Search Results (86)

Titanium dioxide (TiO₂) is one of the most widely produced nanomaterials. Many products contain nanoparticles because they have various technological, medical, and economic benefits. However, the presence of nanoparticles in the environment has a negative impact on public health. Due to the presence of TiO₂ NPs in food, food packaging, and drinking water, they can easily enter the human gastrointestinal tract (GIT), which includes environments with different pH values. These pH changes can affect the stability, dispersion, and toxicity of nanomaterials. Our experiments aimed to monitor the effect of TiO₂ NPs incubated at a pH similar to the GIT values on DNA structure. DNA damage was monitored using a DNA biosensor and a biosensing approach with electrochemical voltammetric detection. Cyclic voltammetry (CV) detected damage to DNA/GCE biosensors of up to 10%. The best way to monitor the genotoxicity of TiO₂ NPs on DNA structure was the biosensing approach, which changes in the redox indicator current response detected by differential pulse voltammetry (DPV) up to 47.6%. The highest effect of TiO₂ was observed for guanine residues at pH 8.0. The results were confirmed by UV–vis spectrophotometry and hyperchromic and bathochromic spectral shifts. Full article

This study describes the development of catalytic surface immobilizing dopamine via cross-linking or tyrosinase through covalent bonds on an electrografted screen-printed carbon electrode with a 4-nitrobenzenediazonium ion. A simple electrochemical reduction approach was used to covalently graft aryldiazonium ions onto the surface of commercial electrodes. After functionalization with aminophenyl groups, dopamine, an important neurotransmitter, was immobilized by imine bond formation using glutaraldehyde as a bifunctional cross-linking molecule. The presence of immobilized dopamine was confirmed by cyclic voltammetry following the electrochemical response of the hydroquinone/quinone redox process from catechol functionalities on the surface, which are responsible for the catalytic activity. In addition, the surface was also characterized by cyclic voltammetry using the redox probe, [Fe(CN)₆]^3−/4−, obtaining a signal approximately 14 times higher than that of a bare electrode, achieving a dynamic concentration range spanning three orders of magnitude. Remarkable sensitivity was also obtained by combining the electrografting, in situ diazotation, to generate grafted aryl diazonium ions on the surface, and coupling reaction to anchor the tyrosinase enzyme to the electrode surface. The response of the TYR-biosensor towards catechol, using the redox probe as mediator, was 10 times higher than that obtained with the dopamine modified catalytic surface. These modified surfaces offer promising alternatives for the voltammetric quantification of catechol in environmental fields. Full article

Dengue is a neglected disease mainly affecting tropical and subtropical countries. The diagnosis of dengue fever is still a problem since most of it is made from whole or recombinant DENV proteins, which present cross-reactions with other members of the Flavivirus family. Therefore, there is still a huge demand for new diagnostic methods that provide rapid, low-cost, easy-to-use confirmation. Thus, in this study, we developed an affordable electrochemical biosensor for rapidly detecting immunoglobulin G (IgG) serological antibodies in the sera of DENV-infected patients. An identified linear B-cell epitope (DENV/18) specific for DENV 1–4 serotypes recognized by IgG in patient sera was selected as a target molecule after a microarray of peptides using the SPOT-synthesis methodology. After chemical synthesis, the DENV/18-peptide was immobilized on the surface of the working electrode of a commercially available screen-printed gold electrode (SPGE). The capture of DENV-specific IgG allowed for the formation of an immunocomplex that was measured by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) using a potassium ferrocyanide/ferricyanide ([Fe(CN)₆]^3−/4−) electrochemical probe. An evaluation of the biosensor’s performance showed a detection limit of 100 µg mL⁻¹ for the synthetic peptides (DENV/18) and 1.21 ng mL⁻¹ in CV and 0.43 ng mL⁻¹ in DPV for human serum, with a sensitivity of 7.21 µA in CV and 8.79 µA in DPV. The differentiation of infected and uninfected individuals was possible even at a high dilution factor that reduced the required sample volumes to a few microliters. The final device proved suitable for diagnosing DENV by analyzing real serum samples, and the results showed good agreement with molecular biology diagnostics. The flexibility to conjugate other antigenic peptides to SPEs suggests that this technology could be rapidly adapted to diagnose other pathogens. Full article

