Differential Pulse Voltammetry Method Research Articles

Evaluation of antioxidant capacity in different food matrices through differential pulse voltammetry and its correlation with spectrophotometric methods

Differential pulse voltammetry (DPV) and spectrophotometric methods were used to evaluate the antioxidant capacity (AC) in strawberry and orange juice, soluble coffee, rosemary extract, red wine, and sparkling white wine. The AC through spectrophotometric methods showed the following trend in solid foods, coffee > rosemary extract, and red wine > strawberry juice > orange juice > sparkling white wine in liquid samples. Charge measurements by DPV, presented in equivalent units of Trolox and gallic acid, showed the same trend in liquid samples; however, for solid samples, the AC of rosemary extract was greater than that of coffee. The charge expressed in equivalent units showed a high, positive, and significant correlation (p < 0.001) with total phenols (0.7919), FRAP (0.8875), and ABTS (0.8366). The proposed electrochemical technique proves to be a fast, reliable, and environmentally friendly alternative or complement to evaluate antioxidant capacity in food, which is not affected by the turbidity or color of the samples.Graphical abstract

Analysis of catechol as an environmental pollutant based on electropolymerised methyl orange modified carbon paste sensor

ABSTRACT The present research work outlines a low-cost and green electrochemical approach for the assay of ecological toxin catechol (CT) based on electro-polymerised methyl orange (MO)-activated carbon paste electrode (CPE) as a responsive, simple and low-priced electrocatalyst. The CT electrochemical response was premeditated on the surface of poly methyl orange-activated carbon paste electrode (Poly(MO)ACPE) using different voltammetric methods such as cyclic voltammetry (CV) and differential pulse voltammetry (DPV) which recommends that the Poly(MO)ACPE shows good electrocatalytic nature for the electrochemical redox reaction of CT with high peak current response as associated to the bare carbon paste electrode (BCPE). The CT molecules expose electrochemical quasi-reversible reactions (oxidation and reduction nature) at Poly(MO)ACPE, which was done by a diffusion-controlled reaction kinetics. The practicability of this sensor was verified using the DPV method; here the CT peak current was improved with the varied concentration of CT in the range from 1.0 µM to 36.0 µM, and the corresponding limit of detection (LOD) and limit of quantification (LOQ) were 0.880 × 10−8 M and 2.935 × 10−8 M, respectively. The prepared sensor was efficiently tested with different interferents using the DPV method. Here, the sensor shows a lesser interference effect for the CT redox reaction nature. Finally, this sensor was applied for the analysis of CT in water and green tea samples, and the outcomes noticed a good CT recoveries.

Investigation of the Real-Time Release of Doxycycline from PLA-Based Nanofibers

Electrospun mats of PLA and PLA/Hap nanofibers produced by electrospinning were loaded with doxycycline (Doxy) through physical adsorption from a solution with initial concentrations of 3 g/L, 7 g/L, and 12 g/L, respectively. The morphological characterization of the produced material was performed using scanning electron microscopy (SEM). The release profiles of Doxy were studied in situ using the differential pulse voltammetry (DPV) electrochemical method on a glassy carbon electrode (GCE) and validated through UV-VIS spectrophotometric measurements. The DPV method has been shown to be a simple, rapid, and advantageous analytical technique for real-time measurements, allowing accurate kinetics to be established. The kinetics of the release profiles were compared using model-dependent and model-independent analyses. The diffusion-controlled mechanism of Doxy release from both types of fibers was confirmed by a good fit to the Korsmeyer–Peppas model.

The application of multi-walled carbon nanotubes modified pencil graphite electrode for voltammetric determination of favipiravir used in COVID-19 treatment.

This study describes the first application of an improved procedure on a pencil graphite electrode decorated with functionalized multi-walled carbon nanotubes (f-MWCNTs/PGE) for the determination of the COVID-19 antiviral drug, favipiravir (FVP). The electrochemical behavior of FVP at f-MWCNTs/PGE was examined by cyclic voltammetry and differential pulse voltammetry (DPV) methods, and it was noted that the voltammetric response significantly increased with the modification of f -MWCNTs to the surface. The linear range and limit of detection from DPV studies were determined as 1–1500 µM and 0.27 µM, respectively. In addition, the selectivity of the method was tested toward potential interferences, which can be present in pharmaceutical and biological samples, and it was found that f-MWCNTs/PGE showed high selectivity for the determination of FVP in the presence of probable interferences. The results with high accuracies and precisions from the obtained feasibility studies also revealed that the designed procedure can be used for accurate and selective voltammetric determination of FVP in real samples.

