Non-enzymatic Electrochemical Biosensor Research Articles

Development and characterization of a non-enzymatic electrochemical biosensor for rapid determination of sorbent-based extracted trazodone and doxepin in complicated samples

BackgroundGiven the importance of achieving optimal therapeutical concentration in patients treated with antidepressants, this study investigates a novel technique for the simultaneous determination of trazodone (TRZ) and doxepin (DOX) in human plasma and serum samples for the first time. ResultsTo achieve simultaneous determination of two antidepressants, TRZ and DOX, a novel detection system was designed: a non-enzymatic voltammetric biosensor based on boron-reduced graphene oxide/manganese oxide nanoparticles (GCE/B-rGO/MnO NPs). The detection was accomplished after pre-concentration and extraction trace amounts of the analytes using the thin film-solid phase microextraction (TF-SPME) technique, which employed polyvinyl alcohol/polyvinyl acetate/copper oxide Nanoparticles (PVA/PVAc/CuO NPs) electrospun nanofibers.The successful preparation of composite nanofibers and modified electrodes was confirmed using the evaluation of field emission-scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDX). Also, the composite nanofibers were characterized with attenuated total reflectance-Fourier transform-infrared (ATR-FT-IR) and X-ray diffraction (XRD). In the solution of TRZ and DOX, under optimum experimental conditions, the linear dynamic ranges (LDRs) were 0.1 to 20.0 μmol L-1 and 0.5 to 27.0 μmol L-1, respectively. Also, the limit of detection (LOD) values of TRZ and DOX were 0.032 and 0.150 μmol L-1. SignificancePVAc acts as a cross-linking agent for PVA, and their mixture is effective for sample preparation and pre-concentration of analytes in complex matrices. Also, adding CuO NPs to this polymeric mixture enhanced the adsorption efficiency.Taking advantage of the high surface area of MnO NPs and the high electrical conductivity of B-rGO, and considering the superiority of their simultaneous utilization, the constructed electrochemical biosensor is both cost-effectiveness and rapid. It demonstrates excellent stability, repeatability, and sensitivity for the simultaneous determination of TRZ and DOX under optimal conditions.This biosensor, the first of its kind, is specifically designed for the simultaneous determination of TRZ and DOX in human plasma and serum samples, representing a significant advancement in biosensing technology.

Development of a highly sensitive non-enzymatic electrochemical cholesterol biosensor based on Ag with Cu2O nanomaterial deposited on TiO2 nanotubes

We developed a highly sensitive non-enzymatic biosensor based on hybrid Ag-Cu2O@TNTs nanostructure aggregate for the detection of cholesterol. A facile anodization process on a thin titanium alloy (Ti6Al4V) plate was achieved to deposit TiO2 nanotubes (TNTs). Subsequently, TNTs was decorated with Cu2O nanomaterials (NM) using wet chemical bath deposition (CBD) technique. The electro-deposition of silver (Ag) nanoparticles on Cu2O@TNTs hybrid aggregate produced high electroactive surface area which enhanced the electron transfer rate. The structure of Ag-Cu2O@TNTs was examined using X-ray diffraction (XRD), transmission emission microscopy (TEM), and field emission scanning electron microscopy (FE-SEM). Cyclic voltammetry (CV) and amperometry techniques were utilized to study the electrochemical behaviour of nanostructures. The hybrid nanostructure demonstrated great sensitivity (12140.06 μAmM−1cm−2) compared to pure TNTs and Cu2O@TNTs with low detection limit (0.057 mM) and fast response. This study highlights exciting potential of nanocomposites in advancement of reproducible and selective biosensor applications.

