EaSTCHEM, School of Chemistry, The University of Edinburgh, Joseph Black Building, King's Building's, David Brewster Road, Edinburgh, EH9 3FJ, UK.
Faraday Discuss. 2018 Oct 1;210(0):201-217. doi: 10.1039/c8fd00063h.
Nanoelectrodes and nanoelectrode arrays show enhanced diffusion and greater faradaic current densities and signal-to-noise ratios compared to macro and microelectrodes, which can lead to enhanced sensing and detection. One example is the microsquare nanoband edge electrode (MNEE) array system, readily formed through microfabrication and whose quantitative response has been established electroanalytically. Hydrogels have been shown to have applications in drug delivery, tissue engineering, and anti-biofouling; some also have the ability to be grown electrochemically. Here, we combine these two emerging technologies to demonstrate the principles of a hydrogel-coated nanoelectrode array biosensor that is resistant to biofouling. We first electrochemically grow and analyze hydrogels on MNEE arrays. The structure of these gels is shown by imaging to be electrochemically controllable, reproducible and structurally hierarchical. This structure is determined by the MNEE array diffusion fields, consistent with the established hydrogel formation reaction, and varies in structural scale from nano (early time, near electrode growth) to micro (for isolated elements in the array) to macro (when there is array overlap) with distance from the electrode, forming a hydrogel mesh of increasing density on progression from solution to electrode. There is also increased hydrogel structural density observed at electrode corners, attributable to enhanced diffusion. The resulting hydrogel structure can be formed on (and is firmly anchored to/through) an established clinically relevant biosensing layer without compromising detection. It is also shown to be capable, through proof-of-principle model protein studies using bovine serum albumin (BSA), of preventing protein biofouling whilst enabling smaller molecules such as DNA to pass through the hydrogel matrix and be sensed. Together, this demonstrates a method for developing reproducible, quantitative electrochemical nanoelectrode biosensors able to sense selectively in real-world sample matrices through the tuning of their interfacial properties.
纳米电极和纳米电极阵列相对于宏观和微观电极具有增强的扩散能力以及更大的法拉第电流密度和信噪比，这可以导致增强的传感和检测。一个例子是微方纳米带边缘电极 (MNEE) 阵列系统，它可以通过微制造很容易地形成，并且已经通过电化学定量建立了其定量响应。水凝胶已被证明在药物输送、组织工程和抗生物污损方面具有应用；有些水凝胶也具有电化学生长的能力。在这里，我们将这两种新兴技术结合起来，展示了具有抗生物污损能力的水凝胶涂层纳米电极阵列生物传感器的原理。我们首先在 MNEE 阵列上电化学生长和分析水凝胶。通过成像显示，这些凝胶的结构是电化学可控的、可重复的和结构分层的。这种结构由 MNEE 阵列扩散场决定，与已建立的水凝胶形成反应一致，并且在结构尺度上从纳米（早期，靠近电极生长）到微（对于阵列中的孤立元素）到宏观（当有阵列重叠时）变化，在从溶液到电极的过程中，形成越来越密集的水凝胶网格。在电极拐角处还观察到水凝胶结构密度增加，这归因于增强的扩散。所得的水凝胶结构可以形成在（并且牢固地锚定到/穿过）已建立的临床相关生物传感层上，而不会影响检测。通过使用牛血清白蛋白 (BSA) 的原理蛋白质研究，也表明它能够防止蛋白质生物污损，同时使小分子如 DNA 通过水凝胶基质并被检测到。总之，这证明了一种开发可重复、定量电化学纳米电极生物传感器的方法，该方法能够通过调整其界面特性来选择性地在实际样品基质中进行传感。
