Development Of Novel Electrochemical Sensor Research Articles

Heparin-stabilized gold nanoparticles embedded in graphene for the electrochemical determination of esculetin.

A conductive nanocomposite consisting of heparin-stabilized gold nanoparticles embedded in graphene was prepared and characterized to develop an electrochemical sensor for the determination of esculetin in tea and jam samples. The gold nanoparticles were characterized by spectroscopic and microscopic techniques. The different proportions of graphene in the nanocomposite were evaluated and characterized by electrochemical practices. The heterostructure material on the glassy carbon electrode with esculetin showed π-π stacking interactions with an adsorption-controlled process. The voltammetric profile of esculetin using the proposed nanomaterial presented oxidation and reduction peaks at +0.61 and +0.58 V vs. Ag/AgCl, respectively, facilitating the electron transfer with esculetin through the transfer of two moles of protons and two moles of electrons per mole of esculetin. Using optimized conditions and square wave voltammetry, the calibration curve was obtained with two linear ranges, from 0.1 to 20.5 μmol L-1, with a detection limit of 43.0 nmol L-1. The electrochemical sensor showed satisfactory results for repeatability and stability, although interferences were observed in the presence of high concentrations of ascorbic acid or quercetin. The sensor was successfully applied in the determination of esculetin in samples of mulberry jam, white mulberry leaf tea, and white mulberry powder tea, presenting adequate recovery ranges. This directive provides valuable insights for the development of novel electrochemical sensors using heparin-based conductive nanomaterials with improved sensitivity and sensibility.

Three-dimensional porous high boron-nitrogen-doped carbon for the ultrasensitive electrochemical detection of trace heavy metals in food samples.

Exposure to even trace amounts of Cd(II) and Pb(II) in food can have serious effects on the human body. Therefore, the development of novel electrochemical sensors that can accurately detect the different toxicity levels of heavy metal ions in food is of great significance. Based on the principle of green chemistry, we propose a new type of boron and nitrogen co-doped carbon (BCN) material derived from a metal-organic framework material and study its synthesis, characterization, and heavy-metal ion detection ability. Under the optimum conditions, the BCN-modified glassy carbon electrode was studied using square-wave anodic stripping voltammetry, which showed good electrochemical responses to Cd(II) and Pb(II), with sensitivities as low as 0.459 and 0.509 μA/μM cm2, respectively. The sensor was successfully used to detect Cd(II) and Pb(II) in Beta vulgaris var. cicla L samples, which is consistent with the results obtained using inductively coupled plasma-mass spectrometry. It also has a strong selectivity for complex samples. This study provides a novel approach for the detection of heavy metal ions in food and greatly expands the application of heteroatom-doped metal-free carbon materials in detection platforms.

Toxicity warning and online monitoring of disinfection by-products in water by electroautotrophic biocathode sensors

As a result of the 2019 coronavirus pandemic, disinfection byproducts generated by the extensive use of chlorine disinfectants have infiltrated the aquatic environment, severely threatening ecological safety and human health. Therefore, the accurate monitoring of the biotoxicity of aqueous environments has become an important issue. Biocathode sensors are excellent choices for toxicity monitoring because of their special electroautotrophic respiration functions. Herein, a novel electroautotrophic biosensor with rapid, sensitive, and stable response and quantifiable output was developed. Its toxicity response was tested with typical disinfection byproducts dichloromethane, trichloromethane, and combinations of both, and corresponding characterization models were developed. Repeated toxicity tests demonstrated that the sensor was reusable rather being than a disposable consumable, which is a prerequisite for its long-term and stable operation. Microbial viability confirmed a decrease in sensor sensitivity due to microbial stress feedback to the toxicants, which is expected to be calibrated in the future by the standardization of the biofilms. Community structure analysis indicated that Moheibacter and Nitrospiraceae played an important role in the toxic response to chlorine disinfection byproducts. Our research provides technical support for protecting the environment and safeguarding water safety for human consumption and contributes new concepts for the development of novel electrochemical sensors.

