Detection Of Dopamine Research Articles

Photo-electrochemical sensor based on BiOI/ZnIn2S4 heterojunction for detecting hydrogen peroxide and dopamine.

Photoelectrochemical (PEC) detection as a potential development strategy for hydrogen peroxide and dopamine sensors has receivedextensive attentions. Herein, BiOI/ZnIn2S4-X (X = n (BiOI)/n(ZnIn2S4)) heterojunction was synthesized using various molar ratios via a two-step method. A series of characterization techniques were employed to analyze the composition, surface structure, valence state, and optical properties of BiOI/ZnIn2S4-X. The results show that BiOI/ZnIn2S4-X perform significantly better than both BiOI and ZnIn2S4. Furthermore, BiOI/ZnIn2S4-9% exhibits superior visible light absorption capacity and photocurrent response among all of the BiOI/ZnIn2S4-Xtested. Therefore, a PEC sensor was developed using BiOI/ZnIn2S4-9% for the detection of hydrogen peroxide and dopamine. The linear detection range for hydrogen peroxide spans from to 1 ~ 40,000 µM, with the LOD of 0.036 µM (S/N = 3). For dopamine, the corresponding values are 2 ~ 250 µM for the linear detection range, and 0.017 μM for the LOD, respectively. Thesensor exhibitsdemonstrates excellent stability, reproducibility and resistance to interference, enabling the detection of real samples and thus holds promising application potential.

A high-performance wearable microneedle sensor based on a carboxylated carbon nanotube-carbon nanotube composite electrode for the simultaneous detection of uric acid and dopamine

Uric acid (UA) and dopamine (DA) are crucial biomarkers in the human body. However, there is limited research on detecting UA or DA in subcutaneous interstitial fluid (SISF), and no studies on their simultaneous detection in SISF. Here, we developed an electrochemical microneedle sensor based on the carboxylated carbon nanotubes/multiwalled carbon nanotubes (CCNT/CNT) composite electrode for the simultaneous detection of UA and DA. Highly carboxylated CCNT was prepared and mixed with CNT and organosilicon-modified acrylic resin to form the CCNT/CNT composite. The carboxyl functional groups of CCNT enhance the electrode’s adsorption of UA and DA, while CNT improves electron conduction. The sensor achieves a wide linear detection range for UA (5–600 μM) with high sensitivity (7.13 μA μM−1 cm−2) and linearity (R2 = 0.994), as well as a wide linear range for DA (2–200 μM) with high sensitivity (13.31 μA μM−1 cm−2) and linearity (R2 = 0.994). The sensor achieved simultaneous detection of DA and UA in artificial interstitial fluid (ISF), with sensitivity and linearity remaining nearly unchanged compared to that in PBS, and is not affected by high levels of ascorbic acid (AA). Finally, the sensor successfully detected changes in UA levels in ISF of subjects before and after alcohol consumption in vivo, demonstrating its practical application capabilities. This study presents a practical strategy for detecting human biomarkers characterized by low cost, easy fabrication and excellent performance of electrode materials, and a well-designed microneedle sensor preparation scheme, making it highly promising for further research extension.

Fabrication of Cu-BTC@PW12/GO for multivariate sensing dopamine and acetaminophen as electrochemical sensor

Dopamine (DA) and acetaminophen (AP) are closely associated with many physiological and pathological processes, monitoring their levels precisely is of significance in the early diagnosis of diseases. Herein, a polyoxometalate-based metal-organic framework (POMOF) based on phosphotungstate (Cu-BTC@PW12) was immobilized on graphene oxide (GO) to fabricate Cu-BTC@PW12/GO (CPG) as an electrochemical sensor for the quantification of DA and AP. The spatial confinement effect of copper-based MOF (Cu-BTC) remained the catalytic activity phosphotungstate (PW12) avoiding the aggregation, facilitating electro-catalysis performance for detection of DA and AP. The CPG electrochemical sensor achieved the analysis of DA and AP with the limit of detection (LOD) of 24.8 nM and 62.3 nM, respectively. Furthermore, CPG can be applied for the quantification of DA and AP in real human serum and environmental water samples with satisfied recoveries. Therefore, this work expanded the utilization of POMOF in electrochemical analysis and has promising prospects for the early diagnosis of diseases and environmental treatment.