The development of sensitive, selective, and reliable glucose biosensors remains a persistent challenge in clinical diagnostics. In this study, we exploited the advantageous (electro)catalytic properties of bismuth ruthenate (Bi₂Ru₂O₇) pyrochlore clusters, known for their high surface activity and metallic-like conductivity, and the favorable physicochemical properties of multi-walled carbon nanotubes (MWCNTs) by combining them with glucose oxidase (GOD) in a sensitive and selective disposable glucose biosensor. The integration of Bi₂Ru₂O₇ enabled an enhanced and more reproducible response of the biosensor along with fast and improved communication between the supporting electrode and the upper biosensing layer. The architecture of the biosensor involves the deposition of an MWCNT layer on a ferrocyanide-modified screen-printed carbon electrode (FCN-SPCE), followed by the application of a biorecognition layer including GOD and Bi₂Ru₂O₇ clusters. The voltammetric biosensor showed excellent electroanalytical performance, capable of detecting low glucose concentrations with a detection limit of 40 µM along with a linear response across the examined concentration range of 1.0–20.0 mM. The biosensor exhibited good reproducibility with a relative standard deviation (RSD) of 1.2% and interference-free operation against several of the most common interfering compounds. The practical applicability of the biosensor was demonstrated by the determination of glucose in a real serum sample spiked with different concentrations of glucose. Full article

A novel composite voltammetric biosensor has been developed for the first time, utilizing a glassy carbon electrode modified with yttria-stabilized zirconia doped with titanium dioxide and carbon black (YSZTiO₂-CB/GCE), specifically designed for the detection of trimetazidine (TMZ). The measurement conditions, including both the supporting electrolyte and instrumental settings, were optimized to enhance performance. In the concentration range of 0.5 to 7 µM, it is not necessary to use preconcentration time for the determination of TMZ. The limit of detection (for 60 s of preconcentration time) was equal to 5.5 nM (1.87 ng mL⁻¹), outperforming other voltammetric methods in terms of sensitivity. The reproducibility of the trimetazidine signal (with a concentration of 0.05 µM) exhibited a relative standard deviation (RSD) of 3.3% over 10 measurements. Additionally, our biosensor is characterized by excellent stability, ease of use, and straightforward preparation. The proposed biosensor and method have proven effective in analyzing TMZ in a variety of matrices, including urine, blood plasma, pharmaceutical formulations, as well as gastric and intestinal fluids, yielding recovery rates ranging from 97.7 to 102.3%. Full article

Medical devices have progressed from their initial bulky forms to smart devices. However, their rigidity hampers their seamless integration into everyday life. The fields of stretchable, textile, and flexible electronics are emerging research areas with the potential to drive significant technological progress. This research presents a laboratory-based technique to produce highly sensitive and flexible biosensors for detecting the chikungunya virus. These biosensors are based on 0D nanomaterials and demonstrate significant advancements in voltammetry. The electrochemical platform was created utilizing the stencil printing (StPE) technique. Adapting the biosensor setup involved the selection of aptamer as the biorecognition element bound with silver nanoparticles (AgNPs). This biosensor was employed in the voltammetric identification of the Chikungunya virus antigen (CHIKV-Ag) within a solution containing 0.5 mM potassium ferro/ferri cyanide, a redox pair. The biosensor was employed to evaluate CHIKV-Ag within a human serum sample. It demonstrated a linear detection span ranging from 0.1 ng/mL to 1 μg/mL, with a detection limit of 0.1 ng/mL for CHIKV-Ag. The proposed approach, due to its flexibility in production and the electrocatalytic attributes displayed by the zero-dimensional nanostructure, presents innovative opportunities for cost-effective and tailored aptamer-based bioelectronics, thereby broadening the scope of this domain. Full article

This paper describes the design and development of a novel electrochemical biosensor for measuring glycerol in wine. Our initial detailed studies were aimed at deducing the optimum conditions for biosensor operation by conducting hydrodynamic voltammetric and amperometric studies. The resulting voltammograms revealed a maximum electrocatalytic current at 0.0 V vs. Ag/AgCl, which we used for all further studies. We also examined the effect of pH (8–10) on the amperometric responses of different glycerol concentrations over a range of 0.04 to 0.20 mM. Based on our findings, we propose that pH 9 would be suitable as the supporting electrolyte for further studies with the amperometric biosensor. The biosensor was constructed by immobilising 10 units of GLDH and 660 μg NAD⁺ onto the MB-SPCE surface using glutaraldehyde (GLA) as a cross-linking agent. Calibration studies were performed with glycerol over the 1.0–7.5 mM concentration range. Chronoamperometry was the electrochemical technique chosen for this purpose as it is convenient and can be performed with only 100 μL of sample directly deposited onto the biosensor’s surface. In the current study, we observed linear calibration plots with the above standard solutions using current measurements at a selection of sampling times along the chronoamperograms (30–340 s). We have evaluated the glycerol biosensor by carrying out an analysis of commercially available red wine. Overall, these findings will form a platform for the development of novel rapid technology for point-of-test evaluation of glycerol in the production and quality control of wine. Full article

