Fabrication And Antitumor Application Of The Bioinspired Poly(Cation-π) Micelles Drug Delivery Platform

Background and ObjectivePolymer micelles self-assembled from amphiphilic block copolymers has been widely used in drug delivery,due to its simple structure,easy preparation and non-toxic effect.However,the self-assembly driving force of traditional micelles is the hydrophobic interaction between their hydrophobic chain segments,thus the formed core of micelles is hydrophobic and obviously led to the limitation that conventional micelles could only loaded hydrophobic drugs through hydrophobic interactions.On the other hand,liposomes and polymer vesicles are composed of a hollow structure consisting of a special hydrophilic cavity and hydrophobic bilayer,and thus can be used to load both hydrophilic and hydrophobic drugs.However,compared with polymer micelles,the preparation of liposome and polymer vesicles usually requires lipid molecules and polymer molecules with specific chemical structures.Besides,the preparation process of the latter is more time-consuming than micelles(such as rapid nanoprecipitation).More importantly,the stability of the vesicle structure and the drugloading stability of its corresponding drug-loading systems have been obstacles to limit their biological applications.Therefore,the construction of a new drug delivery system needs to meet the following requirements:1.It can be used for hydrophobic drugs but also for the efficient loading of hydrophilic drugs;2.The structure of nanocarrier is stable enough and the drug loading stability should be equally enhanced;3.The preparation method is simple and efficient,and has wide applicability to the molecular structure of raw materials.Cation-π interactions widely exist in biological systems and play important roles in driving the self-assembly of biological molecules,stabilizing protein structures,and mediating molecular recognitions.Thus,this study developed a drug loaded poly(cation-π)micelles using nanoprecipitation method,which was driven from cationπ interaction during the process of micelles structure formation and hydrophobic/hydrophilic drugs encapsulation.Meanwhile,the stability of the micelle structure is further improved by the introduction of cation-π interaction.Method and Results1.Preparation and characterization of drug-loaded poly(cation-π)loaded micelles.Results of NMR,Independent Gradient Model(IGM)and Isothermal Titration Calorimetry(ITC)experiments indicated the existence of strong cation-π interaction inside poly(cation-π)copolymers as well as poly(cation-π)copolymer and hydrophobic/hydrophilic drugs.The hydrophilic/hydrophobic drug-loaded poly(cation-π)micelles were prepared from nanoprecipitation method and the formation of micelles structure was characterized by DLS and TEM.Stability experiment indicated the excellent structure and drug loaded stability of drug-loaded poly(cation-π)micelle during the dilution of DMSO.Study of H2O2 response behaviors of poly(cation-π)micelle shows sensitive and rapid response properties toward H2O2.Mechanism of sensitive and rapid response behavior of poly(cation-π)micelle induced by cation-πinteraction were further illustrated by electrostatic potential analysis,differential charge density analysis and 11B-NMR.2.In vitro drug release,cytotoxicity and preliminary biocompatibility evaluation of drug-loaded poly(cation-π)loaded micelles.Drug-loaded poly(cation-π)micelle shows rapidly and completely drug release behavior triggered by 100 μM H2O2.The results of in vitro cytotoxicity show that drugloaded poly(cation-π)micelles can be rapidly uptake by tumor cells and significantly enhanced the anti-tumor efficacy compared with free drugs.The toxicity against normal cells and in vitro hemolysis assays indicated the excellent biocompatibility of poly(cation-π)micelles.3.In vivo anti-tumor effect and safety evaluation of drug-loaded poly(cation-π)micellesFirst of all,poly(cation-π)micelles exhibit tumor enrichment property.Most importantly,drug-loaded poly(cation-π)micelles have the strongest tumor suppression effect against subcutaneous 4T1 tumor model compared with the other group.It should be emphasized that drug loaded poly(cation-π)micelles possess excellent biocompatibility in vivo.4.Poly(cation-π)copolymer for protein encapsulation and intracellular delivery.FRET experiments demonstrated the existence of interaction between model protein BSA and poly(cation-π)copolymer.The DLS results suggested that the formation of copolymer/BSA nanocomplexes.Results of intracellular delivery experiment demonstrated that the formation of copolymer/B S A nanocomplexes greatly promoted the intracellular delivery efficiency of BSA.Finally,we proved that poly(cation-π)copolymer are biocompatible materials for in vitro application.Conclusion:The newly designed drug-loaded poly(cation-π)micelles possesses excellent structure and drug loaded stability,along with rapid and sensitive H2O2 responsive behavior,which shows rapidly drug release behaviors under the tumorrelated H2O2 level.It significantly enhanced the anti-tumor effect in vitro and in vivo compared with free drug.Importantly,poly(cation-π)micelles show no toxicity effect for in vivo application.In addition,poly(cation-π)copolymers also perform well in protein loading as well as in promoting intracellular delivery.