Electrodeposition Of Gold Nanoparticles Research Articles

Development of a Multiplexed Electrochemical Aptasensor for the Detection of Cyanotoxins

In this study, we report a multiplexed platform for the simultaneous determination of five marine toxins. The proposed biosensor is based on a disposable electrical printed (DEP) microarray composed of eight individually addressable carbon electrodes. The electrodeposition of gold nanoparticles on the carbon surface offers high conductivity and enlarges the electroactive area. The immobilization of thiolated aptamers on the AuNP-decorated carbon electrodes provides a stable, well-orientated and organized binary self-assembled monolayer for sensitive and accurate detection. A simple electrochemical multiplexed aptasensor based on AuNPs was designed to synchronously detect multiple cyanotoxins, namely, microcystin-LR (MC-LR), Cylindrospermopsin (CYL), anatoxin-α, saxitoxin and okadaic acid (OA). The choice of the five toxins was based on their widespread presence and toxicity to aquatic ecosystems and humans. Taking advantage of the conformational change of the aptamers upon target binding, cyanotoxin detection was achieved by monitoring the resulting electron transfer increase by square-wave voltammetry. Under the optimal conditions, the linear range of the proposed aptasensor was estimated to be from 0.018 nM to 200 nM for all the toxins, except for MC-LR where detection was possible within the range of 0.073 to 150 nM. Excellent sensitivity was achieved with the limits of detection of 0.0033, 0.0045, 0.0034, 0.0053 and 0.0048 nM for MC-LR, CYL, anatoxin-α, saxitoxin and OA, respectively. Selectivity studies were performed to show the absence of cross-reactivity between the five analytes. Finally, the application of the multiplexed aptasensor to tap water samples revealed very good agreement with the calibration curves obtained in buffer. This simple and accurate multiplexed platform could open the window for the simultaneous detection of multiple pollutants in different matrices.

Potential powered EC-SERS for sensitive detection of acetamiprid

Surface-enhanced Raman spectroscopy (SERS) is a powerful tool for rapid and sensitive detection of pesticide residues in food, and the applied potential regulated SERS technique can be endowed with a higher sensitivity. In this work, we developed an electrochemical-surface enhanced Raman spectroscopy (EC-SERS) sensor for the rapid detection of acetamiprid (AAP) in vegetables. AuNPs/ITO were prepared via in-situ electrodeposition of gold nanoparticles (AuNPs) on an indium tin oxide (ITO) both as a SERS substrate and working electrode. By adding AAP into an in-situ Raman electrolytic cell with an applied electrochemical potential (+0.3 V), the SERS intensity was enhanced by 4-fold and the characteristic signal was linearly related to the concentration of AAP. Under the optimal conditions, the EC-SERS method exhibited a linear detection range from 0.05 to 50 μM, with a limit of detection (LOD, 3S/M) of 0.02 μM. Simultaneously, based on density functional theory (DFT), the adsorption characteristics of AAP on AuNPs/ITO were studied in the presence of electric field. The method was finally confirmed by HPLC-MS for the detection of real samples, revealing its potential application in food safety.

Ratiometric Electrochemical Sensor Using Chitosan@Rhodamine B/Gold Nanoparticles (AuNPs) for the Sensitive Determination of Rutin by Differential Pulse Voltammetry (DPV)