Development of novel electrochemical sensor based on PtNPs-SeNPs-FTO nanocomposites via electrochemical deposition for detection of hydrogen peroxide

The PtNPs-SeNPs-FTO nanocomposites as electrochemical sensor was developed via electrochemical deposition method for hydrogen peroxide detection. The synthesis and growth of selenium nanoparticles (SeNPs), platinum nanoparticles (PtNPs) and nanocomposites of PtNPs-SeNPs on fluorine doped tin oxide (FTO) substrate by using electrochemical deposition for H2O2 detection was reported. Morphological and structural study of bare FTO, PtNPs-FTO, SeNPs-FTO and PtNPs-SeNPs-FTO sensor was confirmed by FEGSEM, EDS mapping, and XPS. Morphology of synthesized PtNPs and SeNPs decorated on the FTO surface showed nano-flower structure and spherical in shape respectively. The XPS analysis was carried out to identify elemental composition on the surface-modified PtNPs-SeNPs-FTO sensor. The survey spectra of PtNPs-SeNPs-FTO electrode displayed a considerable strong peak of C, F, Sn, O, Pt, and Se, which confirmed the existence of these elements on the FTO surface. The synthesized SeNPs-FTO, PtNPs-FTO, and PtNPs-SeNPs-FTO sensor displayed wide range of linear concentration response from 0.01 to 40 mM and response time 0.5 s. The synthesized SeNPs-FTO, PtNPs-FTO and PtNPs-SeNPs-FTO sensor showed sensitivity of 0.4 µA mM−1 cm−2 (R2 =0.9904), 17.2 µA mM−1 cm−2 (R2 =0.9917) and 7.3 µA mM−1 cm−2 (R2 = 0.9835) respectively. The SeNPs-FTO, PtNPs-FTO and PtNPs-SeNPs-FTO based sensor also demonstrated high selectivity towards detection of H2O2 with interfering agents.

Development of novel electrochemical sensor for the detection of biological warfare agents: enzyme, antibody, and DNA free

There is an urgent need to develop a novel sensor that can quickly and accurately detect biological warfare agents (BWAs). A novel electrochemical sensor was specially designed and developed for Staphylococcus aureus as a potential BWAs without using any enzyme, antibody, or genetic material. Cyclic voltammetry (CV), linear resistance polarization (LRP), chronoamperometry, impedance spectroscopy, and Differential Pulse Voltammetry (DPV) techniques were used for fast and accurate detection of BWAs. Co-precipitation technique was used for the synthesis of CuO nanoparticles (NPs) for their use in the electrochemical sensor. The effect of temperature, stirring and addition of CuO NPs was thoroughly investigated. The storage, stability, and performance of electrochemical sensor was tested for 45 days. The current response of the electrochemical sensor was found linear with the correlation coefficient, R2 = 0.991. The major advantage of this novel electrochemical sensor is that immobilization of enzyme, antibody, or DNA is not required in sensing technology as the immobilization process makes biosensors a highly specific. The novel electrochemical sensor was very quick, accurate, non-specific, and provide reliable results in the qualitative and quantitative estimation of pathogenic bacteria as a potential BWAs. A novel electrochemical sensor was specially designed and developed for the detection of Staphylococcus aureus pathogenic bacteria as a potential BWAs without using any enzyme, antibody, or genetic material. Cyclic voltammetry, linear resistance polarization, chronoamperometry, impedance spectroscopy, and Differential Pulse Voltammetry (DPV) experiments were carried out for fast and accurate detection of BWAs. Storage, stability, and reusability of the electrochemical sensor was tested for continuous 45 days. The current response of the electrochemical sensor was found to be linear with the correlation coefficient, R2 = 0.991. The major advantage of this novel sensor is that immobilization of enzyme, antibody, or DNA is not required in sensing technology as the immobilization process makes biosensor a highly specific. The novel electrochemical sensor was proved to be very quick, accurate, non-specific, and provide reliable results in the qualitative and quantitative estimation of pathogenic bacteria as a potential BWAs.

Progress in electrochemical detection of neurotransmitters using carbon nanotubes/nanocomposite based materials: A chronological review

AbstractNeurotransmitters (NTs) are chemical compounds that play an important physiological role in the functioning of central nervous, renal, hormonal, and cardiovascular systems. Their function is to regulate neural interactions by reducing the permeability of gap junctions between adjacent neurons of the same type. The abnormal level may lead to diseases, such as Parkinson's disease, Huntington's disease, Alzheimer's diseases, and other neurological diseases. The devastating health hazards associated with the abnormal presence of NTs in biological systems coupled with the demerits of most modern detection methods necessitates the continuous development of novel electrochemical sensors. Carbon nanotube (CNT)‐based sensors, as a result of the large surface area, biocompatibility, and chemical stability supplied by CNTs, have proven to offer massive sensitivity and low limit of detection (LOD). Its significance in sensors applications toward the detection of different group of compounds cannot be overemphasized. There are several review articles on NTs and their determination using different chemically modified electrodes and sensor platform. However, this review highlights the significance of notable NTs and the progress made in the last decade in the design of CNT‐based sensors for the detection of common NTs. Secondly, the review intends to highlight some of the challenges associated with the use of CNT‐modified electrodes for NT detection, quantification, and in real‐life application. Lastly, it will evaluate the future perspective in the use of CNT and its composite modified electrode over other surface modification materials used in sensor fabrication for the determination of NTs.

