Screen-printed Gold Electrode Research Articles

Development of a Biosensor to Detect Venom of Malayan Krait (Bungarus candidus).

Malayan krait (Bungarus candidus) envenoming is a cause of significant morbidity and mortality in many Southeast Asian countries. If intubation and specific antivenom administration are delayed, the most significant life-threatening outcome may be the inhibition of neuromuscular transmission and subsequent respiratory failure. It is recommended that krait-envenomed victims without indications of neurotoxicity, e.g., skeletal muscle weakness or ptosis, immediately receive 10 vials of antivenom. However, the administration of excess antivenom may lead to hypersensitivity or serum sickness. Therefore, monitoring venom concentrations in patients could be used as an indicator for snake antivenom treatment. In this study, we aimed to develop a screen-printed gold electrode (SPGE) biosensor to detect B. candidus venom in experimentally envenomed rats. The gold electrodes were coated with monovalent Malayan krait IgG antivenom and used as venom detection biosensors. Electrochemical impedance spectrometry (EIS) and square wave voltammetry (SWV) measurements were performed to detect the electrical characterization between B. candidus venom and monovalent IgG antivenom in the biosensor. The EIS measurements showed increases in charge transfer resistance (Rct) following IgG immobilization and incubation with B. candidus venom solution (0.1-0.4 mg/mL); thus, the antibody was immobilized on the electrode surface and venom was successfully detected. The lowest current signal was detected by SWV measurement in rat plasma collected 30 min following B. candidus experimental envenoming, indicating the highest level of venom concentration in blood circulation (4.3 ± 0.7 µg/mL). The present study demonstrates the ability of the SPGE biosensor to detect B. candidus venom in plasma from experimentally envenomed rats. The technology obtained in this work may be developed as a detection tool for use along with the standard treatment of Malayan krait envenoming.

Comparison of Faradaic and Non-Faradaic Impedance Biosensors Using 2-Electrode and 3-Electrode Configurations for the Determination of Bovine Serum Albumin (BSA)

This paper presents a study on the impedance spectroscopy methods applied to 2-electrode and 3-electrode biosensors. While 3-electrode electrochemical biosensors have been extensively studied and applied in various applications, the 2-electrode configuration of electrochemical biosensors still lacks comprehensive investigation for real-world applications. In particular, the miniaturization of the 3-electrode configuration for integration into microfluidic devices has been explored due to the relatively limited number of previous studies. A commercial screen-printed gold electrode was employed to develop immunosensors for bovine serum albumin (BSA) detection. The comparisons were performed on non-Faradaic and Faradic immunosensors corresponding to 2-electrode and 3-electrode configurations through impedance measurements. The results show the performance of both types of sensors in detecting BSA protein. While the 2-electrode configuration-based sensor can detect the BSA protein with a sensitivity of 12 Ω/µM, the 3-electrode configuration-based sensor shows superior results with a sensitivity of 7.2 kΩ/µM. Besides, the results also indicate that the 2-electrode configuration-based sensor can easily be miniaturized to integrate into a microfluidic channel to develop lab-on-a-chip systems. Although the 3-electrode configuration demonstrates advancements compared to the 2-electrode configuration, the 2-electrode system based on non-Faradaic processes still shows high potential for future applications.

Deaeration of incubation buffer to minimize electrochemical impedance spectroscopy signal drift on screen-printed gold electrodes and its use for label-free detection of vancomycin

Disposable screen-printed gold electrodes (SPAuEs) are used for the development of numerous immunosensors owing to their ease of modification with biorecognition molecules. A major limitation in the development of SPAuEs based biosensors is the single-use of the electrodes leading to higher costs for sensor development, whereas multiple measurements can affect the sensor stability and reproducibility. Especially, label-free electrochemical impedance spectroscopy (EIS) based SPAuEs sensors are prone to signal drift resulting in false-positive or false-negative data questioning the reliability of the assay. We found that repeated EIS measurements on SPAuEs in ferri- and ferrocyanide solution yielded a significant increase in resistance to charge transfer (Rct) value (positive signal drift) even in a control solution (without the target analyte). The positive signal drift follows the typical pattern of a concentration-dependent calibration curve, rendering repeated measurement error-prone for sensing purposes. In this study, it is shown that the incubation of the SPAuEs in nitrogen purged deaerated phosphate buffered saline (N-PBS) minimized this signal drift in repeated/multiple EIS measurements. This method was then used to develop a peptide-based EIS biosensor for the detection of Vancomycin, a last-line antibiotic used for the treatment of severe multidrug-resistant bacterial infection. This protocol can be followed for the biosensing of other clinically important biomarkers.

