Dopamine sensor based on a hybrid material composed of cuprous oxide hollow microspheres and carbon black

Using nanostructured carbon black-based electrochemical (bio)sensors for pharmaceutical and biomedical analyses: A comprehensive review

The outstanding electronic properties of carbon black (CB) and its economic advantages have fueled its application as nanostructured electrode material for the development of new electrochemical sensors and biosensors. CB-based electrochemical sensing devices have been found to exhibit high surface area, fast charge transfer kinetics, and excellent functionalization. In the present work, we set forth a comprehensive review of the recent advances made in the development and application of CB-based electrochemical devices for pharmaceutical and biomedical analyses - from quantitative monitoring of drug formulations to clinical diagnoses - and the underlying challenges and constraints that need to be overcome. We also present a thorough discussion about the strategies and techniques employed in the development of new electrochemical sensing platforms and in the enhancement of their analytical properties and biocompatibility for anchoring active biomolecules, as well as the combination of these sensing devices with other materials aiming at boosting the performance and efficiency of the sensors.

A state of the art overview of carbon-based composites applications for detecting and eliminating pharmaceuticals containing wastewater

The growing prevalence of new toxins in the environment continues to cause widespread concerns. Pharmaceuticals, organic pollutants, heavy metal ions, endocrine-disrupting substances, microorganisms, and others are examples of persistent organic chemicals whose effects are unknown because they have recently entered the environment and are displaying up in wastewater treatment facilities. Pharmaceutical pollutants in discharged wastewater have become a danger to animals, marine species, humans, and the environment. Although their presence in drinking water has generated significant concerns, little is known about their destiny and environmental effects. As a result, there is a rising need for selective, sensitive, quick, easy-to-handle, and low-cost early monitoring detection systems. This study aims to deliver an overview of a low-cost carbon-based composite to detect and remove pharmaceutical components from wastewater using the literature reviews and bibliometric analysis technique from 1970 to 2021 based on the web of science (WoS) database. Various pollutants in water and soil were reviewed, and different methods were introduced to detect pharmaceutical pollutants. The advantages and drawbacks of varying carbon-based materials for sensing and removing pharmaceutical wastes were also introduced. Finally, the available techniques for wastewater treatment, challenges and future perspectives on the recent progress were highlighted. The suggestions in this article will facilitate the development of novel on-site methods for removing emerging pollutants from pharmaceutical effluents and commercial enterprises.

Partial sulfidation for constructing Cu2O–CuS heterostructures realizing enhanced electrochemical glucose sensing

A Cu₂O–CuS heterostructure was constructed to elucidate the relationship between heterojunctions and electrochemical glucose sensing.

Single-atom doping of MoS2 with manganese enables ultrasensitive detection of dopamine: Experimental and computational approach

Two-dimensional transition metal dichalcogenides (TMDs) emerged as a promising platform to construct sensitive biosensors. We report an ultrasensitive electrochemical dopamine sensor based on manganese-doped MoS2 synthesized via a scalable two-step approach (with Mn ~2.15 atomic %). Selective dopamine detection is achieved with a detection limit of 50 pM in buffer solution, 5 nM in 10% serum, and 50 nM in artificial sweat. Density functional theory calculations and scanning transmission electron microscopy show that two types of Mn defects are dominant: Mn on top of a Mo atom (MntopMo) and Mn substituting a Mo atom (MnMo). At low dopamine concentrations, physisorption on MnMo dominates. At higher concentrations, dopamine chemisorbs on MntopMo, which is consistent with calculations of the dopamine binding energy (2.91 eV for MntopMo versus 0.65 eV for MnMo). Our results demonstrate that metal-doped layered materials, such as TMDs, constitute an emergent platform to construct ultrasensitive and tunable biosensors.

Boosting glucose oxidation by constructing Cu–Cu2O heterostructures

An octahedral Cu–Cu₂O heterostructure with loose and porous structure was fabricated and exhibits enhanced electrocatalytic activity towards glucose oxidation.

