Preparation And Antibacterial Performance Of Semiconductor Nanomaterials-based Bionic Functional Surfaces

Bacterial infection has become a major public health problem.In the process of“infection-and-against”,antibiotics were applied and identified as the ultimate weapon.However,the emergence and spread of resistant genes gradually highlighted the ineffectiveness of antibiotic treatment.Recently,rapid advances in nanotechnology and nanomaterials have provided effective alternatives for combatting bacterial infection.Among them,semiconductor nanomaterials occupy an important position in practical applications due to their unique physicochemical properties,structural characteristics and environmental stability.Organisms in nature have evolved perfect structures and functions in the fierce competition for survival.Researchers have found that the surfaces of many plants and insects possess antibacterial properties and protect them from bio-fouling.Inspired by this,we applied the bionic thinking to the synthesis of nanomaterials and the construction of functional surfaces to achieve the enhanced bactericidal efficiency.(1)Inspired by natural lotus leaf,we immobilized spiky TiO₂/Au photocatalysts on the one side of hydrophobic nanoPE substrate(denoted as PE-TiO₂/Au).In a typical process,gaseous reactant(O₂)from external environment can be transferred to the reaction zone through the hydrophobic and porous nanoPE,thus constructing an air-liquid-solid coexistence interface.Due to the unique interfacial microenvironment(thriphase interface)and smart heterostructures(spiky TiO₂/Au),PE-TiO₂/Au contributes to sufficient supply of O₂ at the reaction centre,which promotes the effective separation of hole-electron pairs and the generation of active species,thus improving the photocatalytic efficiency.To further investigate the O₂ supply on the photocatalytic performance,PE-TiO₂/Au was floated on the Rh B solution(exposed mode)or immersed in the solution(immersed mode)for two different gas transport paths.Importantly,the exposed PE-TiO₂/Au achieved a more effective three-phase contact,which significantly increased the O₂ supply at the reaction interface and improved the degradation efficiency by 5.5 times and 1.8times compared with diphase system and the immersed PE-TiO₂/Au,respectively.Under visible light irradiation,PE-TiO₂/Au also exhibited antibacterial effect,which effectively inactivated S.aureus(>99.9%)in just 30min.Therefore,the construction of thriphase photocatalytic system could enhance the sterilization efficiency and provide an effective method for wastewater purification.(2)It is shown that the slippery zone of Nepenthes pitcher plants can prevent their surfaces from biological contamination.Herein,a Nepenthes-mimicking nanosheet array of MoS₂ on carbon fibers(CF-MoS₂)has been proposed to achieve dual bactericidal activities.First,the sharp edges of synthesized surfaces were capable of inducing physical disruption of cell membranes,demonstrating mechanical antibacterial activity like their natural counterparts.Second,in the presence of near-infrared light(NIR),bioinspired CF-MoS₂ nanosheet arrays were able to cause the death of damaged bacteria owing to their inherent photothermal properties.Such dual-functional modes endowed the surfaces with nearly 100%killing efficiency for highly concentrated Escherichia coli(E.coli)and Staphylococcus aureus(S.aureus).Furthermore,their potential to be applied as wound dressings for photothermal treatment of infectious wound was also investigated in vivo.The results showed that CF-MoS₂ dressing had the best antimicrobial effect under NIR irradiation and promoted wound healing by reducing the inflammatory response and accelerating collagen deposition,achieving a 68.3%wound closure rate on day5,with the wound largely covered by new skin formation on day 10(98.1%),and complete epithelial formation and follicular repair were also observed.It is foreseen that this high-performance and multifunctional CF-MoS₂ could afford a feasible broad-spectrum treatment for non-antibiotic disinfection.(3)Inspired by the superhydrophobicity and low-adhesion of lotus leaf,we developed an integrated functional surface by combining superhydrophobic passive antiadhesive and active bactericidal properties.In this work,poly(lactic acid)(PLA)and polydimethylsiloxane(PDMS)substrates were modified for their enhanced antimicrobial properties.First,we introduced graphene(GE)into the polymer matrix of PLA,and in the presence of NIR light,the modified sample showed strong bactericidal effect,and an outstanding shape memory effect can be achieved by PLA-GE/SiO₂;secondly,hydrophobic SiO₂nanoparticles were immobilized on the surface of PLA-GE,which endued PLA-GE/SiO₂ with superhydrophobic properties and low-adhesion behavior.The results showed that PLA-GE/SiO₂ could inactivate 99.8%of E.coli and99.1%of S.aureus within 5 min under the irradiation of NIR light.In addition,PLA-GE/SiO₂ effectively prevented E.coli and S.aureus colonization on the surface,with an anti-adhesion rate of over 99.0%.Inspired by dragonfly wings,we also prepared ZnO/Au nanopillar arrays on the surface of PDMS,and the sample could realize rapid and efficient sterilization by the synergy of physical rupture and photocatalytic effect.Owing to its special structure and properties,PDMS-ZnO/Au was endowed with superhydrophobic and low adhesion performance,which effectively prevented E.coli colonization with an anti-adhesion rate of more than 99.9%.Overall,this dual-function antibacterial surface significantly reduces the formation of bacterial biofilms,thus reducing the risk of bacterial infection.