Internal reference probes can effectively eliminate internal and external interferences. Hence, finding a suitable internal reference probe is the key to ratiometric electrochemistry. In this study, a simple and sensitive ratiometric electrochemical sensor for the determination of rutin was prepared for the first time using rhodamine B (Rh B) as an internal reference probe. The modified electrochemical sensor was constructed by electrodepositing gold nanoparticles (AuNPs) on a glassy carbon electrode followed by drop-coating chitosan-immobilized rhodamine B (CS@Rh B). Rh B has a dual function in that it has a stable electrochemical signal (1.18 V) (vs. Ag/AgCl) that is completely separated from the oxidation peak of rutin (0.52 V) to serve as an internal reference probe. At the same time, it synergistically enhances the electrochemical signal of rutin with AuNPs. When differential pulse voltammetry was used for the determination of rutin, the current ratio of I Rutin/I Rh B was employed as the signal for rutin determination with a wide linear range (0.1 to 70 μM) and a low detection line (0.028 μM). The recoveries for the determination of rutin in Coreopsis tinctoria and Buckwheat tea were 95.4%–106% and 95.3%–104%, respectively. This work successfully demonstrated the feasibility of Rh B as an internal reference probe.

3D printed skyscraper electrochemical biosensor for the detection of tumour necrosis factor alpha (TNFα) in faeces

Tumour necrosis factor alpha (TNFα) is an important inflammatory mediator in the body andand thus, is considered an important biomarker in a host of inflammatory disorders such as ulcerative colitis. Many biosensing strategies are expensive and use complex fabrication approaches. Therefore, this study aimed to develop a simple yet robust TNFα sensor, which could conduct measurement within biological environments. 3D printing was utilised to fabricate an electrode with skyscraper structures to provide increased surface area for the sensor. The sensor was made by covalent immobilization of anti-TNFα onto carboxylic acid bearing conducting polymer thiophene-2-carboxylic (Th2CA) after electrodeposition of gold nanoparticles (AuNPs) onto the SS electrode. The development of the biosensor was characterised using field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). The linear range for TNFα was from 160 to 1820 pg/ml with a limit of detection of 44.5 pg/ml on the skyscraper (SS) immunosensor. The sensor was selective for the detection of TNFα when compared to other commonly found extracellular biological molecules. The sensor was able to monitor levels of TNFα from faecal pellets, where an increase in TNFα was observed with increasing age. These findings highlight that 3D printing could be used to make a simple yet robust immunosensor for the detection of a host of key biomolecules providing the potential for vital diagnostic tools.

Electrochemical determination of butylhydroxyanisole (BHA) using a carbon fiber microelectrode modified by electrodeposition of gold nanoparticles and poly-NiTSPc film

Electrochemical determination of butylhydroxyanisole (BHA) using a carbon fiber microelectrode modified by electrodeposition of gold nanoparticles and poly-NiTSPc film

Fabrication of an affordable and sensitive corticosteroid-binding globulin immunosensor based on electrodeposited gold nanoparticles modified glassy carbon electrode

Herein, we fabricated an ultrasensitive electrochemical immunosensor for the quantitative detection of corticosteroid-binding globulin (CBG). CBG is a protein that regulates glucocorticoid levels and is an important biomarker for inflammation. A decrease in CBG levels is a key biomarker for inflammatory diseases, such as septic shock. To enhance the electrochemical performance and provide a large surface area for anti-CBG immobilization, we functionalized the glassy carbon electrode surface with AuNPs. Electrochemical characterization methods including cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to examine the construction of the fabricated immunosensor. The electrochemical signal demonstrated a remarkable sensitivity to the CBG antigen, with a detection range from 0.01 to 100 μg/mL and a limit of detection of 0.012 μg/mL, making it suitable for both clinical and research applications. This label-free immunosensor offers significant advantages, including high sensitivity, low detection limits and excellent selectivity, making it a promising tool for detecting CBG in complex biological samples. Its potential applications include early disease diagnosis, treatment monitoring and studying CBG-related physiological processes.

Gold Nanoparticle-Modified Carbon-Fiber Microelectrodes for the Electrochemical Detection of Cd2+ via Fast-Scan Cyclic Voltammetry.