Carbon Black-Carbon Nanotube Co-Doped Polyimide Sensors for Simultaneous Determination of Ascorbic Acid, Uric Acid, and Dopamine

Carbon black (CB) and carbon nanotube (CNT) co-doped polyimide (PI) modified glassy carbon electrode (CB-CNT/PI/GCE) was first prepared for the simultaneous determination of ascorbic acid (AA), dopamine (DA), and uric acid (UA). The CB-CNT/PI/GCE exhibited persistent electrochemical behavior and excellent catalytic activities. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used for the simultaneous detection of AA, DA, and UA in their ternary mixture. The peak separations between AA and DA, and DA and UA, are up to 166 mV and 148 mV, respectively. The CB-CNT/PI/GCE exhibited high sensitivity to DA and UA, with the detection limit of 1.9 µM and 3 µM, respectively. In addition, the CB-CNT/PI/GCE showed sufficient selectivity and long-term stability, and was applicable to detect AA, DA, and UA in human urine sample.

Morphologically Tunable MnO2 Nanoparticles Fabrication, Modelling and Their Influences on Electrochemical Sensing Performance toward Dopamine

The morphology or shape of nanomaterials plays an important role in functional applications, especially in the electrochemical sensing performance of nanocomposites modified electrodes. Herein, the morphology-dependent electrochemical sensing properties of MnO2-reduced graphene oxide/glass carbon electrode (MnO2-RGO/GCE) toward dopamine detection were investigated. Firstly, various morphologies of nanoscale MnO2, including MnO2 nanowires (MnO2 NWs), MnO2 nanorods (MnO2 NRs), and MnO2 nanotubes (MnO2 NTs), were synthesized under different hydrothermal conditions. Then the corresponding MnO2-RGO/GCEs were fabricated via drop-casting and the subsequent electrochemical reduction method. The oxidation peak currents increase with the electrochemical activity area following the order of MnO2 NWs-RGO/GCE, MnO2 NTs-RGO/GCE, and MnO2 NRs-RGO/GCE. The spatial models for MnO2 NWs, MnO2 NTs, and MnO2 NRs are established and accordingly compared by their specific surface area, explaining well the evident difference in electrochemical responses. Therefore, the MnO2 NWs-RGO/GCE is selected for dopamine detection due to its better electrochemical sensing performance. The response peak current is found to be linear with dopamine concentration in the range of 8.0 × 10−8 mol/L–1.0 × 10−6 mol/L and 1.0 × 10−6 mol/L–8.0 × 10−5 mol/L with a lower detection limit of 1 × 10−9 mol/L (S/N = 3). Finally, MnO2 NWs-RGO/GCE is successfully used for the determination of dopamine injection samples, with a recovery of 99.6–103%. These findings are of great significance for understanding the relationship between unlimited nanoparticle structure manipulation and performance improvement.

Trace level electrochemical determination of the neurotransmitter dopamine in biological samples based on iron oxide nanoparticle decorated graphene sheets

The trace level electrochemical determination of dopamine in biological samples based on an iron oxide nanoparticle-capped graphene sheet modified electrode.

A glassy carbon electrode modified with hollow cubic cuprous oxide for voltammetric sensing of L-cysteine

This paper reports on an electrochemical sensing system for L-cysteine. It is based on the use of hollow cubic Cu₂O particles that were prepared in two steps. First, the Cu₂O/ polystyrene (PS) composites were prepared by a surface ion exchange strategy for in-situ reductive deposition on the surface of carboxy-capped PS particles. Thereafter, the PS particles were removed from the Cu₂O/PS composites by treatment with tetrahydrofuran (THF). The resulting hollow cubic Cu₂O particles were placed in a Nafion matrix on a glassy carbon electrode (GCE) which exhibits high surface area, good site accessibility and excellent electrocatalytic activity for L-cysteine. The cyclic voltammetric response of the modified GCE to L-cysteine is about 2.8-fold stronger than when using a GCE modified with pure Cu₂O. The detection limit for L-cysteine is lower by about 1 order of magnitude, and the working voltage is rather low (-0.08 V vs. Ag/AgCl). An excellent electrochemical selectivity for L-cysteine over other amino acids was also achieved. The method was successfully applied to the determination of L-cysteine in pharmaceutical samples. Graphical abstract An electrochemical sensing system for the detection of L-cysteine in amino acid injections has been established by using the hollow cubic Cu₂O particles as recognition element.