L-Cysteine functionalized magnetite nanoparticle adorned Ti3C2-MXene nanohybrid based screen printed immunosensor for oral cancer biomarker detection.

Nanohybrid based non-invasive biosensing platforms are emerging as promising alternatives to detect biomarkers in complex and diverse bio-fluids toward ultrasensitive point-of-care diagnostics. Herein, we report the development of a highly sensitive, facile, non-invasive, label free, affordable, and innovative electrochemical screen printed immunosensor for identifying CYFRA 21-1, an established and crucial biomarker for oral cancer. Until now, no work has been reported utilizing a titanium carbide Ti3C2 MXene nanosheet and L-cysteine (L-Cyst) functionalized magnetite nanoparticle (MNPs) nanohybrid based immunosensor for electrochemical detection of CYFRA 21-1. The L-Cyst@MNPs/Ti3C2-MXene nanohybrid was synthesized via the co-precipitation method and later deposited on a gold screen printed electrode (GSPE) offering enhanced surface area and electrochemical properties. The nanohybrid modified GSPE was then surface immobilized with monoclonal antibodies (anti-CYFRA-21-1) to fabricate an anti-CYFRA-21-1/L-Cyst@MNPs/Ti3C2-MXene/GSPE immunoelectrode and the non-specific locations of the immunoelectrode were covered with bovine serum albumin (BSA). The spectroscopic, morphological, and structural analyses of the synthesized nanohybrid and the fabricated electrodes were performed using different analytical techniques. The electrochemical studies of modified electrodes were evaluated using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV). The fabricated BSA/anti-CYFRA-21-1/L-Cyst@MNPs/Ti3C2-MXene/GSPE immunosensor has shown an excellent limit of detection of 0.023 ng mL-1, a linear detection range of (0.5-30) ng mL-1, a sensitivity of 277.28 μA (ng mL-1)-1 cm-2 and a lower limit of quantification of 0.618 ng mL-1 for electrochemical CYFRA 21-1 determination. Hence, this L-Cyst@MNPs/Ti3C2-MXene nanohybrid could also be explored as a potential candidate for determining other cancer biomarkers.

An impedimetric sensor based on molecularly imprinted nanoparticles for the determination of trypsin in artificial matrices - towards point-of-care diagnostics.

A high-performance impedimetric sensing platform was designed to detect proteins by employing molecularly imprinted polymeric nanoparticles (nanoMIPs) as selective receptors. This was achieved via the combination of the nanoMIPs with a self-assembled thioctic acid (SAM-TA) monolayer onto screen-printed gold electrodes, providing stable covalent attachment of the selective binder to the transducer. Taguchi design has been modelled to achieve the optimal level of sensor fabrication parameters and to maximise the immobilisation of nanoMIPs and their response (e.g. the response of imprinted polymers compared with the non-imprinted control). The developed sensor was tested towards a range of concentrations of trypsin dissolved in ammonium acetate (pH = 6) and showed promising applicability in artificial saliva, with a recovery percentage between 103 and 107%.

Portable smartphone-enabled dydrogesterone sensors based on biomimetic polymers for personalized gynecological care.

