Stable Electrochemical Biosensor Research Articles

Advancement in SARS-CoV-2 diagnosis: A new and stable electrochemical biosensor for genomic RNA detection

Coronavirus disease (COVID-19) is caused by infection with the SARS-CoV-2 virus, having already caused more than seven million deaths worldwide. Conventional techniques for SARS-CoV-2 detection have limitations, as high cost, low specificity, and longer analysis time, among others. Biosensors emerge as a necessary alternative to overcome the difficulties of current diagnostics. This paper reports a sensor platform where silver-doped zinc oxide nanomaterial (Ag:ZnONp) was used onto carbon screen-printed electrode and ethidium bromide as indicator for development of a specific electrochemical genosensor for COVID-19. This genosensor demonstrated good linearity between the concentrations of 5.62 × 104–5.62 copies/mL and a detection limit of 5 copies/mL with gRNA in patient’s samples, with a response time within 30 min. Molecular modeling and morphological analysis are in agreement with obtained electrochemical results. Additional techniques such as AFM, SEM, and EIS were conducted to characterize the morphological and electrochemical properties of the biosensor’s surface. The biosensor was also capable of detecting the target presence in spiked samples and demonstrated a stability of 60 days, higher than other similar biosensors for SARS-CoV-2.

Highly stable acetylcholinesterase electrochemical biosensor based on polymerized ionic liquids microgel for pesticides detection

Ahighly stable electrochemical biosensor for pesticide detection was developed. For the first timepolymeric ionic liquids (PILs) were introduced to construct an acetylcholinesterase (AChE) biosensor . AChE was entrapped in PILs microspheres through an emulsion polymerization reaction, where negatively charged Au nanoparticles (Au NPs) can be immobilized by the positively charged PILs, leading to improved catalytic performance. The results suggest that the positively charged PILs not only provide a biocompatible microenvironment around the enzyme molecule, stabilizing its biological activity and preventing its leakage, but also act as a modifiable interface allowing other components with electron transport properties to be loaded onto the polymer substrate, thus providing an efficient electron transport channel for the entrapped enzyme. More notably, when AChE was immobilized in a positively charged environment, the active site iscloser to the electrode, promoting faster electron transfer. The detection limits of the constructed electrochemical biosensor AChE@PILs@Au NPs/GCE toward carbaryl and dichlorvos (DDVP) were 5.0 × 10-2ngml-1 and 3.9 × 10-2ngml-1, in a wide linear range of 6.3 × 10-2-8.8 × 102ngml-1 and 1.3 × 10-1-1.4 × 103ngml-1, respectively. More importantly, the biosensor has high thermal and storage stability, which facilitates rapid field analysis of fruits and vegetables in a variety of climates. In addition, the biosensor reported has good repeatability and selectivity and has high accuracy in the analysis of peaches, tap water, and other types ofsamples.

Rapid detection of nitrite based on nitrite-oxidizing bacteria biosensor and its application in surface water monitoring

Timely and sensitive detection of nitrite is of great significance for human health protection and water pollution treatment. However, many biosensors can only determine the comprehensive toxicity of the water, and there are few electroactive biofilm (EAB) sensors for the specific detection of pollutants. Biofilms formed by bacteria with specific functions can improve the specificity of nitrite identification by biosensors. This study developed a novel, rapidly responding, high sensitivity (958.6 μAμM−1cm−2), wide detection range and anti-interference electrochemical biosensor based on electroactive nitrite-oxidizing bacteria. The biosensor could accurately detect nitrite in the range of 0.3–100 mg/L within 3 min by the cyclic voltammetry (CV) method. The bioelectrode could perform stable detection of nitrite over 200 cycles. The specificity of the biosensor for detecting nitrite was demonstrated by the presence of nitrite oxidizing bacteria (NOB) and nitrite oxidase enzyme (NXR) on the electrode biofilm. The biosensor performed well in wetlands and rivers, with an RSD <14.8% in the detection of nitrite at low concentrations, and further revealed the nitrification occurrence. Our study provided a feasible way for the development of a highly sensitive, rapidly responding and stable electrochemical biosensor, which also exhibited potential applications for long-term detection of nitrite and assessment of ecological function in surface water (rivers, lakes, wetlands, marshes, etc.).

