Next-Generation Diamond Electrodes for Neurochemical Sensing: Challenges and Opportunities

Abstract

Carbon-based electrodes combined with fast-scan cyclic voltammetry (FSCV) enable neurochemical sensing with high spatiotemporal resolution and sensitivity. While their attractive electrochemical and conductive properties have established a long history of use in the detection of neurotransmitters both in vitro and in vivo, carbon fiber microelectrodes (CFMEs) also have limitations in their fabrication, flexibility, and chronic stability. Diamond is a form of carbon with a more rigid bonding structure (sp3-hybridized) which can become conductive when boron-doped. Boron-doped diamond (BDD) is characterized by an extremely wide potential window, low background current, and good biocompatibility. Additionally, methods for processing and patterning diamond allow for high-throughput batch fabrication and customization of electrode arrays with unique architectures. While tradeoffs in sensitivity can undermine the advantages of BDD as a neurochemical sensor, there are numerous untapped opportunities to further improve performance, including anodic pretreatment, or optimization of the FSCV waveform, instrumentation, sp2/sp3 character, doping, surface characteristics, and signal processing. Here, we review the state-of-the-art in diamond electrodes for neurochemical sensing and discuss potential opportunities for future advancements of the technology. We highlight our team’s progress with the development of an all-diamond fiber ultramicroelectrode as a novel approach to advance the performance and applications of diamond-based neurochemical sensors.

In vitro electrochemical measurement of serotonin release in the human jejunum mucosa using a diamond microelectrode

“…In recent years, there have been several comprehensive reviews on diamond electrodes and current applications in neurochemical analysis. [14][15][16] Diamond microelectrodes (DMEs) are suitable materials for neurochemical analysis in vitro and in vivo in both the peripheral and central nervous systems. [14][15][16] However, measurements made with DMEs tend to be in vitro rather than in vivo, as is customary with carbon fiber microelectrodes and investigations of neurochemical signalling in the brain.…”

“…[14][15][16] Diamond microelectrodes (DMEs) are suitable materials for neurochemical analysis in vitro and in vivo in both the peripheral and central nervous systems. [14][15][16] However, measurements made with DMEs tend to be in vitro rather than in vivo, as is customary with carbon fiber microelectrodes and investigations of neurochemical signalling in the brain. 17 Our group has demonstrated in in vitro continuous amperometric measurements that DMEs provide a reproducible, stable, and sufficiently sensitive oxidation current response for norepinephrine released from sympathetic nerves innervating the arteries and veins of rats and mice, [18][19][20] and serotonin (5-hydroxytryptamine, 5-HT) [21][22][23][24] and nitric oxide 25 in the small intestine and colon of guinea pigs, rats, and mice.…”

Diamond-Based Electrodes for Detection of Metal Ions and Anions

“…In particular, the boron-doped diamond (BDD) electrodes were noted as low-biofouling materials and were engaged in the electrochemical quantification of metal ions, anions, biomolecules, drugs, environmental hazards, pesticides, organic molecules, etc. [ 27 , 28 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 ].…”

“…As for the analytical importance of diamond-based electrodes, although many specific reviews are available to describe their analyte detection ranges and detection/quantification limits [ 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 ], the majority of the reviews did not discuss and provide clear information on the diamond-based electrode-facilitated detection of metal ions and anions. Therefore, this review discloses details of electrochemical discrimination of metal ions and anions by diamond-based electrodes, as illustrated in Figure 1 .…”

Resource-constrained FPGA/DNN co-design

“…Analyzing the FSCV signals helps detect the state of some neurological disease [ 10 , 11 ], e.g., Parkinson’s disease [ 12 ], depression [ 13 ], etc. Currently, many researchers are focusing on the development of sensing platforms to provide precise recording of the signals acquired using FSCV in response to certain types of neurochemical reactions [ 14 ]. For instance, Nasri et al proposed a sensing system by developing a hybrid COMS-graphene sensor array to improve the sensitivity of measuring the response to a dopamine solution [ 15 ].…”