Sensitive Electrochemical Immunosensor Research Articles

A Highly Sensitive Creatine Kinase Detection in Human Serum using 11-mercaptoundecanoic acid Modified ITO-PET Electrodes.

The enzyme creatine kinase (CK) is a biomarker that plays an extremely significant role in the early detection of cardiovascular disorders. Serum levels of CK are regularly monitored in patients with heart attacks, one of the most critical cardiovascular illnesses. In this study, a highly sensitive electrochemical immunosensor system was designed for the importance of early diagnosis of CK. This immunosensor system was developed by immobilizing 11- mercaptoundecanoic acid (11-MuA) on disposable indium tin oxide-polyethylene terephthalate (ITO-PET) electrodes. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and single frequency impedance (SFI) techniques were utilized throughout the immobilization process during the construction of the immunosensor. In addition, the proposed CK immunosensor system involves thorough analytical research, which may include linear determination range, repeatability, reproducibility, square wave voltammetry, storage capability, and regeneration. The suggested immunosensor was also characterized using scanning electron microscopy (SEM). The proposed immunosensor system demonstrated a broad dynamic range (0.1 pg mL-1 - 100 pg mL-1), as well as a low limit of detection (LOD) and a low limit of quantification (LOQ) of 0.018 pg mL-1 and 0.0394 pg mL-1, respectively. Finally, the immunosensor was tested on human serum samples, proving that it could be utilized in clinical situations.

A highly sensitive electrochemical immunosensor based on PET/GO/pPd/MAb nanofiber-particles for metolachlor detection

Herbicide-metolachlor (MA) residue seriously pollutes the environment and endangers human health. A novel electrochemical immunosensor featuring the surface-adhered nanofiber-particle films has been developed for the specific detection of metolachlor. The three-dimensional nanofiber-particle films, fabricated through the combination of nanomaterial modification techniques, including alkali treatment of polyethylene terephthalate (PET) and carboxylation of graphene oxide (GO), along with electrospinning technology, served as the platform for the immobilization of the catalyst p-Phenylenediamine (pPd) and the reactant metolachlor antibody (MAb). The sensor exhibited a satisfactory linear detection range (2.00 to 30.00 ng mL−1), a low limit of detection (LOD, 0.17 ng mL−1), and good repeatability and stability (detection activity ≥ 90.00 % after 10.00 uses/storage for 10.00 days, remaining at 80.00 % after 30 uses/storage). Furthermore, it demonstrated acceptable recovery rates (89.73 % to 92.78 %) in real sample detection. In the future, our sensor is anticipated to play a crucial role in detecting MA residues in crops.

Construction of a portable and sensitive electrochemical immunosensor for the rapid detection of erythromycin based on semiconductive bimetallic MOF

The sensitive determination of antibiotics in food products is vital for ensuring food safety and protecting human health. Herein, we have fabricated a novel electrochemical portable and sensitive electrochemical immunosensor for the efficient detection of erythromycin (ERY) containing in food stuffs. For this, a semiconductive cooper/ferric bimetallic metal-organic framework (scMOF), which was synthesized using 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) as linking ligand (denoted as CuxFe3-x(HHTP)2), was utilized simultaneously as the platform for anchoring antibody and for modifying the sprinted printed electrode (SPE) to construct the electrochemical immunosensor. The obtained scMOF, CuxFe3-x(HHTP)2, exhibited high porosity, promoted conductivity, and enhanced anchoring ability toward antibody. Thereby, the developed SPE immunosensor demonstrated the superior biosensing performance for the detection of ERY. Within a wide range from 1.0 fg mL−1 to 1.0 ng mL−1, the CuxFe3-x(HHTP)2-based portable SPE immunosensor had an ultralow detection limit of 0.69 fg mL−1, together with high selectivity, good reproducibility, and excellent long-term stability, as well as acceptable practicality. The present SPE immunosensor based on scMOFs not only provides an innovative biosensing strategy for the sensitive inspection of antibiotics, but also extends the application of scMOF in the field of food analysis.

Structure Remodeling Strategy for Open-Cage NiFe@Fe-bis-PBA with Enhanced Peroxidase-like Activity To Monitor Tumor Markers.

