Antibacterial And Healing Functions Of New Inorganic Nanobiomaterials In Multi-drug Resistant Bacterial Infection Chronic Non-healing Wound And Keratitis

ObjectivesChronic nonhealing wounds are caused by severe trauma,burns,radiation damage,and diabetes.Among them,chronic skin wounds complicated by diabetes cause ischemia and dystrophy of tissues due to neurological and vascular diseases,etc.In the process of wound healing,it is easy to cause wounds to endure and become a danger to patients' health and a burden on social medical resources.In the late stage of the injury,difficultto-heal wounds are more prone to secondary bacterial infections due to sustained epithelial damage and inability to the body's defense mechanism.In ophthalmology,the incidence of secondary infectious keratitis in the late stage of corneal injury of diabetic patients has reached more than 70%.After bacterial infection,it induces an uncontrolled inflammatory response in a short period of time,forming a very severe acute suppurative corneal ulcer.Corneal ulcer can spreads to the whole cornea,even the entire eyeball,and further causes serious complications that threaten vision,such as ulcer perforation,exudation of eye contents,and endophthalmitis.These ocular diseases are with a high blinding rate.In recent years,the clinical situation of bacterial resistance has become more and more severe,and traditional antibiotics have encountered bottlenecks during their treatment.Therefore,it is urgently needed to develop a new therapeutic strategy that can quickly eradicate multi-drug-resistant bacterial infections and promote wound healing at the same time.Based on the above background,this topic addresses the two major problems of anti-infection and healing in chronic wounds and nonhealing keratitis.A series of new inorganic nanobiomaterials which are in conjunction with near-infrared laser photothermal therapy has been developed to reduce diabetes in vitro and in vivo.The murine animal model was systematically analyzed for its antibacterial and healing functions and mechanisms in chronic wounds and nonhealing keratitis infected by multidrug-resistant bacteria.MethodsIn this study,three new types of inorganic nanobiomaterials,triangular silver nanoparticles,ultra-small-sized copper sulfide nanodots,and gold-silver-cuprous oxide composite nanoshells,were constructed using one-step chemical and template methods.The morphology,structure,optical absorption properties,thermal stability,and photothermal conversion efficiency of nanomaterials were tested through experimental techniques such as high-resolution transmission electron microscopy,ultraviolet-visible spectrophotometer,dynamic light scattering instrument,and X-ray diffractometer.Bacterial and cellular in vitro models were performed by thiazole blue colorimetry,turbidity method,plate method,fluorescent labeling method,transmission electron microscope,scanning electron microscope,scratch method,angiogenesis method,and other experimental methods.With statistical quantitative analysis,in vitro antibacterial efficacy and mechanism of nanomaterials were evaluated.We established animal skin wounds and keratitis models of db/db mice infected with drug-resistant bacteria.Thermal imager detection,monitoring of wound closure rate,ophthalmic clinical scores,and histological analysis were implemented to evaluate antibacterial fuction and promotinghealing effects of nanomaterials in vivo.Through relevant immunohistochemical analysis,Western blotting and quantitative polymerase chain reaction tests,we revealed the main signal pathways of nano therapy to promote healing.Finally,the toxicological investigation of nanomaterials in animals was performed by means of bodyweight monitoring,hemolysis experiments,biochemical index examination,hematological analysis,and histological examination of major organs.ResultsIn this study,three new types of inorganic nanobiomaterials including triangular silver nanoparticles,ultra-small-sized copper sulfide nanodots,and gold-silver-cuprous oxide composite nanoshells were successfully constructed.The results show that nearinfrared laser-induced triangular silver nanoparticles can significantly inhibit clinically isolated methicillin-resistant Staphylococcus aureus and extended-spectrum ?-lactamase Escherichia coli,two multi-resistant strains,can accelerate wound crusting and contraction in skin wounds infected by drug-resistant bacteria in mice with some promoted healing effects.Ultra-small-sized Copper sulfide nanodots that cooperate with near-infrared laser can not only effectively kill multi-resistant strains including methicillin-resistant Staphylococcus aureus and extended-spectrum ?-lactamase Escherichia coli,but also release copper ions to promote fiber formation cell migration and regeneration of vascular endothelial cells can effectively accelerate chronic wound healing caused by drug-resistant bacteria.The gold-silver-cuprous oxide composite nanoshells combines the advantages of the former two,which not only can activate the hollow gold-silver alloy core by combining near-infrared laser to release silver ions,produce photothermal effect and photodynamic effect to effectively kill multi-resistant bacteria,but also can control the cuprous oxide shell releases copper ions to promote the migration of surrounding epithelial cells.It has been proven to effectively eliminate multidrug resistance in methicillin-resistant Staphylococcus aureus-infected diabetic mice with chronic skin wounds and nonhealing keratitis disease models.Bacterial infection,while promoting chronic wound healing,so as to achieve the purpose of healing.At the therapeutic dose,none of the three materials showed significant toxicity to mouse body weight,blood,and major organs.ConclusionIn this study,aiming at the two major problems of drug-resistance infection, chronic wounds and nonhealing keratitis,we have successfully constructed triangular silver nanoparticles with major outcome of anti-multidrug resistant bacteria and indirect healing promoting effects,ultra-small-sized copper sulfide nanodots with major outcome of promoted healing and some anti-multidrug resistant bacteria effect,and gold-silvercuprous oxide composite nanoshells which have both strong anti-multi-drug resistant bacteria and promoting healing effects.All the three nanomaterials were combined with near-infrared laser for photothermal treatment,and there is no obvious toxic and side effect on the surrounding normal tissues,blood,weight and main organs.These materials all demonstrated dual antibacterial and wound-healing effects.The nanotherapy system is suitable for chronic wound and nonhealing keratitis treatment and offers a promising candidate for clinical transformation.