Construction Of Supramolecular Assemblies Based On Pillar[n]arenes And Their Functional Applications For Drug Delivery And Artificial Light-harvesting Systems

In recent years,supramolecular assemblies based on noncovalent interactions have become a research hotspot in the field of chemistry,biology,and functional materials,since these assemblies exhibit excellent stimuli-responsiveness,defined morphology,photophysical property,catalyst capacity,and biological activity,which also make them hold potential applications in nanomaterials.Therefore,novel supramolecular assemblie also attracted widly attentions.Pillar[n]arenes,as a new class of macrocyclic hosts,have played more and more important roles in host-guest chemistry and also became important building blocks for constructing functional nanomaterials.In recent years,supramolecular assembies based on water soluble pillar[n]arenes have attracted much more interest,as thess assmbies hold great potential applications in biomedical and functional materials.In this dissertation,we have constructed novel pillararenes-based supramolecular assemblies by inducing aggregation capacity of water-soluble pillar[n]arenes,and we have also explored their aplications in the construction of photodegradable materials,targeted drug delivery,and artificial light-harvesting systems,which includes the following three parts:In the first part,a bola-type supra-amphiphile assembled from a water-soluble pillar[5]arene host(WP5)and a rod-coil guest molecule(G1)containing photoactive 9,10-dialkoxyanthracene group has been successfully constructed,which could further assemble into monolayer supramolecular vesicles.Interestingly,the photodecomposition rate of G1 is remarkably promoted after its aggregation with WP5,accompanied by the disassembly of the formed supramolecular vesicle,especially with the coassembly of a photosensitizer eosin Y,which holds potential applications in phototherapy.In the second part,supramolecular polymersomes are constructed by biocompatible water-soluble pillar[5]arene(WP5)and cationic poly(glutamamide)s(polymer 1)with good biodegradbility.Based on the host-guest complexation between WP5 and butyl-ammonium groups on polymer 1,stable supramolecular macromolecular amphiphiles are obtained,which could self-assemble into supramolecular polymersomes.Furthermore,the generated polymersomes are able to encapsulate hydrophilic anticancer drug mitoxanetrone(MTZ)to achieve MTZ-loaded polymersomes.Importantly,decorated with biotin ligands on the surface,these polymersomes exhibits good targeting ability to deliver MTZ specifically to biotin receptor-positive cancer cells.After internalization into cancer cells,the loaded MTZ is released efficiently triggered by the acidic environment-induced polymersome disassembly.Moreover,MTZ-loaded polymersomes with targeting ligands on their surface could not only enhance the anticancer efficiency of MTZ but also could effectively reduce the undesirable side effects to normal cells.The present work provides a novel strategy for the construction of smart supramolecular polymersomes,which may hold potential biomedical applications for targeted drug delivery.In the third part,highly efficient light-harvesting systems are successfully fabricated in aqueous solution based on the supramolecular self-assembly of a water-soluble pillar[6]arene(WP6),a salicylaldehyde azine derivative(G2),and two different fluorescence dyes,nile red(NiR)or eosin Y(ESY).The WP6-G2 supramolecular assembly exhibits remarkably improved aggregation-induced emission enhancement and acts as a donor for the artificial light-harvesting system,and NiR(or ESY)which is loaded within the WP6-G2 assembly acts as different acceptors.Notably,efficient energy-transfer process takes place from the WP6-G2 assembly not only to NiR but also to ESY for these two different systems.Furthermore,both of the WP6-G2-NiR and WP6-G2-ESY systems show ultrahigh antenna effect at a high donor/acceptor ratio.These highly efficient aqueous artificial light-harvesting systems are veryimportant and versatile platform for mimicking photosynthesis.In summary,three types of supramolecular amphiphiles are constructed on the basis of molecular recognition and inducing aggregation effect of pillar[n]arenes in this thesis.These supramolecular assemblies are applied for photodegradable materials,targeted drug delivery and artifical light-harvesting systems,which will provide some reference value for pillar[n]arene-based supramolecular assemblys.