Highly Efficient Non-Enzymatic Electrochemical Glucose Biosensor Based on Copper Metal Organic Framework Coated on Graphite Sheet

Detection of glucose is highly informative, creating a constant demand for fabricating high-precision glucose biosensors. Metal–organic frameworks, a family of porous materials renowned for their tunability, can be an excellent choice for developing such sensors. We have developed a highly-sensitive, non-enzymatic sensor for electrochemical detection of glucose fabricated using Copper Metal–Organic Framework (Cu MOF), synthesized by a simple, room-temperature stirring method using Benzene-1,3,5-tricarboxylic acid (BTC) as ligand and Copper nitrate trihydrate as precursor. The synthesized nanostructure was characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, and energy-dispersive X-ray analytical techniques. Powder X-ray diffraction study and thermogravimetric analysis were also done. Further, Brunnauer-Emmett-Teller analysis revealed the porous nature of Cu MOF. The materials exhibited strong electro-catalytic activity for glucose oxidation as revealed from cyclic voltammetry and chronoamperometric studies done under alkaline pH conditions. The Cu MOF deposited on a conducting graphite sheet electrode displayed a significantly low detection limit of 0.019 mM through a broad detection range (1–15 mM) and a strong sensitivity of 229.4 μAmM−1 cm2. Overall, the Cu MOF/GS exhibits exceptional stability, short response time (less than 1 s), and good repeatability and reproducibility, making it a promising future material for non-enzymatic glucose detection.

Novel MoS2-decorated Cu2O hybrid nanoparticles for enhanced non-enzymatic electrochemical cholesterol detection

Precise identification of cholesterol levels is crucial for the early diagnosis of cardiovascular risk factors. This paper presents a novel approach for cholesterol detection that circumvents the reliance on enzymatic processes. Leveraging the unique properties of advanced materials and electrochemical principles, our non-enzymatic approach demonstrates enhanced sensitivity, specificity, and limit of detection in cholesterol analysis. A non-enzymatic electrochemical biosensor for Cholesterol, employing a nanohybrid comprising Cu2O nanoparticles decorated with MoS2, is presented. The cyclic voltammetry (CV), differential pulse voltammetry (DPV), and amperometry techniques were employed to investigate the electrochemical behaviour of the glassy carbon electrode modified with the Cu2O/MoS2 nanohybrid. The modified electrode exhibited an excellent sensitivity of 111.74 μA μM−1 cm−2 through the CV method and showcased a low detection limit of 2.18 μM and an expansive linear range spanning 0.1–180 μM when employing the DPV method. The electrode also showed good selectivity to various interfering components in 0.1 M NaOH and a satisfied stability of about 15 days at room temperature. The study demonstrates the potential for broader applications in clinical diagnostics and monitoring cardiovascular health, paving the way for a paradigm shift in cholesterol detection methodologies and offering a more efficient and cost-effective alternative to traditional enzymatic assays.

Nonenzymatic Electrochemical Biosensor Constructed by Nanocomposites Applied to the Detection of Cold-Resistant RNA in Winter Wheat

Nonenzymatic Electrochemical Biosensor Constructed by Nanocomposites Applied to the Detection of Cold-Resistant RNA in Winter Wheat

A {P6Mo18}-type heteropolyblue modified NiO-based carbon nanofibers for bifunctional biosensors

Non-enzymatic electrochemical biosensors have great application value in the identification and detection of organic biological small molecules, especially in biomedical detection. In this paper, a carbon-based sensing material consisting of basket-type polyoxometallates (POMs) modified with synergistic multicomponent active centers was prepared. A novel POMs with heteropolyblue properties, {Co(phen)3}3[{Co(H2O)2}{Co(H2O)3}4}{Sr ⊂ P6MoVI16MoV2O73}2]·8H2O (CoP6Mo18), was modified on NiO-loaded carbon nanofibers (NiO-CNFs) to construct novel nanocomposites CoP6Mo18@NiO-CNFs. Differential pulse voltammetry (DPV) tests show that the nanocomposite electrode had a strong response to L-tryptophan (L-Trp) and dopamine (DA) with lower detection limit of 22.2 nM and 27.8 nM (S/N = 3) in the linear range of 66.7 nM-478 μM and 83.3 nM-437 μM, respectively. The results demonstrated that the modified electrode can quickly and efficiently detect DA and L-Trp alone or together due to catalytic synergy between CoP6Mo18 and NiO-CNFs. The combination of the two materials not only enhances the current response signals of the electrodes to the analytes DA and L-Trp, but also effectively improves the selectivity and stability of the sensor. Importantly, the prepared sensor can be used for trace detection of DA and L-Trp in pre-treated human serum samples in practical applications, and the recovery rate is as high as 98.9 %, which suggests that the CoP6Mo18@NiO-CNFs/GCE sensor has potential application value in biology and medical fields.

