A pH-Responsive Smart Copolymer For Selective Removal of Cariogenic Oral Biofilms

项目总结/摘要 控制致龋生物膜是预防龋病的关键。然而，这是一个重大挑战， 破坏坚固的胞外聚合物（EPS）基质结构或杀死嵌入的细菌。 使用化学或物理手段的治疗性处理不能充分控制致龋生物膜，并且不能 降低龋齿风险。为了解决这个问题，我们提出了一个全新的删除策略，通过转换 生物膜从粘性变成脆性，不依赖于酶或化学降解的EPS。我们有 设计了一种低分子量阳离子甲基丙烯酸酯聚合物，其可以渗透到生物膜基质中， 通过静电相互作用与阴离子生物膜生物聚合物结合。这种作用可以交联生物膜基质， 防止EPS基质在应力下的结构重新排列，从而导致内聚破坏， 生物膜去除不及时。引人注目的是，我们的研究表明，聚合物去除了60%的链球菌 变形杆菌生物膜生物量，而氯己定和阳离子表面活性剂， （CTAB）未能去除相同的生物膜。在这项研究中，我们将扩展我们的方法，以解决未满足的问题。 靶向致龋生物膜的挑战。我们假设pH响应智能聚合物可以 被设计成通过酸性pH从中性状态切换到阳离子状态，因此它们的抗生物膜和杀菌 只有在致龋生物膜的酸性微环境中才能触发活性，而在中性健康环境中则不能。 生物膜为了验证这一假设，我们将设计和开发一种具有相同数量的无规共聚物， 阳离子铵和阴离子羧基，其在pH为 4.5这是由于羧基的质子化。本研究的意义在于设计和开发一个高度 有效、安全和直接的抗生物膜方法，与目前使用 化学和生物制剂。本研究的创新之处在于结合了针对 生物膜固有的物理化学（酸性微环境）和机械（粘弹性）性质 基质，以实现选择性和有效地去除致龋生物膜。在目标1中，我们将评估酸- 引发的共聚物对嗜酸性口腔细菌的杀菌活性。在目标2中，我们将评估其 利用唾液衍生物去除产酸生物膜和杀死包埋细菌的效力和选择性 生物膜模型所提出的方法具有降低疾病风险的巨大潜力， 牙齿腐烂的风险，改善数百万人的生活。

PROJECT SUMMARY/ABSTRACT Controlling cariogenic biofilms is the key for prevention of dental caries. However, it is a significant challenge to disrupt robust extracellular polymeric substances (EPS) matrix structures or kill embedded bacteria. Therapeutic treatments using chemical or physical means inadequately control cariogenic biofilms and fail to reduce caries risk. To address this problem, we propose a completely novel removal strategy by transforming biofilms from sticky into brittle, not dependent on enzymatic or chemical degradation of EPS. We have designed a low molecular weight cationic methacrylate polymer that can penetrate into a biofilm matrix and bind to the anionic biofilm biopolymers by electrostatic interactions. This action can crosslink the biofilm matrix, preventing structural re-arrangement of the EPS matrix under stress, and thus it causes cohesive failure and untimely biofilm removal. Strikingly, our study demonstrated that the polymer removed 60% of Streptococcus mutans biofilm biomass by using hydrodynamic cycles for 30 sec, while chlorhexidine and cationic surfactant (CTAB) failed to remove the same biofilms. In this study, we will extend our approach to address the unmet challenge of targeting cariogenic biofilms. We hypothesize that pH-responsive smart polymers can be designed to switch from neutral to cationic states by acidic pH, and thus their anti-biofilm and bactericidal activities can be triggered only in the acidic microenvironment of cariogenic biofilms, but not in neutral healthy biofilms. To test this hypothesis, we will design and develop a random copolymer with an equal number of cationic ammonium and anionic carboxylic groups, that switches from neutral charge to cationic at the pH of 4.5 due to the protonation of carboxylic groups. The significance of this study is to design and develop a highly effective, safe, and straightforward anti-biofilm approach, as compared to current inadequate treatments using chemical and biological agents. The innovation of this study is the combination of mechanisms that target the inherent physicochemical (acidic microenvironment) and mechanical (viscoelasticity) properties of a biofilm matrix to achieve selective and effective removal of cariogenic biofilms. In Aim 1, we will evaluate the acid- triggered bactericidal activity of copolymer against planktonic oral bacteria. In Aim 2, we will evaluate its efficacy and selectivity to remove acidogenic biofilms and kill embedded bacteria by using saliva-derived biofilm models. The proposed approach has the significant potential of reducing the risk of disease for individuals at risk of tooth decay improving the lives of millions of people.