Synthesis Of Photo-Sensitive ZnO-Based Composites And Their Applications In Stomatology

In recent years,the photoresponse of Zinc Oxide(ZnO)has been widely used in photocatalytic antibacterial,photothermal therapy,drug delivery,implant materials,biological detection and medical imaging.At present,ZnO used in stomatology has a wide band gap,mostly stimulated by short-wavelength light sources such as ultraviolet light or blue-violet light,which will cause damage to skin and mucous tissues after long-term excessive action.How to use long-wavelength light energy is the prerequisite to ensure the biological safety of ZnO and develop the practical application of stomatology.In this paper,a kind of Tremella-like ZnO(Tre ZnO)with high specific surface area and narrow band gap was synthesized,and a series of photoresponsive composites based on Tre ZnO were constructed.Their physicochemical properties and applications in the prevention and treatment of some common oral diseases were mainly studied.The main results are summarized as follows:(1)Tre ZnO with light response was prepared by a hydrothermal-microwave method,and its physicochemical properties were systematically discussed.The results showed that compared with conventional ZnO rod,Tre ZnO had higher specific surface area,which endowed it with better adsorbability.It also held a narrower band gap(2.125 e V),which enabled it to exhibit effective antibacterial activity against Grampositive Staphylococcus aureus(S.aureus)and Gram-negative Escherichia coli(E.coli)under yellow light excitation with low intensity and long-wavelength.In addition,Tre ZnO might be served as a potential photothermal candidate due to its photothermal conversion ability under near infrared(NIR)laser irradiation.(2)A multifunctional composite with photosensitive broad-spectrum antibacterial and osteogenic properties was constructed by adsorption of Tre ZnO on collagen type I(Col-I),and the application value of Tre ZnO@Col-I(denoted as ZC)as Titanium(Ti)surface coating in the prevention and treatment of peri-implant diseases was discussed.In vitro experiments demonstrated that ZC coating could be effectively activated through a mild visible yellow light to provide accurate,safe and broad-spectrum antibacterial properties(even including specific oral bacteria).In addition,due to the stable photothermal conversion properties induced by NIR irradiation,ZC could generate a local hyperthermal microenvironment conducive to osteogenesis.Combined with the improved hydrophilicity of Ti surface and the effect of Col-I,ZC could promote osteogenic gene expression of bone marrow mesenchymal stem cells(BMSCs).Meanwhile,in vivo experiments further verified that ZC coating combined with yellow light could effectively fight local bacterial infection and significantly promote the formation of new bone around Ti under the synergistic effect of dual light.(3)A sprayable dental protector composed of Tre ZnO,fluorine modified nano silica(FSNs)and polydimethylsiloxane(PDMS)was developed for routine dental care.This protective agent(denoted as ZFP)could form a superhydrophobic coating on teeth surface by simple spraying,which could resist the adhesion of foreign bacteria,pigments and proteins,etc.,with a satisfied stability.At the same time,we found that the FSNs and PDMS could effectively endure the external acidic environment by establishing a concrete-like protective layer,thereby preventing teeth from acid erosion.In addition,Tre ZnO showed an excellent antibacterial activity against Streptococcus mutans(S.mutans)combined with yellow light,which further ensured dental health.The results of in vitro cell experiments and in vivo animal experiments confirmed that ZFP protectant had no obvious effect on cells and tissues,which made it a safe and effective dental protection strategy.