New Insights on Potentiometric Immunosensor at Carbon Fiber Microelectrode for Alpha-Fetoprotein in Hepatocellular Carcinoma

Herein, we investigated the analytical features of potentiometric immunosensors for detection of alpha-fetoprotein (AFP) in hepatocellular carcinoma at different electrodes, such as carbon fiber microelectrode (CFME) and carbon-disk electrode (CDE), respectively. To construct such an immunosensor, anti-AFP capture antibodies were first conjugated covalently onto the activated electrodes through typical carbodiimide coupling. Thereafter, one-step immunoreaction protocol was successfully introduced to develop a new potentiometric immunoassay upon addition of AFP. Accompanying the antigen-antibody reaction, the surface charges of the modified electrodes were changed for the readout of electric potential. Results indicated that the linear range of CDE-based immunosensor was 0.1–100 ng mL⁻¹ AFP, whereas the assay sensitivity by using CFME could be further increased to 3.2 pg mL⁻¹ with the linear range from 0.01 to 500 ng mL⁻¹ AFP. Meanwhile, CFME-based immunosensor showed high sensitivity, good reproducibility and specificity, and could be utilized for the analysis of human serum specimens with consistent results relative to commercialized ELISA kit.     

FeS2−AuNPs Nanocomposite as Mimicking Enzyme for Constructing Signal‐off Sandwich‐type Electrochemical Immunosensor Based on Electroactive Nickel Hexacyanoferrate as Matrix

In this work, a novel sandwich‐type electrochemical immunosensor with electroactive nickel hexacyanoferrate nanoparticles (NiHCFNPs) as matrix was constructed for α‐fetoprotein (AFP) detection in a signal‐off manner by using FeS₂?AuNPs nanocomposite catalyzed insoluble precipitation to significantly inhibit the electrochemical signal. Initially, the NiHCFNPs with excellent electrochemical property was modified on the electrodeposited nano‐Au electrode to obtain a strong initial electrochemical signal. Subsequently, another nano‐Au layer was formed for immobilization of capture antibody (Ab₁). In the presence of target AFP, the prepared FeS₂?AuNPs‐Ab₂ bioconjugate could be specifically recognized and immobilized on electrode through the sandwich‐type immunoreaction. The FeS₂ with large specific surface areas were used as scaffolds to load abundant mimicking enzyme AuNPs. With the help of hydrogen peroxide (H₂O₂), FeS₂?AuNPs with peroxidase‐like activity accelerated the 4‐chloro‐1‐naphthol (4‐CN) oxidation with generation of insoluble precipitation on electrode, which would greatly hinder the electron transfer and thus caused the decrease of electrochemical signal for quantitative determination of AFP. This approach achieved a wide dynamic linear range from 0.0001 to 100 ng mL^?1 with an ultralow limit detection of 0.028 pg mL^?1. Especially, the proposed AFP immunosensor can be applied to detect human serum samples with satisfactory results, indicating a potential application in clinical monitoring of tumor biomarkers.     

Biomolecule‐Doped Organic/Inorganic Hybrid Nanocomposite Film for Label‐Free Electrochemical Immunoassay of α‐1‐Fetoprotein

A new electrochemical immunosensor for the detection of α‐1‐fetoprotien (AFP) was developed based on AFP antibody (anti‐AFP)‐functionalized organic/inorganic hybrid nanocomposite membrane. To fabricate such a hybrid composite membrane, 3,4,9,10‐perylenetetracarboxylic acid‐bound thionine molecules (PTCTH) were initially doped into titania colloids (TiO₂), and then gold nanoparticles and anti‐AFP were immobilized onto the composite film in turn. Comparison with the electrode fabricated only with thionine not 3,4,9,10‐perylenetetracarboxylic acid, the immunosensor with PTCTH exhibited high sensitivity and fast electron transfer. The presence of gold nanoparticles provided a good microenvironment for the immobilization of biomolecules, enhanced the surface coverage of protein, and improved the sensitivity of the immunosensor. The modified process was characterized by scanning electron microscope (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The surface topography of the membrane was investigated by scanning electron microscopy (SEM). Under optimal conditions, the proposed immunosensor exhibited a wide linear range from 2.5 to 200.0 ng/mL towards AFP with a detection limit of 0.5 ng/mL (S/N=3). The stability, reproducibility and precision of the immunosensor were acceptable. Comparison with the conventional enzyme‐linked immunosorbent assay (ELISA), the present method did not require more labeled procedures and washing steps. Significantly, the detection methodology provides a promising approach for other proteins or biosecurities.     