Electrochemical biosensors are critical in advancing biomedical and pharmaceutical therapies because of their adaptability and cost-effectiveness. Voltammetric and amperometric sensors are of particular interest. These sensors typically consist of a specialized tip or biorecognition element and a transducer that converts biological data into readable signals. Efficient biosensor materials are essential for addressing health emergencies, with coordination polymers (CPs) and metal–organic frameworks (MOFs) showing promise. Functionalization strategies are necessary to enhance the usability of pristine MOFs, owing to issues such as low conductivity. The integration of conductive polymers with MOFs has resulted in the development of highly efficient biosensors. Both enzymatic and nonenzymatic biosensors are used for analyte detection; nonenzymatic approaches are gaining popularity owing to their durability and accuracy. MOFs and CPs have been applied in sensitive electrochemical biosensors to detect fatal brain tumors such as glioblastomas (GBM). These biosensors demonstrate enhanced selectivity and sensitivity, highlighting the potential of MOFs and CPs in advancing electrochemical biosensor technology for both in vivo and in vitro applications. Full article

Heavy metals constitute pollutants that are particularly common in air, water, and soil. They are present in both urban and rural environments, on land, and in marine ecosystems, where they cause serious environmental problems since they do not degrade easily, remain almost unchanged for long periods, and bioaccumulate. The detection and especially the quantification of metals require a systematic process. Regular monitoring is necessary because of seasonal variations in metal levels. Consequently, there is a significant need for rapid and low-cost metal determination methods. In this study, we compare and analytically validate absorption spectrometry with a sensitive voltammetric method, which uses a bismuth film-plated electrode surface and applies stripping voltammetry. Atomic absorption spectroscopy (AAS) represents a well-established analytical technique, while the applicability of anodic stripping voltammetry (ASV) in complicated sample matrices such as soil samples is currently unknown. This sample-handling challenge is investigated in the present study. The results show that the AAS and ASV methods were satisfactorily correlated and showed that the metal concentration in soils was lower than the limit values but with an increasing trend. Therefore, continuous monitoring of metal levels in the urban complex of a city is necessary and a matter of great importance. The limits of detection of cadmium (Cd) were lower when using the stripping voltammetry (SWASV) graphite furnace technique compared with those obtained with AAS when using the graphite furnace. However, when using flame atomic absorption spectroscopy (flame-AAS), the measurements tended to overestimate the concentration of Cd compared with the values found using SWASV. This highlights the differences in sensitivity and accuracy between these analytical methods for detecting Cd. The SWASV method has the advantage of being cheaper and faster, enabling the simultaneous determination of heavy elements across the range of concentrations that these elements can occur in Mediterranean soils. Additionally, a dsDNA biosensor is suggested for the discrimination of Cu(I) along with Cu(II) based on the oxidation peak of guanine, and adenine residues can be applied in the redox speciation analysis of copper in soil, which represents an issue of great importance. Full article

Lead poses severe effects on living organisms, and since Pb²⁺ ions tend to accumulate in different organs, it is crucial to monitor Pb²⁺ concentration in samples such as water and soil. One of the approaches is the utilization of biosensors combined with aptamer-based layers for the electrochemical detection of lead ions. Herein, we present the studies of applying miniaturized screen-printed transducers as solid surfaces to fabricate aptamer layers. As the research is the direct continuation of our previous studies regarding the use of gold disk electrodes, the working parameters of elaborated aptasensors were defined, including the range of linear response (10–100 nM), selectivity as well as stability, regeneration, and feasibility of application for the analysis of real samples. This was achieved using voltammetric techniques including cyclic and square-wave voltammetry in the presence of methylene blue redox indicator. Full article

This paper describes the development of a simple voltammetric biosensor for the stereoselective discrimination of myo-inositol (myo-Ins) and D-chiro-inositol (D-chiro-Ins) by means of bovine serum albumin (BSA) adsorption onto a multi-walled carbon nanotube (MWCNT) graphite screen-printed electrode (MWCNT-GSPE), previously functionalized by the electropolymerization of methylene blue (MB). After a morphological characterization, the enantioselective biosensor platform was electrochemically characterized after each modification step by differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). The results show that the binding affinity between myo-Ins and BSA was higher than that between D-chiro-Ins and BSA, confirming the different interactions exhibited by the novel BSA/MB/MWCNT/GSPE platform towards the two diastereoisomers. The biosensor showed a linear response towards both stereoisomers in the range of 2–100 μM, with LODs of 0.5 and 1 μM for myo-Ins and D-chiro-Ins, respectively. Moreover, a stereoselectivity coefficient α of 1.6 was found, with association constants of 0.90 and 0.79, for the two stereoisomers, respectively. Lastly, the proposed biosensor allowed for the determination of the stereoisomeric composition of myo-/D-chiro-Ins mixtures in commercial pharmaceutical preparations, and thus, it is expected to be successfully applied in the chiral analysis of pharmaceuticals and illicit drugs of forensic interest. Full article