An electrochemical sensor for the detection of arsenic using nanocomposite-modified electrode

The aim of this research is to develop an electrochemical sensor based on a conducting polymer, polyaniline, and a cationic polymer, poly(diallyldimethylammonium chloride), reinforced with graphene oxide nanosheets functionalized with acrylic acid. The two-dimensional nature of acrylic acid functionalized graphene oxide nanosheets and clusters made of conductive polymers and acrylic acid functionalized graphene oxide nanosheets were confirmed by microscopic tests. The prepared nanocomposite was deposited on the glassy carbon electrode in order to prepare an electrochemical sensor for the detection of arsenic by cyclic voltammetry and differential pulse voltammetry methods. It should be mentioned that the presence of acrylic acid functionalized graphene oxide nanosheets increases the surface area due to the nano size effect and better dispersion of this nanomaterial, poly(diallyldimethylammonium chloride), increases the adsorption capacity of the analyte due to electrostatic interaction between the negatively charged analyte and positively charged surface, and polyanilin increases the charge transfer rate due to the good conductivity. The results show that the prepared electrode has a sensitivity equal to 1.79 A/M with 0.12 μM as the detection limit. The proposed sensor could be used for the determination of total inorganic arsenic by first oxidative pretreatment for conversion of As(III) to As(V).

A molecularly imprinted polymer-based electrochemical sensor for the determination of tofacitinib.

Tofacitinib citrate (TOF) is a Janus kinase-3 inhibitor used for rheumatoid arthritis treatment. In this study, a molecularly imprinted polymer (MIP)-based sensor was produced using acrylamide as the functional monomer via photopolymerization technique for the electrochemical determination of TOF. This study is the first one to explain the electrochemical determination of TOF with a highly selective MIP-based sensor. The surface characterization of the MIP-based sensor was performed with scanning electron microscopy and energy-dispersive X-ray spectroscopy methods, and it was expanded with electrochemical characterization by cyclic voltammetry and electrochemical impedance spectroscopy (EIS) methods. TOF determination was performed using differential pulse voltammetry (DPV) and EIS methods in standard solution and spiked serum sample in the linear range between 1×10-11 M and 1×10-10 M. Very low limit of detection and limit of quantification values were found, confirming the sensitivity of the sensor. Recovery analysis with spiked serum and tablet samples verified the sensor's accuracy and applicability using DPV and EIS methods. The selectivity of the sensor was confirmed with imprinting factor and interference studies, and the sensor performance was controlled using non-imprinted polymer for comparisonat every step.

Bimetallic Biogenic Pt-Ag Nanoparticle and Their Application for Electrochemical Dopamine Sensor

In this study, Silver-Platinum (Pt-Ag) bimetallic nanoparticles were synthesized by the biogenic reduction method using plant extracts. This reduction method offers a highly innovative model for obtaining nanostructures using fewer chemicals. According to this method, a structure with an ideal size of 2.31 nm was obtained according to the Transmission Electron Microscopy (TEM) result. The Pt-Ag bimetallic nanoparticles were characterized using Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffractometry (XRD), and Ultraviolet-Visible (UV-VIS) spectroscopy. For the electrochemical activity of the obtained nanoparticles in the dopamine sensor, electrochemical measurements were made with the Cyclic Voltammetry (CV) and Differential Pulse Voltammetry (DPV) methods. According to the results of the CV measurements taken, the limit of detection (LOD) was 0.03 µM and the limit of quantification (LOQ) was 0.11 µM. To investigate the antibacterial properties of the obtained Pt-Ag NPs, their antibacterial effects on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) bacteria were investigated. In this study, it was observed that Pt-Ag NPs, which were successfully synthesized by biogenic synthesis using plant extract, exhibited high electrocatalytic performance and good antibacterial properties in the determination of dopamine (DA).

