Electrochimica Acta 126 (2014) 98–103 Contents lists available at ScienceDirect Electrochimica Acta j our na l ho me pa g e: www.elsevier.com/locate/electacta Practical Implications of using Nanoelectrodes for Bioanalytical Measurements Reshma Sultana a , Naser Reza a , Nicola J. Kay a , Ilka Schmueser b,c , Anthony J. Walton c , Jonathan G. Terry c , Andrew R. Mount b , Neville J. Freeman a,∗ a NanoFlex Ltd, Daresbury Innovation Centre, Keckwick Lane, Daresbury, WA4 4FS, United Kingdom b EaStCHEM, School of Chemistry, The University of Edinburgh, Joseph Black Building, King’s Buildings, Edinburgh, Scotland, EH9 3JJ, United Kingdom c Institute for Integrated Micro and Nano Systems, School of Engineering, The University of Edinburgh, King’s Buildings, Edinburgh, EH9 3JF, United Kingdom a r t i c l e i n f o Article history: Received 18 May 2013 Received in revised form 5 December 2013 Accepted 7 December 2013 Available online 30 December 2013 Keywords: Nanoelectrode Nanoband Bioelectrochemical Bioanalysis Biosensor a b s t r a c t The performance of a 50 nm thick nanoband electrode structure which forms an array of nano-scale elec- trodes has been investigated for bioelectrochemical applications, specifically the performance related to the detection of three common bioelectrochemical redox species, ferrocene carboxylic acid, hydrogen peroxide and 4-aminophenol. The detection limits were established to be 89, 2 and 36 × 10 -9 mol dm -3 respectively, which is consistent with the increased sensitivity of nanoelectrode systems compared to larger electrodes. The limit of detection determined for H 2 O 2 is comparable to those previously obtained by using both nanowires and modified electrodes for enhanced detection suggesting these arrays are highly suited for use in bioanalysis. This relatively simple nanoband electrode architecture is shown to be capable of fast scan cyclic voltammetric detection up to 10 V s -1 while at the same time being relatively insensitive to hydrodynamic perturbations. The paper considers the implications of these enhanced per- formance characteristics within bioanalytical measurement systems and their practical benefits in the development of electroanalytical devices. © 2014 Elsevier Ltd. All rights reserved. 1. Introduction Nanoelectrodes have been of intense interest for the past two decades in the field of bioelectrochemistry. The potential benefits of nanoelectrodes compared to electrodes of larger dimensions have been demonstrated by numerous workers and they are very well understood from a theoretical perspective. Such benefits include enhanced mass transport, increased signal-to-noise ratio, greater sensitivity and increased immunity to hydrodynamic perturba- tions [1–4]. However, there still remain considerable challenges in the production of robust, reproducible nano-scale devices and the extent to which these theoretical benefits can be realised experimentally. This arises, at least in part, from the complexities involved in nanoelectrode fabrication and the verification of elec- trochemical performance post fabrication [2]. More recently, the fabrication of reproducible nanoelectrode arrays with highly con- trolled electrode geometry, array spacing and quantifiable response has been achieved by taking advantage of processes and equipment ∗ Corresponding author. NanoFlex Limited, The Innovation Centre, Sci-Tech Dares- bury, Keckwick Lane, Daresbury, WA4 4FS, United Kingdom. Tel.: +44 0 1925 864042. E-mail address: neville.freeman@nanoflex.com (N.J. Freeman). more readily associated with semiconductor fabrication technol- ogy [5–8]. One of the key potential applications of nanoelectrodes is in bioanalytical measurement systems e.g. for healthcare applica- tions. In principle, the theoretical benefits of nanoelectrodes can be exploited to give enhanced Limits Of Detection (LOD) for a range of physiologically relevant redox active biomolecules, especially as the critical dimension of the nanoelectrode approaches the molec- ular scale [2]. A key area of interest would be to improve the overall performance of bioelectroanalytical devices through this enhanced sensitivity. The objective of this paper is to demonstrate the prac- tical feasibility of this approach. 1.1. Nanoband electrode characterisation Previously, we have described the precise semiconductor pro- cesses employed to produce a model nanoband electrode structure (the Microsquare Nanoband Edge Electrode (MNEE) array system [5]) and the enhanced performance benefits observed compared to a single microdisc electrode of comparable electrode area under similar experimental conditions [5–7]. In the previous papers the characterisation of these structures for several elec- trode geometries and dimensions has been undertaken in detail [6]. This work demonstrated good agreement between finite element 0013-4686/$ – see front matter © 2014 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.electacta.2013.12.026