Synthesis of CuSe/PVP/GO and CuSe/MWCNTs for their applications as nonenzymatic electrochemical glucose biosensors.

Copper selenide (CuSe) is an inorganic binary compound which exhibits metallic behavior with zero band gap. CuSe has multiple applications in electrocatalysis, photothermal therapy, flexible electronic and solar cells. In the current study, copper selenide based nanocomposites CuSe/PVP/GO and CuSe/MWCNTs were synthesized by using the sol-gel method for application as a non-enzymatic glucose biosensor. Different characterization methods were employed, such as X-ray diffraction (XRD), photoluminescence (PL), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible (UV-Vis) spectroscopy, and photoluminescence for determining various aspects of CuSe/PVP/GO and CuSe/MWCNTs nanocomposites including phase formation, functional group analysis, band gaps and morphology. Electrochemical impedance spectroscopy (EIS) showed that the resistances of modified electrode/bare electrode were 12.3 kΩ/17.3 kΩ and 6.3 kΩ/17.3 kΩ for CuSe/PVP/GO and CuSe/MWCNTs nanocomposites, respectively. Cyclic voltammetry showed that both CuSe/PVP/GO and CuSe/MWCNTs nanocomposites are promising biosensors for detection and monitoring of the glucose level in an analyte. The sensitivity and limit of detection are 2328 μA mM-1 cm-2/0.2 μM and 4157 μA mM-1 cm-2/0.3 μM for CuSe/PVP/GO and CuSe/MWCNTs, respectively. Chronoamperometry confirmed that our nanocomposite was the best sensor for glucose even in the presence of other interferents like ascorbic acid (AA), uric acid (UA) and dopamine (DA).

Developments of Materials for Nonenzymatic Biosensing Applications

Nonenzymatic electrochemical biosensors, characterized by high sensitivity, good tolerance, simple preparation and low cost, have become a new research focus in recent years. Nanomaterials exhibit nonenzymatic catalytic mechanisms that enhance electrocatalytic activity and promote electron transfer, making them the popular materials used in nonenzymatic electrochemical sensors. Although catalytic activity and electrical conductivity of conductive polymers are not as good as inorganic nanomaterials, the introduction and doping of metal or carbon nanoparticles as well as the construction of composites with various modified groups can improve the performance of the sensors, and at the same time endow the sensors with the properties of lightweight, flexibility, plasticity, and better biocompatibility, which develops up a great potential opportunity of application in biosensing. This review summarizes the latest research developments of conductive polymer-based materials in nonenzymatic electrochemical sensors in recent years to provide ideas for the construction of sensors.

NiCo2O4/Ti2NbC2 (double MXene) nanohybrid-based non-enzymatic electrochemical biosensor for the detection of glucose in sweat.

The non-enzymatic electrochemical sensors are attractive due to their high sensitivity, quick detection, low cost, and simple construction. Hence, in this work, a non-enzymatic biosensor was constructed with NiCo2O4 nanoparticles (~ 82nm) decorated over Ti2NbC2 nanosheets by an in-situ method. The crystal structure, phase purity, morphology and elemental composition of the synthesized NiCo2O4/Ti2NbC2 nanohybrid was investigated using XRD, Raman and FESEM analysis. The electrocatalytic and electrochemical behaviour of the prepared nanohybrid was investigated using cyclic voltammetry and amperometry analysis. Hybrid of NiCo2O4/Ti2NbC2 produces a biocompatible, electrochemically active surface with enhanced electrical conductivity. The enhanced surface area of NiCo2O4 and superior electrical conductivity of Ti2NbC2 nanosheets helped to develop non-enzymatic electrochemical glucose sensor with enhanced sensitivity (425.6 µA mM-1cm-2), low limit of detection and quick response time that satisfy glucose detection applications. Thus, the developed non-enzymatic electrochemical glucose sensor has excellent electrochemical properties and making it as a strong candidate for the detection of glucose concentration in sweat.

