| Photothermal surfaces refer to the material surfaces that are capable to efficiently convert the absorbed light energy into heat.Under light irradiation,the local high temperature generated by photothermal surfaces affects the behaviors of attached bacteria/cells.On the one hand,it can kill attached bacteria efficiently by interfering with microbial metabolism and denaturing proteins;on the other hand,it can enhance membrane permeability of cells,thus facilitating the entry of exogenous macromolecules in cells However,the reported photothermal surfaces still have some concerns and limitations related to the attached dead bacteria and "engineered" cells on the surfaces.The attached dead bacteria may trigger severe immune responses and inflammation;the attached "engineered"cells delivered with exogenous molecules are unable to be used for subsequent applications such as cell therapy.Considering that the surfaces modified by stimuli-responsive materials can change the physicochemical properties of the surface under external stimulus to regulate the interaction between the surface and bacteria/cells,in this thesis,we introduced stimuli-responsive materials to photothermal surfaces to construct two types of so-called smart photothermal surfaces and investigated their applications in antibacterial area and intracellular deliveryDetailed research contents are as follows:(1)A smart photothermal surface capable of controllable functions between photothermal killing bacteria and releasing dead bacteria was fabricated by combining gold nanoparticle layer(GNPL)possessing photothermal effect and vitamin C(Vc)-degradable phase-transitioned lysozyme film(PTLF).Firstly,PTLF was deposited on the substrate,and the degradation of PTLF in Vc solution and the release of biological entities(proteins,bacterias and cells)attached on the surface of PTLF under Vc treatment were investigated.Subsequently,a hybrid GNPL-PTLF coating with smart antibacterial capability was developed by sequential deposition of GNPL and PTLF.Due to the excellent photothermal effect of the GNPL,the hybrid coating was able to kill various attached bacteria(including drug-resisitant bacteria)under 808 nm near-infrared light irradiation.Moreover,the topmost PTLF layer could be degraded and detached from the surface by immersion in Vc solution,leading to efficient removal of the killed bacteria.Especially,taking the advantage of the fact that the sequential degradation of the PTLF could be realized by adjusting the concentration of Vc and the treatment time,the fresh GNPL-PTLF coating could be obtained for reuse after one "kill and release" cycle,maintaining high-performance of photothermal killing bacteria and releasing dead bacteria in three cycles.This is a simple and universal method and it can be applied to a variety of substrates with diverse surface properties.In addition,GNPL-PTLF was stable after immersed in defferent medium for 14 days as it maintained high-performance of photothermal killing bacteria and releasing dead bacteria.(2)A smart photothermal surface integrated with three sequential functions(cell capture,intracellular molecular delivery,and cell harvesting)for "engineering" living cells was fabricated by the combination of silicon nanowire arrays(SiNWAs)possessing photothermal effect and sugar-responsive polymer containing phenylboronic acid groups(PHB).Firstly,the cell capture ability of surfaces was investigated using fluorescence staining and scanning electron microscopy.Due to the topological enhancement effect by SiNWAs and phenylboronate ester bonds that form between phenylboronic acid and sialic acid,the SN-PHB surface showed a high capture capacity for both surface adherent cells(Hela cells)and suspension cells(Ramos and T cells)overexpressing sialic acid on the membrane.Next,the delivery of diverse macromolecules to various cell types was investigated using fluorescence staining and flow cytometry.Under 808 nm near-infared light irradiation,SiNWAs can efficiently convert absorbed light energy into heat to enhance membrane permeability of attached cells,therefore,diverse macromolecules(protein and plamid DNA)could be delivered into numerous cell types.Especially,plamid DNA was transfected into hard-to-transfect suspension immune T cells using this system with 80%high efficiency,significantly higher than that using the commercial transfection reagent.Finally,the"engineered" cell harvest ability and cell viability were measured using fluorescence staining and CCK-8 assay.Due to the sugar-responsiveness of phenylboronate ester bonds,the"engineered" cells could be released from the SN-PHB surface by sugar treatment achieving cell harvest,and the harvested "engineered" cells were able to resume normal growth and proliferation.In summary,two kinds of smart photothermal surfaces were fabricated by incorporation of stimuli-responsive materials to regulate interaction between surfaces and bacteria/cells,and their applications in antibacterial area and intracellular delivery were investigated.The fabricated smart photothermal antibacterial surface could kill attached bacteria effectively and release dead bacteria and debris under Vc treatment to keep surface clean.The fabricated smart photothermal intracellular delivery surface could deliver diverse macromolecules into various cell types,and release the "engineered" cells simply by treatment with a nontoxic sugar solution.These results provide new ideas and methods for fabrication of novel smart photothermal surfaces,and showed potentials in medical materials and devices,cancer therapy and tissue engineering. |
