Metal nanoparticles (NPs) find widespread application as a result of their unique physical and chemical properties. NPs have generated considerable interest in catalysis and electrocatalysis, where they provide a high surface area to mass ratio and can be tailored to promote particular reaction pathways. The activity of NPs can be analyzed especially well using electrochemistry, which probes interfacial chemistry directly. In this Review, we discuss key issues related to the electrochemistry of NPs. We highlight model studies that demonstrate exceptional control over the NP shape and size, or mass-transport conditions, which can provide key insights into the behavior of ensembles of NPs. Particular focus is on the challenge of ultimately measuring reactions at individual NPs, and relating the response to their structure, which is leading to imaginative experiments that have an impact on electrochemistry in general as well as broader surface and colloid science.

Electrochemistry of nanoparticles.

Affinity-based electrochemical detection in complex biological fluids could enable multiplexed point-of-care diagnostics for home healthcare; however, commercialization of point-of-care devices has been limited by the rapid loss of sensitivity caused by electrode surface inactivation and biofouling. Here, we describe a simple and robust antifouling coating for electrodes consisting of a three-dimensional porous matrix of cross-linked bovine serum albumin supported by a network of conductive nanomaterials composed of either gold nanowires, gold nanoparticles or carbon nanotubes. These nanocomposites prevent non-specific interactions while enhancing electron transfer to the electrode surface, preserving 88% of the original signal after 1 month of exposure to unprocessed human plasma, and functionalization with specific antibodies enables quantification of anti-interleukin 6 in plasma with high sensitivity. The easy preparation, stability and simplicity of this nanocomposite allow the generation of electrochemical biosensors that can operate in complex biological fluids such as blood plasma or serum. An antifouling coating for electrodes that consists of a three-dimensional porous matrix of cross-linked bovine serum albumin supported by a network of conductive nanomaterials enables robust affinity-based electrochemical biosensing in complex biological fluids.

An antifouling coating that enables affinity-based electrochemical biosensing in complex biological fluids

https://ora.ox.ac.uk/objects/uuid:986633c4-e60a-4470-b246-fa90e1bc437e/download_file?safe_filename=jnianjunCarbon_Diamond%2BNanoelectrochemistry_final.pdf&file_format=application%2Fpdf&type_of_work=Journal+article

Diamond electrochemistry at the nanoscale: A review

Wearable electrochemical sensors capable of noninvasive monitoring of chemical markers represent a rapidly emerging digital-health technology. Recent advances toward wearable continuous glucose monitoring (CGM) systems have ignited tremendous interest in expanding such sensor technology to other important fields. This article reviews for the first time wearable electrochemical sensors for monitoring therapeutic drugs and drugs of abuse. This rapidly emerging class of drug-sensing wearable devices addresses the growing demand for personalized medicine, toward improved therapeutic outcomes while minimizing the side effects of drugs and the related medical expenses. Continuous, noninvasive monitoring of therapeutic drugs within bodily fluids empowers clinicians and patients to correlate the pharmacokinetic properties with optimal outcomes by realizing patient-specific dose regulation and tracking dynamic changes in pharmacokinetics behavior while assuring the medication adherence of patients. Furthermore, wearable electrochemical drug monitoring devices can also serve as powerful screening tools in the hands of law enforcement agents to combat drug trafficking and support on-site forensic investigations. The review covers various wearable form factors developed for noninvasive monitoring of therapeutic drugs in different body fluids and toward on-site screening of drugs of abuse. The future prospects of such wearable drug monitoring devices are presented with the ultimate goals of introducing accurate real-time drug monitoring protocols and autonomous closed-loop platforms toward precise dose regulation and optimal therapeutic outcomes. Finally, current unmet challenges and existing gaps are discussed for motivating future technological innovations regarding personalized therapy. The current pace of developments and the tremendous market opportunities for such wearable drug monitoring platforms are expected to drive intense future research and commercialization efforts.

Wearable Electrochemical Sensors for the Monitoring and Screening of Drugs.