Ultrasmall platinum nanoclusters densely immobilized on hairy metal organic framework for nonenzymatic glucose detection

Rational design of non-enzymatic nanomaterials that possess the similar functions to natural enzymes holds great promise in chemical and biological molecule detection. In this work, a non-enzymatic electrochemical biosensor for detection of glucose was developed based on poly(2-vinylpyridine) (P2VP) grafted UiO-66 metal organic framework decorated with ultrafine platinum nanoclusters (PtNCs). The as-fabricated UiO-66-g-P2VP/PtNCs nanocomposite was then placed on an indium tin oxide (ITO) electrode to construct non-enzymatic glucose biosensor for electrochemical detection of glucose in alkaline electrolyte. The resulting UiO-66-g-P2VP/PtNCs/ITO modified electrode showed two linear responses over glucose concentration ranging of 0.01–5 mM and 5–18 mM with a low detection limit of 2.18 μM (S/N = 3). Moreover, the UiO-66-g-P2VP/PtNCs/ITO serving as an electrochemical biosensor was successfully applied to the rapid determination of glucose in human serum sample with a desirable result. Our findings pave the way for design and development of a promising artificial enzyme for the construction of high performance sensing platform.

Effect of Hydrogen Plasma Treatment on the Sensitivity of ZnO Based Electrochemical Non-Enzymatic Biosensor.

Information on vitamin C-ascorbic acid (AA)-content is important as it facilitates the provision of dietary advice and strategies for the prevention and treatment of conditions associated with AA deficiency or excess. The methods of determining AA content include chromatographic techniques, spectrophotometry, and electrochemical methods of analysis. In the present work, an electrochemical enzyme-free ascorbic acid sensor for a neutral medium has been developed. The sensor is based on zinc oxide nanowire (ZnO NW) arrays synthesized via low-temperature chemical deposition (Chemical Bath Deposition) on the surface of an ITO substrate. The sensitivity of the electrochemical enzyme-free sensor was found to be dependent on the process treatments. The AA sensitivity values measured in a neutral PBS electrolyte were found to be 73, 44, and 92 µA mM-1 cm-2 for the ZnO NW-based sensors of the pristine, air-annealed (AT), and air-annealed followed by hydrogen plasma treatment (AT+PT), respectively. The simple H-plasma treatment of ZnO nanowire arrays synthesized via low-temperature chemical deposition has been shown to be an effective process step to produce an enzyme-free sensor for biological molecules in a neutral electrolyte for applications in health care and biomedical safety.

Development of a miniaturised potentiostat for urea detection using the LMP91000

In this report, we develop a low-cost cyclic voltammetry platform for electrochemical analyses based on the LMP91000 integrated circuit (IC). The proposed system can be suitable to detect chemicals of interest in food safety or biology. The system includes three main blocks: the electrodes, electrochemical measuring circuit, and data acquisition. An algorithm was also built to process and display the data on the screen. Experiments are carried out with a standard redox solution containing Fe(II)/Fe(III) 5 mM and KCl 0.1 mM to evaluate system performance and make comparisons to the commercial potentiostat. The results show that the obtained signals from the proposed system and the commercial potentiostat device are similar. With applications of the miniaturised potentiostat, a non-enzymatic electrochemical biosensor for urea detection was fabricated on cobalt sulphide materials (CoS) synthesized via a microwave assisted method. The sensing performance for urea was determined by changing the oxidation potential peak of 100 mV. The sensor had a linear range from 1-8 mM corresponding to the urea concentration in blood. The sensor sensitivity was comparable (7.5 μAmM-1cm-2) to some previous publications. With the achieved results, the proposed system demonstrates potential in urea detection and can be a prototype to develop a commercial device for point-of-care testing in the future.