SERS detection of dopamine in artificial cerebrospinal fluid and in Parkinson’s disease-induced mouse cortex using a hybrid ZnO@Ag nanostructured platform

Rapid, direct, and sensitive detection of metabolites or clinically relevant biomarkers in complex biological samples is still challenging. We report a label-free surface-enhanced Raman scattering (SERS)-based approach for highly sensitive detection of dopamine (DA) in artificial cerebrospinal fluid (aCSF) and mouse brain tissue samples. The hybrid SERS-active sensing platform was designed to maximize the hot spot distribution. It encompasses a network of flexible and polymeric nanotrenches and nanogaps fabricated by nanoimprint lithography (NIL) covered by thin films of zinc oxide (ZnO) and silver (Ag) deposited using pulsed laser deposition (PLD) and direct current magnetron sputtering (DC-MS), respectively. The growth of the ZnO and Ag thin films was assessed by scanning electron microscopy (SEM) technique. The proposed SERS substrate benefits from the interlayered semiconductor–metal contribution in SERS enhancement, leading to a versatile sensing platform with improved detection sensitivity through the increased hot spots distribution. Using this strategy, the proposed assay can achieve an ultralow DA determination at the nM level, a short testing time (<30 min), and high signal reproducibility (RSD 11 %). We also assessed the sensing attributes of our in house developed SERS platform to detect DA in spiked aCSF samples, and a limit of detection (LOD) of 10 μM was achieved. Additionally, after in vivo inducing Parkinson’s disease (PD) in mice, relevant biological samples (striatum and cortical brain tissue) were investigated by SERS and ELISA. Given its good stability and accuracy in complex samples, the SERS-ELISA analysis has great potential to be a powerful tool for the reliable detection of DA in remote conditions.

Pd Nanoparticles Loaded on Cu Nanoplate Sensor for Ultrasensitive Detection of Dopamine.

The detection of dopamine is of great significance for human health. Herein, Pd nanoparticles were loaded on Cu nanoplates (Pd/Cu NPTs) by a novel liquid phase reduction method. A novel dopamine (DA) electrochemical sensor based on the Pd NPs/Cu/glass carbon electrode (Pd/Cu NPTs/GCE) was constructed. This sensor showed a wide linear range of 0.047 mM to 1.122 mM and a low limit of detection (LOD) of 0.1045 μM (S/N = 3) for DA. The improved performance of this sensor is attributed to the obtained tiny Pd nanoparticles which increase the catalytic active sites and electrochemical active surface areas (ECSAs). Moreover, the larger surface area of two-dimensional Cu nanoplates can load more Pd nanoparticles, which is another reason to improve performance. The Pd/Cu NPTs/GCE sensor also showed a good reproducibility, stability, and excellent anti-interference ability.

Simultaneous Determination of Tobacco Smoke Exposure and Stress Biomarkers in Saliva Using In-Tube SPME and LC-MS/MS for the Analysis of the Association between Passive Smoking and Stress.

Passive smoking from environmental tobacco smoke not only increases the risk of lung cancer and cardiovascular disease but may also be a stressor triggering neuropsychiatric and other disorders. To prevent these diseases, understanding the relationship between passive smoking and stress is vital. In this study, we developed a simple and sensitive method to simultaneously measure nicotine (Nic) and cotinine (Cot) as tobacco smoke exposure biomarkers, and cortisol (CRT), serotonin (5-HT), melatonin (MEL), dopamine (DA), and oxytocin (OXT) as stress-related biomarkers. These were extracted and concentrated from saliva by in-tube solid-phase microextraction (IT-SPME) using a Supel-Q PLOT capillary as the extraction device, then separated and detected within 6 min by liquid chromatography-tandem mass spectrometry (LC-MS/MS) using a Kinetex Biphenyl column (Phenomenex Inc., Torrance, CA, USA). Limits of detection (S/N = 3) for Nic, Cot, CRT, 5-HT, MEL, DA, and OXT were 0.22, 0.12, 0.78, 0.39, 0.45, 1.4, and 3.7 pg mL-1, respectively, with linearity of calibration curves in the range of 0.01-25 ng mL-1 using stable isotope-labeled internal standards. Intra- and inter-day reproducibilities were under 7.9% and 14.6% (n = 5) relative standard deviations, and compound recoveries in spiked saliva samples ranged from 82.1 to 106.6%. In thirty nonsmokers, Nic contents positively correlated with CRT contents (R2 = 0.5264, n = 30), while no significant correlation was found with other biomarkers. The standard deviation of intervals between normal beats as the standard measure of heart rate variability analysis negatively correlated with CRT contents (R2 = 0.5041, n = 30). After passive smoke exposure, Nic levels transiently increased, Cot and CRT levels rose over time, and 5-HT, DA, and OXT levels decreased. These results indicate tobacco smoke exposure acts as a stressor in nonsmokers.

