Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, United States.
Department of Restorative Dentistry, Oregon Health and Science University, Portland, Oregon 97201, United States.
Anal Chem. 2023 Apr 18;95(15):6332-6340. doi: 10.1021/acs.analchem.2c05258. Epub 2023 Apr 5.
Dental plaque biofilm is a complex ecosystem. The distribution of microbial species in the biofilm is heavily influenced by local chemical interactions that result from diverse metabolic activities and the nature of the released molecules. As a relevant example, HO-producing bacteria can antagonize disease-associated bacteria, leading to the maintenance of a healthy oral microbiome. Herein, we report the development of a triple-sensor (redox, pH, and HO) scanning electrochemical microscopy (SECM) tip capable of simultaneously mapping the pH and HO concentration produced by a dental plaque-derived multispecies biofilm grown on hydroxyapatite. The pH sensor of the triple SECM tip showed a near Nernstian slope of -71.1 ± 2 mV/pH ( = 3), whereas the HO sensor showed a slope of -0.052 ± 0.002 nA/μM HO at pH 7.2 and a detection limit of 1.0 ± 0.2 μM ( = 7). There is no significant difference in the sensitivities of HO sensors at pH 6.2, 7.2, and 8.2 at 95% CI ( = 7). The pH and HO sensors demonstrated excellent reversibility with response times of 3 and 5 s, respectively, along with reliable stability over 4 h at 37 °C. The sensors did not show any cross talk between pH and HO concentration ([HO]) measurements, highlighting the accuracy and versatility of the SECM tip. Simultaneous chemical imaging of pH and [HO] across the biofilm revealed a clustered distribution of local HO concentrations, ranging from 0 to 17 μM. Conversely, the local pH remained constant at 7.2. The relation of local chemical profiles and the distribution of bacterial species within the oral microbiome was experimentally investigated in the context of bacterial HO antagonism. The benefit of clustered HO production was that the total area of HO produced by smaller clusters was 67% more than that of a single cluster with the same starting number of bacteria. Thus, this triple SECM tip can potentially be used to study local molecular mechanisms that result in dysbiosis of the oral microbiome.
牙菌斑生物膜是一个复杂的生态系统。生物膜中微生物物种的分布受到局部化学相互作用的强烈影响，这些相互作用是由各种代谢活动和释放分子的性质引起的。作为一个相关的例子，HO 产生菌可以拮抗与疾病相关的细菌，从而维持健康的口腔微生物组。在此，我们报告了一种三传感器（氧化还原、pH 和 HO）扫描电化学显微镜（SECM）尖端的开发，该尖端能够同时绘制在羟基磷灰石上生长的源自牙菌斑的多物种生物膜产生的 pH 和 HO 浓度。三 SECM 尖端的 pH 传感器显示出接近 Nernst 斜率的-71.1 ± 2 mV/pH（= 3），而 HO 传感器在 pH 7.2 时显示出-0.052 ± 0.002 nA/μM HO 的斜率和 1.0 ± 0.2 μM 的检测限（= 7）。在 95%置信区间（= 7）内，在 pH 6.2、7.2 和 8.2 下，HO 传感器的灵敏度没有显著差异。pH 和 HO 传感器的响应时间分别为 3 和 5 s，在 37°C 下稳定 4 小时以上。传感器在 pH 和[HO]测量之间没有表现出任何串扰，突出了 SECM 尖端的准确性和多功能性。通过对生物膜进行 pH 和[HO]的同时化学成像，揭示了局部 HO 浓度的聚类分布，范围从 0 到 17 μM。相反，局部 pH 保持在 7.2。在细菌 HO 拮抗的背景下，实验研究了口腔微生物组中局部化学图谱与细菌物种分布之间的关系。局部 HO 产生的聚类的好处是，具有相同起始细菌数量的较小簇产生的 HO 总面积比单个簇多 67%。因此，这种三传感器 SECM 尖端可用于研究导致口腔微生物组失调的局部分子机制。