Wearable hollow microneedle sensing patches for the transdermal electrochemical monitoring of glucose

According to the World Health Organization, about 422 million people worldwide have diabetes, with 1.5 million deaths directly attributed each year. Therefore, there is still a need to effectively monitor glucose in diabetic patients for proper management. Recently, wearable patches based on microneedle (MN) sensors provide minimally invasive analysis of glucose through the interstitial fluid (ISF) while exhibiting excellent correlation with blood glucose. Despite many advances in wearable electrochemical sensors, long-term stability and continuous monitoring remain unsolved challenges. Herein, we present a highly stable electrochemical biosensor based on a redox mediator bilayer consisting of Prussian blue and iron-nickel hexacyanoferrate to increase the long-term stability of the readout coupled with a hollow MN array as a sampling unit for ISF uptake. First, the enzymatic biosensor is developed by using affordable screen-printed electrodes (SPE) and optimized for long-term stability fitting the physiological range of glucose in ISF (i.e., 2.5–22.5 mM). In parallel, the MN array is assessed for minimally invasive piercing of the skin. Subsequently, the biosensor is integrated with the MN array leaving a microfluidic spacer that works as the electrochemical cell. Interestingly, a microfluidic channel connects the cell with an external syringe to actively and rapidly withdraw ISF toward the cell. Finally, the robust MN sensing patch is characterized during in vitro and ex vivo tests. Overall, affordable wearable MN-based patches for the continuous monitoring of glucose in ISF are providing an advent in wearable devices for rapid and life-threatening decision-making processes.

Porous PtAg nanoshells/reduced graphene oxide based biosensors for low-potential detection of NADH

A superior NADH sensing platform was constructed based on porous PtAg nanoshells supported on reduced graphene oxide (PtAg/rGO) in the absence of any enzymes and redox mediators. The PtAg/rGO composite was prepared via one-step reduction combined with galvanic replacement reaction. The as-made PtAg/rGO assembles multiple structural advantages of coherent conductive matrix, rich electroactive sites, and high specific surface area, accompanied bythe unique alloying effect. The PtAg/rGO possesses adequate active reactionsites and fluent electron transport pathway towards the electrocatalytic NADH oxidation, thus presenting significantly increased oxidation current and negative shift of 330mV in applied potential relative to the bare GCE. By virtues of the outstanding electrocatalytic activity, PtAg/rGO exhibits effective amperometric detection ofNADH at 0.15V within a wide linear concentration rangeof 2-2378μM, a high sensitivity of 92.62μAmM-1cm-2, low detection limit of 0.2μM, and long-term detection over 2500s. Moreover, the as-constructed biosensors can achieve accurate NADH detection in human serum samples, indicating its promising application feasibility in fundamental and clinic research. Graphical Abstract Porous PtAg alloy nanoshells supported on reduced graphene oxide (PtAg/rGO) was prepared via a facile one-step reduction and spontaneous replacement reaction strategy. A sensitive and highly stable electrochemical biosensor based on PtAg/rGO is constructed for the quantitative detection of NADH at low applied potential.

Composites of Bimetallic Platinum-Cobalt Alloy Nanoparticles andReduced Graphene Oxide for Electrochemical Determination of Ascorbic Acid, Dopamine, andUric Acid

The ultimate aim of this study is to produce a composite of bimetallicplatinum-cobalt nanoparticles and reduced graphene oxide (Pt-Co@rGO) based biosensorfor the detection of ascorbic acid (AA), dopamine (DA) and uric acid (UA). Those arebiologically important molecules with the key functions for the human body.Pt-Co@rGO was synthesized using a microwave-assisted technique and utilized for theproduction of a highly sensitive and stable electrochemical biosensor. Detailedspectral XPS and Raman analysis, XRD, and TEM/HR-TEM characterization were alsostudied. Due to the superior activity and excellent conductivity of rGO,well-separated oxidation peaks of these biomolecules is proven by DPV (differentialpulse voltammetry) and CV (cyclic voltammetry) measurements. The preparedPt-Co@rGO-based biosensor showed high electrochemical activity, a broad linearresponse, high sensitivity, and acceptable limit of detection values for individualand simultaneous determination of AA, DA, and UA, under optimized conditions. Thelinear range of Pt-Co@rGO was found to be 170–200; 35–1500 and 5–800 µM for AA, DA,and UA, respectively. Moreover, the detection limit of the prepared composite wascalculated as 0.345; 0.051; 0.172 µM for AA, DA, and UA, respectively. In the fieldof electrochemical biosensors, Pt-Co@rGO based sensor is highly promising due to itssuperior sensitivity and good selectivity properties.