A Cutting-Edge Sensor to Detect Clenbuterol in Animal Biological Fluids

This research work successfully synthesized the MF (MgFe2O4) material at various hydrothermal temperatures. The XRD, BET, SEM and EDX characterization techniques were employed to confirm the formation of MF-190. The electrochemical characteristics of the glassy carbon electrode (GCE) were investigated after dropping MF-190 material with nanoscale particles onto its surface zone to generate the modified electrode-MF/GCE. Moreover, by applying this modified MF-190 electrode, CBT (clenbuterol) signals were detected by using two electrochemistry techniques, CV (cyclic voltammetry) and DPV (differential pulse voltammetry). The MF/GCE described the great responsiveness to CBT signals using the DPV method with a LOD (limit of detection) and LOQ (limit of quantification) of 0.45 μM and 1.56 μM, compared to the bare GCE. The linear CBT concentration ranges from 1 to 50 μM. Several interferents such as NH4NO3, CaCl2, Na2SO4, uric acid, terbutaline, salbutamol and paracetamol did not affect the CBT signals within the modified electrode’s operation. Furthermore, this work shows that the determination of CBT in real purine samples with the RSD values (not higher than 4.45%) and the recovery values (97.7%–104.3%) was suitable. In addition, compared to the previous reports, this original research work would emphasize the novel detection of CBT via the MF/GCE with the costless, simple, reliable technique.

Graphene oxide/cellulose nanofibril composite: A high-performance catalyst for the fabrication of an electrochemical sensor for quantification of p-nitrophenol, a hazardous water pollutant

The detection and quantification of p-Nitrophenol in environmental samples are important for understanding the extent and impact of environmental pollution, protecting human health, ensuring regulatory compliance, and guiding remediation efforts. The main objective of this work was to investigate the electrochemical performance of a graphene oxide/cellulose nanofibril composite (GO/CNF) modified carbon paste electrode (GO/CNF/CPE) for the sensitive and reliable detection of p-nitrophenol in water samples. The transmission electron microscopy (TEM) technique was employed to enlighten the structure of nanocomposites. The electrochemical behavior of the fabricated electrochemical sensor was characterized via differential pulse voltammetry (DPV), linear sweep voltammetry (LSV), and electrochemical impedance spectroscopy (EIS). Under optimized analytical conditions, the peak current of the analyte showed a wide linear relationship with its concentration in a range of 3.0 nM–210 μM with a low amount of the limit of detection (LOD) value of 0.8 nM determined by the DPV method. The proposed electrochemical sensor demonstrated excellent sensitivity, selectivity, and accuracy metrics in real sample analysis of p-nitrophenol.

Yttria-zirconia electrochemical sensor for the detection of tyrosine

A simple enzyme-free electrochemical sensor, based on modified yttria-doped zirconium oxide screen-printed carbon electrode (SPCE) has been developed for the determination of tyrosine (Tyr). Firstly, the morphology, microstructure and the electrochemical characteristics of commercial yttria-doped zirconium oxides with different yttria loading (0–40 mol. %) were reported. Cyclic voltammetry (CV) tests performed in phosphate buffer solutions (0.01 M PBS; pH = 7.4) in the absence and the presence of Tyr showed that the modified Zr8Y/SPCE (containing 8 mol. % of yttria) exhibits better electrochemical properties compared to other electrodes investigated. Finally, the Zr8Y/SPCE sensor was tested for the detection of tyrosine by using the differential pulse voltammetry (DPV) method, providing a sensitivity of 0.140 μA μM−1cm−2 and a limit of detection (LOD) of 0.1 μM (at S/N = 3). The performed study shows excellent results for tyrosine detection in a real food supplement sample. The calculated relative standard deviation (RSD) was 1.41 %. To our knowledge, this is the first device developed with a commercial yttria-doped zirconia nanomaterial for the electroanalytical determination of tyrosine.

Simultaneous Detection of Naphthol Isomers with a 3D-Graphene-Nanostructure-Based Electrochemical Microsensor

Naphthol is a widely used chemical and medical detection biomarker, but it is harmful to human health and the environment. Therefore, a highly sensitive detection method for naphthol is urgently required. Herein, an electrochemical microsensor for the simultaneous detection of naphthol isomers was fabricated by the in situ growth of a three-dimensional graphene network (3DGN) on screen-printed electrodes. The microsensor exhibited good electrochemical sensing responses to typical isomers of naphthol (1-NAP and 2-NAP). Using the differential pulse voltammetry (DPV) method, the microsensor successfully realized the electrochemical detection of 1-NAP, 2-NAP, and naphthol isomer mixtures. Whether detecting naphthol isomers individually or simultaneously, the microsensor exhibited a good linear relationship for 1-NAP and 2-NAP in a wide range of concentrations. For the simultaneous detection of naphthol isomers, the limit of detection (LOD) of the microsensor to 1-NAP reached 10 nM, and the LOD for 2-NAP was about 20 nM. The microsensor also showed good selectivity, reproducibility, and stability. The simultaneous quantitative detection of 1-NAP and 2-NAP was also successfully achieved in synthetic urine samples.

