Electrochemical Sensor For Simultaneous Detection Research Articles

An electrochemical sensor for simultaneous voltammetric detection of ascorbic acid and dopamine enabled by higher electrocatalytic activity of co-modified MCM-41 mesoporous molecular sieve

It is of great value to develop effective methods for accurately and simultaneously detecting ascorbic acid (AA) and dopamine (DA) in the field of biochemistry. This work reports a nonenzymatic electrochemical sensor for the simultaneous detection of AA and DA by employing a Co-modified MCM-41 (CoMCM-41) mesoporous molecular sieve as an efficient electrocatalytic material, which was synthesized by a two-step hydrothermal method. Subsequently, the high structural organization of the CoMCM-41 mesoporous structure was characterized, and the electrocatalytic performance of CoMCM-41 toward AA and DA oxidation was then evidenced by the catalytic effect of different electrodes modified with or without CoMCM-41. By virtue of the superior electrocatalytic activity of the CoMCM-41, a much wider peak potential difference (ΔEpa) of 310 mV was obtained for the oxidation of AA and DA in their mixture solution, and the parameters that influenced the electrochemical signals of the modified electrode were also optimized. Under optimal conditions, a good linear response to AA and DA was observed on the CoMCM-41 modified electrode. For individual detection of AA and DA, the linear ranges were 7 ~ 105 μM and 5 ~ 110 μM respectively, while the linear response range was 20 ~ 100 μM for simultaneous detection of AA and DA. Satisfactory recovery results were obtained when the fabricated sensor was applied to determine AA in orange juice and DA in madopar pill samples.

MOF derived ZnCo2O4@nitrogen-doped carbon as an electrochemical sensor for simultaneous detection of acetaminophen and p-aminophenol

In this study, a rapid and sensitive electrochemical sensor (ZnCo2O4@NC) based on metal-organic frame (MOF)-derived metal oxide material (ZnCo2O4) and chitosan derived nitrogen-doped carbon material (NC) was successfully constructed for the simultaneous determination of acetaminophen (APAP) and p-aminophenol (PAP). A series of electrochemical experiments proved that the MOF derived ZnCo2O4@NC composite has excellent electrochemical response to APAP and PAP in the phosphate buffer saline (PBS) (pH 7.0). The current response varies linearly with the increase of APAP concentration in the range of 8.0 μmol L−1 to 520 μmol L−1 and PAP concentration in the range of 6.0 μmol L−1 to 420 μmol L−1. The sensitivity and limit of detection (LOD) of ZnCo2O4@NC for APAP and PAP detection are 0.1024 and 0.2749 μA μmol L−1 cm−2, 0.0608 and 0.2489 μmol L−1, respectively. The ZnCo2O4@NC composite modified electrode exhibits good selectivity, reproducibility and stability. Additionally, in the detection for acetaminophen sustained-release tablets, the recovery rates of APAP are in the range of 90.00 % –100.00 %. The theoretical content is consistent with our detection results, showing that this method has good accuracy in actual sample analysis. This study provides an innovative idea to improve electrochemical performance of simultaneous detection of acetaminophen and p-aminophenol through the comprehensive strategy of structural design, heteroatom doping.

MoS2_CNTs_aerogel-based PEDOT nanocomposite electrochemical sensor for simultaneous detection of chloramphenicol and furazolidone in food samples

