Functionalised microscale nanoband edge electrode (MNEE) arrays: the systematic quantitative study of hydrogels grown on nanoelectrode biosensor arrays for enhanced sensing in biological media

Abstract

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 antibiofouling; 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

Weaving Off‐The‐Shelf Yarns into Textile Micro Total Analysis Systems (μTAS)

“…We compare the wicking properties of Coolmax yarns and conductive properties of Au, Ag, and CNT coated The field of diagnostics has for many years now been pushing toward miniaturized point-of-care devices. [1][2][3][4] These have typically been made using microfabrication technologies. [5][6][7][8] However, these often require complex and expensive fabrication.…”

“…The field of diagnostics has for many years now been pushing toward miniaturized point‐of‐care devices. [ 1–4 ] These have typically been made using microfabrication technologies. [ 5–8 ] However, these often require complex and expensive fabrication.…”

Recent advances in biomedical, biosensor and clinical measurement devices for use in humans and the potential application of these technologies for the study of physiology and disease in wild animals

“…The issue of biofouling is a key area of biosensor research with many groups working on improved surface chemistries or gel-based systems which reduce biofouling and improve the reporting of a device's true analytical response. The ability to precisely control the formation of hydrogels was shown in a study that used nanoelectrode structures to monitor the formation of gels in real time and then used the underlying electrode as a sensor for specific drug resistance DNA gene sequences with the formed hydrogel behaving as a filter, effectively screening out background interferents to improve the analytical response of the device [74].…”

Band Electrodes in Sensing Applications: Response Characteristics and Band Fabrication Methods

“…The electrical connection was achieved via the contact pad using a commercial nanoelectrode substrate holder and the substrate was then able to be immersed into the solution and to be interrogated by commercial potentiostat systems . The MNEE arrays have been suggested to have improved sensitivity, selectivity, and/or detection limits, notably regarding the functionalization of the electrode surface with a corresponding thiol layer toward a specific target, which are suitable for electrochemical and biochemical sensing. ,,,, However, the very thin top insulating layer (typically 300-nm-thick silicon nitride) which was used to protect the top surface of the electrode layer from the electrolyte might produce significant stray capacitance, affecting the device response, which is a generic consideration in this area.…”