Electrospun nanofibers for extraction of thymoquinone from Nigella-Stevia prior to detection using electrochemical biosensor based on GCE/rGO/CuO

Thymoquinone (TQ) is the main constituent of Nigella sativa that has some effects on the treatment of many illnesses such as cancer and kidney diseases. Electrospun nanofibers with polyvinyl chloride/ethylene vinyl acetate latex/electrochemically (reduced graphene oxide/polypyrrole)/Silybum marianum inflorescence extract (PVC/EVA/(rGO/Ppy)/SM) were first prepared, and then TQ was extracted from black seed with using these nanofibers as a sorbent. Finally, TQ was detected with the construction of a simple nonenzymatic electrochemical biosensor using copper (II) oxide nanoparticles/reduced graphene oxide/glassy carbon electrode (CuO/rGO/GCE). Factors affecting TQ adsorption/desorption, time and potential values for constructed biosensor were optimized by methods such as design-expert 12.0 and one-at-a-time (OAT). The morphology of PVC/EVA/(rGO/Ppy)/SM nanofibers and rGO/CuO nanocomposites was characterized. Finally, the electrochemical biosensor was put into human blood serum samples and the standard addition method was applied with the spike of TQ to them. The linear range and detection limit reached 50–1000 μM and 4.85 μM, respectively (S/N = 3).

Eco-friendly fabrication of nonenzymatic electrochemical sensor based on cobalt/polymelamine/nitrogen-doped graphitic-porous carbon nanohybrid material for glucose monitoring in human blood

The design and development of eco-friendly fabrication of cost-effective electrochemical nonenzymatic biosensors with enhanced sensitivity and selectivity are one of the emerging area in nanomaterial and analytical chemistry. In this aspect, we developed a facile fabrication of tertiary nanocomposite material based on cobalt and polymelamine/nitrogen-doped graphitic porous carbon nanohybrid composite (Co-PM-NDGPC/SPE) for the application as a nonenzymatic electrochemical sensor to quantify glucose in human blood samples. Co-PM-NDGPC/SPE nanocomposite electrode fabrication was achieved using a single-step electrodeposition method under cyclic voltammetry (CV) technique under 1 M NH4Cl solution at 20 constitutive CV cycles (sweep rate 20 mV/s). Notably, the fabricated nonenzymatic electroactive nanocomposite material exhibited excellent electrocatalytic sensing towards the quantification of glucose in 0.1 M NaOH over a wide concentration range from 0.03 to 1.071 mM with a sensitive limit of detection 7.8 μM. Moreover, the Co-PM-NDGPC nanocomposite electrode with low charge transfer resistance (Rct∼81 Ω) and high ionic diffusion indicates excellent stability, reproducibility, and high sensitivity. The fabricated nanocomposite materials exhibit a commendable sensing response toward glucose molecules present in the blood serum samples recommends its usage in real-time applications.

Flexible electrochemical sensor for highly sensitive and selective non-enzymatic detection of creatinine via electrodeposited copper over polymelamine formaldehyde.

A non-enzymatic electrochemical biosensor was developed for highly sensitive detection of creatinine using copper nanoparticles supported over polymelamine formaldehyde. The synergy between the electrodeposited copper nanoparticles over the highly porous polymer (eCu-PMF) provided a greener platform to boost up the electron transport at the electrode electrolyte interface by eliminating the role of redox species as well as interference of major interferents like glucose, dopamine, and ascorbic acid in physiological media 0.1 M PBS (pH 7.4). The proposed sensor exhibited a wide detection range of 100 fM-60 mM with high sensitivities of 0.320 mA nM-1 cm-2 and 3.8 mA nM-1 cm-2. Moreover, the sensor was applied to real samples of serum creatinine and recoveries of 97 to 114% were found. Additionally, a paper-based flexible screen-printed electrode was fabricated which displayed an excellent activity with the same detection range of 100 fM-60 mM and long-term storage stability of 15 days.