Highly Sensitive Electrochemical Immunosensor Based on Mesoporous PdPt Nanoparticles Anchored on a Three-dimensional PANI@CNTs Network as Nanozyme Labels

In this study, a novel strategy to amplify electrochemical signals by mesoporous PdPt nanoparticles with core-shell structures anchored on a three-dimensional PANI@CNTs network as nanozyme labels (PdPt/PANI@CNTs) was proposed for the sensitive monitoring of α-fetoprotein (AFP, Ag). First, the mesoporous PdPt nanoparticles prepared by a facile chemical reduction method had excellent biocompatibility with biomolecules, which could capture a large amount of AFP-Ab₂ (Ab₂) and exhibit plentiful pores to entrap more thionine (Thi) into mesoporous PdPt nanoparticles with enhanced loading and abundant active sites. Furthermore, the resulting mesoporous PdPt nanoparticles were abundantly dotted on the surface of a three-dimensional PANI@CNTs network with excellent conductivity and a high specific surface area through the bonding of the amino group to form PdPt/PANI@CNTs nanozyme labels. Most importantly, the as-prepared PdPt/PANI@CNTs nanozyme labels exhibited unexpected enzyme-like activity towards the reduction of hydrogen peroxide owing to the highly indexed facets, enhancing the current response to realize signal amplification. In view of the advantages of nanozyme labels and the involvement of gold nanoparticles (AuNPs, which behave as electrode materials) for the sensitive determination of AFP, the as-developed immunosensor could obtain a dynamic working range of 0.001 ng mL^−1–100.0 ng mL⁻¹ at a detection limit of 0.33 pg mL⁻¹ via DPV (at 3σ). Furthermore, the nanozyme-based electrochemical immunosensor exhibited remarkable analytical performance, which brought about feasible ideas for disease diagnosis in the future.     

Electro‐nano Diagnostic Platforms for Simultaneous Detection of Multiple Cancer Biomarkers

In this study, a bimetallic nanomaterial‐based electrochemical immunosensor was developed for the detection of carcinoembryonic antigen (CEA) and vascular endothelial growth factor (VEGF) cancer biomarkers at the same time. CEA and VEGF biomarkers are indicators for colon and breast cancers and stomach cancers, respectively. During the study, gold nanoparticle (AuNp), lead nanoparticle (PbNp), copper nanoparticle (CuNp) and magnetic gamma iron(III)oxide (γFe₂O₃ Np) were synthesized, characterized and used together for the first time in the structure of an electrochemical biosensor based on anti‐CEA and anti‐VEGF. For this purpose, Au SPE based sandwich immunosensor was fabricated by using labeled anti‐CEA (labeled with Pb⁺²) and labeled anti‐VEGF (labeled with Cu⁺²). As a result, CEA and VEGF biomarkers were detected following the oxidation peaks of label metals (Pb⁺² and Cu⁺²) by using differential pulse voltammetry. After the experimental parameters were optimized, the linear range was found in the concentration range between 25 ng/mL and 600 ng/mL with the relative standard deviation (RSD) value of (n=3 for 600 ng/mL) 3.33 % and limit of detection (LOD) value of 4.31 ng/mL for CEA biomarker. On the other hand, the linear range was found in the concentration range between 0.2 ng/mL and 12.5 ng/mL with the RSD value of (n=3 for 12.5 ng/mL) 5.31 % and LOD value of 0.014 ng/mL for VEGF biomarker. Lastly, sample application studies for synthetic plasma sample and interference studies with dopamine, ascorbic acid, BSA, cysteine and IgG were carried out.     

