| In clinical work,sensory control in high-risk departments,such as dental clinics,gastrointestinal endoscopy rooms,and intensive care units,has always been subject to focal attention.It is equally critical to seek a safe,efficient,and inexpensive antibacterial material to disinfect the surrounding environment,surface and equipment.Great importance is also attached to preventing cross-infection and blocking iatrogenic infections and ensuring patient safety.Photodynamic inactivation based on nanomaterials has been considered to be one of the most promising strategies for maintaining ecological security and human health far away from pathogens.Graphene carbon nitride(g-C3N4),a most popular two-dimension nanomaterials,has been widely employed in photodynamic inactivation of various microorganisms.However,it is still necessary to explore effective strategies to overcome the inherent defects of g-C3N4,such as weak visible light response and high photoelectron-hole recombination rate.In this paper,a series of g-C3N4-based nanomaterials with high inactivation efficiency against E.cloacae were designed and synthesized based on the synergistic effects between combinatorial modification strategies.The inactivation activity and chemicobiological mechanism over these nanomaterials were explained in detail.The main research contents and conclusions were as follows:1.A series of novel visible-light-driven Ti and O co-doped g-C3N4photocatalysts were successfully prepared by a facile thermal copolymerization with formic acid and titanium tetrachloride as doping sources and urea as precursor.Under visible light radiation,the obtained Ti/OCN nanomaterials exhibited good inactivation activity against E.cloacae and could eliminate more than 6.2 log CFU·m L-1E.cloacae within 60 min.In inactivation process,the cell structural damage,the functional molecules release and oxidation were observed,which led to the cell death of E.cloacae.The enhanced visible light response ability,accelerated separation and migration of photogenerated electrons,and increased generation of reactive oxygen free radicals,such as·O2-,·OH in Ti/OCN system were proven by various characterization,which contributed to the improved bactericidal performance.2.The Ti/OCN/PDA nanomaterials were obtainded by self-polymerization reaction of polydopamine on the surface of Ti/OCN.The modification of PDA was confirmed by the characterization results of XPS,SEM and TEM.The Ti/OCN/PDA possessed excellent anchoring and improved wettability properties,which facilitated the damage of reactive oxygen species to E.cloacae.Meanwhile,the enhanced visible light response and accelerated ROS generation were also responsible for the high inactivation activity of Ti/OCN/PDA.3.A novel Ag deposited O doped g-C3N4(OCN)nanomaterials with different Ag content were constructed via a facile calcination combining with biogenic-reduction method using dihydromyricetin as reducing agent.The doping of O could regulate the charge distribution of g-C3N4and promote the generation of photogenerated electrons.The localized surface plasmon resonance(LSPR)of Ag nanoparticles could prolongs the lifetime of photogenerated electrons.Thus,a large amount of·O2-generated through multiple pathways based on the above synergistic effect,and Ag/OCN-5 exhibited the strongest photocatalytic inactivation and could inactivate E.cloacae at a lower concentration and a shorter time,completely.4.Similarly,the photodynamic inactivation activity of the modified Ag/OCN/PDA was further improved.This improved bactericidal performance was mainly attributed to the synergistic effects of oxygen doping,silver loading and PDA modification,which held enhanced visible light response,increased probability of photoelectron transition,separation and utilization,and improved wettability and anchoring properties.Our present work presented a promising and environmentally friendly strategy to enhance the photocatalytic capacities of CN based composites for oral pathogens inactivation. |
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