One-pot synthesis of dendritic Pt3Ni nanoalloys as nonenzymatic electrochemical biosensors with high sensitivity and selectivity for dopamine detection

Preparation of Pt-based nanocatalysts with high catalytic activity and exploration of their novel applications have attracted significant interest in the nanoscale field. Herein, we report a facile synthesis of dendritic Pt₃Ni nanoalloys and their applications for electrochemical nonenzymatic dopamine biosensors. As a result of their unique structure, the dendritic Pt₃Ni nanoalloys show high electrocatalytic activity towards dopamine oxidation. Amperometric dopamine biosensors based on dendritic Pt₃Ni nanoalloy microelectrode exhibit a wide linear detection ranges from 0.5 μM to 250 μM with ultrahigh sensitivity, fast response, and excellent selectivity at a potential of 0.3 V in a 0.1 M phosphate buffered solution (pH = 7.2). The limit of detection on dendritic Pt₃Ni nanoalloy microelectrodes can decrease down to 10 nM, which is the least concentration of dopamine in serum samples with a value of sensitivity up to 4.6 μA mg^-1_Pt cm^-2. This study shows an effective approach for the development of dendritic Pt₃Ni nanoalloys as electrocatalysts for electrochemical nonenzymatic dopamine biosensors.

Synthesis and thermo-physical properties of deep eutectic solvent-based graphene nanofluids

This study introduces a new class of heat transfer fluids by dispersing functionalised graphene oxide nanoparticles (GNPs) in ammonium and phosphonium-based deep eutectic solvents (DESs) without the aid of a surfactant. Different molar ratios of salts and hydrogen bond donors (HBD) were used to synthesise DESs for the preparation of different concentrations of graphene nanofluids (GNFs). The concentrations of GNPs were 0.01 wt%, 0.02 wt% and 0.05 wt %. Homogeneous and stable suspensions of nanofluids were obtained by high speed homogenisation and an ultrasonication process. The stability of the GNFs was determined through visual observation for 4 weeks followed by a centrifugal process (5000-20,000 rpm) for 30 min in addition to zeta potential studies. Dispersion of the GNPs in DES was observed using an optical microscope. The synthesised DES-based GNFs showed no particle agglomeration and formation of sediments in the nanofluids. Thermo-physical properties such as thermal conductivity and specific heat of the nanofluids were also investigated in this research. The highest thermal conductivity enhancement of 177% was observed. The findings of this research provide a new class of engineered fluid for heat transfer applications as a function of temperature, type and composition DESs as well as the GNPs concentration.

Nanoarchitectonics for carbon-material-based sensors

Recently, the nanoarchitectonics concept has been proposed to fabricate functional materials on the basis of concerted harmonization actions to control materials organization.

A copper hexacyanocobaltate nanocubes based dopamine sensor in the presence of ascorbic acid

A highly selective and sensitive dopamine sensor was demonstrated based on copper hexacyanocobaltate nanocubes in the presence of ascorbic acid.

Simultaneous determination of dopamine and uric acid in the presence of high ascorbic acid concentration using cetyltrimethylammonium bromide–polyaniline/activated charcoal composite

Simultaneous determination of dopamine and uric acid is described using CTAB–PANI/AC composite and attained detection limits of 0.06 and 0.20 μM, respectively. Practicality is demonstrated in rat brain, injection, serum and urine samples.

PdSn nanocatalysts supported on carbon nanotubes synthesized in deep eutectic solvents with high activity for formic acid electrooxidation

A novel strategy in DESs for the fabrication of MWCNTs-supported PdSn alloy nanostructures is reported. The prepared PdSn/MWCNT shows remarkably improved electrocatalytic performance towards formic acid oxidation reaction.

Monoamine oxidase B layer-by-layer film fabrication and characterization toward dopamine detection

In this work nanostructured film composites of the monoamine oxidase B (MAO-B) enzyme, free or encapsulated in liposomes, were fabricated by the layer-by-layer (LbL) self-assembly technique, employing polyethylene imine (PEI) as polycation. Initially, the MAO-B enzyme was incorporated into liposomes in order to preserve its enzymatic structure ensuring their activity and catalytic stability. The LbL film growth was monitored by surface plasmon resonance (SPR) by gold resonance angle shift analysis after each bilayer deposition. Subsequently, the films were applied as amperometric biosensors for dopamine detection using Prussian Blue (PB) as the electron mediator. The biosensor fabricated by MAO-B incorporated into liposomes composed of DPPG:POPG in the ratio (1:4) (w/w) showed the best performance with a sensitivity of 0.86 (μA cm(-2))/(mmol L(-1)) and a detection limit of 0.33 mmol L(-1).