Toxic intermediates in food caused by chloramphenicol (CP) and furazolidone (FZ) have gained interest in research toward their detection. Hence, fast, reliable, and accurate detection of CP and FZ in food products is of utmost importance. Here, a novel molybdenum disulfide-connected carbon nanotube aerogel/poly (3,4-ethylenedioxythiophene) [MoS2/CNTs aerogel/PEDOT] nanocomposite materials are constructed and deposited on the pretreated carbon paste electrode (PCPE) by a facile eletropolymerization method. The characterization of MoS2/CNTs aerogel/PEDOT nanocomposite was analyzed by scanning electron microscopy (SEM), cyclic voltammetry, and differential pulse voltammetry. The modified MoS2/CNTs aerogel/PEDOT nanocomposite has improved sensing characteristics for detecting CP and FZ in PBS solution. For this work, we have studied various parameters like electrocatalytic activity, the effect of scan rates, pH variation studies, and concentration variation studies. Under optimum conditions, the modified electrode exhibited superior sensing ability compared to the bare and pretreated CPE. This improvement in electrocatalytic activity can be the higher conductivity, larger surface area, increased heterogeneous rate constant, and presence of more active sites in the MoS2/CNTs aerogel/PEDOT nanocomposite. The modified electrode demonstrated distinct electrochemical sensing toward the individual and simultaneous analysis of CP and FZ with a high sensitivity of 0.701 µA. µM−1 .cm−2 for CP and 0.787 µA. µM−1 .cm−2 for FZ and a low detection limit of 3.74 nM for CP and 3.83 nM for FZ with good reproducibility, repeatability, and interferences. Additionally, the prepared sensor effectively detects CP and FZ in food samples (honey and milk) with an acceptable recovery range and a relative standard deviation below 4%.

A ratiometric electrochemical sensor for simultaneous detection of multiple heavy metal ions in water and herbal medicines based on methylene blue-functionalized metal–organic framework

Heavy metal contamination in water and herbal medicine poses a global threat to human health. There is a pressing need for the development of a simple and rapid method for simultaneous quantification. In this study, a ratiometric electrochemical sensor was first constructed using a hybrid material composed of methylene blue functionalized metal–organic framework (MB-UiO66-NH2) and multi-walled carbon nanotubes (MWCNTs). Then, MB-UiO66-NH2/MWCNTs harnessed the large specific surface area of UiO66-NH2 and good conductivity of MWCNTs, resulting in a sensor with superior analytical performance for Cd2+, Pb2+, and Hg2+ detection. Meanwhile, the ratiometric probe uses MB as an internal reference, with the ratio signal (Imetalion/IMB) serving as output. This ratiometric electrochemical sensor was able to enhance the reproducibility and reliability and eliminate interference, particularly in complex environments. Importantly, based on this ratiometric electrochemical platform, the low detection limit were 11.08 nM for Cd2+, 5.47 nM for Pb2+, and 6.42 nM for Hg2+, which realized the simultaneous, sensitive, and reliable detection. In addition, it has been successfully applied in real water and representative herbal medicine sample analysis. Therefore, this work provides a new approach for the risk assessment of heavy metal accumulation, which is conducive to safeguarding people's lives and health.

Design and Fabrication of NiMn Layered Double Hydroxide/Reduced Graphene Oxide as Electrochemical Sensor for Simultaneous Detection of Ascorbic Acid, Dopamine and Uric Acid

Design and Fabrication of NiMn Layered Double Hydroxide/Reduced Graphene Oxide as Electrochemical Sensor for Simultaneous Detection of Ascorbic Acid, Dopamine and Uric Acid

Electrospun cobalt-doped 2D-MoSe2/polypyrrole hybrid-based carbon nanofibers as electrochemical sensing platforms

A novel cobalt-doped two-dimensional molybdenum diselenide/polypyrrole hybrid-based carbon nanofiber (Co/MoSe2/PPy@CNF) was prepared using the hydrothermal method followed by electrospinning technique. The structural and morphological properties of the 2D-TMD@CNF-based hybrids were characterized through X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), and transmission electron microscopy (TEM). The Co-MoSe2/PPy@CNF exhibited large surface area, porous structure, and improved active sites due to the synergistic effect of the components. The electrochemical and electrocatalytic characteristics of the 2D-TMD@CNF-modified electrodes were also investigated using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The Co/MoSe2/PPy@CNF electrode was used as an electrochemical sensor for simultaneous detection of ascorbic acid (AA), dopamine (DA), and uric acid (UA) and showed enhanced catalytic activity and sensitivity. Using DPV measurements, the Co/MoSe2/PPy@CNF demonstrated wide linear ranges of 30–3212 μM for AA, 1.2–536 μM for DA, and 10–1071 μM for UA with low detection limits of 6.32, 0.45, and 0.81 μM, respectively. The developed sensor with the Co/MoSe2/PPy@CNF-modified electrode was also applied to a human urine sample and gave recoveries ranging from 94.0 to 105.5% (n = 3) for AA, DA, and UA. Furthermore, the Co/MoSe2/PPy@CNF-based sensor exhibited good selectivity and reproducibility for the detection of AA, DA, and UA.Graphical abstract

Two-dimensional covalent organic framework-based hybrid nanosheets for electrochemical detection of 5-fluorouracil and uracil in biofluids

A 2D covalent organic framework (COF), supramolecule cucurbit[8]uril, and an AuNP-based electrochemical sensor for simultaneous detection of 5-fluorouracil and uracil, in concentrated biofluids, holding promise for practical sensing.

