Paper-based Electrochemical Sensor Research Articles

A Paper-Based Electrochemical Sensor Based on Chain Structured ZIF-8@MWCNTs for Efficient Determination of Rutin

Rapid and accurate determination of rutin content in pharmaceuticals in an important issue. Here, a paper-based electrochemical sensor for in situ growth of chain ZIF-8 using multi-walled carbon nanotubes (MWCNTs) as a template was constructed by hydrothermal method. The results showed that the combination of ZIF-8 and MWCNTs not only promoted the dispersion of MWCNTs, but also made up for the conductivity of ZIF-8. Under optimum conditions, the Ipa was linearly related to the concentration of rutin in the range of 0.01–10 and 10–190 μM with a limit of detection (LOD) of 2.82 nM. Finally, the paper-based electrochemical sensor can be used for the electrochemical detection of rutin through the determination of rutin in pharmaceuticals.

A novel paper-based electrochemical device modified with Ni-doped TiO2 nanocrystals-decorated graphene oxide for ascorbic acid detection

This study presents the development of a novel paper-based electrochemical device modified with pure and nickel-doped TiO2 nanocrystals and graphene oxide to enhance its ability to detect ascorbic acid (AA). The use of nanomaterials in the fabrication of the sensor provides a high surface area-to-volume ratio, leading to an increase in the sensitivity and selectivity of the device. The nanomaterials were synthesized, and a combination with the best properties was selected for detecting AA. The morphological, structural, and electrical properties of the nanomaterials in the paper device were investigated using scanning electron microscopy (SEM), Raman spectroscopy (Raman), and cyclic voltammetry (CV), respectively. The sensor's performance was evaluated through various experiments, including cyclic voltammetry, to measure its sensitivity and selectivity in detecting AA. The results indicate that adding Ni-doped TiO2 nanocrystals improves the sensor's sensitivity while incorporating graphene oxide enhances its selectivity. Furthermore, the sensor's performance was compared to that of other commonly used sensors, and it was found to be highly sensitive and selective. Therefore, this paper-based electrochemical sensor, modified with nanomaterials, shows great potential for detecting AA and other applications, such as environmental monitoring and medical diagnostics, due to its high sensitivity and selectivity, low cost, and ease of use.

Graphene Pseudoreference Electrode for the Development of a Practical Paper-Based Electrochemical Heavy Metal Sensor.

Paper-based electrochemical devices (PEDs) have emerged as versatile platforms that bridge analytical chemistry and materials science, demonstrating advantages of portability, cost-effectiveness, and environmental sustainability. This study investigates the integration of a graphene pseudoreference electrode (GPRE) into a PED, and it exhibits potential advantages over the traditional Ag/AgCl pseudoreference electrode (PRE). In addition, the electrochemical properties and stability of GPRE are compared with those of the traditional Ag/AgCl PRE. The results demonstrate that GPRE exhibits a stable and reproducible potential during electrochemical measurement throughout 180 days, demonstrating its suitability as an alternative to an expensive metal PRE. Furthermore, a GPRE-incorporated paper-based device is designed and evaluated for use in the electrochemical detection of cadmium (Cd) and lead (Pb) using an in situ bismuth-modified electrode. The GPRE-incorporated PED exhibited good analytical performance, with a low limit of detection of 0.69 and 5.77 ng mL-1 and electrochemical sensitivities of 70.16 and 38.34 μA·mL·μg-1·cm-2 for Cd(II) and Pb(II), respectively. More than 99.9% accuracy of the sensor was obtained for both ions with respect to conventional inductively coupled plasma-mass spectrometry. The results highlight the effectiveness and suitability of the GPRE-incorporated PED as a sensor for various applications, such as environmental monitoring, food quality control, and medical diagnostics.

