Construction And Evaltuion Of Stimuli-responsive Drug Delivery/Diagnostics Nanoplatforms Based On Polyphosphoester

The development of stimuli-responsive drug delivery and theranostics nanoplatforms is of great significance for the individualized diagnosis and the precise treatment.Smart drug delivery systems possess several advantages,including passive accumulation in the lesion site,stimuli-responsive controlled drug release,enhanced therapeutic efficacy and minimized side effect.Theranostics can not only be able to detect the lesion site precisely,but also monitor and adjust the treatment process timely for enhanced drug targeting and anti-cancer efficiency with reduced side effects.Although lots of new stimuli-responsive materials have been applied for smart drug delivery and theranostics platforms in recent years,the biocompatibility of those materials and therapeutic efficacy are still unsatisfied.Polyphosphesters are a kind of famous biocompatible and biodegradable synthetic macromolecules.They are widely used in biomimetic nanomaterials,biomedicine and other relative fields due to their easy synthesis,adjustable structure and enzyme degradability.On the base of above advantages,here polyphosphesters are applied to construct stimili-responsive nano-drug delivery system and nanotheranostics,including reduction-responsive prodrugs,light-triggered ROS-responsive nano-drug delivery system,biomimetic nanovesicles and nanotheranostics conbining photothermal-chemotherapy and photoacoustic imaging.The detailed works include the following four parts:1.The design,synthesis and application of reduction-responsive amphiphilic polymeric prodrugs of camptothecin-polyphospoester.The clinic applications of traditional polymeric prodrugs were limited due to the uncontrollable drug loading content and unsatisfied biodegradation of polymer chains.Here a reduction-responsive polymeric prodrug of camptothecin-polyphospoester with controllable drug loading content was constructed.Firstly,we designed and synthesized a novel cyclic phosphoester monomer?CPTSP?containing a disulfide bond linker and CPT as a side group.Then a reduction-responsive polymeric prodrugs?PCPTSP-co-PEEPs?are synthesized through the ring opening copolymerization of CPTSP and another cyclic phosphoester monomer containing a side group of ethyl?EEP?by using1,8-diazabicycloundec-7-ene?DBU?and thiourea?TU?as catalysts.The resulting PCPTSP-co-PEEPs could self-assemble into micelles in water due to their hydrophilic polyphosphoester main chain and some hydrophobic CPT side groups.The average size and the drug loading content of these micelles could be controlled by adjusting the feed molar ratio of EEP and CPTSP.The average hydrodynamic diameter of micelles was increased from 190 nm to 230 nm when the molar ratio of EEP/CPTSP was adjusted from9/1 to 49/1.These micelles possessed appropriate stability in physiological conditions and degraded in the reduction medium according to their size change monitored by DLS measurement.The reduction-responsive property of them was also confirmed by in vitro drug release behavior.Moreover,these micelles could enter into HT29 tumor cells via endocytosis and released CPT efficiently to inhibit the cell proliferation.The tumor inhibition rate in vivo of these polymeric prodrugs was 73.4%,which was over two folds of that for free CPT?36.5%?.This approach of stimuli-responsive polyphosphoester prodrugs can be extended to other anticancer drugs to construct smart drug delivery systems for cancer treatment.2.The preparation and evaluation of amphiphilic light-triggered ROS-responsive drug delivery system based on hyperbranched polyphosphoester.The clinic application of traditional drug delivery nanoparticles was restricted due to the limited penetration in solid tumor and poor therapeutic efficiency.Herein,a ROS-responsive drug delivery system with light-triggered size-reducing was prepared for enhanced tumor penetration and improved therapeutic efficiency.Firstly,we designed and synthesized a novel cyclic phosphoester monomer containing thioketal units?CMP?.Then a ROS-responsive hyperbranched polyphosphoester?HBPTK-Ce6?was prepared through the self-condensing ring-opening polymerization of CMP and further end-capped with photosensitizer Chlorin e6.HBPTK-Ce6 could self-assemble into micelles in water with the initial averaged diameter of²10 nm.They were appropriate stable in blood circulation and could be used as drug carriers to load camptothecin.The CPT-loaded nanoparticles could