Cellulose-derived hierarchical porous carbon based electrochemical sensor for simultaneous detection of catechol and hydroquinone

Cellulose-derived hierarchical porous carbon based electrochemical sensor for simultaneous detection of catechol and hydroquinone

Photo-assisted “co-movement catalysis”: CoFe2O4/CNS heterojunction based portable electrochemical sensor for simultaneous detection of Pb2+ and Cd2+ in natural water

Heavy metal ions (HMIs) seriously threaten human health even under trace conditions. Therefore, accurate, efficient and simultaneous detection of multiple HMIs is of great significance. Here, a strategy of "co-movement catalysis" based on photo-assisted electrochemical catalysis is proposed by constructing a flexible electrochemical sensor with CoFe2O4/CNS heterojunction-modified nickel foam as the working electrode for simultaneous detection of HMIs. Regarding photo-assisted catalysis, CoFe2O4/CNS nanocomposites formed a p-n type heterojunction, effectively separating photo-generated electron-hole pairs and reducing photo-generated carriers' recombination rate, leading to the catalytic reaction of photogenerated electrons and holes with HMIs and atoms to improve the efficiency of preconcentration and stripping, further amplifying the electrochemical signal. Regarding electrochemical catalysis, the CoFe2O4 spinel contains variable valence transition metal ions Fe2+/Fe3+ and Co2+/Co3+, which can reduce and oxidize HMIs circularly, further enhancing the sensor’s sensitivity. The portable sensor based on "co-movement catalysis" exhibited sensitive detection performance. The linear range is 0.100–10.0 μM for Pb2+ and 1.00–10.0 μM for Cd2+, with the detection limit of 0.0310 μM for Pb2+ and 0.219 μM for Cd2+, respectively. The recovery rate of the sensor to natural water samples is between 96% and 105%, which proves its development potential in environmental monitoring.

Noncovalent assembly of non-metallic porphyrin on graphene oxide nanosheets and its application for simultaneous determination of Cu2+ and Pb2+ in real water

A newly developed electrochemical sensor for simultaneous detection of Cu2+ and Pb2+ in polluted water using the non-metallic porphyrin functioned graphene oxide (GO) by π-π noncovalent interactions is demonstrated. Introduction of 5,10,15,20-tetra(4-hydroxyphenyl)-21H, 23H-porphine (THPP) on GO nanosheets resulted in enhanced electron transfer due to the high electron mobility of GO and the excellent electron-feeding properties of THPP. Due to the synergistic effect between THPP and GO, the prepared sensors showed remarkable electrocatalytic activity for the reduction of Cu2+ and Pb2+. It exhibited two-segmentinear response over the concentration range from 5 − 300 μM and 300–––900 μM with a detection limit of 1.5 μM for Cu2+ and two-segment corresponding linear range of 5–––250 μM and 250–––900 μM with a detection limit of 1.6 μM for Pb2+. In addition, the proposed sensor has excellent anti-interference ability for some common cations and anions. The technique can be used successfully for simultaneously detection of residual Cu2+ and Pb2+ in real water, thus demonstrating its high utility for conventional sensing applications in real environments.