An easy fabrication of glucose oxidase-dipeptide-reduced graphene oxide nanocomposite for glucose sensing

We present an easy and fast way to fabricate glucose oxidase-diphenylalanine-reduced graphene oxide (GOx-FF-rGO) film by using pulsed potentiostatic method. Glassy carbon electrode (GCE) modified by the obtained GOx-FF-rGO nanocomposite film is systematically characterized for its application in glucose detection. Under optimized condition, the biosensor exhibits a wide linear response in the range from 0.1 to 30.0mmolL−1, with a low detection limit down to 0.01mmolL−1. Our results indicate that the pulsed potentiostatic deposition approach may lead to production of highly sensitive and stable electrochemical biosensors.

Encapsulation of enzyme into mesoporous cages of metal–organic frameworks for the development of highly stable electrochemical biosensors

The thermal stability of biosensors based on the confinement of an enzyme within MOFs was significantly improved.

Influence of droplet coverage on the electrochemical response of planar microelectrodes and potential solving strategies based on nesting concept.

Recently, biosensors have been widely used for the detection of bacteria, viruses and other toxins. Electrodes, as commonly used transducers, are a vital part of electrochemical biosensors. The coverage of the droplets can change significantly based on the hydrophobicity of the microelectrode surface materials. In the present research, screen-printed interdigitated microelectrodes (SPIMs), as one type of planar microelectrode, were applied to investigate the influence of droplet coverage on electrochemical response. Furthermore, three dimensional (3D) printing technology was employed to print smart devices with different diameters based on the nesting concept. Theoretical explanations were proposed to elucidate the influence of the droplet coverage on the electrochemical response. 3D-printed ring devices were used to incubate the SPIMs and the analytical performances of the SPIMs were tested. According to the results obtained, our device successfully improved the stability of the signal responses and eliminated irregular signal changes to a large extent. Our proposed method based on the nesting concept provides a promising method for the fabrication of stable electrochemical biosensors. We also introduced two types of electrode bases to improve the signal stability.

Screening of Food Samples for Zearalenone Toxin Using an Electrochemical Bioassay Based on DNA–Zearalenone Interaction

This study was conducted to design a biosensor as a new, rapid, and sensitive tool for investigation of binding of zearalenone with double-stranded DNA (dsDNA). Polydiallyldimethylammonium chloride (PDDA) as a polycation and multiwall carbon nanotubes (MWCNTs) provide a positively charged surface with a high surface area for the immobilization of dsDNA as a polyanion on the surface of pencil graphite electrode (PGE). Using the dsDNA/MWCNT–PDDA-modified PGE, it was possible to detect the interaction of zearalenone with dsDNA, which allowed us to apply the dsDNA-modified electrode for trace determination of zearalenone. The changes at the oxidation signal of adenine were evaluated before/after each modification/immobilization step. By using dsDNA/PDDA–MWCNT/PGE, zearalenone could be detected as low as 0.005 ng mL−1. The relative standard deviation of five measurements of 0.5 ng mL−1 zearalenone was found to be 4.2 %. Finally, the highly stable electrochemical biosensor was applied to analyze the zearalenone concentration in milk and wheat samples.

Biosensing of naringin in marketed fruits and juices based on its interaction with DNA

A new electrochemical biosensor is introduced to study naringin–DNA interaction and naringin detection, using a modified pencil graphite electrode (PGE). The biosensor was prepared by modification of a PGE with MWCNTs-poly dialyldimethylammonium chloride (PDDA) decorated with ds-DNA (dsDNA/PDDA-MWCNTs/PGE). Change in the oxidation signals of adenine and guanine was used as probes for the biosensor evaluation, using differential pulse voltammetry. Under the optimized conditions, naringin could be measure from 0.058 to 580.0 µg mL−1 with a limit of detection of 0.010 µg mL−1. The relative standard deviation for five measurements of 0.58 µg mL−1 naringin was found as 3.7 and 4.2 %, based on the guanine and adenine signals, respectively. The biosensor was used as a selective sensor for the determination of naringin. In addition, electrochemical impedance spectroscopy was performed to evaluate the charge-transfer resistance of the modified and unmodified PGEs. Finally, this highly stable electrochemical biosensor was used to analyze naringin contents in various citrus juices.