Copper oxide nanoparticles encapsulated in HKUST-1 metal-organic framework for electrocatalytic oxidation of citric acid

Metal-organic frameworks have poor electrochemical properties. However their electron transfer kinetics can be improved by doping these materials with known conductive materials. In this contribution we have proved that electron transfer kinetics of [Cu3(benzene‐1,3,5‐tricarboxylate)2(H2O)3]n (HKUST-1) can be improved by loading its channels using copper oxide nanoparticles to give CuO@HKUST-1. Electrochemical studies showed that the synergy of copper oxide nanoparticles and HKUST-1 in the nanocomposite lead to high electrocatalysis, fast response for catalysis (less than 5 s) with good signal strengths and excellent selectivity toward the oxidation of citric acid (CA). It was also noted that the oxidation of CA occurred at lower potential (+ 0.47) in comparison to the commonly observed (+ 1.00) for most reported systems and displayed a very high resistance to passivation. This result was attributed to the presence of numerous catalytically active sites and the large surface area of the nanocomposite material which can lower the activation energy barrier for the oxidation of CA. Compared to the precursors, the composite displayed superior electron transfer kinetic suggesting that a synergistic relationship was formed. This work, strongly suggests that the combination of MOFs and conductive nanoparticles maybe used for the development of novel electrochemical sensors.

One pot synthesis of nitrogen-doped hollow carbon spheres with improved electrocatalytic properties for sensitive H2O2 sensing in human serum

N-doped hollow carbon spheres (N-HCS) have been proved as efficient electrical catalytic materials with outstanding oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) ability. However, conventional approaches for the synthesis of N-HCS always involved multistep procedures. In this paper, by appropriately controlling the polymerization of tetraethoxysilane (TEOS) and resorcinol/formaldehyde (RF), N-HCS have been synthesized through “one pot” method without use of surfactant. Next, the ORR and OER of N-HCS were conducted to examine its electrocatalytic ability. Finally, it was modified on the glassy carbon electrode (GCE) as an improved electrical catalyst to monitor H2O2 in human serum samples. The linear ranges for monitoring H2O2 were from 0.05 mM to 29.5 mM and from 29.5 mM to 47.5 mM with a limit of detection of 0.02 mM. The recoveries for the assays in human serums were between 92.5% and 107.4%. Therefore, we believe that this newly synthesized N-HCS will play a significant role in the synthesis and application of electrocatalytic materials and the development of novel electrochemical sensors.

Development of novel electrochemical sensor on the base of molecular imprinted polymer decorated on SiC nanoparticles modified glassy carbon electrode for selective determination of loratadine

A novel and selective electrochemical sensor was successfully developed for the determination of loratadine by drop coating of synthesized loratadine molecularly imprinted polymers on the surface of glassy carbon electrode modified with silicon carbide nanoparticles. The performance of the constructed sensor was evaluated by cyclic voltammetry, scanning electron microscopy, and electrochemical impedance spectroscopy techniques. Under optimized conditions, the resulting calibration curve exhibited a linear response within a concentration range of 1–33μM with a low detection limit (S/N=3) of 0.15μM. Finally, the proposed method was successfully applied as a selective, stabile, sensitive, simple, reproducibility electrochemical sensor with good repeatability for the determination of loratadine in real samples and satisfactory results were obtained.

Fabrication of highly sensitive and selective nanocomposite film based on CuNPs/fullerene-C60/MWCNTs: An electrochemical nanosensor for trace recognition of paracetamol