The inherent metal elements and structures of Prussian blue analogue (PBA) nanozymes have restricted their enzyme-mimicking activity. Therefore, the rational regulation of PBA nanozymes to improve their catalytic activity is highly desirable for biosensing applications. Herein, we propose a structure remodeling strategy to construct an open-cage Fe PBA-anchored NiFePBA (NiFe@Fe bis-PBA) nanozyme with significantly enhanced enzyme-mimicking activity. The formation process and mechanism for this bis-PBA nanozyme were studied in detail. Specifically, a cubic NiFePBA precursor was first synthesized and modified with polyvinylpyrrolidone (PVP). With the aid of hydrochloric acid, the added potassium ferricyanide was reduced by PVP and re-coordinated on the surface of NiFePBA to form the NiFe@Fe bis-PBA nanozyme with a special open-cage core-shell structure. The resultant NiFe@Fe bis-PBA nanozyme was further exploited to immobilize secondary antibodies, serving as a novel signal probe for developing highly sensitive electrochemical immunosensors for monitoring tumor markers. The constructed electrochemical immunosensor possesses a very wide linear range of 0.005-100 ng/mL and a low detection limit of 0.89 pg/mL for alpha-fetoprotein with high specificity and acceptable reproducibility and stability. This work offers a general and promising strategy for remodeling PBA nanozymes with a very favorable structure and metal element distribution, which enhances their enzyme-mimicking properties for applications in different fields.

Sensitive electrochemical immunosensor for rapid detection of Salmonella in milk using polydopamine/CoFe-MOFs@Nafion modified gold electrode

Food contaminated by pathogenic bacteria poses a serious threat to human health. Consequently, we used Salmonella as a model and developed an electrochemical immunosensor based on a polydopamine/CoFe-MOFs@Nafion nanocomposite for the detection of Salmonella in milk. The CoFe-MOFs exhibit good stability, large specific surface area, and high porosity. However, after modification on the electrode surface, they were prone to detachment. This issue was effectively mitigated by incorporating Nafion into the nanocomposite. A polydopamine (PDA) film was deposited onto the surface of CoFe-MOFs@Nafion through cyclic voltammetry (CV), accompanied by an investigation into the polymerization mechanism of the PDA film. PDA contains a substantial number of quinone functional groups, which can covalently bind to amino or sulfhydryl groups via Michael addition reaction or Schiff base reaction, thereby immobilizing anti-Salmonella antibodies onto the modified electrode surface. Under the optimal experimental conditions, the Salmonella concentration exhibited a good linear relationship within the range of 1.38 × 102 to 1.38 × 108 CFU mL−1, with a detection limit of 1.38 × 102 CFU mL−1. Furthermore, the constructed immunosensor demonstrated good specificity, stability, and reproducibility, offering a novel approach for the rapid detection of foodborne pathogens.

Highly sensitive electrochemical multimodal immunosensor for cluster of differentiation 5 (CD5) detection in human blood serum for early stage cancer detection based on laser-processed Ti/Au electrodes

In the rapidly evolving field of medical diagnostics, biomarkers play a pivotal role, particularly in the early detection of cancer. Cluster of differentiation 5 (CD5), a cell surface glycoprotein found on T cells and B-1a lymphocytes, is instrumental in immune regulation and is associated with both autoimmune diseases and malignancies. Despite its significant diagnostic and therapeutic potential, CD5 detection has been limited by modern methods in the pg/ml range. This study presents a novel multimodal electrochemical immunosensor that employs laser-processed Ti/Au electrodes for the ultra-sensitive detection of CD5 in human blood serum. The “multimodal” approach combines different analytical techniques - differential pulse volctammetry (DPV) and electrochemical impedance spectroscopy (EIS) - to ensure comprehensive analysis, enhancing both the accuracy and reliability of the sensor. This novel sensor significantly outperforms existing commercial ELISA kits, achieving a limit of detection (LOD) of 1.1 ± 0.2 fg/mL with DPV and 3.9 ± 0.5 fg/mL with EIS in phosphate-buffered saline (PBS) and 6.6 ± 3.1 fg/mL and 15.6 ± 3.1 fg/mL in human serum (HS), respectively. These results highlight the immunosensor's potential for improving early-stage cancer diagnosis and broader medical applications.