Dydrogesterone, a frequently prescribed synthetic hormone integral to the treatment of diverse gynecological conditions, necessitates precise quantification in complex human plasma. In this study, the development of a portable, smartphone-based electrochemical sensor employing screen-printed gold electrodes (SPAuEs) modified with a biomimetic, molecularly imprinted poly(methacrylic acid-co-methyl methacrylate) (MIP) is presented for dydrogesterone detection in human plasma. FTIR spectroscopy illustrates the transformation of a pre-polymer mixture into a polymerized matrix, while SEM reveals a uniform MIP/SPAuE surface morphology. The sensor fabrication protocol, encompassing MIP/SPAuE composition, polymerization solvent, incubation time, and scan rate, is optimized to achieve enhanced sensitivity. The MIP/SPAuEs sensor exhibits a linear sensor response to dydrogesterone within the concentration range of 1-500 nM, as evidenced by cyclic and differential pulse voltammetry. The MIP/SPAuE sensor demonstrates exceptional sensitivity, recording 8.2 × 10-3 μA nM-1, with a sub-nanomolar limit of detection (LOD = 370 pM), and low limit of quantification (LOQ = 1.12 nM), along with appreciable selectivity over common interferents. In real-world clinical applications, the designed sensor is effectively employed for the rapid and precise determination of dydrogesterone in human blood plasma, achieving a remarkable recovery of 81%. Furthermore, MIP/SPAuE coatings possess suitable stability over 15 days, indicating the robustness of the sensor material for multiple rounds of analysis. The developed sensor provides a sensitive, selective, and cost-effective solution for monitoring dydrogesterone in plasma during various gynecological disorders, allowing for personalized healthcare applications.

Precision phenylalanine sensing in blood with nanomaterial-enhanced electrodes

Modified screen-printed gold electrodes (Au-ERGO) increase sensitivity and reduce LOD and LOQ of the quantitation of Phenylalanine in human whole blood.

Electrochemical and imaging evaluations of electrochemically activated screen-printed gold electrodes.

Sulfuric acid is commonly used to electrochemically activate gold electrodes in a variety of electrochemical applications. This work provides the first evaluations of the electrochemical behaviors and a 3D image of an activated screen-printed gold electrode (SPGE, purchased commercially) through electrochemical and imaging analyses. The activated SPGE surface appears rougher than the unactivated SPGE surface when viewed through microtopography images using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Nevertheless, the roughened microscopy structure does not exhibit any substantial changes in roughness factor for the activated SPGE, as indicated by capacitive current analyses. The significant improvement in electrochemical responsiveness of the activated SPGE is mainly attributed to the presence of surface pores created in the microscopic structure as a result of gold oxide layer formation. The presence of surface pores on the activated surface has significantly improved its conductivity by 10-fold. As a result, electron transfer kinetics and mass transports of the activated SPGE are greatly improved. The results presented in this work indicate that the surface of the activated SPGE greatly increased its intrinsic surface pores, and conductivity of the electrode surface and uncovered the electrocatalytic active sites. This significantly improves the activated SPGE's performance in electrochemical applications such as oxygen reduction reaction (ORR). An activated SPGE considerably enhanced limiting current density as well as ∼172 mV versus Ag shifted onset potential to more positive potentials compared to unactivated SPGE.

Sensing of trans-cleavage activity of CRISPR/Cas12a for detection of Salmonella

Salmonella typhimurium (S. typhi) a predominant foodborne pathogen, significantly impacting global public health. Therefore, timely diagnosis is imperative to safeguard overall human health. To address this, we developed a novel CRISPR/Cas12a-mediated electrochemical detection system (biosensor) for targeting the SifA gene of S. typhi. To construct the biosensor, we utilized a screen-printed gold electrode (SPGE) as an electrochemical transducer and CRISPR/Cas12a for detection of SifA gene of S. typhi. The developed electrochemical biosensor exhibited an exceptional detection limit of 0.634 ± 0.029 pM, which was determined through differential pulse voltammetry (DPV) by utilizing a potentiostat. We compared the fabricated biosensor with gold standard RT-PCR and the visual detection limit of SifA was found to be 10 μM (in spiked buffer samples). The lower detection limit of fabricated biosensor provides an upper edge over the RT-PCR. Further, the fabricated biosensor also has the potential to serve as a rapid, stable, efficient, and early detection tool for S. typhi, offering promising advancements in diagnostic realms.