An Efficient Electrochemical Biosensor to Determine 1,5-Anhydroglucitol with Persimmon-Tannin-Reduced Graphene Oxide-PtPd Nanocomposites

1,5-Anhydroglucitol (1,5-AG) is a sensitive biomarker for real-time detection of diabetes mellitus. In this study, an electrochemical biosensor to specifically detect 1,5-AG levels based on persimmon-tannin-reduced graphene oxide-PtPd nanocomposites (PT-rGO-PtPd NCs), which were modified onto the surface of a screen-printed carbon electrode (SPCE), was designed. The PT-rGO-PtPd NCs were prepared by using PT as the film-forming material and ascorbic acid as the reducing agent. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV-vis), and X-ray diffraction (XRD) spectroscopy analysis were used to characterise the newly synthesised materials. PT-rGO-PtPd NCs present a synergistic effect not only to increase the active surface area to bio-capture more targets, but also to exhibit electrocatalytic efficiency to catalyze the decomposition of hydrogen peroxide (H2O2). A sensitive layer is formed by pyranose oxidase (PROD) attached to the surface of PT-rGO-PtPd NC/SPCE. In the presence of 1,5-AG, PROD catalyzes the oxidization of 1,5-AG to generate 1,5-anhydrofuctose (1,5-AF) and H2O2 which can be decomposed into H2O under the synergistic catalysis of PT-rGO-PtPd NCs. The redox reaction between PT and its oxidative product (quinones, PTox) can be enhanced simultaneously by PT-rGO-PtPd NCs, and the current signal was recorded by the differential pulse voltammetry (DPV) method. Under optimal conditions, our biosensor shows a wide range (0.1-2.0 mg/mL) for 1,5-AG detection with a detection limit of 30 μg/mL (S/N = 3). Moreover, our electrochemical biosensor exhibits acceptable applicability with recoveries from 99.80 to 106.80%. In summary, our study provides an electrochemical method for the determination of 1,5-AG with simple procedures, lower costs, good reproducibility, and acceptable stability.

4-Mercaptopyridine-Modified Sensor for the Sensitive Electrochemical Detection of Mercury Ions

As a highly toxic heavy metal ion, mercury ion (Hg2+) pollution has caused serious harm to the environment and human health. In this paper, 4-mercaptopyridine (4-MPY) was selected as the sensing material and decorated on the surface of a gold electrode. Trace Hg2+ could be detected by both differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) methods. The proposed sensor displayed a wide detection range from 0.01 μg/L to 500 μg/L with a low limit of detection (LOD) of 0.002 μg/L by EIS measurements. Combined with molecular simulations and electrochemical analyses, the chelating mechanism between Hg2+ and 4-MPY was explored. Through the analysis of binding energy (BE) values and stability constants, 4-MPY showed an excellent selectivity for Hg2+. In the presence of Hg2+, the coordination of Hg2+ with the pyridine nitrogen of 4-MPY was generated at the sensing region, which caused a change in the electrochemical activity of the electrode surface. Due to the strong specific binding capability, the proposed sensor featured excellent selectivity and an anti-interference capability. Furthermore, the practicality of the sensor for Hg2+ detection was validated with the samples of tap water and pond water, which demonstrated its potential application for on-site environmental detection.

AIEE Active Azomethine-Based Rhodamine Derivative For Ultrasensitive Multichannel Detection of Au3+ Through a Fluorimetrically, Electrochemically, and RGB-Based Sensing Assay.

In this study, a novel rhodamine-based optically and electrochemically active chemosensor, integrated with a p-DMAC moiety, demonstrated extremely selective identification of Au3+ ions relative to other metal species, including (Li+, Na+, K+, Ba2+, Ca2+, Mg2+, Co2+, Mn2+, Zn2+, Pb2+, Ni2+, Fe2+, Hg2+, Fe3+, Cd2+, Pd2+, Al3+, Cr3+, Cu2+, and nitrate salt of Ag+). These compounds demonstrated a novel and outstanding aggregation-induced emission enhancement (AIEE) behavior by aggregating in DMF/H2O medium. Furthermore, the degree of quenching was varying linearly with a Au3+ concentration from 0 to 40 nM, with a lower detection limit by RH-DMAC nanoaggregates of 118.79 picomolar (40.35 ppm). The Stern-Volmer plots, Job's plot, Benesi-Hildebrand plot, 1H NMR titrations, ESI-mass, and FTIR all revealed significant interactions between the sensor and Au3+. Moreover, the proposed electrochemical sensor afforded a linear correlation before the peak current and concentration of Au3+ in the range of 0-40 nM, with a detection limit of 483.73 pM or 164.36 ppt (by cyclic voltammetry method) and 298.0 pM or 101.24 ppt (by the Differential Pulse Voltammetry method). Furthermore, the proposed sensing assay was used to measure Au3+ ion in spiked water samples (tap, drinking, waste, and river water), achieving acceptable accuracy and precision with high recovery rates. Furthermore, RH-DMAC-coated fluorescence paper test strips were designed for on-site Au3+ detection. Apart from this, the use of smartphone-based RGB (Red Green Blue) color analysis shortened the operating process, accelerated the detection technique, and provided a novel methodology for the instantaneous, real-time examination of Au3+ in real water samples.