A "signal-off" anodic photoelectrochemical sensor based on ZnIn2S4/TiO2 heterojunction for dopamine detection

Dopamine (DA) is an important neurotransmitter. Abnormal levels of it in human body can increase the risk of many neurological diseases. Thus, developing a simple, sensitive detection method of DA is crucial. In this paper, we reported a "signal-off" anodic PEC sensor based on fluorine-doped tin oxide (FTO) glass modified ZnIn2S4/TiO2 heterojunction (ZnIn2S4/TiO2/FTO) for DA detection. The experimental results show that the ZnIn2S4/TiO2/FTO electrode prepared by two-step hydrothermal method has a good photocurrent response performance under visible light. After incubation with DA, the photocurrent response decreases significantly because DA can rapidly oxidizes to polydopamine (PDA) through the action of superoxide radical (·O2−) and hydroxyl radical (·OH) intermediate species, which are intermediates produced by the ZnIn2S4/TiO2/FTO electrode under visible light irradiation. The constructed PEC sensor has a good linear relationship in the concentration range from 0.5 to 1000.0 μM, and its detection limit is 0.253 μM. In addition, the results of the proposed PEC sensor in real serum samples are satisfactory. The PEC sensor provides a promising platform for DA detection, laying the foundation for future advances in disease diagnosis and prevention.

Selective sensing of dopamine using copper hollow tube-integrated conjugated poly(arylene-ethynylene)-4 in the presence of epinephrine and norepinephrine

The Sonagashira-Hagihara coupling reaction was employed to prepare the conjugated Poly(arylene-ethynylene)-4 (CMP-4), into which copper hollow tubes (Cu-HT) were incorporated. This incorporation significantly enhanced the electrical conductivity and the selectivity of CMP-4 for dopamine (DA). The resulting composite exhibited high selectivity for DA over norepinephrine (NE) and epinephrine (EP) in a PBS-urine electrolyte. The peak current displayed a linear relationship with DA concentrations ranging from 100 to 900 nM, with limits of detection (LODs) of 17.84 and 16.03 nanomolar (R2 = 0.9906). This selective DA sensing is attributed to the adsorption of the analyte on the CMP-Cu-4-GCE surface, facilitated by aromatic functionality, soft–soft interactions, Lewis basicity, and steric hindrance. Additionally, the CMP-Cu-4-GCE demonstrated remarkable sensitivity, stability, selectivity, and reproducibility in DA detection. Voltammetric results from the screen-printed electrode (SPE) using CMP-Cu-4-SPE suggest that it is a promising electrochemical probe for detecting DA in a PBS-urine solvent.

Amperometric Determination of Dopamine and Ascorbic Acid with a Carbon Paste‐Yttrium Oxide Electrode

AbstractThis report presents a new application for yttrium oxide (YOX) in the modification of carbon paste electrodes with excellent electroactivity for the independent detection of dopamine (DA) and ascorbic acid (AA). The surface of the YOX‐modified electrode was characterized with SEM and EDS. The electroactive properties of DP and AA were studied with cyclic voltammetry (CV), square wave voltammetry (SWV) and amperometry (Am). The activity of DA and AA increased by more than 100 % when YOX/CPE was used, which allowed us to obtain detection limits of 0.04 and 0.06 μmol/L for DA and AA, respectively. The usefulness of YOX/CPE was tested with real human urine, fresh orange juice and vitamin C tablets, and the results were acceptable.