Preparation of novel azobenzene derivatives/potassium niobate nanocomposite and its application in electrochemical sensors

The guest molecule trans-[2-(2,2,3,3,4,4,4-heptafluorobutylamino) ethyl]-{2-[4-(4-hexanobenzazo)-phenoxy] ethyl} -dimethylammonium (abbreviated as C3F7-azo[Formula: see text]Br[Formula: see text]) were inserted into the K 4Nb6O[Formula: see text]laminated by the guest–guest exchange method to synthesize C3 F7-azo[Formula: see text]/Nb6 O[Formula: see text]type-A nanocomposite with excellent electrochemical properties. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier Transform infrared (FTIR) spectrometer and energy dispersive spectroscopy (EDS) were used to characterize the structure and morphology of nanocomposite C3F7-azo[Formula: see text]/Nb 6O[Formula: see text]. C3F7-azo[Formula: see text]ions were speculated to form bilayer between the [Nb6O[Formula: see text] ][Formula: see text]lamellar at an angle of [Formula: see text] by morphology analysis and lamellar spacing calculation. This nanocomposite was used to fabricate an electrochemical sensor for simultaneous detection of dopamine (DA) and ascorbic acid (AA). Differential pulse voltammetry, cyclic voltammetry and electrochemical impedance spectroscopy in N2-saturated phosphate buffered solution (0.1 M, pH = 5) demonstrated excellent electrocatalytic activity. The sensor achieved detection limits of 1.74 [Formula: see text]M for DA and 1.57 [Formula: see text]M for AA.

MOF-derived Cu/N–C Composite Based Electrochemical Sensor for Simultaneous Detection of Catechol and Hydroquinone

In this work, Cu/N-C derived from MOF composites were synthesized and characterized by SEM, XRD, FTIR, XPS and EIS, which was modified on the glassy carbon electrode (GCE) to construct a novel electrochemical sensor (Cu/N-C/GCE). Due to the good electrical conductivity and abundant catalytic active sites of Cu/N-C, Cu/N-C/GCE exhibited excellent electrocatalytic performance for catechol (CC) and hydroquinone (HQ) with the oxidation peak potential difference of 112 mV. The proposed sensor could realize the simultaneous detection of CC and HQ successfully. Under optimal conditions, the redox peak currents of both CC and HQ have good linear relationship with their concentrations in the ranges of 0.50–100.00 μM and 0.50–150.00 μM with the detection limits for CC and HQ of 0.12 μM and 0.09 μM, respectively. At the same time, the sensor exhibits good stability, reproducibility and selectivity in the analysis of practical samples.

Simultaneous electrochemical detection of Cd (II) and Pb (II) based on L-cysteine functionalized gold nanoparticles/metal-organic frameworks-graphene oxide nanocomposites

In this paper, a facile electrochemical sensor for simultaneous detection of Cd2+ and Pb2+ was fabricated, on the base of in situ growing gold nanoparticles (AuNPs) on L-cysteine functionalized metal-organic frameworks (L-MOFs) and graphene oxide (GO) nanocomposites (L-Au-MOFs-GO). First, L-MOFs were in-situ synthesized on the GO nanosheets by a one-step hydrothermal method. Then, the L-cysteine in L-MOFs-GO nanocomposite was used as a reductant to react with HAuCl4 and in-situ obtain AuNPs, finally forming the L-Au-MOFs-GO composite. This L-Au-MOFs-GO composite not only can enhance the conductivity of the composite by accelerating the electron transfer, but also can act as an enrichment medium phase of heavy metal ions because of the interaction between metal cations and hydrophilic groups of L-MOFs or GO. The morphology of L-Au-MOFs-GO composites were characterized by transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectrometer (FT-IR), and X-ray diffraction (XRD). The results showed that the electrochemical performance of L-Au-MOFs-GO composite was better than GO material or MOFs-GO composite. Under the optimal conditions, the L-Au-MOFs-GO modified electrode was successfully applied to individually and simultaneously detect the Cd2+ and Pb2+ in an acetic acid buffer solution with good selectivity and high sensitivity. This method was utilized for simultaneous detection of Cd2+ and Pb2+ in river water and the leaching solution of watermelon with great reliability and accuracy. This new nanomaterial for simultaneous detection of Cd2+ and Pb2+ has the potential application in complicated samples.

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.