Electrochemical Sensors for Detection of Glucose based on Electrochemically Reduced Graphene Oxide: Optimization of pH and Number of Cycles

Glucose determination method had gain significant interest from the industry for a fast and efficient response especially in the medical area for diabetes patient. Reduced graphene oxide (RGO) had been reported to help and improve the sensitivity of a sensor. The investigation for the optimum pH concentrations using FESEM, EDX, XRD analysis and Raman spectroscopy indicate that the pH 9 was suited to be deposited on the SPGE. In addition to that, different number of cycles during electrodeposition process was employed. Electrochemical impedance spectroscopy (EIS) was used to investigate the charge transfer resistance for each cycle. All the deposited RGO on screen-printed gold electrode (SPGE) was being compared to the bare SPGE to confirmed that the electrodeposition of RGO could decrease the charge transfer resistance. For the detection of glucose, cyclic voltammetry (CV) and differential pulse voltammetry (DPV) was used. 10 cycles deposition of RGO shows the highest sensitivity of 1.0525 μA·mM−1·cm−2 in the detection of glucose compared to the other cycles. The ease of use and scalability of the electrodeposition technique may make it easier to build upon the results of this work and produce glucose sensors that are more widely available and less expensive.

Fast Screening of Fentanyl Illicit Drug By the Electrochemical Enhancement of Raman Intensity

Fentanyl is a potent opioid drug used as an analgesic and anesthetic because it is approximately 100 times more potent than morphine and 50 times more potent than heroin as an analgesic. However, the overdose of fentanyl requires small dose and can cause stupor, changes in pupil size, clammy skin, cyanosis, coma, and respiratory failure leading to death. During the last years the illicit fentanyl and its analogues have been responsible for most drug overdose deaths in different countries and for that reason, the development of identification and detection methods is mandatory.Spectroelectrochemical methods are currently proposed for the screening of this drug [1]. For instance, the combination of electrochemistry (EC) and surface-enhanced Raman scattering (SERS) has received growing attention due to the enhancement of Raman intensity associated with EC-SERS effect. However, the generation of reproducible SERS substrates is a traditional limitation of this effect. In that way, activation of metallic screen-printed electrodes (SPEs) by electrochemical routes allows to obtain reproducible nanostructures with excellent SERS properties [2], opening new gates for analytical applications.In this work, the development of a fentanyl detection method based on EC-SERS effect is achieved. Spectroelectrochemical screening of this drug with metallic SPEs consists of two consecutive steps performed in a single experiment: (1) electrochemical generation of metallic NPs with SERS effect and (2) Raman detection of fentanyl present in solution.Metallic SPEs provide interesting results being not only useful in the characterization of fentanyl, but also for analytical purposes. The proposed EC-SERS method with gold SPEs allows the detection of 0.33 ug/ml fentanyl and offers a rapid, efficient, and accurate approach for the detection of this drug.

A TiO2-adenine nanocomposite as modification material for screen-printed gold electrode to detect H1N1 (swine flu) virus: A disposable genosensor

A genosensor based on TiO2-adenine nanocomposites (NCs) modified screen-printed gold electrode surface (TA-SPGE) was immobilized with haemagglutinin (HA) gene specific probe containing 5′ amine group and investigated for swine flu virus (H1N1). Bare SPGE surface was modified by drop coating of the nanocomposites. The NCs and precursors were characterized structurally and morphologically by adopting various techniques such as Fourier Transform Infrared (FTIR) spectra, X-ray Diffraction (XRD) spectra, UV–Visible spectra, Raman spectra, Zeta sizer, Field-Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive spectra (EDS) and High-Resolution Transmission Electron Microscopy (HR-TEM) with Selected Area Electron Diffraction (SAED) pattern. Electrochemical techniques termed as cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectra (EIS) were employed for analytical detection of single-stranded viral genome in phosphate buffer saline (pH-7.2) by using methylene blue (MB) redox indicator. Moreover, the performance of designed electrode was optimized at different concentration, pH, and scan rates. The proposed genosensor revealed high sensitivity 10.6 μA/ng.cm2, lower detection limit (LOD) of 6.7 × 10-8 ng/mL and wide linear range of 3 × 10-8-3 × 10-3 ng/mL with regression coefficient of R2 = 0.989 towards swine flu virus DNA. Additionally, the modified genosensor revealed good stability and specificity against human DNA and various pathogens such as H3N2 influenza virus, Bacillus subtilis, Neisseria meningitidis, Staphylococcus aureus and Streptococcus pyogenes. The proposed genosensor is based on relatively simple methodology, quite amicable and could promptly be used as point-of-care test for swine flu virus detection.

