Preparation Of Dual-light Defined Oral Mucoadhesive And Its Application In Oral Mucosal Injury

Background and objective:Oral mucosal injury is a range of diseases caused by the loss of mucosal integrity from various causes,such as mechanical trauma,invasive surgery,infectious inflammation,radiotherapy,etc.Oral mucosal ulcers,the most common type of oral mucosal injury,with a worldwide prevalence of more than 25%,seriously affect the patients’quality of life.Topical treatments,represented by antibiotics,growth factors,fibrin,hyaluronic acid and glucocorticoids,combined with various forms of dosage,are the main method of repairing oral mucosal injury.However,the complex oral flora as well as moist and mobile oral mucosa,make it difficult for drugs to reside for precise treatment purposes.At the same time,drugs such as antibiotics and glucocorticoids inevitably have side effects of antibiotic resistance and mucosal discoloration.In addition,the ideal goal for the treatment of oral mucosal injury varies depending on the progression and severity of the injury,but there is no individualized topical treatment strategy.All of these factors pose a challenge to the treatment of oral mucosal injuries.It is generally believed that the formation of a pseudomembrane after oral mucosal injury can act as a wound barrier to promote healing.Therefore,we constructed a pseudomembrane-like mucoadhesive to accelerate mucosal healing at the injury site.At the same time,inspired by the light-curing composite resin filling technology in dentistry,the light-regulated hydrogel adhesive was combined with a photocatalytic system to regulate the antimicrobial and pro-healing modes in real-time by light sources to meet the treatment needs of different stages of oral mucosal injury.Compared with the short wavelength visible light（<500 nm）commonly used in dentistry,highly efficient green light（GL）and 808 nm near-infrared（NIR）light that causes less cell damage,better tissue penetration and deeper curing depth were used.Under GL irradiation,similar to the mussel,the adhesive polymerizes in situ and forms an adhesion target with the wet oral mucosa,leading to rapid hemostasis,while also stimulating the photocatalytic component of the hydrogel to produce active bactericidal substances for early and precise antibacterial effects.Under NIR irradiation,the photothermal effect mediated by the photothermal agent promotes the release of plant polyphenols with anti-inflammatory effects,which synergistically promotes injury healing by reducing the secretion of inflammatory factors and accelerating microcirculatory blood flow.Research contents and results:（1）Porous zinc oxide（Zn O）was synthesized by hydrothermal method,followed by the formation of hybrid Zn O（ZP）on its surface by polydopamine（PDA）autoxidative polymerization,and the physicochemical properties were systematically investigated.The results showed that ZP had a narrower energy band gap（2.70 e V）and could generate reactive oxygen species（ROS）by photocatalysis under GL.The oral mucoadhesive ZPTA-G/HMA was constructed by mixing type II photoinitiator,tannic acid（TA）,ZP,gelatin methacrylate anhydride（Gel MA）and hyaluronic acid methacrylate（HAMA）by sol-gel method,and then in vitro adhesion properties as well as physicochemical properties were further investigated.The results showed that GL irradiation（～240 s）achieved in situ polymerization of this mucoadhesive,while also stimulating the photocatalytic effect to produce singlet oxygen（¹O₂）,which laid the foundation for the in situ elimination of bacterial microorganisms.The lap-shear,compression,swelling and degradation experiments confirmed the good physicochemical and in vitro oral mucosal adhesion properties,which have the potential to be used in oral mucosa.（2）In vitro hemostasis results showed that the ZPTA-G/HMA promoted erythrocyte adhesion and fibrin mesh formation for rapid hemostasis.In vitro antimicrobial studies have shown that ZPTA-G/HMA has good antibacterial activity under GL against Gram-positive and Gram-negative bacteria,as well as against Candida albicans（a fungus that colonizes oral mucosa）.Mechanistic studies confirmed that the production of ROS and the release of Zn²⁺synergistically disrupted bacterial cell membrane structure,and promoted protein leakage andβ-galactosidase hydrolysis.Cellular biosafety assays have shown that ZPTA-G/HMA has good biosafety under GL irradiation.In vitro warming experiments confirmed that ZPTA-G/HMA could be warmed rapidly under NIR irradiation and that the high temperature would lead to a slight collapse of the hydrogel structure to promote TA release.Finally,the lipopolysaccharide（LPS）stimulated macrophage inflammation model verified that ZPTA-G/HMA could reduce the secretion of TNF-α,IL-6 and IL-1βwith the aid of NIR,suggesting that this mucoadhesive is a potential biomaterial for the treatment of oral mucosal injury.（3）A tail severing model for Sprague Dawley（SD）rats was constructed by severing the tail,and the results showed that ZPTA-G/HMA exerted an excellent hemostatic effect through the combined physical sealing effect.By comparing the residence time of different materials through adhesion experiments in vivo,it was confirmed that the mucoadhesive could stay stably in the mouth for 8 h,providing an experimental basis for its further in vivo treatment.Finally,an in vivo oral mucosal chemical injury model was constructed with 70%acetic acid.The results showed that the ZPTA-G/HMA cleared pathogenic microorganisms from the injury site in situ under GL irradiation.Hematoxylin-eosin（H&E）and immunofluorescence staining confirmed the anti-inflammatory and pro-healing properties of the mucoadhesive under NIR irradiation,which could effectively reduce the infiltration of inflammatory cells and form a complete epithelial regeneration similar to that of the normal oral mucosa.It was tentatively demonstrated that this mucoadhesive could be used to repair oral mucosal damage in rats by dual-mode mediated by dual lights.Conclusion:We developed a novel oral mucoadhesive（ZPTA-G/HMA）and explored their application in oral mucosal injury by investigating their physicochemical properties as well as biocompatibility.In vitro experiments confirmed that this mucoadhesive had good mechanical and swelling properties,it could effectively sterilize by ROS production under GL irradiation and promoted TA release by photothermal warming under NIR irradiation,which had enhanced anti-inflammatory ability and promoted healing.In vitro and in vivo experiments have demonstrated that mucosadhesive could adhere to the oral mucosal surface for a longer period of time,effectively stopping bleeding.The oral mucosadhesive could also promote healing in oral mucosal chemical injury model in vivo with the aid of dual light.