Preparation Of Light-Responsive Zinc Oxide Composite Material And Its Antibacterial Application In Eyes

Zinc oxide（Zn O）has been approved by the United States Food and DrugAdministration（FDA）for its excellent biosafety,which is widely used by researchers in antibacterial,anticancer,biosensing and bioimaging research.However,the wide energy band gap（3.37 e V）restricts the use of Zn O in the eyes because it can only be excited by some short wavelength（ultra violet（UV）or blue-violet light）sources that are harmful to humans.In this thesis,the construction of Zn O-based composites with long wavelength photoresponsive properties and their application to ocular antimicrobial applications are explored by improving the conventional Zn O.The details of this thesis are as follows:Chapter 1:The research background,physicochemical properties and applications of photoresponsive antibacterial materials,Zn O and nanozymes in biomedicine are introduced.On this basis,the subject selection basis and innovation point of this paper are put forward.Chapter 2:Doping is regarded as the most representative strategy to improve the photocatalytic performance of Zn O,and the excellent optical properties of rare earth elements are considered as“activators”for the modification of Zn O.In this study,doped terbium（Tb）into the lattice of Zn O to form Tb-Zn O（ZT）by co-precipitation method and examined its photocatalytic performance.The experimental results showed that the narrowed energy band gap of ZT（2.4 e V）could respond to long wavelength light sources,which verified that more reactive oxygen species（ROS）were produced under the excitation of green light（GL）,thus achieving efficient photodynamic bactericidal effects.However,its anti-inflammatory effects were limited.Nitric oxide（NO）,an important signaling molecule in the body,is involved in important cellular and biochemical reactions in the human body.It has been shown that NO can exert its immunomodulatory effects by regulating the expression of inflammatory factors.Therefore,we constructed a Tb-doped Zn O nitric oxide release platform（CL-ZT@P@B）by loading the NO precursor（ZT@P@B）on a surface-modified polydopamine（PDA）coating of Tb-doped Zn O and modifying it on the surface of contact lenses（CL）.The combination of Zn O based photodynamic antimicrobial therapy and NO gas therapy was expected to address the root cause of bacterial keratitis by modulating the inflammatory response.Chapter 3:As a typical family of ideal alternative antimicrobial method,ROS is an excellent material for rapid sterilization.Most current antimicrobial materials are utilized to produce ROS under their stimulating conditions,thus exhibiting excellent bactericidal properties.We designed a mesoporous Zn O-based nanoenzyme（ZRG）with an acid-enhanced triple antimicrobial strategy in synergy with Zn O which released Zn²⁺with bactericidal properties under acidic conditions.By integrating glucose oxidase（GOx）and ruthenium nanoparticles（Ru NPs）,the“byproduct”of the cascade catalytic reaction,gluconic acid,could generate an acidic environment that promoted the production of ROS and the release of Zn²⁺,further enhancing the overall antimicrobial performance.At the same time,it had excellent warming ability under near infrared（NIR）irradiation,thus achieving photothermal sterilization.The nanoenzyme exhibited outstanding bactericidal ability and was loaded into a casein hydrogel with remarkable biocompatibility for the treatment of bacterial ocular infections,which had great potential for the efficient bacterial eradication in the clinical applications in ophthalmology.