be concentrated in tumor by enhanced permeability and retention?EPR?effect.Upon 660 nm laser irradiation on tumor tissues,the Ce6s in nanoparticles could effectively generate ROS to kill cancer cells meanwhile cleave the thioketal units to sequentially reduce the size of nanoparticles,which facilitated them enhanced tumor penetration with a programmable release of CPT.Such enhanced tumor penetration and cellular uptake of HBPTK-Ce6 upon 660 nm laser were confirmed by in vitro 3D cell assay.In vivo experiment showed that HBPTK-Ce6@CPT had the highest tumor accumulation and therapeutic efficiency.Such ROS-responsive nanoparticles with light-triggered size-reducing provide a feasible approach to improve drug tumor penetration and achieve satisfied therapeutic efficacy.3.Morphology transformation of hyperbranched copolymer assemblies containing polyphosphoester and their application research.Nanovesicles are one of most fundamental features in living cells,which is associated with biological catalysis,material transfer,signal transduction and immune antigen presenting.However,it is still a challage to contruct biomimetic nanovesicles within the cells based on enzyme.Herein,biomimetic vesicles within cells were first prepared on the base of the alkaline phosphatase?ALP?responsive hyperbranched copolymers and further used as specific tumor ultrasound imaging agents.Such copolymers?HBPO-star-PEEPs?were synthesized through ring opening polymerization of 2-ethyl-5,5-dimethyl-1,3,2-dioxaphosphorinan-2-oxide?EEP?with hyperbranched poly?3-ethyl-3-oxetanemethanol??HBPO?as macroinitiator and TBD as catalyst.The resulting HBPO-star-PEEP copolymers could self-assemble into²30 nm unimolecule micelle aggregates?UMAs?in water due to their multiple hydrophilic polyphosphoester arms and hydrophobic HBPO core.Those UMAs could transform into⁴00 nm biomimetic vesicles in ALP overexpressing MC3T3 cells,which was ascribed to the fact that ALP induced PEEP arms degradation and changed the hydrophilic/hydrophobic ratio in HBPO-star-PEEP.The degradation of PEEP arms was characterized by ¹H ³¹P NMR GPC and MALDI-TOF-MS.In addition,perfluoropentane?PFC?could be encapsulated in HBPO-star-PEEP UMAs.Those PFC-loaded UMAs could be concentrated in tumor through the EPR effect and then transformed to hollow vesicles in ALP overexpressing Hela tumor,which resulted in a two times increase of ultrasonic intensity at tumor site.Such endogenous enzyme induced contruction of biomimetic polymer nanovesicle within the cells provide a feasible way to bionics and specific ultrasound tumor imaging.4.Preparation of hyperbranched polyphosphoester-polydopamine hybrid photo-thermal nanotheranostics and their application research.In traditional photothermal thrapy?PTT?,cancer cells under hyperthermia condition would over-express heat shock proteins?HSPs?,then caused hyperthermia resistance and finally resulted in the treatment failure.Herein,nanotheranostics with light-induced fast17-AAG release property based on hyperbranched polyphosphoester and polypolydopamine nanoparticles were prepared to induce cancer cells apoptosis,inhibite HSPs and reverse hyperthermia resistance for improved thermaltherapy.Firstly,we designed and synthesized a novel cyclic phosphoester monomer containing aliphatic hydrocarbon?CP?.Then a hyperbranched polyphosphoester?HCP?was synthesized through the self-condensing ring-opening polymerization of CP.Light-triggered nanotheranostics?PDA-HCP?was prepared by the co-self-assembly of HCP with hexadecylamine modified polydopamine nanoparticles.The resulting PDA-HCP could be used as drug carriers to load HSPs inhibitors 17-AAG,which were appropriate stable in blood circulation.The PDA-HCP@17-AAG nanoparticles could be concentrated in tumor through the EPR effect.Upon 808 nm laser irradiation on tumor tissues,PDA-HCP nanoparticles could effectively convert NR light into heat to induce cancer cell apoptosis.Meanwhile,the heat enhanced the movement of polyphosphosester chains to trigger the rapid release of 17-AAG.In vitro cell assay showed that light-induced temperature increasement could also enhance the cellular uptake of PDA-HCP@17-AAG and resulted in the enhanced anti-cancer proliferation efficiency.In addition,PDA-HCP nanoparticles could be used as effective contrast agents of photoacoustic imaging.Such nanotheranostics provide a very promising way to conbine photoacoustic imaging for tumor diagnosis and thermaltherapy for precision medicine to achieve the satisfied therapeutic efficacy.