Porous carbon fabricated by a residue from Longquan lignite ethanolysis as an electrochemical sensor for simultaneous detection of hydroquinone and catechol in the presence of resorcinol

Catechol (CC), resorcinol (RS), and hydroquinone (HQ) are regarded as both important raw materials widely applied in chemical industry and highly toxic organic pollutants, so accurately detecting them is very necessary. In this work, Longquan lignite residue with low added value was fabricated as highly active porous carbons (PCs). The morphology, specific surface area (SSA), and electrocatalytic oxidation performance of the PCs prepared at different activated temperatures (600 ∼ 900 °C) were studied in detail. All PCs have different portions of micropores and mesoporous, and their SSAs can reach up to 3028 m2/g. Such well-developed microporous and mesoporous structures can provide abundant active sites to facilitate ion and electron transport, and thereby improving the electrocatalytic performance. Among them, the PC prepared at 800 °C shows the best detection performance. It can successfully detect HQ and CC simultaneously in the presence of RS, with detection limits of 0.15 and 0.81 µM for HQ, 0.09 and 0.53 µM for CC comparable to some graphene-based electrochemical sensors. Additionally, the constructed electrochemical sensor also displays a good reproducibility, stability, and anti-interference, which makes it a promising candidate material for monitoring phenolic compounds in actual water samples.

Ternary nanocomposite-based smart sensor: Reduced graphene oxide/polydopamine/alanine nanocomposite for simultaneous electrochemical detection of Cd2+, Pb2+, Fe2+, and Cu2+ ions

Heavy metal ion (HMI) sensors are the most sought commercial devices for environmental monitoring and food analysis research due to serious health concerns associated with HMI overdosage. Herein, we developed an effective electrochemical sensor for simultaneous detection of four HMI (Cd2+, Pb2+, Fe2+, and Cu2+) using a ternary nanocomposite of reduced graphene oxide functionalized with polydopamine and alanine (ALA/pDA/rGO). Comprehensive spectroscopic and microscopic characterizations were performed to ensure the formation of the ternary nanocomposite. The developed nanocomposite on glassy carbon electrode (GCE) yields >2-fold higher current than GO/GCE electrode with excellent electrochemical stability and charge transfer rate. Using DPV, various chemical and electrochemical parameters, such as supporting electrolyte, buffer pH, metal deposition time, and potential, were optimized to achieve highly sensitive detection of targeted HMI. For Cd2+, Pb2+, Fe2+, and Cu2+ sensing devised sensor exhibited detection limits of 1.46, 2.86, 50.23, and 17.95 ppb and sensitivity of 0.0929, 0.0744, 0.0051, and 0.0394 μA/ppb, respectively, with <6% interference. The sensor worked similarly well for real water samples with HMI. This study demonstrates a novel strategy for concurrently detecting and quantifying multiple HMI in water and soil using a smart ternary nanocomposite-based electrochemical sensor, which can also detect HMI in food samples.

Amplification-free, highly sensitive electrochemical DNA-based sensor for simultaneous detection of stx1 and stx2 genes of Shiga toxin-producing E. coli (STEC)

Shiga toxin-producing E. coli (STEC) is a food-borne pathogen of significant public health concern, due to the severity of the illness it can cause at a low infection dose. The key targets in molecular-based assays to detect STEC are stx1 or stx2 genes, coding for the ability to produce Shiga T Toxin 1 and 2, respectively. The most commonly used molecular detection techniques, such as PCR and real-time PCR, are considerably time-consuming and there is an urgent need for a more rapid screening assay which could be used in agri-food settings. In this work, an amplification-free multiplex electrochemical sensor for the simultaneous detection of stx1 and stx2 genes was developed using a silicon-based chip comprising six interdigitated gold microelectrodes (IDE) sensors. Two probes complementary to stx1 and stx2 genes were immobilised on a single chip allowing for multiplex detection. The selectivity of the multiplex sensor was confirmed using fluorescence and electrochemistry. The developed assay conditions allowed for an improved limit of detection of three orders of magnitude compared to the previous reports achieving an amplification-free limit of detection of 100 zM (10−19 M) for both, stx1 and stx2 genes. The developed sensor was validated using chromosomal DNA extracted from bacterial cultures containing either no virulence genes, stx1 gene only, and both stx1 and stx2. Such multiplex sensors, if combined with on-chip DNA extraction, could revolutionise the point-of-use detection of STEC as well as other pathogens for instance on-farm or in the food industry.