On‐Off PVC Membrane Based Potentiometric Immunosensor for Label‐Free Detection of Alpha‐Fetoprotein

A poly(vinylchloride) (PVC) membrane based potentiometric immunosensor for the direct detection of alpha‐fetoprotein (AFP) has been developed. First, Au colloid particle was chemisorbed upon amino groups of o‐phenylenediamine, which were dissolved in plasticized PVC membrane. Then alpha‐fetoprotein antibody (anti‐AFP) was immobilized upon the surface of the Au colloid particle to prepare a potentiometric AFP immunosensor. The Au colloid particle modified PVC membrane was characterized by digital photo and transmission electron microscope (TEM). The immunosensor exhibited fast potentiometric response (≤4 min) and showed specific response to AFP in the range of 4.9 to 158.5 ng/mL with a correlation coefficient of 0.9971 and a detection limit of 1.6 ng/mL. The factors influencing the performance of the immunosensor were also studied in detail. Moreover, the proposed method is economical and efficient as well as potentially attractive for clinical immunoassays.     

A novel α-fetoprotein-MIP immunosensor based on AuNPs/PTh modified glass carbon electrode

A new alpha-fetoprotein-MIP (AFP-MIP) immunosensor based on glass carbon electrode (GCE) modified with polythionine (PTh) and gold nanoparticles (AuNPs) was successfully prepared for the sensitive detection of AFP. The AFP-MIP immunosensor presented a facile preparation, low sample consumption, and good stability, and could become a new promising method for the detection of AFP.     

Electrochemical Immunosensor Made with Zein-based Nanofibers for On-site Detection of Aflatoxin B1

A disposable electrochemical immunosensor for on-site detection of aflatoxin B1(AFB1), one of the most toxic mycotoxins in agri-food products, was fabricated through a low-cost cut-printing method and then modified with zein/polypyrrole(PPy) electrospun nanofibers onto which anti-AFB1 monoclonal antibodies were immobilized covalently. Fabrication was possible with an innovative and simple approach to adsorb nanofibers onto the working electrode during electrospinning. Electrochemical impedance spectroscopy was employed as the principle of detection, and the data collected with a portable potentiostat were treated with information visualization techniques. The nanostructured immunosensor showed a high sensitivity for AFB1 with a linear detection range from 0.25 to 10 ng mL⁻¹ and a theoretical limit of detection of 0.092 ng mL⁻¹, which is adequate to detect AFB1 in food, according to regulatory agencies.     

A Dendrimer Supported Electrochemical Immunosensor for the Detection of Alpha‐feto protein – a Cancer Biomarker

The electrochemical detection of alpha‐feto protein based on novel gold nanoparticles‐ poly(propylene imine) dendrimer platform is reported. The platform was prepared by co‐electrodeposition of gold nanoparticles and generation 3 poly (propylene imine) dendrimer on a glassy carbon electrode. Each modifying step was characterised by cyclic voltammetry and electrochemical impedance spectroscopy. The electrochemical measurements showed that the platform was stable, conducting and exhibited reversible electrochemistry. Results obtained from the electrochemical impedance spectroscopy interrogation in [Fe(CN)₆^3−/4−] redox probe showed a marked reduction in charge transfer resistance (R_ct) after each modification step. The immunosensor was prepared by immobilisation of a probe anti‐alpha feto protein (AFP) on the platform for 3 hrs at 35 °C followed by blocking the surface with bovine serum albumin to minimise non‐specific binding. The prepared immunosensor was used to detect AFP over a wide concentration range from 0.005 to 500 ng/mL and detection limits of 0.0022 and 0.00185 ng/mL were obtained for SWV and EIS measurements respectively. The immunosensor gave good stability over a period of fourteen days when stored at 4 °C.     

Sandwich-type electrochemiluminescence immunosensor based on Ru-silica@Au composite nanoparticles labeled anti-AFP

A simple and sensitive sandwich-type electrochemiluminescence immunosensor for α-1-fetoprotein (AFP) on a gold nanoparticles (nano-Au) modified glassy carbon electrode (GCE) was developed by using Ru-silica (Ru(bpy)₃²⁺-doped silica) doped Au (Ru-silica@Au) composite as labels. The primary antibody, anti-AFP was first immobilized on the gold nanoparticles modified electrode due to the covalent conjugation, then the antigen and the Ru-silica@Au composite nanoparticles labeled secondary antibody was conjugated successively to form a sandwich-type immunocomplex through the specific interaction. The surfaces of Ru-silica nanoparticles were modified via the assemble of Au nanoparticles. The prepared Ru-silica@Au composite nanoparticles own the large surface area, good biocompatibility and highly effective electrochemiluminescence properties. The morphologies of the Ru-silica@Au composite nanoparticles were investigated by using transmission electronic microscope (TEM). The Ru-silica@Au composite nanoparticles labeled anti-AFP/AFP/bovine serum albumin (BSA)/anti-AFP/nano-Au modified GCE electrode was evaluated by means of cyclic voltammetry (CV) and electrogenerated chemiluminescence (ECL). The immunosensor performed high sensitivity and wide liner for detection AFP in the range of 0.05-50 ng/mL and the limit detection was 0.03 ng/mL (defined as S/N = 3).     