Au NPs modified Ni-B nanosheets/graphene oxide three-dimensional network as label-free electrochemical immunosensor for the detection of diethylstilbestrol

Three-dimensional (3D) network provide a promising platform for construction of high sensitive electrochemical immunosensor due to the benefits of high specific surface area and electron mobility. Herein, a sensitive label-free electrochemical immunosensor based on Au nanoparticles modified Ni-B nanosheets/graphene matrix was constructed to detect diethylstilbestrol (DES). The 3D network not only could increase the electron transport rate and surface area, but also could provide confinement area, which is conducive to increases the collision frequency with the active site. Moreover, Au NPs also have good biocompatibility, which is beneficial for ligating antibodies. Benefiting from the 3D network structure and Au collective effect, the electrochemical immunosensor possess sterling detection ability with wide linear response range (0.00038–150 ng/mL) and low detection limit (31.62 fg/mL). Moreover, the constructed immunosensor can also be extend to detect DES in Tap-water and river water. This work may provide a novel material model for the construction of high sensitive immunosensor.

A highly sensitive electrochemical immunosensor based on rGO-PEI-Ag nanocomposites for the detection of tilmicosin

A label-free electrochemical immunosensor was developed to rapidly detect tilmicosin (TMC) residues in pork and milk. The immunosensor was constructed by immobilizing a high-affinity monoclonal antibody against TMC on an rGO-PEI-Ag nanocomposite-modified electrode. The rGO-PEI-Ag nanocomposites were prepared by mixing polyethyleneimine (PEI) modified reduced graphene oxide (rGO) with AgNO3 solution. The prepared rGO-PEI-Ag nanocomposites showed good redox activity and conductivity, as characterized by ultraviolet-visible spectroscopy (UV–Vis), transmission electron microscopy (TEM), and X-ray diffraction (XRD). During the preparation process, staphylococcal protein A (SPA) was added to targetedly bind the Fc segment of the monoclonal antibody. The immunosensor showed a low detection limit (LOD) of 0.0013 ng/mL, a linear range of 0.01–100 ng/mL, and recoveries ranging from 92.77 to 100.02% in pork and 92.26–101.23% in milk. Furthermore, the immunosensor exhibited good stability, reproducibility, and specificity in detecting TMC in pork and milk real samples.

Enzymatic Precipitation of Highly Electroactive and Ion-Transporting Prussian Blue for a Sensitive Electrochemical Immunosensor.

Sensitive and/or multiplex electrochemical biosensors often require efficient (bio)catalytic conversion of substrates into insoluble electroactive products. The enzymatic formation and precipitation of coordination polymers under mild conditions offers a promising solution for this purpose. Herein, we report the enzymatic precipitation of Prussian blue (PB), a highly electroactive and ion-transporting coordination polymer, on an immunosensing electrode for application in a sensitive electrochemical immunosensor for detecting thyroid-stimulating hormone (TSH). Five pairs of redox enzymes and their specific reductants were examined to achieve rapid PB precipitation and electrochemical oxidation. Among these pairs, O2-insensitive flavin adenine dinucleotide-dependent glucose dehydrogenase (FAD-GDH) paired with glucose yielded the highest electrochemical signal-to-background (S/B) ratio. FAD-GDH catalyzed the conversion of Fe(CN)63- to Fe(CN)64-, which coordinated with Fe3+, leading to PB formation and subsequent precipitation through repeated conversions. The resulting PB precipitate, with its close proximity to the electrode, facilitated rapid electrochemical oxidation and generated a strong electrochemical signal. Notably, the precipitation and electrochemical oxidation of PB were more effective than those of its analogues. When applied to a sandwich-type immunosensor for TSH detection, the enzymatic PB precipitation achieved a calculated detection limit of approximately 2 pg/mL in artificial serum, covering the clinically relevant range. These findings indicate the potential widespread utility of PB precipitation and electrochemical oxidation for sensitive multiplex biomarker detection.

