Construction Of Multiple Responsive Nano Drug Carrier System For The Application In Cancer Photochemotherapy

In recent years,researchers have deepened their researches on stimuli-responsive polymers,and more and more new functional polymer materials have been developed,employing in medicine,national defense,industrial purification,etc.In the medicine field,because it is easy to modify,prepare and purify,functional polymer materials have shown great potential in cancer treatment.At the same time,smart responsive drug carriers based on sensitive polymers generally have the properties of good stability,high drug loading rate,strong intelligent response ability and easy preparation.Therefore,they are widely used for controllable drug release and synergistic treatment of cancer.In addition,photothermal therapy(PTT)and photodynamic therapy(PDT)have achieved satisfactory therapeutic effects in the field of cancer therapy,and researchers have attempted to combine smart responsive drug carriers with PTT/PDT photosensitizers to improve the therapeutic effect of cancer by changing the single chemotherapy.Therefore,this paper is based on the smart responsive drug carriers,combining chemotherapy with photothermal therapy or photodynamic therapy to achieve synergistic cancer treatment and further carried out the following work:First,we prepared a degradable glutathione-sensitive mixed drug-loaded micelle DCBM by ring-opening polymerization,high temperature polycondensation and chemical bonding,respectively.The micelles were mainly composed by glutathioneresponsive polymer PCL-SS-BPLP and a photothermal polymer biotin-PEG-cypate,and DCBM combines the advantages of both polymers.At the same time,DCBM showed a lower critical micelle concentration(1.41 μg/mL),indicating that it can maintain the structure stability under the condition of blood dilution,and could realize the drug loading characteristics.In addition,this ester group-based PCL-SS-BPLP polymer showed good degradability in vitro among 16 weeks.We assigned chemotherapy and optical therapy ability to the micelles by loading the chemotherapeutic drug doxorubicin and the photosensitizer cypate.The cyanine dye cypate in DCBM micelles could produce photothermal effect(10 μg/mL cypate corresponding to 15.2 ℃)and photodynamic effect under the stimulation of nearinfrared light,which could kill cancer cells in vitro and tumor tissue ablation in vivo.Under the condition of high concentration of glutathione and near-infrared laser,the drug-loaded micelles could achieve rapid drug release,synergistically enhanced the therapeutic effect of cancer,and provided a new strategy for the synergistic treatment of tumor.Secondly,in order to further enhance the efficacy of photochemotherapy,we introduced nitric oxide(NO)to enhance the effect of synergistic thermochemotherapy.We prepared temperature and glutathione sensitive nanospheres by emulsion polymerization using N-isopropylacrylamide(NIPAM)and 2-acrylamide-2-methylpropanesulfonic acid(AMPS)as monomers,N,N’-bis(acryloyl)cystamine(BAC)as cross-linking agent and potassium persulfate(KPS)as initiator.Further,the microsphere aimed to generating nitric oxide to enhance cancer thermochemotherapy by loading with a photosensitizer cypate,a chemotherapeutic drug doxorubicin(DOX)and a nitric oxide donor S-nitroso-N-acetyl-D,L-penicillamine(SNAP).The nearinfrared light-induced temperature increase promotes volumetric contraction of the drugs-loaded microspheres(about 30% elevation in 10 h),increasing drug release rate and promoting the conversion of SNAP to nitric oxide.The released DOX could interfere DNA synthesis by inserting into a base pair in the DNA double helix strand and binding to the nucleic acid,thereby realizing the chemotherapy effect.At the same time,high concentrations of nitric oxide could induce DNA damage and enzyme inhibition in cancer cells,and also produced cancer cell toxicity.In addition,hyperthermia generated by near-infrared light stimulation also killed cancer cells.Our study proposed a new strategy for nitric oxide-enhanced synergistic thermochemotherapy,demonstrated an enormous potential for future clinical applications.Further,we combined photodynamic therapy to enhance the efficacy of photochemotherapy at both the subcellular level and cell-level chemotherapy.We synthesized hydrogen peroxide-sensitive mitochondria-targeted micelles to achieve chemotherapy and photodynamic therapy.The micelles were composed both a hydrogen peroxide-sensitive polyethylene glycol polymer mPEG-PO-PTX and a polyethylene glycol polymer TPP-PEG-Ce6 containing a mitochondrial targeting group triphenylphosphine(TPP).Among them,the mPEG-PO-PTX segment was an amphipathic structure by binding paclitaxel(PTX)with mPEG segment through an oxalyl ester group.The high concentration of hydrogen peroxide could cleave the oxalyl ester bond,which promoted the detachment of PTX from PEG segment and induce PEG segment become completely hydrophilic,and caused the whole micelles dissociation and released the payload(PTX).Therefore,chemotherapy was achieved in the cytoplasm of cells.Because TPP was a lipophilic cation,which could be enriched in mitochondria relying on mitochondrial membrane potential.TPP-PEG-Ce6 segment could be accumulated in the mitochondria by TPP.Upon the laser irradiation,the photosensitizer(Ce6)in the polymer segment could promote the generation of reactive oxygen species.The high concentration of reactive oxygen species in the mitochondria could break the redox properties of the mitochondria and caused oxidative damage to the mitochondria and promoted mitochondrial apoptosis.This work achieved both chemical treatment in cancer cells and the sub-cellular structure of photodynamic therapy,achieving the goal of synergistic treatment.Finally,we tried to apply cationic nanospheres to photochemotherapy.We prepared a pH-responsive cationic nanosphere(VANPs)by emulsion polymerization using benzyltrimethylammonium chloride and acrylic acid as monomers,respectively.Further,the ammonium group in DOX could combine with the negative charge molecule by Coulomb force.Scilicet,it could combine with the carboxylate on the cationic microsphere.Because each indocyanine green(ICG)contained two sulfonate groups,it could combine with the positive charge microspheres by Coulomb force and firmly adsorbed on the surface of the microspheres.Therefore,we prepared ICG and DOX-loading cationic nanospheres in the form of layer-by-layer Coulomb adsorption.We prepared a pH-responsive cationic drug carrier ID@VANPs by loading drug molecules through Coulomb force between VANPs and drug.The ID@VANPs could be enriched in tumor tissue by enhanced permeability and retention effect(EPR),and exhibited more excellent photothermal treatment effects under the same of ICG injection dose(20 μg/mL ICG corresponding to 15.9 ℃).Under near-infrared laser stimulation,ID@VANPs showed a significant ICG concentration-dependent temperature increase,indicating that ID@VANPs generated more heat locally around tumor tissue by EPR,resulting in a better heat-killing effect.At the same time,the low pH of the tumor tissue could promote the protonation of carboxylate and reduce the Coulomb force between DOX and carboxylate,accelerating drug release and achieving the purpose of concentrated hyperthermia and chemotherapy.