Impact of protein fouling on electrochemistry of hyaluronic acid/curcumin/carbon nanotubes modified electrode: Toward electrochemical measurement of dopamine

Dopamine detection and concentration identification using electrochemical sensing technique is critically important for a wide range of disease diagnosis and monitoring. However, the sensitivity of electrochemical sensing can be significantly affected from the non-specific protein adsorption in biological fluid samples. In this study, we aim to creating a modified electrode with excellent resistance to protein fouling. Herein, we have developed an antifouling electrochemical dopamine sensing interface integrated hydrophilicity hyaluronic acid (HA) with curcumin/multi-walled carbon nanotubes (CM/MWCNTs) via a facile method. The HA integrated with CM/MWCNTs composites-based electrochemical sensor exhibited synergistic effects: (i) the abundant hydrophilic groups in the HA structure (water contact angle, 30.88°) facilitated the formation of a hydrated layer on the electrode surface to prevent fouling; (ii) CM/MWCNTs catalyzed the electrooxidation of dopamine; (iii) electrostatic interactions between the negatively charged HA/CM/MWCNTs and positively charged dopamine in neutral condition. The morphology and structure of the nanocomposite were characterized. The HA/CM/MWCNTs-modified electrode exhibited the improved hydrophilicity with a water contact angle of 30.92° and enhanced electrochemical response of the modified electrode for dopamine sensing in a variety of conditions with protein in the electrolyte. Moreover, the HA/CM/MWCNTs-modified sensor also exhibited superior dopamine analytical performance in human serum samples, with the dopamine detection accuracy approaching 97 % and be interference-free from proteins. The constructed electrochemical sensor presented great potential in dopamine detection in clinic setups.

Production of conductive microfibers based on Polybutylene adipate terephthalate and graphite using a 3D printed electrospinning system and their application as electrochemical dopamine sensor

The use of fibers has intensified in the application of technological and industrial devices and systems, due to their characteristics such as mechanical resistance, elasticity, and a wide range of morphological configurations. In this sense, conductive microfibers based on graphite powder (GP) and the polylactic acid/ Polybutylene adipate terephthalate polymeric blend were developed through the electrospinning technique using a new 3D printer automatized collector. The obtained microfibers were characterized and used in the manufacture of an electrochemical sensor for the determination of dopamine, which presented a linear range of 0.5 to 20 μmol L−1 with a limit of detection of 0.008 μmol L−1. The sensor was applied for the detection of dopamine in a human serum sample and had a recovery range of 85.5 to 101.0 %. Therefore, conductive microfibers manufactured by electrospinning have potential as a material for the development of electrochemical sensors.

Effect of cytosine and adenine on graphene oxide for the sensing of dopamine: Electrochemical and theoretical studies

In this work, the electrochemical interaction between dopamine and cytosine/adenine on the graphene oxide (GO) is elucidated by quantum chemical simulation methods. Initially, GO, cytosine-functionalized GO (CGO), and adenine-functionalized GO (AGO) were prepared, and then utilized for the carbon paste electrode (CPE) modification. The as-prepared CGO-modified CPE (CGCPE) and AGO-modified CPE (AGCPE) were applied for the electrochemical sensing of dopamine (DA), and the obtained consequences illustrate the improved sensitivity of modified CPEs (MCPEs) compared to bare CPE (BCPE). Here, applied theoretical concepts based on analytical Fukui functions and frontier molecular orbitals (FMO) for cytosine and adenine functional groups in order to find active sites, and explained with evidence for the detection of DA by enhancing sensitivity. Moreover, the AGCPE has been shown higher electrochemical response compared to CGCPE for the detection of DA, and this result also agreed with theoretically from Global electron transfer results. The MCPEs were also utilized to examine the different electrochemical parameters and determine the DA concentration in the nanomolar range. The detection limit for CGCPE and AGCPE was found to be 9 nm and 7 nm, respectively.

Green synthesis of CoVS2-MOF@CMS nanocomposite electrode for sustainable approach towards eco-friendly energy storage and dopamine detection