Abstract Electrode fouling is a phenomenon that can severely affect the analytical characteristics of a technique or a sensor, such as sensitivity, detection limit, reproducibility, and overall reliability. Electrode fouling generally involves the passivation of an electrode surface by a fouling agent that forms an increasingly impermeable layer on the electrode, inhibiting the direct contact of an analyte of interest with the electrode surface for electron transfer. Some potential fouling agents include proteins, phenols, amino acids, neurotransmitters, and other biological molecules. Various antifouling strategies have been reported to reduce or eliminate electrode fouling. Most antifouling strategies exploit a protective layer or barrier on an electrode substrate to prevent the fouling agent from reaching the electrode surface. Although such strategies can be quite effective, they are inappropriate for systems in which the analyte itself is also the fouling agent. In such cases, other strategies must be used, including electrode surface modification and electrochemical activation. In this review, recent strategies to minimise and efforts to overcome electrode fouling across a diverse range of analytes and fouling agents will be presented.

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Recent strategies to minimise fouling in electrochemical detection systems

Although microdisk electrode arrays (MEAs) have been extensively used for more than three decades, the existing rules do not provide an unambiguous formula for the calculation of the minimum interelectrode distance (d) necessary for steady-state current response. With the aim of formulating generally applicable guidelines for design and experiment with MEAs, cyclic voltammograms were simulated for coplanar and shallow recessed microdisk electrode arrays with various interelectrode distances and dimensionless scan rates (V). The dimensionless scan rate (V) is a function of the radius (a) of the individual electrodes in the array, the diffusion coefficient (D) of the analyte, and the potential scan rate (v). The cyclic voltammograms at microdisk electrode arrays are grouped into five categories corresponding to the contributions of linear and radial diffusion to the overall responses. These categories are illustrated in a zone diagram based on the effect of V and d on the shape of cyclic voltammograms. The ...

/pdf/cyclic-voltammograms-at-coplanar-and-shallow-recessed-u3ab0tu55y.pdf

Cyclic voltammograms at coplanar and shallow recessed microdisk electrode arrays: guidelines for design and experiment.

Propofol is a widely used, potent intravenous anesthetic for ambulatory anesthesia and long-term sedation. The target steady state concentration of propofol in blood is 0.25–10 μg/mL (1–60 μM). Although propofol can be oxidized electrochemically, monitoring its concentration in biological matrixes is very challenging due to (i) low therapeutic concentration, (ii) high concentrations of easily oxidizable interfering compounds in the sample, and (iii) fouling of the working electrode. In this work we report the performance characteristics of an organic film coated glassy carbon (GC) electrode for continuous monitoring of propofol. The organic film (a plasticized PVC membrane) improved the detection limit and the selectivity of the voltammetric sensor due to the large difference in hydrophobicity between the analyte (propofol) and interfering compounds of the sample, e.g., ascorbic acid (AA) or p-acetamidophenol (APAP). Furthermore, the membrane coating prevented electrode fouling and served as a protective ...

Toward feedback-controlled anesthesia: voltammetric measurement of propofol (2,6-diisopropylphenol) in serum-like electrolyte solutions.

Cyclic voltammetry at shallow recessed microdisc electrode : Theoretical and experimental study

The invention relates to a method for the controlled delivery of a drug as a function of bioavailable drug concentration, a sensor device for detecting bioavailable drug concentration, and a delivery device that controls delivery of the drug based on the real-time detection of bioavailable drug concentration.

Method and device for detection of bioavailable drug concentration in a fluid sample

A method and system for electrochemical detection of an analyte in a vapor or gas sample is provided. The method and system include exposing a vapor or gas sample to an electrochemical sensor comprising one or more electrodes and a coating that surrounds the one or more electrodes, which coating is capable of partitioning the analyte directly from the vapor or gas sample. The method and system include detecting an oxidation/reduction current during the exposing, wherein the detected current relates to a concentration of analyte in the vapor or gas sample.

Jidong Guo

Papers

Cyclic voltammograms at coplanar and shallow recessed microdisk electrode arrays: guidelines for design and experiment.

Toward feedback-controlled anesthesia: voltammetric measurement of propofol (2,6-diisopropylphenol) in serum-like electrolyte solutions.

Cyclic voltammetry at shallow recessed microdisc electrode : Theoretical and experimental study

Method and device for detection of bioavailable drug concentration in a fluid sample

Method and device for detection ofanalyte in vapor or gaseous sample