Sensors & Actuators: B. Chemical 327 (2021) 128881 Available online 14 September 2020 0925-4005/© 2020 Elsevier B.V. All rights reserved. Hydrogenating carbon electrodes by n-butylsilane reduction to achieve an antifouling surface for selective dopamine detection Shajahan Siraj , Christopher R. McRae 1 , Danny K.Y. Wong * Department of Molecular Sciences, Macquarie University, Sydney, NSW 2109, Australia A R T I C L E INFO Keywords: Dopamine detection Antifouling carbon electrodes Conical-tip carbon electrodes n-Butylsilane reduction Ascorbic acid Dopamine-o-quinone ABSTRACT In this work, we have developed an antifouling carbon surface by hydrogenating it using n-butylsilane reduction. After incubating physically small electrodes with such an antifouling carbon surface for 30 min in a synthetic fouling solution containing 1.0 % (v/v) caproic acid (a lipid), 4 % (w/v) bovine serum albumin and 0.01 % (w/v) cytochrome c (both are proteins), and 0.002 % (w/v) human fbrinopeptide B (a peptide), a ~35 % lower dopamine detection signal was measured. However, no further signifcant change in dopamine detection signal was observed at electrodes that were incubated in the same synthetic fouling solution for one week, compared to a total loss of detection signal at non-hydrogenated carbon electrodes. We have also demonstrated the unique characteristic of these hydrogenated carbon electrodes in detecting dopamine with minimal interference from as high as 500 μM ascorbic acid that is generally expected in extracellular fuid. Meanwhile, there was also no observable fouling effect at hydrogenated carbon electrodes by the dopamine oxidation product, dopamine-o- quinone (itself a well-known fouling reagent), in the presence of ≤1.0 μM dopamine, which is a 100-fold higher concentration than that in the central nervous system. These results support minimal fouling at n-butylsilane hydrogenated carbon electrodes during dopamine detection in vitro. 1. Introduction Dopamine is a well-known neurotransmitter released in the forebrain for responding to both reward and non-reward motivations. It is also involved in brain networks for seeking, evaluating and value learning. In some cases, it is implicated with supporting brain network for orienting, cognition, and general motivation [1]. For example, the development of obesity is linked with a defcit in neural reward responses related to dopamine concentration in the central nervous system [2]. Similarly, dopamine serves important physiological functions in the kidney as defciency of intra-renal dopamine may lead to hypertension and decreased longevity [3]. Diabetes may cause a reduction in retinal dopamine and could cause early visual defects [4]. Disruption of dopamine in brain is also associated with common neurological disor- ders such as Parkinson’s and Alzheimer’s diseases. Therefore, quanti- tative determination of dopamine is of interest to neuroscientists studying factors infuencing its actions and roles in neuronal signalling. Owing to the ease of oxidation of dopamine, there have been many re- ports on electrochemical detection of dopamine in vitro [5–8] and in vivo [9–11]. However, a major challenge in electrochemical detection of dopamine in vivo is electrode fouling in which high-molecular weight amphiphilic proteins, peptides, lipids or other biomolecules present in extracellular fuid irreversibly adsorb on an oxygenated sp 2 -carbon electrode surface through dipole-dipole interaction, hydrogen bonding or ion dipole interaction to form a barrier that deters dopamine from making direct contact with the electrode surface for electron transfer reaction, leading to attenuated transient dopamine responses. Meanwhile, the oxidation product of dopamine, dopamine-o- quinone, can undergo a series of cyclisation reactions to form polymeric compounds such as polydopamine and poly(dopamine-o-quinone) that covalently bond with organic moieties and non-covalently bond with inorganic species present on the electrode surface to form an insulating flm [12]. Similar to the barrier formed by adsorbed biological mole- cules discussed above, this flm will also inhibit the direct contact of dopamine on an electrode surface for electron transfer reaction. All the above will undoubtedly jeopardise the long-term electrode stability and compromise the detection process [12–14]. In minimising the problem, most antifouling strategies hitherto * Corresponding author. E-mail address: Danny.Wong@mq.edu.au (D.K.Y. Wong). 1 Present address: SGS Australia, 16/33 Maddox Street, Alexandria, NSW 2015, Australia. Contents lists available at ScienceDirect Sensors and Actuators: B. Chemical journal homepage: www.elsevier.com/locate/snb https://doi.org/10.1016/j.snb.2020.128881 Received 22 July 2020; Received in revised form 8 September 2020; Accepted 8 September 2020