Neurotoxic heavy metals, such as Cd2+, pose a significant global health concern due to their increased environmental contamination and subsequent detrimental health hazards they pose to human beings. These metal ions can breach the blood-brain barrierblood-brain barrier, leading to severe and often irreversible damage to the central nervous system and other vital organs. Therefore, developing a highly sensitive, robust, and rapid in vivo detection method for these hazardous heavy metal ions is of the utmost importance for early detection, thus initiating timely therapeutics. Detecting ultra-low levels of toxic metal ions in vivo and obtaining accurate speciation information remains a challenge with conventional analytical techniques. In this study, we fabricated a novel carbon carbon-fiber microelectrode (CFM)-based sensor that can detect Cd2+ ions using fast-scan cyclic voltammetry by electrodepositing gold nanoparticles (AuNP). We optimized electrochemical parameters that generate a unique cyclic voltammogram (CV) of Cd2+ at a temporal resolution of 100 ms with our novel sensor. All our experiments were performed in tris buffer that mimics the artificial cerebellum fluid. We established a calibration curve resulting in a limit of detection (LOD) of 0.01 µM with a corresponding sensitivity of 418.02 nA/ µM. The sensor's selectivity was evaluated in the presence of other metal ions, and it was noteworthy to observe that the sensor retained its ability to produce the distinctive Cd2+ CV, even when the concentration of other metal ions was 200 times higher than that of Cd2+. We also found that our sensor could detect free Cd2+ ions in the presence of complexing agents. Furthermore, we analyzed the solution chemistry of each of those Cd2+-ligand solutions using a geochemical model, PHREEQC. The concentrations of free Cd2+ ions determined through our electrochemical data align well with geochemical modeling data, thus validating the response of our novel sensor. Furthermore, we reassessed our sensor's LOD in tris buffer based on the concentration of free Cd2+ ions determined through PHREEQC analysis, revealing an LOD of 0.00132 µM. We also demonstrated the capability of our sensor to detect Cd2+ ions in artificial urine samples, showcasing its potential for application in actual biological samples. To the best of our knowledge, this is the first AuNP-modified, CFM-based Cd2+ sensor capable of detecting ultra-low concentrations of free Cd2+ ions in different complex matrices, including artificial urine at a temporal resolution of 100 ms, making it an excellent analytical tool for future real-time, in vivo detection, particularly in the brain.

Disposable Point-of-Care Electrochemical Sensor for Uric Acid Determination in Human Urine Utilizing a Pencil Graphite Electrode Modified with Polydopamine/Gold Nanoparticles

Point-of-care testing (POCT) is an essential approach in clinical analysis due to its rapidity. In the current research and for the first time, we have developed an electrochemical POC sensor for uric acid (UA) determination using pencil graphite electrode (PGE) substrate modified via a facile self-polymerization of dopamine (DA). Alkaline conditions were used to produce polydopamine (PDA) which inspired from mussel adhesive protein. The PDA-modified electrode was further decorated by electrodeposition of gold nanoparticles (Au-NPs). Sensor surface characterization was conducted using surface characterization techniques like X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) imaging. In addition electrochemical characterization methods were performed utilizing electrochemical impedance spectroscopy (EIS) as well as cyclic voltammetry (CV). The sensor yielded a precise voltammetric response upon using differential pulse voltammetry (DPV) (linearity range: 5.0 × 10−5 mol l−1 − 5.0 × 10−4 mol l−1 of UA with 1.57 × 10–5 mol l−1 limit of detection). The developed sensor’s benefits include decreased manufacturing cost and selectivity. Accurate and satisfactory results were obtained upon application to human urine sample analysis.

A label-free aptasensor based on electrodeposition of gold nanoparticles on silver-based metal-organic frameworks for measuring ochratoxin A in black and red pepper.