Comparative electrochemical properties of polyaniline/carbon quantum dots nanocomposites modified screen-printed carbon and gold electrodes

In this study, carbon quantum dots (Cdots) synthesized from a pencil graphite precursor using a bottom-up method were incorporated into polyaniline (PANI) to form Cdots-PANI nanocomposite. Cdots, PANI and Cdots-PANI nanocomposites were characterized using the Fourier-Transform infrared spectroscopy (FT-IR), UV–visible spectroscopy (UV–vis), X-ray diffraction (XRD) spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The FT-IR spectra of graphene and Cdots show the emergence of a peak at 3500 cm−1, which was initially absent in graphene, after the formation of Cdots, among other peaks. The peak at 3500 cm−1 and the stretching vibration at 1647 cm−1 suggest the presence of –OH and C=C in the Cdots. The FT-IR spectra of PANI/Cdots and PANI show that the peaks in PANI shifted to higher wavenumbers after composite formation. Similarly, the UV–visible spectra of the PANI/Cdots composite revealed a hypsochromic shift of the characteristic PANI peaks at 320 and 600 nm to 300 and 560 nm, respectively. Electrochemical characterization of Cdots, PANI and Cdots-PANI nanocomposites was done with screen-printed carbon electrodes (SPCE) and screen-printed gold electrodes (SPAuE) modified with the nanomaterials and the nanocomposites. The electrochemical properties of the as-synthesized nanomaterials and the nanocomposite were investigated with Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) in 10 mM K3[Fe(CN)6] solution using the bare screen-printed electrodes and the modified electrodes. The modified electrodes gave higher anodic peak current (Ipa) responses and lower charge transfer resistance (Rct) values in the redox probe than the bare electrodes. The SPCE-Cdots-PANI nanocomposite-modified electrode exhibited better redox potentials, faster electron transfer kinetics, larger surface area, and greater stability than the bare electrodes and the other modified electrodes. The outstanding electrochemical properties of SPCE-Cdots/PANI underscores its potentials as a sensitive electrochemical sensor for a wide range of analytes.

The optimization of self-assembled monolayer of thiols on screen-printed gold electrode

<span>The activated gold-modified electrode surface for self-assembled monolayer (SAM) is suitable for N-(3-dimethylaminopropyl)-N-ethylcarbodiimide hydrochloride (EDC), 16-mercaptohexadecanoic acid (16-MDA), and N-hydroxysuccinimide (NHS). The various substrates could potentially be used for surface functionalization that binds to one another. Using modified screen-printed gold electrodes, 16-MDA, EDC, and NHS, we developed a self-assembling monolayer. Different 16-MDA concentrations were applied to the surface of a screen-printed electrode surface to enhance the sensitivity of the working electrode. The impact of different EDC, NHS, and 16-MDA concentrations (0.4 M, 0.8 M, 1 M, 1.2 M, 1.4 M, and 1.8 M) and incubation times between 5 and 30 minutes were examined and compared. The binding surface of the screen-printed gold electrode was characterized using the differential pulse voltammetry (DPV) technique. It has been demonstrated that the substrate concentrations at 5 minutes and 30 minutes of incubation time used to have the highest surface coverage and electron transfer rates. This concentration would be utilized in the subsequent experiment to evaluate the binding of various bacterial species. These findings suggest that the SAM in a modified screen-printed gold electrode may be functionalized to detect microorganisms.</span>