Progress of Enzymatic and Non-Enzymatic Electrochemical Glucose Biosensor Based on Nanomaterial-Modified Electrode.

This review covers the progress of nanomaterial-modified electrodes for enzymatic and non-enzymatic glucose biosensors. Fundamental insights into glucose biosensor components and the crucial factors controlling the electrochemical performance of glucose biosensors are discussed in detail. The metal, metal oxide, and hybrid/composite nanomaterial fabrication strategies for the modification of electrodes, mechanism of detection, and significance of the nanomaterials toward the electrochemical performance of enzymatic and non-enzymatic glucose biosensors are compared and comprehensively reviewed. This review aims to provide readers with an overview and underlying concept of producing a reliable, stable, cost-effective, and excellent electrochemical performance of a glucose biosensor.

Development of single-use thin film electrodes based on Zn2SnO4 on In2O3:SnO2 substrates with their biosensing applications

Dopamine (DA) has a significant impact on the emergence and treatment of certain diseases (e.g., Alzheimer’s and Parkinson’s diseases). Therefore, monitoring of DA is important, and using biosensors is a favorable option instead of time-consuming and expensive conventional methods. In biosensor manufacturing, thin films have become a rapidly emerging field. In this study, a non-enzymatic electrochemical biosensor based on thin film electrodes is developed for monitoring DA levels. The thin film electrodes (ZTO/ITO) are developed by deposition of Zn 2 SnO 4 (ZTO) on In 2 O 3 :SnO 2 (ITO) substrates by magnetron sputtering. 3-aminopropyltriethoxysilane (APTES) is used to modify the surface of these electrodes. Physical, optical, and structural properties of the electrodes are determined by applying surface profilometry, UV-VIS-NIR spectrophotometry, X-ray diffraction (XRD), and scanning electron microscopy (SEM) measurements. According to these measurements, it has been observed that the ZTO/ITO combination has a higher optical transmission value than the bare ITO, depending on the deposition time and the oxygen concentration used during ZTO deposition. In addition, the ITO thin film has a crystalline structure, while the ZTO thin film has an amorphous structure and both thin films have a good surface morphology. As electrochemical analysis, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV) measurements are performed. As a result of CV and EIS measurements, a remarkable change (63.54%) was observed after applying APTES modification onto the surface of ZTO/ITO electrode, and the ones obtained by DPV showed successful detection of DA by APTES modified ZTO/ITO. In addition, the experiments in the presence of interferences such as ascorbic acid (AA), uric acid (UA), bovine serum albumin (BSA), and fish sperm double-stranded DNA (fsDNA) show that the electrodes can be successfully applied for voltammetric determination of DA. The detection limit of DA was estimated to be 0.013 µM in the range of DA between 0.1 – 1 µM, and sensitivity was calculated and found to be 11.057 μA μg −1 mL cm −2 , which means ZTO/ITO electrodes have a good sensitivity. • ZTO/ITO thin film electrodes are fabricated by DC magnetron sputtering. • Surface of the ZTO/ITO electrodes are modified with APTES. • Single-use transparent APTES/ZTO/ITO electrodes are used for voltammetric detection of dopamine (DA). • APTES/ZTO/ITO electrodes have been used for the first time for detection of DA. • APTES/ZTO/ITO electrodes provided a low detection limit and good selectivity on DA detection.

Machine Learning with Neural Networks to Enhance Selectivity of Nonenzymatic Electrochemical Biosensors in Multianalyte Mixtures.