Since ochratoxin A (OTA) is immunotoxic, teratogenic and carcinogenic, it is very important to monitor this compound in food samples. In the present work, the development and fabrication of a label-free electrochemical aptasensor based on the gold nanoparticles/silver-based metal-organic framework (AuNPs/Ag-MOF) for the determination of ochratoxin A (OTA) is introduced. The aptasensor was fabricated by electrodeposition of AuNPs on a glassy carbon electrode modified with Ag-MOF. The characteristics of the synthesized Ag-MOF were determined by field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and UV-Visible spectroscopy. The aptamer was immobilized on the modified electrode and then OTA was incubated on it. The process of different stages of the aptasensor construction has been confirmed by two methods of electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) and using [Fe(CN)6]3-/4- as a redox probe. The EIS method has also been used for the OTA quantitative determination. The difference in charge transfer resistance (Rct) before and after the interaction of OTA with the immobilized aptamer was considered as the analytical response of the aptasensor. Using the developed aptasensor, it is possible to measure OTA in the concentration range of 1.0 × 10-3 to 200.0 ng mL-1 with a detection limit of 2.2 × 10-4 ng mL-1. Finally, the ability of the aptasensor to measure OTA in red and black pepper was investigated and completely satisfactory results were obtained.

Triplex DNA Helix Sensor Based on Reduced Graphene Oxide and Electrodeposited Gold Nanoparticles for Sensitive Lead(II) Detection.

A triplex DNA electrochemical sensor based on reduced graphene oxide (rGO) and electrodeposited gold nanoparticles (EAu) was simply fabricated for Pb2+ detection. The glass carbon electrode (GCE) sequentially electrodeposited with rGO and EAu was further modified with a triplex DNA helix that consisted of a guanine (G)-rich circle and a stem of triplex helix based on T-A•T base triplets. With the existence of Pb2+, the DNA configuration which was formed via the Watson-Crick and Hoogsteen base pairings was split and transformed into a G-quadruplex. An adequate electrochemical response signal was provided by the signal indicator methylene blue (MB). The proposed sensor demonstrated a linear relationship between the differential pulse voltammetry (DPV) peak currents and the logarithm of Pb2+ concentrations from 0.01 to 100.00 μM with a detection limit of 0.36 nM. The proposed sensor was also tested with tap water, river and medical wastewater samples with qualified recovery and accuracy and represented a promising method for Pb2+ detection.

Ultrasensitive MicroRNA Photoelectric Assay Based on a Mimosa-like CdS-NiS/Au Schottky Junction.

Seeking and constructing superior photoactive materials have the potential to improve the performance of photoelectrochemical (PEC) biosensors. In this work, we proposed a novel mimosa-like ternary inorganic composite with a significantly enhanced light-harvesting ability and photogenerated carrier separation rate. This ternary photoactive material was obtained via electrodeposition of gold nanoparticles (Au) on the surface of transition metal sulfide composite of CdS and NiS (CdS-NiS/Au). The experimental results showed that the high initial photocurrent was acquired on CdS-NiS/Au (68-fold higher than that of individual CdS) with the synergistic effect of p-n heterojunction, Schottky junction, and the eminent optical properties of gold nanoparticles. Meanwhile, using silver nanoclusters prepared by link DNA protection as an effective quencher, integrating the duplex-specific nuclease-assisted rolling circle amplification strategy, a "Signal ON" PEC biosensor was fabricated for the detection of microRNA 21 (miRNA 21). With the release of the quencher, the recovered photocurrent is able to achieve determination of miRNA 21 within the range from 10 aM to 1 pM with a detection limit down to 4.6 aM (3σ). Importantly, this work not only provides a superb idea for designing ternary inorganic heteromaterials with exceptional photoactive ability but also allows the detection of other biomarkers by selecting appropriate recognition units.

Diamonds in the Rough: Direct Surface Enhanced Infrared Spectroscopic Evidence of Nitrogen Reduction on Boron-Doped Diamond Supported Metal Catalysts.

