Preparation And Biological Application Of Optically Functional Organic Nanomaterials

Recently,optically functional organic nanomaterials have achieved rapid development in the interdisciplinary fields of materials,chemistry,and biology due to their excellent optical properties and nano-characteristics.Through rational design of molecular structure,optically functional organic materials can achieve strong fluorescence emission,large Stokes shift and long fluorescence lifetime.Nanomaterials based on optically functional organic materials have the advantages of customizable morphology and size,facile multifunctional modification.Therefore,optically functional organic nanomaterials are widely used in biological imaging,chemical sensing,and photodynamic therapy.This thesis mainly carried out the following research work around optically functional organic nanomaterials:1.The fluorescent molecules with electron-withdrawing groups were designed and synthesized as acceptors to dope with fluorescent polymer poly(N-vinylcarbazole)(PVK).Optically functional organic nanoparticles with tunable emission were prepared and cell-targeted imaging was realized.Through fine design of structures for different small molecules as electron acceptors,the stacking structures between electron donors and acceptors in the aggregates were optimized,and the formation of exciplex in the composite nanoparticles was accelerated.The fluorescence emission of PVK/acceptor nanoparticles was regulated effectively by the exciplex and endowed with a large Stokes shift,which can avoid the interference of background fluorescence.The PVK/acceptor nanoparticles were further modified with the cyclic peptide RGD,and they could specifically recognize the cancer cells which overexpressed integrin ?v?3 and maintain stable emission.Efficient targeted imaging of cancer cells was obtained.2.Optically functional organic nanoparticles based on small-molecule electron acceptor and electron donor were designed and prepared,in which the formation of exciplex was regulated.Tunable multicolor emission was obtained and the nanoparticles were applied for cell imaging.In the aggregated structure of organic nanoparticles,the appropriate stacking distance between the electron donor TAPC and the electron acceptor BPOTZ-OR was conducive to the occurrence of intermolecular charge transfer,resulting in efficient exciplex emission.By simply changing the ratio of donor and acceptor,the exciplex emission and monomer emission were effectively regulated and the multicolor emission of optically functional organic nanoparticles was tunable from blue to yellow(through white).The nanoparticles have good stability and low toxicity under physiological conditions,and can be applied as fluorescent probe for cell imaging.3.The fluorescent conjugated polymer PFPPBA modified with phenylboronic acid(PBA)and quaternary ammonium salt(QA)groups was designed and synthesized,and optically functional organic nanoparticles was prepared.A"saccharide bridge" strategy was designed to promote fast binding of PFPPBA nanoparticles on specific bacterial surface,and achieve controllable targeted accumulation of fluorescent conjugated polymer and efficient antibacterial activity.Based on the specific recognition between bacterial lectins and saccharide,the galactose moieties in lactulose could recognize and bind with bacterial lectins.Then CH-? interactions between the PBA group on PFPPBA nanoparticles and fructose moieties of lactulose,and electrostatic interactions between positive QA salts and negative bacteria together promoted the formation of covalent bonds between PBA and lactulose,so the fluorescent nanoparticles were controlled to tightly bind with specific bacterial surface.Under irradiation,the large amount of reactive oxygen species generated by the optically functional organic nanoparticles were applied to achieve high-efficiency photodynamic killing of pathogenic bacteria and avoid the generation of drug-resistant bacteria.4.The fluorescent conjugated polymer nanoparticles modified with PBA groups were designed and prepared.The "saccharide bridge" strategy was applied to control accumulation of fluorescent conjugated polymer nanoparticles on adhesive bacterial surface,inhibit adhesion of adhesive bacteria to epithelial cells,and realize photodynamic sterilization simultaneously.Based on the adhesion FimH/mannose specific recognition,the mannotriose was introduced to the bacterial adhesion system and occupied adhesion sites of bacteria,thus inhibited bacterial adhesion to cells.At the same time,the mannotriose on bacterial surface promoted nanoparticles actively accumulated on bacteria due to the high affinity between diols of mannotriose and PBA of nanoparticles.Furthermore,under irradiation,the reactive oxygen species produced by the accumulated nanoparticles effectively killed the adhesive bacteria.