Smartphone-enabled 3D origami-fluidic paper-based electrochemical detection of myeloperoxidase activity for assessing wound infection

Early diagnosis of wound infections that aid in the assessment of the stage of wound infection is gaining interest for development of a new biomarker. In present research, a simple and portable 3D origami-fluidic paper-based electrochemical sensor is proposed for the detection of myeloperoxidase (MPO) activity in wound exudate samples. The flow can be manipulated by an origami pattern of the paper allowing the electrochemical reaction to occur on the electrode surface. Glucose oxidase (GOx) was used for producing hydrogen peroxide (H2O2) and MPO antibodies were immobilized to capture the MPO to enhance the specificity. Prussian blue/MXene composite modified on the electrode act as a nanozyme for catalyzing H2O2. Then, data is wirelessly transferred to a smartphone using near-field communication (NFC) technology. Under the optimal conditions, our proposed device can detect MPO activity in ranges 0.5–5 U/ml (R2 =0.9697), demonstrating a strong correlation with a colorimetric MPO activity kit when tested with real wound fluid samples (n = 6, R2 = 0.9198). Notably, our method can differentiate between non-infected and infected wounds (p-value < 0.05) by analyzing MPO activity extracted from used wound-dressing gauzes (n = 10). Therefore, our device offers a rapid portable device for MPO activity that is promising for resource-limited settings.

µPED based electrode modified with nanocomposite for the detection of proline: An abiotic stress biomarker in plant

Plants when exposed to stressful conditions, accumulates array of metabolites. Among them proline plays significant and beneficial role as osmolyte, metal chelator and as anti-oxidative defense and regulator molecule. Thus the proline content is one of the potent bio-marker for the early detection of abiotic stress in plant. In this work a microfluidic paper-based electrochemical device (µPED) modified with copper oxide nanoparticles (CuO) decorated reduced graphene oxide (rGO) nanocomposite is utilized to develop disposable system for the detection of proline. Wax and screen printings were utilized to create microfluidic chambers and electrode pattern on paper device, respectively. Portable potentiostat was used for measuring the current in response from the addition of proline. The proposed sensor exhibits excellent electrochemical performance with broad linear responses over a proline concentration ranging from 0.1 mM to 7.5 mM (R2 =0.99) and showed lower detection limit of 0.05 mM at 0.4 V vs. pseudo Ag/AgCl. Excellent electrochemical performance may be attributed to presence of electroactive rGO and catalytic activity towards proline is due to the coordination between proline and copper (II) oxide nanoparticles. These results demonstrate that the proposed paper-based electrochemical sensor can be utilized in disposable and portable way to detect proline content in the abiotic-stressed plants and has potential to be applied in on-site application.

Recycling 3D Printed Residues for the Development of Disposable Paper-Based Electrochemical Sensors.

Here, we propose a recyclable approach using acrylonitrile-butadiene-styrene (ABS) residues from additive manufacturing in combination with low-cost and accessible graphite flakes as a novel and potential mixture for creating a conductive paste. The graphite particles were successfully incorporated in the recycled thermoplastic composite when solubilized with acetone and the mixture demonstrated greater adherence to different substrates, among which cellulose-based material made possible the construction of a paper-based electrochemical sensor (PES). The morphological, structural, and electrochemical characterizations of the recycled electrode material were demonstrated to be similar to those of the traditional carbon-based surfaces. Faradaic responses based on redox probe activity ([Fe(CN)6]3-/4-) exhibited well-defined peak currents and diffusional mass transfer as a quasi-reversible system (96 ± 5 mV) with a fast heterogeneous rate constant value of 2 × 10-3 cm s-1. To improve the electrode electrochemical properties, both the PES and the classical 3D-printed electrode surfaces were modified with a combination of multiwalled carbon nanotubes (MWCNTs), graphene oxide (GO), and copper. Both electrode surfaces demonstrated the suitable oxidation of nitrite at 0.6 and 0.5 V vs Ag, respectively. The calculated analytical sensitivities for PES and 3D-printed electrodes were 0.005 and 0.002 μA/(μmol L-1), respectively. The proposed PES was applied for the indirect amperometric analysis of S-nitroso-cysteine (CysNO) in serum samples via nitrite quantitation, demonstrating a limit of detection of 4.1 μmol L-1, with statistically similar values when compared to quantitative analysis of the same samples by spectrophotometry (paired t test, 95% confidence limit). The evaluated electroanalytical approach exhibited linear behavior for nitrite in the concentration range between 10 and 125 μmol L-1, which is suitable for realizing clinical diagnosis involving Parkinson's disease, for example. This proof of concept shows the great promise of this recyclable strategy combining ABS residues and conductive particles in the context of green chemical protocols for constructing disposable sensors.

