在微生物发酵过程中制造一种纳菲安涂层、还原石墨烯 Oxide/Polyaniline 化学电阻传感器, 以实时监测 ph 值
Summary
在这里, 我们报告了制造纳菲安涂层, 聚苯胺功能化, 电化学还原氧化石墨烯化学电阻微 ph 传感器的协议。这种基于化学电阻的固态微 ph 传感器可以实时检测乳酸乳球菌发酵过程中的 ph 值变化。
Abstract
在这里, 我们报告了基于聚苯胺功能化、电化学还原氧化石墨烯 (ergo-pa) 的固态微 ph 传感器的工程。电化学还原的氧化石墨烯起导电层的作用, 聚苯胺作为 ph 敏感层。聚苯胺的 ph 依赖性电导率是在质子化过程中通过掺杂孔和在脱质子过程中对孔的掺杂而产生的。我们发现 ergo-pa 固态电极在发酵过程中不能发挥这样的作用。细菌在发酵过程中产生的电化学活性物种会干扰电极的反应。我们成功地将纳菲翁作为质子导电层应用于 ergo-pa 上。在化学电阻传感器测量中, nafion 涂层电极 (ergo-pa-na) 的灵敏度为1.71 ω/ph 值 (ph 值 4-9)。我们在乳酸乳球菌发酵过程中实时测试了 ergo-pa-na 电极。在乳酸生长过程中,培养基的 ph 值从 ph 值7.2 变为 ph 4.8, ergo-pa-na 固态电极的电阻从294.5ω改为288.6 ω (每 2.4 ph 单位 5.9ω)。ergo-pa-na 电极的 ph 响应与传统玻璃基 ph 电极的响应相比表明, 无参考的固体微传感器阵列在微生物发酵中成功运行。
Introduction
ph 值在许多化学和生物过程中起着至关重要的作用。即使 ph 值的微小变化也会改变过程, 并对工艺结果产生不利影响。因此, 有必要在实验的每个阶段监测和控制 ph 值。玻璃基 ph 电极已成功地用于监测许多化学和生物过程中的 ph 值, 尽管玻璃电极的使用对 ph 值的测量构成了若干限制。玻璃基 ph 电极是相对较大的, 易碎的, 电解质的小泄漏到样品是可能的。此外, 电极和电子产品相对昂贵, 适用于96孔筛选发酵系统。此外, 电化学传感器具有侵入性, 消耗样品。因此, 它更有利于使用非侵入性、无参考的传感器。
目前, 微型化反应系统在许多化学工程和生物技术应用中受到青睐, 因为这些微系统提供了增强的过程控制, 以及与宏观系统类似物相比的许多其他优势。要监视和控制微型化系统中的参数是一项具有挑战性的任务, 因为测量传感器的尺寸 (例如 ph 值和o2) 也需要最小化。生物系统微反应器的成功生产需要不同种类的过程监测分析工具。因此, 智能微传感器的发展在微反应器中开展生物过程中发挥着重要作用。
最近, 已经尝试了几次使用化学电阻传感材料, 如碳纳米管和导电聚合物1开发智能ph 传感器.这些化学电阻传感器不需要参考电极, 并且易于与电子电路集成。成功的化学电阻传感器可以生产出经济高效、易于制造、测试量小、无创的智能传感器。
在这里, 我们报告了一种方法, 以开发电极与聚苯胺功能化, 电化学还原氧化石墨烯。在乳酸发酵过程中, 化学电阻率电极作为 ph 传感器工作。乳酸是一种乳酸产生的细菌, 用于食品发酵和食品防腐剂的生产过程。在发酵过程中, 乳酸的产生降低了 ph 值, 细菌停止在低 ph 值2,3,4生长。
发酵介质是一种复杂的化学环境, 含有多肽、盐和氧化还原分子, 它们往往会干扰传感器表面5、6、7、8、9。研究表明, 在这种复杂的发酵介质中, 基于具有适当表面保护层的化学电阻材料的 ph 传感器可以用来测量 ph 值。在本研究中, 我们成功地使用 nafion 作为聚苯胺涂层的保护层, 电化学还原的氧化石墨烯在l.乳酸发酵过程中实时测量 ph 值。
Protocol
Representative Results
Discussion
go 层在 go 沉积后完全覆盖金电极线是非常重要的。如果黄金电极不被 go 覆盖, 聚苯胺不仅会沉积在 ergo 上, 还会直接沉积在可见的金电极电线上。聚苯胺在金电极线上的沉积可能会对电极的性能产生影响。在 go 还原到 ergo 后, 电极在100°c 下干燥, 以加强 ergo 层与金电极线之间的粘合。每个电极的电阻根据沉积在金电极上的 go 层的数量而变化。因此, 每个电极的 go 浓度相同是很重要的, 并且很难在?…
Disclosures
The authors have nothing to disclose.
Acknowledgements
提交人感谢格罗宁根大学的财政支持。
Materials
| Graphite flakes | Sigma Aldrich | ||
| Sulfuric acid (H2SO4) | Merck | ||
| Sodium nitrite (NaNO2) | Sigma Aldrich | ||
| Potassium permanganate (KMnO4) | Sigma Aldrich | ||
| 30 % H2O2 | Sigma Aldrich | ||
| HCL | Merck | ||
| Aniline | Sigma Aldrich | ||
| 5wt % Nafion | Sigma Aldrich | ||
| M17 powder | BD Difco | ||
| Phosphoric acid (H3PO4) | Sigma Aldrich | ||
| Boric acid (HBO3) | Merck | ||
| Acetic acid | Merck | ||
| Sodium Hydroxide | Sigma Aldrich | ||
| Potassium dihydrogen phosphate | Sigma Aldrich | ||
| Dipostassium hydrogen phosphate | Sigma Aldrich | ||
| Au Interdigitated electrodes | BVT technology – CC1 W1 | ||
| Potentiostat | CH Instruments Inc (CH-600, CH-700) |
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