基于金粒子修饰二硫化钼纳米复合材料的电化学发光免疫传感器的构建及其应用研究

生物标志物的快速、精准检测对控制和预防疾病或病毒的暴发具有重要意义。该研究将三维花状Au@(MoS2/GO/o-MWNTs)纳米复合物(AMGMs)作为一种理想的基底,利用“三明治”免疫夹心组装法构筑一种高灵敏的电化学发光免疫传感器,并用于前列腺特异性抗原(PSA)的高灵敏检测。AMGMs不仅具有良好的导电性和生物相容性,其三维花状的立体结构可提供更多活性位点并加载更多抗体,显著增加了传感器的响应信号。采用电化学交流阻抗法和循环伏安法对组装过程进行跟踪,证实了该传感器组装的可行性,并采用电化学发光法研究了传感器对底液中不同浓度PSA的响应。结果表明,该传感器实现了对肿瘤标志物PSA的灵敏检测,其线性范围为0.1 pg/mL~50 ng/mL,检出限(S/N=3)为0.1 pg/mL,对实际样品的加标回收率为98.2%~106%。该方法的准确度良好,可为临床PSA检测提供准确可靠的新方法。     

Amperometric Immunosensor for the Determination of α‐1‐Fetoprotein Based on Core‐Shell‐Shell Prussian Blue‐BSA‐Nanogold Functionalized Interface

In the present work, a newly functional nanoparticle has been prepared to immobilize the protein for the detection of α‐1‐fetoprotein (AFP). Prussian blue (PB) nanoparticle was initially synthesized under ultrasonic condition, then bovine serum albumin (BSA) was used to coat the PB nanoparticle to improve the stability of the PB nanoparticle as well as functionalize the surface of PB nanoparticle, and then gold colloids were loaded on the BSA‐coated PB nanoparticle to construct a core‐shell‐shell nanostructure via the conjunction of thiolate linkages or alkylamines of the BSA. Finally, a convenient, effective and sensitivity amperometric immunosensor for the detection of α‐1‐fetoprotein (AFP) was constructed by the employment of these functional core‐shell‐shell microspheres. The preparation of the nanoparticle (Au‐BSA‐PB NPs) was characterized by transmission electron microscopy (TEM), and the assembly of the biosensor was characterized with cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The dynamic range of the resulted immunosensor for the detection of AFP is from 0.02 ng/mL to 200.0 ng/mL with a detection limit of 0.006 ng/mL (S/N=3). Moreover, this biosensor displays good selectivity, stability and reproducibility.     

Detection of cortisol at a gold nanoparticle|Protein G-DTBP-scaffold modified electrochemical immunosensor

An ultrasensitive electrochemical immmunosensor was demonstrated to be capable of detecting the hormone cortisol down to concentrations as low as 16 pg mL(-1). In addition, the immunosensor displayed a sensitivity of 1.6 μA pg(-1) mL(-1) and a linear range up to ～2500 pg mL(-1) of cortisol. This immunosensor was constructed based on a Au nanoparticle|dimethyl 3,3'-dithiobispropionimidate·2HCl (DTBP)-Protein G scaffold-modified Au electrode. In this work, the Au nanoparticles were used to increase the electrochemically active surface area by 28% (with a standard deviation of 3%) to enhance the quantity of the Protein G scaffold on the electrode. Thiolation of Protein G by DTBP aided in avoiding the confirmation change of Protein G, while this Protein G-DTBP component offered an orientation-controlled immobilisation of the capture antibody on the Au electrode. In this immunosensor, a monoclonal anti-cortisol capture antibody was optimally aligned by the scaffold before a competitive immunoassay between sample cortisol and a horseradish peroxidase-labelled cortisol conjugate was conducted. For quantitative analysis, square wave voltammetry was used to monitor the reduction current of benzoquinone produced from a horseradish peroxidase catalysed reaction. The improved analytical performance of our immunosensor was attributed to the synergetic effect of Au nanoparticles and the Protein G-DTBP scaffold.     