Paper-based electrochemical sensor for simultaneous detection of salivary Δ⁹-tetrahydrocannabinol and thiocyanate to differentiate illegal cannabis smokers

Cannabis smoking is on the rise as a result of cannabis legalization across the world. The intake of cannabis by smoking has an impact on the mental health of smokers and intimates. Therefore, rapid monitoring of illicit cannabis use via direct saliva samples is necessary. The Δ⁹-tetrahydrocannabinol (Δ⁹-THC) and thiocyanate (SCN) level in saliva can be an effective biomarker to differentiate between cannabis and non-cannabis smokers such as cannabis ingestion, cigarette smokers, and healthy people. In this work, there is a development of an electrochemical sensor, “copper-phthalocyanine-modified screen-printed graphene electrodes (CuPc/SPGE),” for the concurrent determination of Δ⁹-THC and SCN using differential pulse voltammetry. Furthermore, the applicability of the CuPc/SPGE sensor was verified by simultaneously measuring Δ⁹-THC and SCN in saliva samples. The results from the developed sensor were similar to those obtained by high-performance liquid chromatography. This proposed sensor represents a first step in the differentiation of illegal cannabis smokers using the correlation between the contents of Δ⁹-THC and SCN in saliva, with features of rapidity, simplicity, low cost, and disposability.

A smart paper-based electrochemical sensor for reliable detection of iron ions in serum.

The fast-growing healthcare demand for user-friendly and affordable analytical tools is driving the efforts to develop reliable platforms for the customization of therapy based on individual health conditions. In this overall scenario, we developed a paper-based electrochemical sensor for the quantification of iron ions in serum as a cost-effective sensing tool for the correct supplement administration. In detail, the working electrode of the screen-printed device has been modified with a nanocomposite constituted of carbon black and gold nanoparticles with a drop-casting procedure. Square wave voltammetry has been adopted as an electrochemical technique. This sensor was further modified with Nafion for iron quantification in serum after sample treatment with trifluoroacetic acid. Under optimized conditions, iron ions have been detected with a LOD down to 0.05mg/L and a linearity up to 10mg/L in standard solution. The obtained results have been compared with reference methods namely commercial colorimetric assay and atomic absorption spectroscopy, obtaining a good correlation within the experimental errors. These results demonstrated the suitability of the developed paper-based sensor for future applications in precision medicine of iron-deficiency diseases.

AuNP/Cu-TCPP(Fe) metal-organic framework nanofilm: a paper-based electrochemical sensor for non-invasive detection of lactate in sweat.

Effective and real-time detection of lactate (LA) content in human sweat has attracted considerable attention from researchers. In this work, a novel electrochemical paper-based analysis device (ePAD) was developed for the non-invasive detection of LA in sweat. The electrocatalytic properties of AuNP/Cu-TCPP(Fe) hybrid nanosheets, which were prepared by an optimised synthetic method, were studied by CV and EIS electrochemical methods for the first time and the working electrode can be fabricated using a drip coating method. The lactate sensor was optimised and validated for usability, adoptability and interpretability. To the best of our knowledge, this was the fastest, lowest detection line and widest linear range method reported to date for the detection of lactate. It achieved the detection limit of 0.91 pM and a linear range from 0.013 nM to 100 mM. The dual catalytic effects of the hybrid NSs shortened the detection time by nearly two times and enhanced the sensitivity approximately two times, an accuracy unmatched until now. Furthermore, this sensor was employed for LA analysis and validated by high performance liquid chromatography (HPLC). The ePAD shows superior biocompatibility, accuracy, and high sensitivity and can be easily manufactured. Hence, it is applicable for the long-term monitoring of sweat LA concentrations in point-of-care testing, athletic testing of athletes and military personnel and other subjects in different extreme environments.

Performance Testing of Paper-based Electrochemical Sensor for Blood pH Measurements

Performance Testing of Paper-based Electrochemical Sensor for Blood pH Measurements

Rapid Detection of Staphylococcus aureus Using Paper-Derived Electrochemical Biosensors.