Dopamine, a crucial brain chemical belonging to the catecholamine and phenethylamine chemical families, plays a vital role in promoting a healthy and happy life. Irregular dopamine release has been linked to various neurological disorders and depressive conditions. Therefore, conducting real-time, in vivo monitoring of dopamine levels is essential to gain a comprehensive understanding of its physiological functions. In this research, the hydrothermal technique was employed to synthesize copper‑molybdenum sulfide (Cu2MoS4 (CMS)). Further, we have reported the one-pot hydrothermal synthesis of CoVS2-MOF, using the bioactive chemical as fuel obtained from Euphorbia cognata Boiss. The specific capacity (Qs) of the sample CoVS2-MOF@CMS was calculated to be 820 Cg−1 at 3 mVs−1, a value expressively higher than that of the reference samples. Furthermore, in the supercapattery device, an outstanding Qs of 300 Cg−1 was achieved at 1.5 Ag−1, surpassing the previously observed values. The device demonstrated outstanding performance, including a coulombic efficiency of 89 %, a specific energy of 36.68 Whkg−1, and a power density (Pd) of 2218.53 Wkg−1. Moreover, the sensor typically yielded dopamine (DA) concentrations in human serum ranging from 100.8 % to 102.2 %. The utilization of the multifunctional CoVS2-MOF@CMS nanocomposite electrode material illustrates promising prospects for the fabrication of hybrid devices with applications in biomedical and energy harvesting fields.

Enhanced photoelectrochemical sensor for dopamine detection based on MOFs-derived ZnO and TpPa-1 heterostructure composite

This study used ZIF-8 metal–organic framework as a precursor to create a N-doped ZnO. Subsequently, covalent organic framework named TpPa-1 (Tp, 1,3,5-triformylphloroglucinol; Pa-1, p-phenylenediamine) with a ZnO heterostructure composite (ZnO/TpPa-1) was created through an in-situ synthesis approach. Due to its superior band structure and outstanding photocatalytic performance, the ZnO/TpPa-1 composite is a good candidate for the development of a new type of photoelectrochemical (PEC) sensor for the detection of dopamine (DA). According to experimental data, ZnO/TpPa-1/ITO had a photocurrent that was roughly 1.5 times higher than TpPa-1/ITO and 4.5 times higher than ZnO/ITO. The primary reason for this improvement was the synergistic effects brought about by effective light usage and charge transfer at the interface between the TpPa-1 π-conjugated backbone and ZnO porous structure. The determination ranges for DA demonstrated two linear ranges, 0.005–0.25 μmol/L and 0.25–1.00 μmol/L, and the detection limit was as low as 1.3 nmol/L. Moreover, the PEC sensor exhibited good stability, selectivity, repeatability, and suitability for real-world samples. This work provides important new understandings for covalent organic framework (COF)-based heterostructure design, which can be used to improve PEC sensor performance.

Enhance electrochemical sensing of ascorbic acid and dopamine using V-CuO/GO nanocomposite

The electrochemical detection of Ascorbic acid and dopamine is crucial due to their vital roles in biological processes. Both biomolecules coexist in the human body and have the same oxidation potential, leading to electrode fouling and overlapping of oxidation potential. Accurate detection enables monitoring their levels in biological samples, aiding in disease diagnosis and treatment. This study presents the fast and green synthesis of a highly sensitive and selective electrochemical biosensor for the simultaneous detection of dopamine and ascorbic acid. The change in spherical cluster morphology into nanorods enhances the electrode's electroactive surface area, enhancing sensor sensitivity and selectivity. Electrochemical characterization techniques, including cyclic voltammetry and electrochemical impedance spectroscopy, demonstrated excellent electron transportation and low charge transfer resistance. The sensor exhibited simultaneous detection with a low limit of detection of 8 µM for dopamine and 6.9 µM for ascorbic acid, with a wide linear working range. Additionally, the sensor showed excellent selectivity and repeatability with a vast potential gap at simultaneous detection, making it suitable for clinical and food industry applications.

Polydopamine functionalized FeTiO3 nanohexagons for selective and simultaneous electrochemical determination of dopamine and uric acid.

Herein we report the simultaneous detection of dopamine (DA) and uric acid (UA) using polydopamine (PDA) functionalized FeTiO3 nanohexagons. The nanohexagons were hydrothermally synthesized and subsequently functionalized with PDA in a Tris-buffer solution. The PDA functionalized nanostructure was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR), respectively. The SEM and TEM investigations revealed the presence of FeTiO3 nanohexagons along with a peripheral coating of PDA over the nanostructures. The XRD pattern confirmed the formation of the ilmenite structure, while the chemical structure was investigated through XPS and FTIR respectively. Using cyclic voltammetry (CV) the efficacy of FeTiO3-PDA electrode was evaluated toward DA oxidation. The enhanced activity of the functionalized electrode in DA oxidation, as compared to the untreated FeTiO3, may be attributed to the significant presence of hydroxyl, amine, and imine functional groups over the polymer layer. Differential pulse voltammetry (DPV) was utilized for the detection of DA and UA. With a linear range of 50 μM to 250 μM, the detection limits of 0.30 μM and 4.61 μM were determined for DA and UA, respectively. The peak separation of 263 mV between DA and UA demonstrates the sensor's remarkable selectivity. In addition, the study displayed the ability to detect both DA and UA simultaneously, and the validity of the sensor was evaluated in serum samples, respectively.

