高效过氧化物纳米酶清除口腔生物膜和预防龋齿的作用及其机制

Dental caries are becoming more and more common in both children and adults in worldwide and heavily affect human health and life. As a critical factor in the onset of dental caries, virulent biofilm (Streptococcus mutans) formed on tooth surface has a spatially heterogeneous and diffusion-limiting matrix comprised of extracellular polymeric substances and generate a local acidic microenvironment leading to the dissolution of adjacent tooth enamel. Bactericides often fail to eliminate cariogenic biofilm because they cannot kill the clusters of microbes that are protected by the extracellular matrix and the local microenvironment. Therefore, new approaches should effectively disrupt the matrix and kill the embedded bacteria at acidic microenvironment, where pathogenic bacteria prosper and actively develop biofilms. To address these challenges, we propose a novel strategy using iron oxide (Fe3O4) nanozyme with peroxidase-like activity that catalyzes hydrogen peroxide (H2O2) to effectively disrupt biofilm matrix and kill internal bacteria under acidic condition. The concept is based on our previous findings that iron oxide nanoparticles have intrinsic peroxidase-like activity (Nature Nanotechnology 2007) and perform the preliminary ability for biofilm elimination (Nanoscale 2014). In this proposal, we will design a small nanozyme library by controlling nanoparticle size, doping and surface modification and screen the nanozyme with high activity and biocompatibility for oral biofilm (Streptococcus mutans) elimination. The matrix degradation, bacteria killing and demineralization prevention will be systematically evaluated with an in vitro single-strain and multi-strain biofilm models and the relevant biochemical mechanism will be investigated to better understand how nanozyme works in the biofilm. We will also assess the efficiency of caries prevention, influence on oral microbial ecology and biosafety of nanozyme in in a well-established rodent model of the disease. The outcome of this project will provide a systematic understanding for the comprehensive effects and the mechanisms of nanozyme in oral biofilm elimination and caries prevention. We envision a completely novel and highly viable technology to eradicate virulent oral biofilms and prevent dental caries. Our approach also has broad and potential applicability for the biofilms associated with many other infectious diseases.

龋齿在我国儿童和成人中均具有很高的患病率，严重影响人们的健康和生活。致龋性口腔生物膜是诱发龋齿的关键因子之一，常用的抗菌剂对此生物膜清除效果有限，主要原因是很难突破基质屏障杀灭内部细菌。为此，申请人提出利用四氧化三铁过氧化物纳米酶介导的催化反应降解生物膜基质屏障和杀灭内部细菌，实现口腔生物膜的高效清除。本项目将设计适合在口腔致龋性生物膜酸性环境下工作的纳米酶，系统研究其生物膜基质降解能力和杀菌效率、防止牙齿脱矿以及相关的生物化学机理，并用动物模型评估其预防龋齿的效果、对口腔微生态的影响和生物安全性。通过以上研究，阐明纳米酶在生物膜清除和龋齿防治中的多种生物效应和相关的分子机理，为口腔生物膜清除和龋齿预防提供新的策略，同时也为其他生物膜相关疾病的治疗提供参考。

龋齿等口腔疾病具有很高的发病率，严重影响人们的日常生活和健康。细菌生物膜难以清除是造成龋病防治困难的关键问题之一，源于细菌对多种药物产生耐药性。本项目旨在开发高性能纳米酶用于清除口腔细菌生物膜，评估其在龋齿防治和改善口腔卫生健康的应用潜力。. 首先利用水热法、模板法等纳米合成技术制备了纳米酶库，从中筛选具有高活力、高抗菌效果的纳米酶。在系统研究纳催化活性和物理化学性质的基础上，测试了纳米酶的抗菌性能，对口腔细菌及其生物膜、多菌种生物膜及相关的龋病和牙周炎的防治效果，并进一步拓展了纳米酶对其他耐药菌及相关疾病防治的应用研究。. 主要取得以下重要发现：（1）由氧化铁纳米酶杀菌拓展到了硫化铁纳米酶杀菌。本项目初期计划利用氧化铁纳米酶过氧化物酶活性杀菌，在筛选纳米酶文库过程中发现硫化铁纳米酶具有更强的杀菌效果，对口腔细菌及其生物膜和多种耐药菌具有快速杀伤能力，在此基础上提出硫化铁是一种潜在的抗菌材料，并提出了新的杀菌机制，首次报道了亚铁与多硫协同引发的细菌铁死亡，对铁与多硫的生物学性能有了新的认识，表明铁死亡不仅局限于真核系统，原核系统也存在这种死亡方式。（2）铁基纳米酶不仅具有抗菌作用，还具有抗病毒功能。在课题项目过程中对纳米酶应用研究进行了拓展，发现氧化铁纳米酶引发流感病毒囊膜发生脂质过氧化，造成12中不同亚型的流感病毒失活，可用于防病毒口罩开发；此外氧化铁纳米酶还可作为催化佐剂增强灭活流感病毒鼻腔粘膜免疫效果，这一发现对增强新冠病毒疫苗免疫具有潜在的应用前景。（3）纳米酶的抗菌性能具有多用途。除口腔防龋应用外，还发现纳米酶具有口腔溃疡修复，烧伤感染和肠道感染防治等作用，具有广泛的应用前景。. 综上，通过该项目，不仅筛选得到了氧化铁纳米酶和硫化铁纳米酶用于龋齿防治，阐明了其杀菌效率和新机制，还进一步拓宽了纳米酶抗菌应用范围，为纳米酶抗菌药物和技术开发奠定了基础。