Several groups have recently explored the idea of developing electrochemical paper-based wearable devices, specifically targeting metabolites in sweat. While these sensors have the potential to provide a breadth of analytical information, there are several key challenges to address before these sensors can be widely adopted for clinical interventions. Toward this goal, we describe the development of a paper-based electrochemical sensor for the detection of Staphylococcus aureus. Enabling the application, this report describes the use of paper-derived carbon electrodes, which were modified with a thin layer of sputtered gold (that minimizes lateral resistivity and significantly improves the electron transfer process) and with chitosan (used as a binder, to offer flexibility). The resulting material was laser-patterned and applied for the development of an electrochemical biosensor controlled (via a wireless connection) by a custom-built, portable potentiostat. As no interference was observed when exposed to other bacteria or common metabolites, this wearable system (paper-derived electrodes + potentiostat) has the potential to detect the presence of S. aureus in the skin, a commonly misdiagnosed and mistreated infection.

A Paper-Based Electrochemical Sensor Based on PtNP/COFTFPB-DHzDS@rGO for Sensitive Detection of Furazolidone.

Herein, a paper-based electrochemical sensor based on PtNP/COFTFPB−DHzDS@rGO was developed for the sensitive detection of furazolidone. A cluster-like covalent organic framework (COFTFPB−DHzDS) was successfully grown on the surface of amino-functional reduced graphene oxide (rGO-NH2) to avoid serious self-aggregation, which was further loaded with platinum nanoparticles (PtNPs) with high catalytic activity as nanozyme to obtain PtNP/COFTFPB−DHzDS@rGO nanocomposites. The morphology of PtNP/COFTFPB−DHzDS@rGO nanocomposites was characterized, and the results showed that the smooth rGO surface became extremely rough after the modification of COFTFPB−DHzDS. Meanwhile, ultra-small PtNPs with sizes of around 1 nm were precisely anchored on COFTFPB−DHzDS to maintain their excellent catalytic activity. The conventional electrodes were used to detect furazolidone and showed a detection limit as low as 5 nM and a linear range from 15 nM to 110 μM. In contrast, the detection limit for the paper-based electrode was 0.23 μM, and the linear range was 0.69–110 μM. The results showed that the paper-based electrode can be used to detect furazolidone. This sensor is a potential candidate for the detection of furazolidone residue in human serum and fish samples.

Highly sensitive detection of arsenic in groundwater by paper-based electrochemical sensor modified with earth-abundant material

The toxicity of arsenic and its hazards to the human body are well known and its timely, accurate, and cost-effective detection in water and foodstuffs and other environmental matrices is highly essential. Herein, we present a simple and easy method for the synthesis of reduced graphene oxide-ceria (rGO-CeO2) nanocomposite and its use for low-level detection of As(III) in water up to 0.93 μg/L. The presence of CeO2 on rGO surface is attributed to the enhanced electron transfer rate. The material characterization was performed with different analytical techniques including scanning electron microscopy (SEM), Raman spectroscopy, and X-ray diffraction (XRD), Infrared spectroscopy (FTIR) and Electrochemical Impedance Spectroscopy (EIS). The electrochemical behaviour of the rGO-CeO2 modified screen-printed electrodes (SPE) has been investigated by using Cyclic Voltammetry (CV) and Differential Pulse Stripping Voltammetry (DPSV). A highly linear response with a correlation coefficient of 0.9986 is achieved with a detection limit of 0.39 μg/L. Finally, the sensor was also tested with real-world groundwater samples collected from the arsenic-contaminated areas and acceptable recoveries were observed in the range of 85–95% as compared to Inductively Coupled Plasma Mass Spectrometer (ICP-MS) analysis. The electroanalytical performances of rGO-CeO2 modified SPE confirm that the as prepared sensor can be used for practical applications owing to its high sensitivity, good selectivity, robustness, low cost, high reproducibility, reusability, and ease of high scale production.