The design of an indicator electrode made of carbon paste of ergonomic design for the voltammetric determination of a number of substances of inorganic and organic origin is described. The electrode is made of a graphite rod with a diameter of 6 mm and a length of 70 mm, covered with insulation, and having a cavity filled with an electroactive carbon-containing material at the end of the rod. The characteristic features of the proposed electrode—the insulating shell of the housing made of shrink tubing and the electrolytic coating of the cavity surface with a conductive metal film—make it possible to simplify the design of the electrode and increase mechanical strength, extend the service life of the electrode, and also provide the possibility of volumetric and surface modifications with an economical consumption of modifying reagents. Examples of the use of an indicator electrode modified with mercury and bismuth films and volumetrically modified with manganese dioxide nanoparticles in the analysis of food, beverages, natural objects for the content of heavy metal ions, pharmaceuticals for the content of hydrogen peroxide, and vitamins of groups B and C are given. The simplicity of making the developed indicator electrode from carbon paste and its mechanical strength and cost-effectiveness when using expensive and scarce modifiers allow us to recommend it for use in voltammetric analysis and the creation of various biosensor systems. Full article

A novel electrochemical DNA sensor was developed for the detection of the anthracycline drug, valrubicin, on the base of poly(Azure C) electropolymerized from the deep eutectic solvent reline and covered with adsorbed DNA from calf thymus. Biosensor assembling was performed by multiple scanning of the potential in one drop (100 µL) of the dye dissolved in reline and placed on the surface of a screen-printed carbon electrode. Stabilization of the coating was achieved by its polarization in the phosphate buffer. The electrochemical characteristics of the electron transfer were determined and compared with a similar coating obtained from phosphate buffer. The use of deep eutectic solvent made it possible to increase the monomer concentration and avoid using organic solvents on the stage of electrode modification. After the contact of the DNA sensor with valrubicin, two signals related to the intrinsic redox activity of the coating and the drug redox conversion were found on voltammogram. Their synchronous changes with the analyte concentration increased the reliability of the detection. In the square-wave mode, the DNA sensor made it possible to determine from 3 µM to 1 mM (limit of detection, 1 µM) in optimal conditions. The DNA sensor was successfully tested in the voltammetric determination of valrubicin in spiked artificial urine, Ringer-Locke solution mimicking plasma electrolytes and biological samples (urine and saliva) with a recovery of 90–110%. After further testing on clinical samples, it can find application in the pharmacokinetics studies and screening of new drugs’ interaction with DNA. Full article

L-Dopa is an intermediate amino acid in the biosynthesis of endogenous catecholamines, such as dopamine. It is currently considered to be the optimal dopaminergic treatment for Parkinson’s disease, a neurodegenerative disorder affecting around 1% of the population. In an advanced stage of the disease, complications such as dyskinesia and psychosis are caused by fluctuations in plasma drug levels. Real-time monitoring of L-Dopa levels would be advantageous for properly adjusting drug dosing, thus improving therapeutic efficacy. Electrochemical methods have advantages such as easy-to-use instrumentation, fast response time, and high sensitivity, and are suitable for miniaturization, enabling the fabrication of implantable or wearable devices. This review reports on research papers of the past 20 years (2003–2023) dealing with enzyme-based biosensors for the electrochemical detection of L-Dopa in biological samples. Specifically, amperometric and voltammetric biosensors, whose output signal is a measurable current, are discussed. The approach adopted includes an initial study of the steps required to assemble the devices, i.e., electrode modification and enzyme immobilization. Then, all issues related to their analytical performance in terms of sensitivity, selectivity, and capability to analyze real samples are critically discussed. The paper aims to provide an assessment of recent developments while highlighting limitations such as poor selectivity and long-term stability, and the laborious and time-consuming fabrication protocol that needs to be addressed from the perspective of the integrated clinical management of Parkinson’s disease. Full article

The screening and early diagnosis of diseases are crucial for a patient’s treatment to be successful and to improve their survival rate, especially for cancer. The development of non-invasive analytical methods able to detect the biomarkers of pathologies is a critical point to define a successful treatment and a good outcome. This study extensively reviews the electrochemical methods used for the development of biosensors in a liquid biopsy, owing to their ability to provide a rapid response, precise detection, and low detection limits. We also discuss new developments in electrochemical biosensors, which can improve the specificity and sensitivity of standard analytical procedures. Electrochemical biosensors demonstrate remarkable sensitivity in detecting minute quantities of analytes, encompassing proteins, nucleic acids, and circulating tumor cells, even within challenging matrices such as urine, serum, blood, and various other body fluids. Among the various detection techniques used for the detection of cancer biomarkers, even in the picogram range, voltammetric sensors are deeply discussed in this review because of their advantages and technical characteristics. This widespread utilization stems from their ability to facilitate the quantitative detection of ions and molecules with exceptional precision. A comparison of each electrochemical technique is discussed to assist with the selection of appropriate analytical methods. Full article