A sensitive electrochemical immunosensor based on high-efficiency catalytic cycle amplification strategy for detection of cardiac troponin I

An electrochemical immunosensor based on the novel high efficiency catalytic cycle amplification strategy for the sensitive detection of cardiac troponin I (cTnI). With its variable valence metal elements and spiny yolk structure, the Cu2O/CuO@CeO2 nanohybrid exhibits high speed charge mobility and exceptional electrochemical performance. Notably, fluorite-like cubic crystal CeO2 shell would undergo redox reaction with Cu2O core, which successfully ensures the continuous recycling occurrence of “fresh” Cu (II)/Cu (I) and Ce (Ⅳ)/Ce (Ⅲ) pairs at the electrode interface. The “fresh” active sites continue to emerge constantly, resulting in a significant increase in the current signal. In light of the electrochemical characterization, the electron transfer pathway and catalytic cycle mechanism among CeO2, Cu2O and CuO were further discussed. The developed electrochemical immunosensor detected cTnI from 100 fg/mL to 100 ng/mL with a LOD of 15.85 fg/mL under optimal conditions. The analysis results indicate that the immunosensor would hold promise for broad application prospects in the biological detection for other biomarkers.

A nanoDiamond/gold nanoparticle-based electrochemical immunosensor for the detection of HER 2 cancer biomarker

We report a highly sensitive electrochemical immunosensor based on a nanohybrid platform for the detection of the breast cancer biomarker human epidermal growth factor receptor 2 (HER 2). NanoDiamond (nanoD) and gold nanoparticles (AuNPs) immobilised by drop coating and electrodeposition methods, respectively, were employed to fabricate an immunosensor for HER 2 detections on a glassy carbon electrode (GCE). Voltammetry and electrochemical impedance spectroscopy (EIS) techniques were used to characterise each step of the modification process of the immunosensor. In addition, transmission electron microscopy (TEM), X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) techniques were used to characterise the materials used to fabricate the modified electrode. Under optimal conditions of temperature, time, and pH (35 °C, 50 min, and pH 7.2), different concentrations were investigated within a wide range of 1 pg mL−1 to 50 ng mL−1 using differential pulse voltammetry (DPV). With a low detection limit of 0.29 pg mL−1 from the DPV analysis, the immunosensor showed very good sensitivity and had a high specificity for HER 2. Additionally, the immunosensor demonstrated good applicability in the analysis of HER 2 in human serum samples, demonstrating a potential for use in the early identification of breast cancer.

Hydrangea-like TiO2/Bi2MoO6 porous nanoflowers triggering highly sensitive electrochemical immunosensing to tumor marker.

Rapid and sensitive detection of carcinoembryonic antigen (CEA) is of great significance for cancer patients. Here, molybdenum (Mo) was doped into bismuth oxide (Bi2O3) by one-pot hydrothermal method forming porous tremella Bi2MoO6 nanocomposites with a larger specific surface area than the spherical structure. Then, a new kind of hydrangea-like TiO2/Bi2MoO6 porous nanoflowers (NFs) was prepared by doping titanium into Bi2MoO6, where titanium dioxide (TiO2) grew in situ on the surface of Bi2MoO6 nanoparticles (NPs). The hydrangea-like structure provides larger specific surface area, higher electron transfer ability and biocompatibility as well as more active sites conducive to the attachment of anti-carcinoembryonic antigen (anti-CEA) to TiO2/Bi2MoO6 NFs. A novel label-free electrochemical immunosensor was then constructed for the quantitative detection of CEA using TiO2/Bi2MoO6 NFs as sensing platform, showing a good linear relationship with CEA in the concentration range 1.0pg/mL ~ 1.0mg/mL and a detection limit of 0.125pg/mL (S/N = 3). The results achieved with the designed immunosensor are comparable with many existing immunosensors used for the detection of CEA in real samples.

Concanavalin A as carrier for sensitive electrochemical immunosensor based on AgNPs-rGO signal amplification

Concanavalin A (ConA), as a carrier for immobilizing antibodies, was used for the first time in electrochemical immunosensor. In this work, a label-free electrochemical immunosensor based on Ag nanoparticles-reduced graphene oxide (AgNPs-rGO) nanocomposite and ConA was successfully prepared to detect arsanilic acid (ASA). AgNPs-rGO nanocomposite displayed superior conductivity and redox capability. Specially, ConA showed excellent binding ability with monoclonal antibody of ASA through lectin-sugar interactions. Under the optimized conditions, the proposed electrochemical immunosensor showed a linear dependence over ASA concentrations ranging from 0.025 ng/mL to 25 ng/mL with a low detection limit of 0.011 ng/mL. Furthermore, the immunosensor was used to monitor ASA in chicken and egg with good precision and accuracy. In conclusion, the simple and low-cost immunosensor was desirably applied as a useful candidate for detection of ASA in animal derived food.