Voltammetric determination of hydrochlorothiazide at a modified carbon paste electrode with polypyrrole nanotubes.

In this paper, the electrochemical behavior of hydrochlorothiazide (HCTZ) is described using carbon paste electrodes modified with polypyrrole nanotubes (PPy-NTs/CPEs) at pH value 7. Experiments revealed that the presence of HCTZ greatly impacts the electrochemical behavior of modified CPEs. The synthesized PPy-NTs were utilized as a sensing material for the electrochemical detection of HCTZ and were investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and chronoamperometry. The key experiment conditions, including supporting electrolyte and electrolyte pH, were studied and optimized. Under optimized conditions, the prepared sensor displayed the linear relationships for the concentrations of HCTZ from 5.0 to 400.0 μM (R2 = 0.9984). The detection limit of the PPy-NTs/CPEs sensor was found to be 1.5 μM using the DPV method. The PPy-NTs is highly selective, stable and sensitive for the determination of HCT. Therefore, we believe the newly prepared PPy-NTs material can be useful for different electrochemical applications.

Detection of Levofloxacin Using a Simple and Green Electrochemically Polymerized Glycine Layered Carbon Paste Electrode

The easy and rapid analytical tool, electrochemically polymerized (EP) glycine (GN) layered carbon paste electrode (LCPE), was used for the analysis of levofloxacin (LN) using cyclic voltammogram (CV) and differential pulse voltammetry (DPV). The surface features and activities of the electrochemical sensors EPGNLCPE and bare carbon paste electrode (BCPE) were analyzed using electrochemical impedance spectroscopy (EIS), field emission scanning electron microscopy (FE-SEM), CV and DPV methods. The modified sensor (EPGNLCPE)offers a vibrant and sensitive electrochemical LN oxidation peak by controlling overpotential and the electrode material fouling effect unlike BCPE. Under improved experimental conditions, the DPV method was used to analyze LN on EPGNLCPE by varying its concentration in 0.2 M phosphate buffer solution from 30 to 90 µM, resulting in a good linear relationship(between peak current and concentration), lower limit of detection (LOD: 8.436 × 10−7 M) and lower limit of quantification (LOQ: 2.812 × 10−6 M). Finally, real-time application of the sensor was tested by analyzing LN in medicinal samples, and good LN recovery was observed.

Construction of isoniazid pharmaceutical logic system based on poly(N, N-diethylacrylamide) hydrogel films

In this work, poly(N,N-diethylacrylamide) (PDEA) hydrogel films were polymerized on glassy carbon (GC) electrode surface, and isoniazid (INH) was chosen as an electroactive pharmaceutical molecule probe, aiming to investigate the switchable electrochemical behaviors of INH. Determining the contents of INH tablets under different external stimuli conditions and constructing its logic gate computing systems. The triple-sensitive electrochemical CV behaviors of INH on this film system toward pH, temperature and salt concentration were observed and explored. Thus, a 3-input/8-output combinational pharmaceutical logic gate network and a 3-to-8 decoder were designed and constructed based on the stimulus-responsive characteristics of the electrochemical response of INH on PDEA hydrogel-modified electrodes. Besides, the relationship between the oxidation peak current (Ipa) and concentration of INH (CINH) was studied by the differential pulse voltammetry (DPV) method. Apply this film system, and the INH tablets could be switchable detected. The construction of the logic-gate computing system based on isoniazid drug molecule may provide a novel approach and model to design new style drug sensors, which might be applied to intelligent medical diagnostics and drug release.