A disposable and low-cost laser-scribed graphene electrochemical sensor for simultaneous detection of hydroquinone, paracetamol and methylparaben

• A new disposable LSG sensor was fabricated using Polyetherimide substrate. • Sensor presented high reproducibility, sensitivity, and selectivity. • A LSG sensor was applied to simultaneous detection of emerging pollutants. • A porous graphene-like material with high electrochemical performance was developed. A novel and inexpensive laser-scribed graphene (LSG) sensor using polyetherimide (PEI) substrate was fabricated using CO 2 laser. The material was characterized by scanning electron microscopy (SEM), Raman spectroscopy, and electrochemical techniques, demonstrating a high porous carbonaceous material, which resulted in an electroactive area with 3.4-fold enhancement compared to geometric area and a high heterogeneous electron transfer rate constant (k°) of 3.20x10 -2 cm/s for ferricyanide redox probe. As a proof of applicability, the LSG-PEI sensor was applied for simultaneous detection of hydroquinone (HQ), paracetamol (PA), and methylparaben (MP) emerging pollutants (EP) in tap water and natural (lake) water samples, providing recoveries between 93.1% and 118% with limits of detection of 9.42x10 -8 , 3.23x10 -7 , and 2.95x10 -7 mol/L for HQ, PA, and MP, respectively.

Applicability of a graphene oxide nanocomposite for fabrication of an electrochemical sensor for simultaneous detection of sunset yellow and rhodamine B in food samples.

Developing a sensitive portable sensor for the determination of food additives is very important. Herein, a simple and sensitive electrochemical sensor has been constructed based on a carbon paste electrode (CPE) modified with graphene oxide (GO) nanosheets for the simultaneous determination of sunset yellow (SY) and rhodamine B (RhB) in phosphate buffer solution (pH = 4). The cyclic and differential pulse voltammetry (CV and DPV) results revealed two well-resolved anodic peaks for SY and RhB with a remarkable increase in oxidation signals of these colorants. Based on this, an electrochemical method was developed for the first time for the simultaneous detection of SY and RhB. Applicability of the sensor was confirmed in various concentrations of two analytes in two linear ranges of 1-20 μM for SY and 1-30 μM for RhB with a limit of detection (LOD) of 10.0 nM and 20.0 nM, respectively. Furthermore, the proposed sensor was successfully employed for the simultaneous detection of SY and RhB in food samples with recoveries of 93.1-106.0% indicating promising potential in practical application.

3D RGO/MWCNTs-loaded bimetallic-organic gel derived ZrFeOx as an electrochemical sensor for simultaneous detection of dopamine and paracetamol

In the current study, bimetallic-organic gel (ZrFe-MOGs) were rapidly prepared without using any toxic or harmful organic solvent, and new bimetallic oxide ZrFeOx were prepared by roasting ZrFe-MOGs directly. Then ZrFeOx nanoparticles were combined with 3D RGO/MWCNTs by a solvothermal method to synthesize 3D RGO/MWCNTs@ZrFeOx hybrid. Due to its three-dimensional structure, large electroactive surface area and more active sites, and excellent conductivity, the electrocatalytic activity of the modified electrode for the oxidation of dopamine (DA) and paracetamol (PAT) was effectively improved, and the overlap of anode peak due to their closer electrochemical oxidation potentials was solved. Under optimal conditions, the linear responses to DA and PAT were in the range of 1 − 12 μM, 12 − 180 μM and 1 − 14 μM, 14 − 190 μM, respectively. The detection limits (S/N = 3) for DA and PAT were 0.230 and 0.212 μM, respectively. The optimized 3D RGO/MWCNTs@ZrFeOx has good reproducibility, repeatability, stability, selectivity, and can be used to detect DA and PAT simultaneously. In addition, the proposed RGO/MWCNTs@ZrFeOx sensor exhibited a good recovery factor in the analysis of real drug and serum samples with a relative standard deviation of less than 5 %. Importantly, the electroactive area of 3D RGO/MWCNTs@ZrFeOx, and the 2 H+/2e- mechanism of DA and PAT oxidation on the surface of 3D RGO/MWCNTs@ZrFeOx were discussed, which provided a theoretical basis for further understanding of this redox process.