Electrodeposition of platinum nanosheets on C60 decorated glassy carbon electrode as a stable electrochemical biosensor for simultaneous detection of ascorbic acid, dopamine and uric acid

ABSTRACT Platinum nanosheets (Pt NSs) were fabricated on fullerene (C 60 ) decorated glassy carbon electrode (GCE) (denoted as Pt NSs/C 60 /GCE) through a simple potentiostatic deposition method. In the coexistence of ascorbic acid (AA), dopamine (DA) and uric acid (UA), the as-prepared Pt NSs/C 60 /GCE electrode exhibited three well-resolved voltammetric peaks (Δ E AA–DA = 176 mV, Δ E DA–UA = 132 mV, Δ E AA–UA = 308 mV) in the differential pulse voltammetry (DPV) measurements, allowing a simultaneous detection of these biomolecules. There are linear relationships between current intensities and concentrations in the region of 10–1800 μM (AA), 0.5–211.5 μM (DA), and 9.5–1187 μM (UA), and the limits of detection (LOD) (S/N = 3) are down to 0.43 μM, 0.07 μM and 0.63 μM for AA, DA and UA, respectively. The as-prepared Pt NSs/C 60 /GCE electrode displayed a good reproducibility and storage stability and was successfully used for detection of AA, DA and UA in real plasma and urine samples.

Preparation of sulfonated poly(ether–ether–ketone) functionalized ternary graphene/AuNPs/chitosan nanocomposite for efficient glucose biosensor

A facile method of preparing water-dispersible sulfonated graphene (SPG) using sulfonated poly(ether–ether–ketone) organic polymer as a modifier was realized. A glucose biosensor was fabricated by immobilizing glucose oxidase (GOx) on the surface of AuNPs used to modify SPG and chitosan (CH) deposited on an indium tin-oxide (ITO) glass electrode by a solution casting method. Morphological and structural characterizations confirm that the AuNPs can be efficiently applied to the SPG–CH matrix. The amperometric response of the GOx/SPG–AuNPs–CH/ITO bioelectrode shows a broad linear range of 0.5 to 22.2mM, with a limit of detection of 0.13mM and a high sensitivity of 6.51μA/(mMcm2). The excellent performance of the constructed biosensor is attributed to the large surface-to-volume ratio and electron transfer ability of SPG, the high catalytic activity of the AuNPs, and the good biocompatibility of CH. In addition, the sensor has important advantages, such as its simple preparation, fast response time (10s), good stability (70 days), and high reproducibility. Favorable results upon examining the electrochemical response for the determination of glucose in human blood serum were obtained, without the assistance of a negligible effect of interfering bio-analytes. The results of studies show that the ternary SPG–AuNPs–CH nanocomposite may offer a new approach for developing novel types of highly sensitive and stable electrochemical biosensors.

Sol–gel derived gold nanoparticles biosensing platform for Escherichia coli detection

A three dimensional polymeric network obtained by the sol–gel process was applied to develop disposable, sensitive, selective and stable electrochemical biosensors for detection and quantification of Escherichia coli. This biosensor is based on the integration of a thiolated capture probe sequence from E. coli and gold nanoparticles (AuNPs) into a sol–gel 3D polymeric network derived from (3-mercaptopropyl)-trimethoxysilane (MPTS), formed onto a screen-printed gold electrode surface. MPTS presents the advantage of forming a 3D polymeric network containing a large number of thiol tail groups distributed throughout its structure that enable both its anchoring onto gold surfaces and the AuNPs incorporation. Moreover, this matrix allows the incorporation of a high amount of capture probe and provides a biocompatible environment that preserves its original recognition capability after its immobilization, which is expected to improve the sensitivity of the final biosensing device. The hybridization event is detected using the ruthenium complex [Ru(NH3)5L]2+, where L is the ligand [3-(2-phenanthren-9-yl-vinyl)-pyridine], as redox indicator, which interacts preferentially with ds-DNA. With the use of this approach, complementary target sequences of E. coli can be quantified over the range of 21–400pmol with a detection limit of 6.3pmol and good reproducibility (RSD=4.3%, n=4, C=10μM). In addition, this approach is very selective allowing the detection, without the need of a hybridization suppressor, of a single mismatch. It is also quite stable under storage conditions, giving response at least for 25 days.