Label free electrochemical DNA biosensor for COVID-19 diagnosis

The COVID-19 pandemic has significantly increased the development of the development of point-of-care (POC) diagnostic tools because they can serve as useful tools for detecting and controlling spread of the disease. Most current methods require sophisticated laboratory instruments and specialists to provide reliable, cost-effective, specific, and sensitive POC testing for COVID-19 diagnosis. Here, a smartphone-assisted Sensit Smart potentiostat (PalmSens) was integrated with a paper-based electrochemical sensor to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). A disposable paper-based device was fabricated, and the working electrode directly modified with a pyrrolidinyl peptide nucleic acid (acpcPNA) as the biological recognition element to capture the target complementary DNA (cDNA). In the presence of the target cDNA, hybridization with acpcPNA probe blocks the redox conversion of a redox reporter, leading to a decrease in electrochemical response correlating to SARS-CoV-2 concentration. Under optimal conditions, a linear range from 0.1 to 200 nM and a detection limit of 1.0 pM were obtained. The PNA-based electrochemical paper-based analytical device (PNA-based ePAD) offers high specificity toward SARS-CoV-2 N gene because of the highly selective PNA-DNA binding. The developed sensor was used for amplification-free SARS-CoV-2 detection in 10 nasopharyngeal swab samples (7 SARS-CoV-2 positive and 3 SARS-CoV-2 negative), giving a 100% agreement result with RT-PCR.

Paper-based electrochemical sensor with a commercial glucose meter to determine L-cysteine by graphene electrode and Ag-doped silica nanoporous SBA-16

Paper-based electrochemical sensor with a commercial glucose meter to determine L-cysteine by graphene electrode and Ag-doped silica nanoporous SBA-16

Low-cost paper-based electrochemical sensor for the detection of ciprofloxacin in honey and milk samples

In this paper, the simple process of manufacturing a paper electrode used for the electroanalytical quantification by differential pulse voltammetry of the antibiotic ciprofloxacin (CIP) in food samples is presented. The sensor was manufactured by employing a low-cost (lab-made) conductive ink composed of nail polish and graphite powder, supported by filter paper. The electrochemical device was characterized by scanning electron microscopy and cyclic voltammetry, where it was found that after the polishing procedure the electrochemical performance was improved by 33%. Furthermore, the proposed optimized method showed a wide linear working range ranging from 9.90 to 220 µmol L−1, adequate sensitivity (LOD = 4.96 µmol L−1), and selectivity towards other classes of antibiotics. The method was applied to monitor CIP in spiked samples of honey, whole and skim milk, with excellent precision (RSD < 3.1%) and adequate accuracy with recovery values ranging from 80% to 95%. Furthermore, the simple manufacturing process (disposable character) coupled with minimal sample treatment (simple dilution in supporting electrolyte) makes the paper sensor a promising tool for food control analysis.

Paper-based electrochemical peptide sensor for label-free and rapid detection of airborne Bacillus anthracis simulant spores

Bacillus anthracis is a fatal biological warfare agent, with a mortality rate of almost 100% when the bacteria are inhaled. Therefore, developing a biosensor for rapidly detecting B. anthracis spores in the ambient air is critical. Conventional techniques tend to be time-consuming, labor-intensive, and require highly trained personnel, thereby preventing rapid onsite detection. Moreover, low-cost, stable probes are required for continuous monitoring of multiple airborne targets. This study presents a paper-based electrochemical peptide sensor for rapid, label-free, sensitive, and economical quantification of liquid-borne and airborne Bacillus subtilis spores, widely used nonpathogenic B. anthracis simulant spores. These sensors were fabricated using wax printing on Whatman filter paper along with stencil-printed carbon paste electrodes and Ag/AgCl ink, as well as subsequent peptide (NHFLPKV) immobilization. These low-cost quickly fabricated sensors were characterized by differential pulse voltammetry and could detect spore concentrations as low as 6.9 × 102 colony-forming units (CFU) mL-1 in 30 min with high specificity towards the spores and stability. Furthermore, spore concentrations were determined from air samples obtained using the BioSampler, which demonstrated that these measurements agreed with those using the plate-counting assay; therefore, the surface proteins of the spores were intact through sampling with the BioSampler. These paper-based peptide sensors can be used for onsite rapid and continuous airborne spore-monitoring systems.

