The Application And Construction Of Functionalized Nanoparticles Based On Biological Surface Display Strategies

Over the past decades,a wide range of ligand-decorated nanocarriers have been exploited for the application of biomedicine.It is well-known that nanoparticle(NP)surface modification strongly enables the expansion of NP function as well as biocompatibilities.NP functionalization generally requires the modification of ligands onto nanovehicles' surface so as to endow nanomaterials with a wide variety of features,such as enzymatically catalytic capabilities,in vivo targeting,biosensors,and biotherapy ability.Widely used ligands for NP functionalization include enzymes,peptides,aptamers,polysaccharides,antibodies,and bioactive small molecules.Among these molecules,antibody proteins,which serve as an important type of linked ligands due to their high affinity to targets and superior bioactivities,were conjugated to the surface of various nanoparticles to achieve the targeted delivery of drugs to tumor tissues.Conventional ligand modification approaches often involve physical adsorption or chemically covalent conjugation.However,nonspecific covalent conjugation,which is the most widely employed method,may lead to the loss of biological activity for vulnerable protein ligands as well as uncontrollable protein orientation,thus resulting into low efficiencies of NP functionalization Ideal coupling approaches for protein ligands should assure optimal ligand orientation,facile accessibilities,good in vivo stabilities and protein activities,which are of great significance for the development of nanomedicine.On the other hand,biological surface display technologies have been developed rapidly,which can exploit genetically engineered methods for displaying biologically active moieties(such as recombinant targeted peptides,proteins and polysaccharides)onto the surface of natural organisms like virus-like particles,virus,yeast,bacteria,phages,ferritins,or other protein cages.This technique has been widely applied to microbiology,immunology,and molecular biology,thereby creating a remarkable clinical value.Besides,to offer nanocarriers more superior functions,such as good biocompatibilities,immunologic escape behaviors,in vivo targeting,stable blood circulation and specifically cellular functions,biomimetic strategies have been employed extensively to develop various nanomaterials.These strategies tend to involve the decoration of bioactive proteins(viral envelope proteins)or cellular components(cell membrane and cytoplasmic organoids)onto NP surface.Taken together,to develop an ideal NP functionalization approach for protein nanoconjugation,we established a new approach for NP functionalization and prepared three types of functionalized nanovehicles(including protein-displaying virus-mimetic nanovesicles,exosome-mimetic nanovesicles and cell membrane-coated NPs),utilizing biological surface display and biomimetic strategies.These functionalized nanovehicles achieved the satisfying therapeutic outcomes in three studies respectively involved in vaccine antigen delivery,tumor-targeting drug transport,and tumor immunotherapy.It suggested the excellent therapeutic capabilities of the functionalized nanovehicles as well as the universality of this established nanoconjugation technique.The main work in this study was described as following:1.I developed a new protein display technique based on nanovesicles,which can be utilized for direct expression of various bioactive protens(targeted antibodies,viral antigen,or enzyme complexes)onto membrane-derived vesicles'surface.The prepared nanovesicle has unique features and functions similar to engineered exosomes.2.On the basis of nanovesicle display techniques as well as biomemitic strategies,influenza envelope proteins(hemagglutinin,HA)were firstly genetically engineered to be expressed onto the cellular plasma membrane,followed by the induction of vesicle budding from cellular surface with the help of chemical surfactants.In this way,HA protein-displaying nanovesicles were successfully prepared that resembled natural influenza viruses in morphologies,immunogenicity,size,and hemagglutination activities.The study showed that the immunization of influenza virus-mimetic nanovesicles(VMVs)could induce high level of neutralizing antibodies in mice,indicating that VMUs have great potential as a straightforward,effective,and versatile vaccine platform against a wide variety of enveloped viruses.3.On the basis of nanovesicle display techniques,membrane-derivied nanovesicles were genetically engineered to be modified with human epidermal growth factor(HEGF)or nanobodies(Affibody),followed by encapsulation of therapeutic drug molecules into vesicles.Thus,the engineered nanovesicles could possess tumor-specific targeting,resulting into the enhanced drug accumulation in tumor tissues and good therapeutic efficacy.4.By combining nanovesicle display techniques and membrane-cloaked nanoparticle approaches,we genetically modified PD-L1 antibodies to make them expressed onto the surface of vesicles.After that,manganese oxide(Mn02)NPs were further coated by antibody-displaying nanovesicles through co-extrusion of MnO2 NPs with nanovesicles to construct targeted membrane-camouflaged nanocarriers.This hybrid nanosystem enabled PD-L1 antibody-targeted transport of immunostimulators to tumor microenviroments largely due to the high efficiency of NP functionalization and PD-L1 antibody display We also found that the new type of membrane-coated NPs were capable of significantly increasing the response rates on radiotherapy-induced abscopal effects(namely systemic antitumor immunity),thus achieving the successful immuno-radio therapeutic outcomes.