In situ investigations of electrocatalytic processes of increasing societal interest such as the nitrogen reduction reaction (NRR) require aggressive experimental conditions that are not readily compatible with surface sensitive techniques such as attenuated total reflection surface enhanced infrared absorption spectroscopy (ATR-SEIRAS). A method for performing ATR-SEIRAS studies at very negative potentials where conventional IR-active films delaminate and fail is reported. The method relies on a thin film of very robust boron-doped diamond deposited on a micromachined Si wafer, which provides extended mid-IR transparency at long wavelengths. SEIRAS activity is achieved by electrodepositing gold nanoparticles onto the conductive BDD layer. The Au@BDD layers are shown to sustain prolonged periods of electrolysis at negative potentials, with no degradation of the modifying layer. The efficacy of these substrates for electrocatalysis is demonstrated by studying the reduction of N2 at -1.5 V vs Ag/AgCl in an aqueous-based electrolyte. Under these conditions, direct spectroscopic evidence of both NH3 and hydrazine formed from the nitrogen reduction reaction (NRR) is provided.

Photoelectrochemical aptasensor based on PTCDA/TiO2 efficient sensitization effect for sensitive protein analysis

Herein, a photoelectrochemical (PEC) aptasensor for sensitive detection of C-reactive protein (CRP) was designed based on the efficient sensitization effect of 3,4,9,10-Perylene tetracarboxylic dianhydride (PTCDA) towards titanium dioxide (TiO2). Initially, TiO2 and PTCDA were continuously incubated on electrode surface to produce a strong PEC signal owing to the PTCDA/TiO2 sensitization structure. Subsequently, electrodeposition of gold nanoparticles (dep Au) was performed to connect with the incubated CRP aptamer (S1) via AuN bonds. After that, 1-hexanethiol (HT) was added on the surface of the modified electrode to block the non-specific adsorption sites. Eventually, with the addition of CRP, the PEC signal decreased significantly because the CRP-S1 complexes generated by the specific recognition of CRP and S1 resulted in high steric hindrance effect and inhibited electron transfer. Under optimal conditions, the proposed PEC aptasensor was applied successfully for sensitive CRP detection with a wide linear range from 10 pg/mL to 10 μg/mL and a low detection limit of 3.33 pg/mL. Moreover, the designed PEC aptasensor based on PTCDA/TiO2 sensitized structure might be a versatile tool that provides a powerful alternative to traditional proteins, ions and RNAs detection methods by changing the corresponding recognition sequences.

Au Nanoparticle/CoFc/Metal–Organic Framework as Enzyme-Free Dual-Signal Ratiometric Electrochemical Sensor for In-Situ Determination of Cell-Secreted H2O2

In-situ determination of cell-secreted biomolecules is important for elucidating its regulation of signal transduction pathways, but detecting these low-level endogenous biomolecules is difficult. Herein, using H2O2 as the detection object, we developed an ultrasensitive enzyme-free ratiometric electrochemical sensing platform in a simple and low-cost method for in-situ determination of cell-secreted H2O2, in which ferrocene (Fc) acts as an internal reference probe and nanoflower Au-Co-MOF acts a detection probe. First, flower-like CoFc-MOF was synthesized in situ on flexible carbon cloth (CC) by a one-step hydrothermal method, and then Au-CoFc-MOF/CC was obtained by electrodeposition of gold nanoparticles. The electrochemical measurement results show that the presence of H2O2 increases the reduction peak signal of Co-MOF (−0.32 V), while that of Fc (+0.4 V) is almost unchanged. By taking full advantage of the obviously separated reduction potential of Fc and Co-MOF, the well-designed sensing platform can reflect the concentration of H2O2 based on the IH2O2 – Iblank/IFc value in the 0.5 μM–10 mM range, with a detection limit as low as 32 nM, which is ∼15.6 times lower than the value obtained from the single signal method. In addition, the sensing platform also demonstrates excellent selectivity, reproducibility, stability, and biocompatibility. More significantly, this ratiometric electrochemical sensing platform based on flexible substrate shows great application potential in the in-situ determination of cell-secreted H2O2, which provides a feasible strategy for detecting other active substances released from living cells in clinical diagnosis.

