Hydrogel encapsulated biofilm inhibitors for dental caries prevention and treatment

作为龋病发生的主要病原体，变形链球菌已经发展成为 多种机制来定植牙齿表面，成为牙齿生物膜不可分割的一部分。在……下面 在不健康的条件下，致病菌，即产酸和耐酸细菌，开始在口腔中占据主导地位。 种群数量和有益微生物的数量，如血链球菌和链球菌 Gordonii显著减少。然后，生物膜发酵饮食中的碳水化合物产生酸性副产品 如乳酸，会导致口腔pH值下降，导致牙齿脱矿。通常情况下， 唾液系统使用缓冲系统，以保持口腔中健康的PH值为6.0-7.5。酸碱度的下降 5.5以下对口腔硬组织(牙釉质和牙本质)和软组织有潜在危害。因此，我们 假设一种不影响口腔共生菌生存能力的生物膜抑制剂被输送到 以对pH有反应(当pH降至5.5时释放)的口腔方式将是一种理想的方法 预防/治疗龋齿。我们实验室的初步研究已经确定了这种特定的低微摩尔 不影响口腔粘连生长的小分子生物膜抑制剂。我们已经确定 这些化合物通过抑制变形链球菌的毒力因子葡萄糖基转移酶来产生其生物膜抑制作用。 从这些研究中鉴定出的两种活性化合物SN204和SN199一直显示出剂量依赖性 抑制生物膜，IC50值分别为16.7微米和15微米。此外，这些化合物确实做到了 不抑制变形链球菌和其他两个共生物种(血链球菌和戈登链球菌)的生存能力 至200微米，这比他们的生物膜IC50值要高得多。43天的S。 用SN204或SN199感染变异菌(UA159)感染龋齿的灵知生菌大鼠已导致相当大的 与对照组相比，颊、沟和近侧龋损评分降低。考虑到唾液 PH值低于5.5对牙釉质有潜在的危害，我们的目标是将我们的铅生物膜抑制剂包裹在 具有pH敏感性的聚甲基丙烯酸(PMAA)水凝胶纳米粒子网络及其探索 水凝胶包埋生物膜抑制剂对生物膜形成和龋病的影响 发展。在初步研究中，SN199已成功地被包裹到水凝胶中 每个颗粒的负载量为1.72×10-5 ng。作为原理的证明，我们已经证明了pH依赖 小分子抗癌药物阿霉素在PMAA水凝胶中的药物释放 已报道的研究。这项提案的总体目标是展示HEBIs的生物膜抑制活性 体外和体内，并建立其作为一种新型的、选择性的生物材料的潜力，可用于 预防和治疗龋齿。该项目的长期目标是将这些HEBI发展为 可在任何时间使用的牙条/牙膏，特别是在夜间睡眠时，以提供稳定的， 按需在口腔中释放生物膜抑制剂，以预防/治疗龋齿。

As the primary etiological agent for the dental caries development, Streptococcus mutans has developed multiple mechanisms to colonize the tooth surface and become an integral part of the dental biofilm. Under unhealthy conditions, pathogenic bacteria, namely acidogenic and aciduric species, begin to dominate the oral population while the number of beneficial organisms such as Streptococcus sanguinis and Streptococcus gordonii decrease significantly. Biofilm then ferments the dietary carbohydrates producing acid byproducts such as lactic acid which causes a decrease on oral pH leading to the demineralization of tooth. Normally, the salivary system employs buffer systems to maintain a healthy pH of 6.0–7.5 in the oral cavity. A drop in the pH below 5.5 is potentially harmful to the hard (enamel and dentin) and soft tissues in oral cavity. Therefore, we hypothesize that a biofilm inhibitor that does not affect the viability of oral commensal bacteria delivered in to oral cavity in a pH responsive (released when the pH drops below 5.5) manner will be an ideal approach to prevent/treat dental caries. Preliminary studies from our labs have identified such specific low micromolar small-molecule biofilm inhibitors that do not affect the growth of oral commensals. We have established that these compounds produce their biofilm inhibition by inhibiting S. mutans virulence factor, glucosyl transferases. Two active compounds identified from these studies, SN204 and SN199 consistently showed dose dependent inhibition of biofilms with IC50 values of 16.7 µM and 15 µM, respectively. Furthermore these compounds did not inhibit the viability of S. mutans and of the other two commensal species (S. sanguinis and S. gordonii) up to 200 µM, which is a much higher concentration than their biofilm IC50 values. A 43 day treatment of S. mutans (UA159) infected dental caries in gnotobiotic rats with SN204 or SN199 have resulted in considerable reduction in buccal, sulcal and proximal caries scores compared to the control groups. Given that the salivary pH less than 5.5 is potentially harmful to the enamel, we aim to encapsulate our lead biofilm inhibitors within the network of poly(methacrylic acid) (PMAA) hydrogel nanoparticles which possess pH sensitivity and explore the effect of such hydrogel encapsulated biofilm inhibitors (HEBIs) on biofilm formation and caries development. In the preliminary studies, SN199 has been successfully encapsulated into hydrogel with a loading capacity of 1.72×10-5 ng per particle. As proof of principle, we have demonstrated the pH dependent drug release of the small-molecule anticancer drug, doxorubicin from PMAA hydrogel in the previously reported studies. The overall goal of this proposal is to demonstrate the biofilm inhibitory activity of HEBIs in vitro & in vivo and establish its potential as a novel and selective biomaterial that can be used for the prevention and treatment of dental caries. The long term goal of this project is to develop these HEBIs as dental strips/creams that can be used any time, especially at night when sleeping in order to provide a steady, on-demand release of biofilm inhibitors in the oral cavity to prevent/treat dental caries.