A new cysteamine-copper chemically modified screen-printed gold electrode for glyphosate determination

A chemically modified screen-printed gold electrode has been prepared by covering the electrode surface with a cysteamine-copper self-assembled monolayer (SAM). The sensor was effective for the voltammetric sensing of glyphosate. The method exploits the interaction of glyphosate with copper ions complexed by cysteamine, which results in a decrease in the intensity of copper redox current. Cyclic voltammetry was employed as a measuring technique. When dealing with voltammograms with numerous peaks changing in shape and size, it is difficult to define which signal is the most significant for the analyte determination; in these cases, a helpful approach is chemometrics. In this work, PLS (Partial Least Square regression) has been applied to build models to correlate the signal with the glyphosate concentration in standard aqueous solutions and tap water samples (matrix-matched calibration). The method's figures of merits were evaluated, obtaining a limit of quantification of about 5 μM. The reliability of the proposed sensor was verified by analyzing tap water spiked with glyphosate; recoveries higher than 90 % were achieved.

Electrocatalytic aptasensor for bacterial detection exploiting ferricyanide reduction by methylene blue on mixed PEG/aptamer monolayers

Pathogen-triggered infections are the most severe global threat to human health, and to provide their timely treatment and prevention, robust methods for rapid and reliable identification of pathogenic microorganisms are required. Here, we have developed a fast and inexpensive electrocatalytic aptamer assay enabling specific and ultrasensitive detection of E. coli. E. coli, a biomarker of environmental contamination and infections, was captured on the mixed aptamer/thiolated PEG self-assembled monolayers formed on electrochemically pre-treated gold screen-printed electrodes (SPE). Signals from aptamer - E. coli binding were amplified by electrocatalytic reduction of ferricyanide mediated by methylene blue (MB) adsorbed on bacterial and aptamer surfaces. PEG operated as an antifouling agent and inhibited direct (not MB-mediated) discharge of ferricyanide. The assay allowed from 10 to 1000 CFU mL−1E. coli detection in 30 min, with no interference from B. subtilis, in buffer and artificial urine samples. This electrocatalytic approach is fast, specific, sensitive, and can be used directly in in-field and point-of-care applications for analysis of bacteria in human environment.

A diagnostic electrochemical aptasensor development for sCD80 protein detection in human serum

Elevating soluble CD80 (sCD80) in human serum is a natural response to autoimmune diseases such as rheumatoid arthritis (RA). The level of sCD80 is associated with RA development and prognosis; therefore, it is potentially used as a biomarker. sCD80 is commonly measured in human serum using immunoassays (e.g., ELISA) with multiple drawbacks, mainly cross-reactivity. Aptamer-based biosensors (aptasensors) development for quantifying and detecting different biological molecules demonstrates applicability in next-generation medicine and biomarker detection. Herein, we selected a specific aptamer for sCD80 by conventional in-vitro selection process (SELEX) with the high-affinity aptamer (Kd = 47.69 nM). A sensitive aptasensor, for the first time, was developed on a screen-printed gold electrode (AuSPE) platform compatible with easy-to-use label-free electrochemical impedance spectroscopy. The immobilization of the aptamer on the gold surface and the presence of sCD80 in a complex with the aptamer were characterized by photo-induced force microscopy, which revealed the uniform assembly of the aptamer monolayer and the distribution of sCD80 on the electrode surface. The developed aptasensor showed a linear performance (0.025–10.0 nM of protein) with a detection limit of 8.0 pM. Furthermore, the aptasensor was tested in a biological matrix, where a linear signal was observed for the increased amount of spiked sCD80 (R2 = 0.9887). The recovery of the spiked amounts ranged from 105 to 125% with coefficient of variation (CV%) <7%, which supported the applicability of this sensor in detecting sCD80 for diagnosis.

TiO2-guanine as a new amalgamation compoundfor fabrication of a disposable biosensor with high sensitivity and rapid detection of H1N1 swine flu virus.