Perovskite lanthanum nickelate nanoparticles: As effective modified screen printed carbon electrode for electrochemical detection of trifluoperazine

Perovskite rare earth nickelates have recently been considered excellent electroanalytical features for sensing a variety of target molecules due to their distinctive properties. In this work, a facile coprecipitation synthesis of perovskite lanthanum nickelate (LaNiO3, LNO) nanoparticles was reported along with its application to the electrochemical sensing of trifluoperazine (TFP). The crystal structure and surface morphology of the LNO was characterized by suitable techniques such as X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) with energy-dispersive X-ray (EDX) analysis. The capability of the modified screen printed carbon electrode (LNO/SPCE) to detect TFP in 0.1 M PBS (pH 7) was then examined using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods. The electrode modified at 0.759 V vs Ag/AgCl and 30 s exhibited the highest peak current (Ip) for TFP electrooxidation. This optimized electrode showed a broad linear range of 0.165–495.5 µM, a low limit of detection (LOD) of 0.017 µM, and a good sensitivity of 0.704 µA µM–1 cm–2. Moreover, the fabricated sensor revealed promising anti-interfering ability, stability, reproducibility, and repeatability toward TFP detection. Finally, the LNO sensor was able to detect TFP in urine and serum samples, and the recovery rates were satisfactory.

Electrochemical detection and quantification of catechol based on a simple and sensitive poly(riboflavin) modified carbon nanotube paste electrode

In the present research work, selective and sensitive catechol (CT) detection and quantification were shown in the presence of resorcinol (RS) in 0.2 M phosphate buffer (PB) solution by preparing a low-cost, simple, and green carbon nanotube paste electrode (CNTPE) surface activated with electropolymerized riboflavin (PRF). The morphological, conductivity, and electrochemical features of the modified electrode (PRFMCNTPE) and bare carbon nanotube paste electrode (BCNTPE) materials were analyzed using electrochemical impedance spectroscopy (EIS), field emission scanning electron microscopy (FE-SEM), cyclic voltammetry (CV), and differential pulse voltammetry (DPV). The PRF-activated electrode displays outstanding sensitivity, stability, selectivity, reproducibility, and repeatability for the redox feature of CT with improved electrochemical current and declined electrochemical potential compared to BCNTPE. The peak currents of CT are correlated to the different CT concentrations (CV method: 6.0–60.0 μM & DPV method: 0.5–7.0 μM), and the obtained detection limit (DL) and quantification limit (QL) are found to be 0.025 μM and 0.085 μM (CV method) and 0.0039 μM and 0.0132 μM (DPV method), respectively. The prepared PRFMCNTPE material was advantageous for the examination of CT in environmentally important tap water sample as a real-time application.

H-rGO-Pd NPs Nanozyme Enhanced Silver Deposition Strategy for Electrochemical Detection of Glypican-3

Glypican-3 (GPC3), as an emerging biomarker, has been shown to be beneficial for the early diagnosis and treatment of hepatocellular carcinoma (HCC). In this study, an ultrasensitive electrochemical biosensor for GPC3 detection has been constructed based on the hemin-reduced graphene oxide-palladium nanoparticles (H-rGO-Pd NPs) nanozyme-enhanced silver deposition signal amplification strategy. When GPC3 specifically interacted with GPC3 antibody (GPC3Ab) and GPC3 aptamer (GPC3Apt), an "H-rGO-Pd NPs-GPC3Apt/GPC3/GPC3Ab" sandwich complex was formed with peroxidase-like properties which enhanced H2O2 to reduce the silver (Ag) ions in solution to metallic Ag, resulting in the deposition of silver nanoparticles (Ag NPs) on the surface of the biosensor. The amount of deposited Ag, which was derived from the amount of GPC3, was quantified by the differential pulse voltammetry (DPV) method. Under ideal circumstances, the response value was linearly correlated with GPC3 concentration at 10.0-100.0 μg/mL with R2 of 0.9715. When the GPC3 concentration was in the range from 0.01 to 10.0 μg/mL, the response value was logarithmically linear with the GPC3 concentration with R2 of 0.9941. The limit of detection was 3.30 ng/mL at a signal-to-noise ratio of three and the sensitivity was 1.535 μAμM-1cm-2. Furthermore, the electrochemical biosensor detected the GPC3 level in actual serum samples with good recoveries (103.78-106.52%) and satisfactory relative standard deviations (RSDs) (1.89-8.81%), which confirmed the applicability of the sensor in practical applications. This study provides a new analytical method for measuring the level of GPC3 in the early diagnosis of HCC.