Optimized ink jetted paper device for electroanalytical detection of picric acid

Picric acid (PA) is one of the essential components utilized in manufacturing of explosives. Therefore, the detection of trace amount of PA is critical in forensic science, criminal investigation, military security and environmental safety. Owing to these attributes, development of a simple, rapid and point-of-care (POC) analytical method for PA detection and quantification is crucial. Herein, a low-cost, POC, ink jetted paper device has been developed for electroanalytical detection of PA. Inkjet printing is an economic fabrication process used for extruding several nanomaterials with diversified applications. By improving the ink viscosity, inkjet printers can simplify the fabrication of paper-based electrochemical sensor, and provide easy, fast, environmental friendly and viable for large scale production sensors, thereby adding its commercialization potential. In this work, a commercially available circuit board printer and an inexpensive high viscosity carbon conductive ink were used to print an electrochemical paper device. The fabricated device was used for electrochemical detection of PA using cyclic voltammetry (CV) and wave voltammetry (SWV). Various parameters like effect of potential scan rate from 10 mVs−1 to 300 mVs−1, effect of variable PA concentration effect was studied. A linear concentration range of 4 μM to 60 μM was obtained. For a working electrode of 7 mm2 surface area, the limit of detection (LOD) was 4.04 μM (922.56 ppb) which was less than the prescribed safe limit of 8 μM. Effect of interference with other chemicals was examined using SWV with the co-existing metals like zinc, lead, copper and mercury. Finally, real sample analysis for tap and lake water was successfully performed with the device. The developed cost-effective paper-based ink-jetted platform, with further fine-tuning and surface modifications, can be used for sensing various analytes as a point-of-care device.

A paper-based electrochemical sensor for H2O2 detection in aerosol phase: Measure of H2O2 nebulized by a reconverted ultrasonic aroma diffuser as a case of study

The outbreak of COVID-19 is caused by high contagiousness and rapid spread of SARS-CoV-2 virus between people when an infected person is in close contact with another one. In this overall scenario, the disinfection processes have been largely improved. For instance, some countries have approved no-touch technologies by vaporizing disinfectants such as hydrogen peroxide, with the overriding goal to boost the safety of the places. In the era of sustainability, we designed an electrochemical paper-based device for the assessment of hydrogen peroxide nebulized by a cost-effective ultrasonic aroma diffuser. The paper-based sensor was fabricated by modifying via drop-casting a filter paper-based screen-printed electrode with a dispersion of carbon black-Prussian Blue nanocomposite, to assess the detection of hydrogen peroxide at −0.05 V vs Ag/AgCl. The use of paper-based modified screen-printed electrode loaded with phosphate buffer allowed for monitoring the concentration of hydrogen peroxide in aerosol, without any additional sampling instrument to capture the nebulized solution of hydrogen peroxide at a concentration up to 7% w/w. Hydrogen peroxide, a reconverted ultrasonic aroma diffuser, and the paper-based electrochemical sensor assisted by smartphone have demonstrated how different low-cost technologies are able to supply an useful and cost-effective solution for disinfection procedures.

Paper-based electrochemical peptide sensor for on-site detection of botulinum neurotoxin serotype A and C

Botulinum neurotoxins (BoNTs) produced by soil bacterium Clostridium botulinum are cause of botulism and listed as biohazard agents, thus rapid screening assays are needed for taking the correct countermeasures in a timely fashion. The gold standard method relies on the mouse lethality assay with a lengthy analysis time, i.e., 2–5 days, hindering the prompt management of food safety and medical diagnosis. Herein, we propose the first paper-based antibody-free sensor for reliable and rapid detection of BoNT/A and BoNT/C, exploiting their cleavage capability toward a synthetic peptide able to mimic the natural substrate SNAP-25. The peptide is labelled with the electroactive molecule methylene blue and immobilized on the paper-based electrode modified with gold nanoparticles. Because BoNT/A and BoNT/C can cleave the peptide with the removal of methylene blue from electrode surface, the presence of these neurotoxins in the sample leads to a signal decrease proportional to BoNT amount. The biosensor developed with the selected peptide and combined with smartphone assisted potentiostat is able to detect both BoNT/A and BoNT/C with a linearity up to 1 nM and a detection limit equal to 10 pM. The applicability of this biosensor was evaluated with spiked samples of orange juice, obtaining recovery values equal to 104 ± 6% and 98 ± 9% for 1 nM and 0.5 nM of BoNT/A, respectively.