Nonenzymatic biosensors hold great potential in the field of analysis and detection due to long-term stability, high sensitivity, and low cost. However, the relative low selectivity, especially the overlapped oxidation peaks of biomarkers, in the biological matrix severely limits the practical application. In this work, we introduce an intelligent back-propagation neural network into nonenzymatic electrochemical biosensing to overcome the limitation of low selectivity for glucose and lactate detection. After simple electrodeposition and dropping modification, three working electrodes with distinct characters are fabricated and integrated into electrochemical microdroplet arrays for glucose and lactic acid detection. By analyzing chronoamperometry data from a standard mixture of glucose and lactate in varying concentrations, a database of highly selective detection can be simply established. The trained neural network model can reliably identify and accurately predict the concentration of glucose and lactic acid in the range of 0.25-20 mM with a correlation coefficient of 0.9997 in multianalyte mixtures. More importantly, the predicted results of serum samples are precise, and the relative standard deviation is less than 6.5%, proving the possible applicability of this method in real scenarios. This innovative method to enhance selectivity can avoid complex material synthesis and selection, and the highly specific nonenzymatic electrochemical biosensing platform paves the way for intelligent and precise point-of-care detection in long-term and is of low cost.

Synthesis and Characterization of TiO2 Thick Films for Glucose Sensing.

In this paper, we present the results of a non-enzymatic electrochemical glucose biosensor based on TiO2. An anatase working electrode was synthesized using the spin coating technique with the polymeric precursor method and dispersed TiO2 nanoparticles. Through scanning electron microscopy, it was observed that the electrode presented an irregular surface with clusters of nanoparticles. Electrochemical characterization indicated that the response was directly related to the morphology of the electrode. In the presence of glucose, the electrode exhibited adsorption behavior toward the molecules, enabling their recognition. The electrode was tested by employing PBS (phosphate buffer solutions) with varying pH values (from 4 to 9), demonstrating its electrochemical stability, even in the presence of glucose. Amperometric characterization was used to determine that the working region appeared from 0.2 mM to 2 mM, with a sensitivity of 4.46 μAcm-2mM-1 in PBS pH 7. The obtained results suggest that TiO2-based electrodes could be used for the detection of glucose concentration in sweat (0.277-1 mM) and saliva (0.23-1.77 mM).

(Digital Presentation) Bismuth and Transition Metal-Doped Bismuth Nanoparticles As Electrochemical Biosensors

Current non-enzymatic electrochemical biosensors rely heavily on transition metal-based nanomaterials, such as Pt, Ni, Co, and Cu, for molecule adsorption and charge transfer. Although high performance (sensitivity and selectivity) was usually demonstrated, these elements are generally toxic, making them less applicable for wearable/in vivo sensors.Two general strategies are approached to address such drawbacks: minimizing their usage without sacrificing the activity and searching for other elements with lower toxicity. In this study, we demonstrated that the overlooked bismuth nanoparticles (NPs) could be used for non-enzymatic electrochemical glucose sensing with comparable performance [1]. Using a laser ablation approach (see Figure 1A), stabilizer-free Bi NPs (~10 nm diameter) were prepared, showing amperometric sensitivity of 127 µA mM−1 cm−2. The synthesis approach also enabled the one-step surface doping of the Bi NPs, producing Ni and Co-doped Bi NPs with an atomic doping ratio of ~10%, and led to further sensitivity boost to 677 and 2326 µA mM−1 cm−2 (see Figure 1B). Kinetic analysis revealed that the oxidation of Bi(III) to Bi(V) species was the key to enabling glucose electrooxidation on Bi NPs. Such results demonstrate the vast potential of the overlooked bismuth in electrochemical biosensing. Figure 1 (A) Top: illustration of the laser ablation approach of preparing Bi and metal-doped Bi NPs; Bottom: TEM images of as-prepared Bi NPs and Co-Bi NPs; (B) Amperometric correlation between glucose concentration and the current density using Bi NPs and Co-Bi NPs as sensors. Reference: Zheng, W.; Li, Y.; Lee, L. Y. S., Bismuth and metal-doped bismuth nanoparticles produced by laser ablation for electrochemical glucose sensing, Sens. Actuators, B 2022, 357, 131334. Figure 1