Hybrid graphene nanoflakes for electrochemical sensing with multianalyte detection capability

This work illustrates the production of highly electrochemically active graphene by liquid phase exfoliation technique for ultrasensitive electrochemical sensors. An airless high-pressure spray technique was designed to exfoliate bulk natural graphite into nm-scaled flakes (referred as HP50). Transmission electron microscopy, Raman and X-ray photoelectron spectroscopy studies reveal that the HP50 sample has a mixed structure composed of amorphous carbon and a few-layer graphene fraction with high amount of edge plane defects. The HP50 flakes are drop cast on glassy carbon electrodes to test the simultaneous and selective electrochemical detection of hydrogen peroxide, ascorbic acid, and dopamine. In cyclic voltammetry measurements, hydrogen peroxide reduces at −0.2 V vs Ag/AgCl (1 M), while ascorbic acid and dopamine oxidize at 0.1 V vs Ag/AgCl (1 M) and 0.3 V vs Ag/AgCl (1 M), respectively. Linear sweep voltammetry demonstrates high sensitivity (164, 739, and 3357 μA mM−1 cm−2) and low limit of detection (15, 1.7, and 2.1 μM) for the three analytes, respectively. Interference studies confirm a high sensitivity and selectivity towards the different chemical species. The HP50-based multianalyte sensors are also tested against different environmental and commercial samples, illustrating their viability in practical applications.

Electrochemical Determination of Dopamine with a Carbon Paste-Lanthanum (III) Oxide Micro-Composite Electrode: Effect of Cetyl Trimethyl Ammonium Bromide Surfactanton Selectivity.

This paper presents a new application of a lanthanum oxide (III)-modified carbon paste electrode (LaOX/CPE) for dopamine (DP) detection in the presence of ascorbic acid (AA). The presence of cetyl trimethyl ammonium bromide (CTAB) facilitated the LaOX/CPE electrode's ability to detect DP amidst AA interference, resulting in a substantial 70.0% increase in the anodic peak current for DP when compared to the unmodified carbon paste electrode (CPE). CTAB enabled clear separation of the anodic peaks for DP and AA by nearly 0.2 V, despite their initially overlapping potential values, through the ion-dipole interaction of AA and CTAB. The electrode was characterized using cyclic voltammetry (CV) and energy-dispersive spectroscopy (EDS). The method demonstrated a detection limit of 0.06 µmol/L with a relative standard deviation (RSD) of 6.0% (n = 15). Accuracy was assessed through the relative error and recovery percent, using urine samples spiked with known quantities of DP.

A novel Cu–Cu2O junction structure for the ultrasensitive detection of dopamine

A novel Cu–Cu2O junction structure for the ultrasensitive detection of dopamine

Microscale Sensor Arrays for the Detection of Dopamine Using PEDOT:PSS Organic Electrochemical Transistors.

We present a sensor array of microscale organic electrochemical transistors (OECTs) using poly (3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) as the channel material. The devices show high sensitivity and selectivity to detect dopamine (DA) with platinum (Pt) as a pseudo-reference gate electrode. First, we describe the wafer-scale fabrication process for manufacturing the PEDOT:PSS OECTs, and then we introduce a dilution method to adjust the thickness of the PEDOT:PSS film. Next, we investigate the effect of the film thickness on the sensitivity of DA detection. Reducing the film thickness enhances the sensitivity of DA detection within the concentration range of 1 μM to 100 μM. The OECTs show impressive sensitivitywith a limit of detection (LoD) as low as 1 nM and a high selectivity against uric acid (UA) and ascorbic acid (AA). Finally, we modify the surface of the Pt gate electrode with chitosan to improve the selectivity of OECTs at high concentrations of up to 100 µM to expand the detection range.