Improvement of the amperometric response to l-lactate by using a cationic bioinspired thymine polycation in a bioelectrode with immobilized lactate oxidase

We report the electroanalytical properties of an amperometric bioelectrode containing l-lactate oxidase (LOx) immobilized on glassy carbon electrode with a hydrogel film composed of laponite and different amounts of a novel bioinspired polycation obtained by copolymerization of 4-vinylbenzyl thymine (VBT) and 4-vinylbenzyl triethylammonium chloride (VBA) in a molar ratio 1:4, respectively. The electrochemical behavior of the redox couple probe [Fe(CN)6]3−/4− of these VBT–VBA bioelectrodes was compared with that observed for a bioelectrode containing the classical polycation polydiallyldimethylammonium chloride (PDDA). The best response was obtained for a bioelectrode containing a VBT–VBA/laponite mass ratio double than the cationic exchange capacity of the clay, demonstrating that under this condition the polycation induces an optimal microenvironment in the interlamellar space of the clay, both for the position and the functionality of LOx.The VBT–VBA bioelectrode displayed a very high sensitivity (7.2±0.2)×102μAmM−1cm−2, a short time response (<5s), a wide linear response range (e.g. 0.01–1.0mM of l-lactate) and an excellent stability over a storage period of 60 days, when sensing l-lactate. The analytical response of the bioelectrode was tested in real food samples, e.g. milk, white wine, and beer, as well as during milk fermentation at 37°C. No effect of molecular interferences in the food matrices was detected, and the quantification of l-lactate was in complete agreement with standard assays reported values.Current results indicate that polycations containing the multifunctional green monomer VBT have high potential for their use in hydrogel film formation producing more responsive and stable electrochemical biosensors.

Direct electrodeposition of a biocomposite consisting of reduced graphene oxide, chitosan and glucose oxidase on a glassy carbon electrode for direct sensing of glucose

We have electrodeposited a composite film consisting of graphene oxide, chitosan and glucose oxidase directly on a glassy carbon electrode (GCE) through electrochemical reduction of a solution of the 3 components under controlled direct electrical potential. The procedure takes only several minutes, and the thickness of the resulting film is uniform and controllable. The GOx has uncompromised bioactivity and exhibits reversible 2-proton and 2-electron transfer in presence of glucose. It therefore can be used amperometric sensing of glucose. The biosensor has a fast response (<3 s), a detection limit of 0.4 μM (which is 50-fold lower compared to the biosensor prepared by drop-casting solutions of the same materials onto an GCE), and a linear response in the 0.4 μM to 2 mM concentration range (which again is much better than that of the biosensor prepared by the drop-casting method). Other features include high reproducibility, long-time storage stability, and satisfactory selectivity. We presume that the direct single-step electrodeposition of this nanocomposite offers a promising approach towards novel types of highly sensitive and stable electrochemical biosensors.

Biomimetically Synthesized Silica−Carbon Nanofiber Architectures for the Development of Highly Stable Electrochemical Biosensor Systems

Biomimetically synthesized silica and conductive activated carbon nanofibers (CNFs) are used in a synergistic manner for the development of a novel electrochemical biosensor system. Poly(L-lysine) templated silica grows and encapsulates the CNF-immobilized enzyme generating a highly stabilizing nanostructured environment for the underlying protein. Concurrently, CNFs provide both the required surface area for the high-capacity enzyme immobilization required in biosensors as well as direct electron transfer to the inner platinum transducer. As a result, this silica/nanofiber superstructure is an ideal architecture for the development of electrochemical biosensor systems that can withstand exposure to extreme operational conditions, such as high temperatures or the presence of proteases. Acetylcholine esterase is used as the model catalyst and with the aid of spectroscopic data it is shown that the observed high operational stability of the biosensor is due to the direct interaction of the protein with the silica backbone, as well as due to the nanostructured enzyme confinement.