Customizable Fabrication Process for Flexible Carbon-Based Electrochemical Biosensors

In recent research, 3D printing has become a powerful technique and has been applied in the last few years to carbon-based materials. A new generation of 3D-printed electrodes, more affordable and easier to obtain due to rapid prototyping techniques, has emerged. We propose a customizable fabrication process for flexible (and rigid) carbon-based biosensors, from biosensor design to printable conductive inks. The electrochemical biosensors were obtained on a 50 µm Kapton® (polyimide) substrate and transferred to a 500 µm PDMS substrate, using a 3D-extrusion-based printing method. The main features of our fabrication process consist of short-time customization implementation, fast small-to-medium batch production, ease of electrochemical spectroscopy measurements, and very good resolution for an extrusion-based printing method (100 µm). The sensors were designed for future integration into a smart wound dressing for wound monitoring and other biomedical applications. We increased their sensibility with electro-deposited gold nanoparticles. To assess the biosensors’ functionality, we performed surface functionalization with specific anti-N-protein antibodies for SARS-CoV 2 virus, with promising preliminary results.

Label-free electrochemiluminescence immunosensor based on conductive PANI to synergistically amplify electrodeposited AuNPs luminophore signal for ultrasensitive detection of 3-nitrotyrosine

As an appropriate biomarker for oxidative stress, 3-nitrotyrosine (3-NT) in biological samples is associated with many neurodegenerative disorders and inflammatory diseases. Herein, a novel and rapid electrochemiluminescence (ECL) immunosensor was successfully fabricated for ultrasensitive detection of 3-NT. Electrodeposited gold nanoparticles (AuNPs) being used as the luminophore and polyaniline being electropolymerized to promote the luminescence of AuNPs, a stable and efficient ECL system was obtained with an ECL intensity 28 times higher than that of bare electrodes. Taking advantage of the good biocompatibility and large specific surface area of AuNPs, the antibody was effectively immobilized on the electrode, achieving high selectivity for 3-NT detection. Under the optimal conditions, the immunosensor exhibited good analytical performance for 3-NT with a wide linear detection in the range of 1 × 10−11–1 × 10−8 mol/L and a low detection limit of 2.57 × 10−12 mol/L. Furthermore, the established sensor had a high recovery rate (85.29%–103.94%) in practical sample applications. The sensor had simple preparation method, high sensitivity and good stability, providing a promising sensing platform for the detection of 3-NT.

An acetylcholinesterase-based biosensor for isoprocarb using a gold nanoparticles-polyaniline modified graphite pencil electrode.

An analysis tool for isoprocarb has been successfully developed as a biosensor system based on enzymatic inhibition of acetylcholinesterase (AChE) by isoprocarb. A gold nanoparticles-polyaniline modified graphite pencil electrode (AuNPs-PANI-GPE) was utilized to detect the change of thiocholine in the presence of isoprocarb. This electrode was prepared by two cyclic voltammetry steps, including the electro-polymerization of aniline on a graphite pencil and the electro-deposition of gold nanoparticles on the polyaniline surface. Characterization performed by SEM-EDX indicates that 8-80nm size of gold nanoparticles could be deposited on the surface of polyaniline-modified graphite pencil (PANI-GPE). Electrochemical characterization using cyclic voltammetry suggested that the active surface area of the prepared electrode was 0.17019 cm2, which was about 4 times higher than (PANI-GPE) and 13 times higher than the unmodified GPE. Furthermore, an oxidation peak of thiocholine could be observed at the modified GPE at a potential of + 0.675V (vs. Ag/AgCl), formed by an enzymatic reaction of AChE in the presence of acetylthiocholine. This peak current was found to linearly increase with acetylthiocholine concentrations, while in the presence of isoprocarb in a constant concentration of AChE and acetylthiocholine the peak linearly decreases. At the optimum condition of 0.1M phosphate buffer solution pH 7.4 containing 0.1M KCl; 100mU/ml AChE; and 1mM acetylthiocholine chloride in an inhibition and contact time of 25 and 15min, respectively, a linear calibration curve of isoprocarb in the concentration range of 0.05-1.0μM could be provided. Estimated limits of detection and quantifications of 0.1615nM and 0.5382nM, respectively, with a sensitivity of 1.7771 μA/μM.mm2 could be achieved. Furthermore, an excellent stability for 8 times measurements was observed with an RSD of 4.87%, suggesting that the developed tool is promising for the real detection of isoprocarb.