A novel electrochemical immunosensor using β-cyclodextrins functionalized silver supported adamantine-modified glucose oxidase as labels for ultrasensitive detection of alpha-fetoprotein

In this work, a novel sandwich-type electrochemical immunosensor based on host-guest interaction was fabricated for the detection of alpha-fetoprotein (AFP). Due to the large specific surface area of multiwalled carbon nanotubes and the unique supramolecular recognition ability of β-cyclodextrins, ferrocenecarboxylic acid (Fc) was incorporated into this sensor platform by host-guest interaction to generate an electrochemical signal. And β-cyclodextrins functionalized silver supported adamantine-modified glucose oxidase (GOD-CD-Ag), was used as a label to improve the analytical performance of the immunosensor by the dual amplification strategy. The obtained GOD-CD-Ag conjugates could convert glucose into gluconic acid with the formation of hydrogen peroxide (H₂O₂). And then silver nanoparticles could in situ catalyze the reduction of the generated H₂O₂, dramatically improving the oxidation reaction of Fc. The developed immunosensor shows a wide linear calibration range from 0.001 to 5.0 ng/mL with a low detection limit (0.2 pg/mL) for the detection of AFP. The method, with ideal reproducibility and selectivity, has a wide application prospect in clinical research.     

Capacitance Polypyrrole‐based Impedimetric Immunosensor for Interleukin‐10 Cytokine Detection

In the present study, we developed a novel label‐free capacitance impedimetric immunosensor based on the immobilization of the human monoclonal antibody anti‐interleukin‐10 (anti‐IL‐10 mAb) onto polypyrrole (PPy)‐modified silicon nitride (Si₃N₄) substrates. The immunosensor was used for the detection of the recombinant interleukin‐10 antigen (rh IL‐10) that may be secreted in patients at the early stage of inflammation. The immunosensor was created by chemical deposition of PPy conducting layer on pyrrole?silane (SPy)‐treated Si/SiO₂/Si₃N₄ substrates (Si/SiO₂/Si₃N₄?SPy), followed by anti‐IL‐10 mAb immobilization through carboxyl‐functionalized diazonium (CMA) protocol and carbodiimide chemistry. The surface characterization and the biofunctionalization steps were characterized by SEM, FTIR and cyclic voltammetry (CV) while the detection process was carried out by using electrochemical impedance spectroscopy (EIS) analyses. The created immunosensor showed two linear fittings (R²=0.999) for the detection of rh IL‐10 within the concentration range from 1–50 pg/mL. It exhibited high sensitivity (0.1128 (pg/mL)^?1) with a very low limit of detection (LOD)=0.347 pg/mL, more particularly, at the low concentration range (1–10 pg/mL). Thus, this developed polypyrrole‐based immunosensor represents a promising strategy for creation of miniaturized label‐free, fast and highly sensitive biosensors for diagnosis of inflammation biomarkers at very low concentrations with reduced cost.     

Disposable Amperometric A-fetoprotein Immunosensor Based on the Biocompatible Silk Protein Membranes-Modified Indium Tin Oxide Electrodes

A simple and disposable electrochemical immunosensor for detection of 68 kDa alpha-fetoprotein (AFP) was fabricated based on films of silk fibroin protein membrane (SFPM)/Prussian blue (PB)/deposition of gold nanoparticles (DpAu). First, DpAu and PB were electrochemically deposited successively on the surface of indium tin oxide (ITO) electrode. Then, SFPM with excellent biocompatibility was modified on the surface of PB/DpAu/ITO. The SFPM could form a stable matrix on the electrode surface for the deposition of immunoactive agents. More importantly, the SFPM could prevent the possible leakage of electron mediator and enhance the stability of immunosensor. Scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were used to characterize the assembly process of the modified electrode. The linear range of the proposed immunosensor extended from 1.0 to 200.0 ng/mL for detection of AFP with a detection limit of 0.6 ng/mL. Moreover, the CV test demonstrated the immunosensor exhibited acceptable reproducibility and stability. This composite membrane could be applied for the detection of different biomarkers, diagnosis, and monitoring of carcinoma.