A TiO2-guanine nanocomposite (TG NC)-based electrochemical biosensor was immobilized with hemagglutinin (HA) gene specific probe with 5' NH2 group on screen-printed gold electrode (probe(ss)DNA-TG-SPGE). The modified biosensor was examined for H1N1 swine flu virus. TG NCs along with precursors were characterized spectroscopically and morphologically by employing several approaches. Electrochemical investigations were performed with the help of cyclic voltammetric (CV) and electrochemical impedance spectroscopy (EIS) in 0.1 M phosphate buffer saline (PBS; pH 7.4) with 1 µM methylene blue (MB) redox indicator. For better detection of single-stranded virus DNA, the modified electrode was optimized at various concentrations, pH, and scan rates. The modified biosensor showed high sensitivity (40.32 μA/ng.cm2), low LOD (0.00024 ng/6 µL), and broad linear range 0.0002-20 ng/6µL with coefficient of determination ofR2=0.9981 for H1N1 virus detection. The HA gene-modified biosensor presented decent stability and specificity against different infectious pathogens including H3N2 virus and human DNA with negative response. Furthermore, the modified biosensor also responded well for real sample target DNA detection with a recovery of >96%. The simply designed HA gene-modified biosensor transduces decreased current response towards target-specific (ss)DNA binding and could be used as a rapid detection tool for H1N1 swine flu virus diagnosis.

Improvement of Low-Cost Commercial Carbon Screen-Printed Electrodes Conductivities with Controlled Gold Reduction Towards Thiol Modification

Effectively detecting bacteria in the environment is crucial for researchers to make informed decisions about the safety of public areas, such as lakes. This led to an increased need in the development of portable handheld devices, capable of on-the-spot chemical and biological sensing applications. Specific interests lie in electrochemical biosensors and screen-printed electrodes (SPEs) due to the decreased costs, an ability to integrate with handheld devices, and their user-friendly nature. Together, these qualities make the devices more accessible in resource-poor settings. Two of the most common substrates used to fabricate SPEs are carbon and gold. Carbon SPEs are effective in sensing applications yet challenged when attempting to covalently attach biomolecules to the surface. Gold SPEs have higher affinity towards biomolecules and improve the sensitivity, selectivity, and stability of a device; yet they can be costly. A carbon SPE modified with gold may be an ideal candidate to create an efficient low-cost device, using electrochemical gold deposition. In this study, electrochemical gold deposition on SPEs is explored to enhance the surface area and conductivity towards sensing applications. These SPEs were then modified with a thiol-based self-assembled monolayer (SAM) which demonstrates this technique could be used for further modification towards biosensing.

Adsorption and Electropolymerization of p-Aminophenol Reduces Reproducibility of Electrochemical Immunoassays

Electrochemical immunoassays are a class of biosensors that achieve high specificity, low detection limits, and low cost attributed to strong antibody-antigen interactions and inexpensive electrochemical instrumentation. Electrochemical assays typically use an enzyme/substrate pair to enable electrochemical signal production. p-Aminophenyl phosphate is a commonly used enzymatic substrate which is hydrolyzed into p-aminophenol (PAP)by alkaline phosphatase. PAP exhibits low oxidation potential and electrochemical reversibility, making it an appealing candidate for assay design. The electrochemical oxidative signal from PAP is increased by its adsorption to the electrode. This is further confirmed by the prevention of PAP adsorption via self-assembled monolayers on gold electrodes reducing PAP’s oxidative current. On bare screen-printed electrodes (SPE), PAP adsorption results in oxidative current variability depending on the electroactive surface area of the working electrode. This variability could not be remedied by cleaning and reusing the same gold SPE. However, adsorption of PAP displays concentration dependence, as the decrease ofthe PAP concentration to 3.8 μM greatly improved the consistency of the measurements. PAP use is also limited in continuous monitoring applications as multiple PAP oxidations on the same electrode caused polymerization. The results from this study suggest that the use of PAP production in immunoassays with SPEs must be fine-tuned and electrodes must be cleaned or disposed of between measurements.