Benchmarking electrodes modified with bi-doped polypyrrole for sensing applications

Polypyrrole-modified electrodes bi-doped with salicylate and perchlorate anions were synthetized, characterized, and benchmarked according to their ability to meet a set of performance criteria, with the aim of obtaining the best potential candidate for the development of electrochemical sensors. Bi-doped PPy films (PPy-DA) were assessed as compared to those resulting from electropolymerization in solutions providing a single doping anion, namely salicylate (PPy-Sa) or perchlorate (PPy-ClO4−) solutions. Morphological and spectroscopic characteristics of the different polymer films were determined by means of SEM and XPS and Raman spectroscopies. The electrochemical response and electrocatalytic activity of PPy-DA electrodes were characterized by chronoamperometric, voltammetric and electrochemical impedance spectroscopy (EIS) measurements. EIS appeared as a singular tool for determining the conditions where electrochemical response is either dictated by the redox process of the polymer film or governed by a redox couple in solution, and for comparing the electrocatalytic activity of the films without the requirement of knowing the real active electrode area. Comparison was also made among PPy-DA films synthesized by varying dopant concentration in the polymerization bath and electropolymerization time. The presence of salicylate ions favored the formation of films with a three-dimensional tubular structure whereas perchlorate ions contribute to increase their conductivity and electrocatalytic activity. The tubular three-dimensional structure of the electrode surface exhibits an open extended-area pattern that is highly suitable for the electrodeposition of gold nanoparticles (AuNPs), offering new possibilities for developing electrodes for voltammetric sensing. Accordingly, electrodes modified with PPy-DA films decorated with AuNPs were successfully tested for hydrazine determination.

Nanoimmunosensor for the electrochemical detection of oncostatin M receptor and monoclonal autoantibodies in systemic sclerosis

Systemic sclerosis (SSc) is a chronic, autoimmune disease that primarily affects connective tissue. SSc can be classified into limited cutaneous (lSSc) and diffuse cutaneous (dSSc). Oncostatin M receptor (sOSMR) is an important inflammatory biomarker expressed in the serum of patients with autoimmune diseases. A nanoengineered immunosensor surface was developed. The biosensor was composed of a conductive layer of polypyrrole, electrodeposited gold nanoparticles, and sOSMR protein for anti-human OSMR monoclonal antibody biorecognition. The electrochemical response evaluated by cyclic voltammetry and electrochemical impedance spectroscopy indicated the detection of the target analyte present in clinical samples from lSSc and dSSc patients. The voltammetric anodic shift for lSSc specimens was 82.7% ± 0.9–93.6% ± 3.2, and dSSc specimens was 118.7 ± 2.6 to 379.6 ± 2.6, revealing a differential diagnostic character for SSc subtypes. The sensor platform was adapted for identifying sOSMR, using anti-OSMR antibodies as bioreceptors. With a linear response range estimated from 0.005 to 500 pg mL−1 and a limit of detection of 0.42 pg mL−1, the sensing strategy demonstrated high sensitivity in identifying the human OSMR protein in clinical samples. The proposed biosensor is a promising and innovative tool for SSc-related biomarker research.

Sensitive dopamine sensor based on electrodeposited gold nanoparticles and electro-modulated MoS2 nanoflakes

Sensitive dopamine sensor based on electrodeposited gold nanoparticles and electro-modulated MoS2 nanoflakes