Preparation And Antibacterial Application Of Ce³⁺,Pr³⁺ Doped Ultraviolet Long Afterglow Luminescent Particles

Wounds can easily lead to bacterial infections when it cannot be kept clean.Bacterial infection can easily lead to other serious problems such as bloodstream infection,infective endocarditis,sepsis,and cellulitis.The use of antibacterial dressings can prevent wound from infection and facilitate wound healing.Antibiotics can kill and inhibit pathogenic bacteria which will invade our bodies.However,the overuse of antibiotics has been one of the world’s problems and it has led to more and more pathogenic bacteria developing resistance.Therefore,it is urgent to develop new antibacterial agents for wound dressings.Ultraviolet long afterglow luminescent materials can emit light in the ultraviolet region when stimulated by external light sources,and the duration of such long afterglow violet light can persist for from a few hours to dozens of hours.In order to meet the needs of sterilization in daily life,this paper explores different synthesis methods to obtain nanoscale ultraviolet long afterglow luminescent materials with long afterglow time and stronger afterglow violet intensity.Then,the principle and mechanism of afterglow emission enhancement is also investigated in detail.Finally,the ultraviolet long afterglow luminescent nanoparticles were utilized to the wound dressing via the combination of silicon gel.Finally,the treatment effect of the novel wound dressing in antibacterial fields was studied.The main research contents of the paper are as follows:1.Violet long afterglow luminescent particles CaB₂O₄:Ce³⁺were prepared by co-precipitation method using a peristaltic pump to control droplet acceleration.The results showed that violet afterglow emission can persist for over 2 hours.The TiO₂ particles were coated on the surface of CaB₂O₄:Ce³⁺via the hydrolysis of tetrabutyl titanate.Under the excitation of violet afterglow emission lights of CaB₂O₄:Ce³⁺,TiO₂ can adsorb oxygen and water to produce active hydroxyl radicals（·OH）and superoxide anion radicals（O₂^-）,which thus showed a continuous bactericidal effect.And the best TiO₂ coating concentration was chosen via the series of tests.The CaB₂O₄:Ce³⁺@TiO₂ particles were mixed with Dow Corning SYLGARD 184 silicone rubber to prepare thin films and their bactericidal effects were explored.The obtained results showed that when the CaB₂O₄:Ce³⁺@TiO₂ film was irradiated by UV lamp firstly,then this film was covered the bacterial solution.After 30 min treatment,the germicidal efficiency can reach 50%.And after 3 hours treatment,the germicidal efficiency can reach 95%.In addition,this sterilization method has no difference between gram-negative bacteria and gram-positive bacteria,suggesting that the sterilization effect is broad-spectrum.And the duration of the afterglow of the CaB₂O₄:Ce³⁺@TiO₂ film is much longer than 2 hours,which can meet the need for the replacement time of bandages in daily life.2.Ultraviolet C long afterglow luminescent particles Lu₂SiO₅:Pr³⁺were prepared by sol-gel method.And the effects of sintering time and co-doped ions on the afterglow properties of the materials have been investigated.The results showed that after co-doping with P⁵⁺,the afterglow emission intensities and time were significantly improved.At the same time,the best afterglow performance was obtained by sintering temperature at 1250℃for 4 h.And the thermoluminescence results were utilized to explore the reason for the enhancement of afterglow after incorporation of P⁵⁺.After the incorporation of P⁵⁺into Lu₂SiO₅:Pr³⁺,P⁵⁺would replace some of the Si⁴⁺lattice sites,which can increase the trap concentration due to unequal substitution.This would enhance the afterglow performance of the particles.In addition,the effect of different concentrations of P⁵⁺doping on the afterglow luminescent properties was investigated.It was found that the best concentrations of P⁵⁺was 4%and excessive incorporation of P⁵⁺led the decrease of afterglow intensity.The sterilization effects of Lu₂SiO₅:Pr³⁺,P⁵⁺thin films was investigated.The results showed that the sterilization rate of the bacterial solution irradiated with Lu₂SiO₅:Pr³⁺,P⁵⁺film afterglow for 30 minutes and the bacterial solution irradiated with 254 nm ultraviolet lamp for 10 minutes both reached more than 80%.This sterilization method had a broad-spectrum sterilization effect,because the afterglow decay time of Lu₂SiO₅:Pr³⁺,P⁵⁺film was far longer than 2 hours,which also meet the needs of daily life for bandage replacement time.