Designing an electrochemical sensor for versatile clinical applications is a sophisticated task and how dedicatedly functionalized composite materials can perform on this stage is a challenge for today and tomorrow's Nanoscience and Nanotechnology. In the present work, we demonstrate a new strategy for the development of novel electrochemical sensor based on catalytic nanocomposite film. Fullerene-C60 and multi-walled carbon nanotubes (MWCNTs) were dropped on the pre-treated carbon paste electrode (CPE) and copper nanoparticles (CuNPs) electrochemically deposited on the modified CPE to form nanocomposite film of CuNPs/C60/MWCNTs/CPE. In this work, an electrochemical method based on square wave voltammetry (SWV) employing CuNPs/C60/MWCNTs/CPE has been presented for the recognition and determination of paracetamol (PT). Developed electrochemical sensor was characterized using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronocoulometry. The composite film made the fabricated sensor to display high sensitivity and good selectivity for PT detection. The influence of the optimization parameters such as pH, accumulation time, deposition potential, scan rate and effect of loading of composite mixture of C60-MWCNTs and CuNPs on the electrochemical performance of the sensor were evaluated. A linear range from 4.0 × 10−9 to 4.0 × 10−7 M for PT detection was obtained with a detection limit of 7.3 × 10−11 M. The fabricated sensor was successfully applied to the detection of PT in biological samples with good recovery ranging from 99.21 to 103%.

Electroanalytical Sensing Properties of Pristine and Functionalized Multilayer Graphene

This paper describes the heterogeneous electron transfer (ET) properties of high-quality multilayer graphene (MLG) films grown using chemical vapor deposition (CVD) on nickel and transferred to insulating poly(ethylene terephthalate) (PET) sheets. An oxygen plasma treatment is used to enhance the ET properties of the films by generating oxygenated functionalities and edge-plane sites and defects. Scanning electron microscopy (SEM), Raman, and X-ray photoelectron spectroscopy (XPS) along with voltammetry of the standard redox probes [Ru(NH3)6]3+/2+, [Fe(CN)6]3–/4–, and Fe3+/2+ are used to demonstrate this effect. The biologically relevant molecules dopamine, NADH, ascorbic acid, and uric acid are employed to show the improved sensing characteristics of the treated films. Control experiments involving commercially available edge-plane and basal-plane pyrolytic graphite (EPPG and BPPG) electrodes help to explain the different responses observed for each probe, and it is shown that, in certain cases, treated MLG provides a viable alternative to EPPG, hitherto considered to be the “best-case scenario” in carbon electrochemistry. This is the first comprehensive study of the electroanalytical properties of pristine and functionalized CVD-grown MLG, and it will serve as an important benchmark in the clarification of ET behavior at graphene surfaces, with a view to the development of novel electrochemical sensors.

Recent Advances in Polymeric Materials Used as Electron Mediators and Immobilizing Matrices in Developing Enzyme Electrodes

Different classes of polymeric materials such as nanomaterials, sol-gel materials, conducting polymers, functional polymers and biomaterials have been used in the design of sensors and biosensors. Various methods have been used, for example from direct adsorption, covalent bonding, crossing-linking with glutaraldehyde on composites to mixing the enzymes or use of functionalized beads for the design of sensors and biosensors using these polymeric materials in recent years. It is widely acknowledged that analytical sensing at electrodes modified with polymeric materials results in low detection limits, high sensitivities, lower applied potential, good stability, efficient electron transfer and easier immobilization of enzymes on electrodes such that sensing and biosensing of environmental pollutants is made easier. However, there are a number of challenges to be addressed in order to fulfill the applications of polymeric based polymers such as cost and shortening the long laboratory synthetic pathways involved in sensor preparation. Furthermore, the toxicological effects on flora and fauna of some of these polymeric materials have not been well studied. Given these disadvantages, efforts are now geared towards introducing low cost biomaterials that can serve as alternatives for the development of novel electrochemical sensors and biosensors. This review highlights recent contributions in the development of the electrochemical sensors and biosensors based on different polymeric material. The synergistic action of some of these polymeric materials and nanocomposites imposed when combined on electrode during sensing is discussed.

Functionalization of CNTs: New Routes Towards the Development of Novel Electrochemical Sensors

Carbon nanotubes (CNTs) possess high electrical conductivity, high chemical stability, and extremely high mechanical strength and modulus. These special properties of both single-walled and multi-walled CNTs (SWNTs and MWNTs, respectively) have attracted much attention in electrochemistry. Functionalization of CNTs is one of the most active fields in carbon nanotube research, which provides an effective tool to broaden the spectrum of electrochemical application of CNTs. In this review, we summarize various approaches to functionalize CNTs for the development of novel electrochemical sensors. Particular emphasis is directed to the use of lipid-functionalized CNTs for sensors and biosensors and for the fabrication of photo switched-functional devices. The functionalization of the nanotubes generates a novel, interesting class of nanomaterials, which combines the properties of the nanotubes and the functional moiety, thus offering new opportunities in electrochemical sensors.