[Supplementary materials are available for this article. Go to the publisher's online edition of Analytical Letters for the following free supplemental resources: additional figures.]     

Electrochemical Immunosensor for Lactate Dehydrogenase Detection Through Analyte-driven Catalytic Reaction on Multi-walled Carbon Nanotubes and Gold Nanoparticle Modified Carbon Electrode

A novel electrochemical immunosensor for lactate dehydrogenase (LDH) detection was proposed based on analyte-driven catalytic reaction by attaching LDH antibodies on multi-walled carbon nanotubes (MWCNTs) and gold nanoparticles (AuNPs) modified glassy carbon electrodes (GCE). As LDH was captured by the antibodies on electrode surface, it catalyzed the formation of pyruvate and the reduced form of nicotinamide adenine dinucleotide (NADH), thus a sensitive electrochemical signal obtained from the above redox reaction was recorded by differential pulse voltammetry (DPV). Under optimum conditions, the developed immunosensor exhibits high sensitivity for LDH quantification ranging from 0.001 μg/mL to 0.5 μg/mL with a low detection limit at 0.39 ng/mL. This developed immunosensor reveals ideal accuracy and feasibility for LDH detection in Streptococcus uberis (S. uberis) induced bovine mammary epithelial cells (MECs) samples by comparison with conventional commercial kit, which shows remarkably application potential in diseases diagnosis.     

基于纳米银与有机多孔材料/纳米金修饰的甲胎蛋白免疫传感器研究

在金电极表面电沉积银为氧化还原探针,利用有机多孔材料(PTC-NH2)、纳米金(nano-Au)固载甲胎蛋白抗体(anti-AFP),制备出用于检测甲胎蛋白(AFP)的安培型免疫传感器。通过交流阻抗技术、循环伏安法研究了电极的电化学特性,考察了孵育时间、测试液pH值等实验条件对传感器性能的影响,并利用扫描电子显微镜(SEM)对电极的修饰过程进行了表征。该传感器对AFP有良好的电流响应,线性范围分别为1.0～20.0ng/mL和20.0～60.0 ng/mL,检测限为0.6 ng/mL。     

双重信号放大的竞争型免疫传感器的制备及其应用于瘦肉精检测的研究

制备了葡萄糖氧化酶(GOD)-克伦特罗(Clenbuterol, CB)功能纳米复合物, 并采用共价键合和温育组装等方法构建了双重信号放大的竞争型免疫传感器. 研究了GOD 催化氧化葡萄糖和普鲁士蓝(PB)催化还原H2O2 双重信号放大的反应机理和传感器检测CB 的作用机制. 用扫描电子显微镜(SEM)等方法表征了纳米复合材料的形貌和复合物中GOD的活性, 复合物中的GOD 保持了良好的电催化性能和酶动力学响应, 并且符合米氏动力学方程. 最佳实验条件下, 该免疫传感器对盐酸克伦特罗的检测线性范围为0.01～100 ng/mL, 检测限达4.50 pg/mL. 实验结果表明, 该传感器对瘦肉精克伦特罗的检测具有灵敏度高, 特异性强, 重现性好, 线性范围宽和检测限低等优点. 将该方法用于猪肝样品的分析, 加标样品回收率在97.5%～102%之间. 该研究为瘦肉精及β-受体兴奋剂的分析提供了一种新方法.     

Fabrication of Electrochemical Immunosensor for Detection of Interleukin 8 Biomarker via Layer-by-layer Self-assembly Process on Cost-effective Fluorine Tin Oxide Electrode

A highly sensitive impedimetric immunosensor for the determination of interleukin 8 (IL 8) cancer biomarker was fabricated via simple fabrication process. A silane agent with isocyanate groups, 3-(triethoxysilyl)propyl isocyanate (IPTES), were utilized for binding of IL 8 antigen specific antibodies and self-assembled on the fluorine tin oxide (FTO) substrate with a standard silanization chemistry. Under optimum experimental conditions, the designed immunosensor had a wide linear detection range of 0.02–4 pg/mL, a low limit of detection of 11.9 fg/mL and a high sensitivity of 4.42 kΩ pg⁻¹ mL cm⁻². The designed biosensor displayed high reproducibility and repeatability, good selectivity against interference biomarkers.