spectrometers,respectively;Hydrodynamic diameter,circular dichroism and circularly polarized light(CPL)spectra of chiral CdSe/CdS DRs were measured by the Malvern Zetasizer Nano ZSE instrument,JASCO J-1500 CD spectrometer and JASCO CPL-300 spectrometer,respectively;In vitro cytotoxicity of chiral and achiral CdSe/CdS DRs and QDs was evaluated by living/dead cell viability assay kits;The ultrastructure of U251 cells after ingestion of D-/L-DR-1 was detected by transmission electron microscopy;Biological imaging effects of chiral CdSe/CdS DRs in U251 and U87 cells were evaluated by inverted confocal microscopy;Reactive Oxygen Species(ROS)assay kit was used to evaluate the ability of D-/L-DR-1 to induce ROS production in U251 cells;The photothermal properties of D-/L-DR-1 were measured;The Fenton-like effect of D-/L-DR-1 was detected by UV-vis-NIR spectroscopy;Fluorescence colocalization of ROS and D-/LDR-1 in U251 cells was determined by inverted confocal microscopy;The D-/L-DR-1induced killing rates of U251 and U87 cells under different CPL laser irradiation were evaluated by living/dead cell viability assay kits;The effects of D-/L-DR-1 on the migration and invasion of glioma cells were determined by wound-healing assay,Transwell migration and invasion assay;The subcutaneous glioma xenograft model using U251 cells was established to explore the feasibility of D-/L-DR-1 tumor imaging and the antitumor effect of D-DR-1 guided phototherapy in vivo.Results:Three pairs of chiral CdSe/CdS DRs with different shell thicknesses were successfully prepared and named as D-/L-DR-1,D-/L-DR-2 and D-/L-DR-3,with shell thicknesses of 0.35 nm,1.45 nm and 5.95 nm,respectively;Chiral CdSe/CdS DRs had uniform size,good dispersion and good luminescence performance;Chiral CdSe/CdS DRs had great in vitro biocompatibility;The penetration ability of D-DR-1to tumor cells was stronger than L-DR-1,and more autophagolysosomes could be observed;CdSe/CdS QDs and DRs modified by achiral MPA with similar shell thickness and particle size to D-/L-DR-1 were successfully prepared;Chiral cysteine modification strategies further improved the biocompatibility of Cd Se-based QDs and DRs;Chiral CdSe/CdS DRs had ideal cellular fluorescence imaging performance;The D-/L-DR-1 with the thinest Cd S shell had the most significant imaging ability on glioma cells;Chiral CdSe/CdS DRs were dual-mode phototherapy agent with a combination of photodynamic and chemodynamic effects;The red fluorescence produced by Cd Se core could co-locate with ROS produced by chiral Cd S shell;Chiral CdSe/CdS DRs showed complete ablation of tumor cells and chiral selective absorption;Chiral CdSe/CdS DRs could effectively inhibit migration and invasion ability of glioma cells by nearly 50%;D-DRs showed stronger EPR effect(enhanced permeability and retention effect)in glioma tissues and in vivo tumor imaging performance;D-DRs had obvious anti-tumor effect and great biocompatibility in vivo.Conclusion:Chiral CdSe/CdS DRs can be candidates for bioimaging with low toxicity due to their fluorescence properties and ligand coverage;With a shell layer thickness of only0.35 nm and photo/chemo-dynamical capabilities,chiral CdSe/CdS DRs can enantioselectively stimulate the generation of ROS via CPL,providing synergistic therapy in glioma with more than 3.14 times higher efficacy compared to phototherapy without chiral selection;Chiral CdSe/CdS DRs can decrease infiltrative growth and metastasis of glioma cells by inhibiting 50% of the migration and invasion ability,showing adjuvant strategies for cancer treatments that suffer from high possibility of recurrence and poor prognosis.