Development of highly sensitive electrochemical immunosensor using PPy-MoS2-based nanocomposites modified with 90MeV C6+ ion beams.

Theevaluation of electrochemical sensing activity of hydrothermally derived PPy-MoS2-based nanocomposites subjected to 90MeV C6+ ion beam with fluence ranging, 1.0 × 1010-1.0 × 1013 ions/cm2, is reported. Cross-linking, chain scissioning, and ion track formation could occur in the irradiated systems, as revealed from Fourier transform infrared (FTIR) spectroscopy and field emission scanning electron microscopy (FE-SEM)studies. Electrochemical studies, viz., cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were performed in 0.1M phosphate buffer solution (PBS) containing 5mM K3[Fe(CN)6] as redox probe. High redox activity, lower charge transfer resistance (Rct = 490 Ω) and larger electroactive area (A = 0.4485 cm2) were obtained in case of the composite system irradiated with a fluence of 3.5 × 1011 ions/cm2. Immunosensor fabrication was executed via immobilization of mouse IgG over the pristine and post-irradiated electrodes. Afterwards, differential pulse voltammetry (DPV) was performed within thepotential window - 0.2 to + 0.6V (vs. Ag/AgCl) for the detection of specific analyte. Noticeably, the electrode system irradiated with a fluence of 3.5 × 1011 ions/cm2 ischaracterized by a lower limit of detection (LOD) of 0.203nM and a higher sensitivity value of 10.0 µAmLng-1cm-2. The energetic particle irradiation at a modest fluence can offer beneficial effects to thePPy-MoS2-based nanohybrid system providing immense scope as advanced electrochemical biosensor.

Construction of highly sensitive electrochemical immunosensor based on Au and Co3O4 nanoparticles functionalized Ni/Co bimetal conductive MOF for quantitative detection of HBsAg

Herein, highly sensitive electrochemical immunosensor based on noble metal and metal oxide nanoparticles functionalized bimetal conductive metal–organic frameworks (c-MOFs) was proposed toward HBsAg detection. The nanorod-like architecture of Ni3(HITP)2c-MOFs was synthesised via a simple and facile route, followed by dopant coble ions formation cobaltosic oxide (Co3O4) nanoparticles decorated bimetal NiCo(HITP) c-MOFs nanocomposites. Benefiting from large specific surface area, high electrical conductivity and abundant active sites of desirable nanostructures, the resultant Co3O4NPS/NiCo(HITP) bimetal c-MOFs nanostructure exhibits fast electron transfer capability and effective specific binding between antigen and antibody. Meanwhile, different amounts of Au nanoparticles were further functionalized on Co3O4NPS/NiCo(HITP) nanocomposites to further improve the electrochemical properties. Under optimum condition, the as-proposed Au@Co3O4NPS/NiCo(HITP) electrochemical immunosensor exhibits superior sensing performances toward HBsAg including wide linear response range from 1 pg mL−1 to 100 ng mL−1 and low detection limit of 15 fg mL−1 (S/N = 3). Meanwhile, the as-fabricated electrochemical immunosensors also displays outstanding selectivity, repeatability and stability. Besides, quantitative detection of HBsAg also achieves satisfactory results in real sample detection. Thereby, our work not only provides a promising strategy to construct highly sensitive electrochemical immunosensor using hybrid c-MOFs nanomaterials but also presents a potential application in the early diagnosis of hepatitis B-related diseases.

Highly sensitive electrochemical immunosensor based on SiO2 nanospheres for detection of EGFR as colorectal cancer biomarker

Colorectal cancer is one of the most common cancers, and its incidence rate keeps increasing worldwide. Epidermal growth factor receptor (EGFR) is highly expressed in colorectal cancer cells, and its activation leads to the activation of downstream kinase pathways to promote cell growth, resulting in tumour growth and progression. EGFR is expressed in only small amounts in normal cells, however, it is overexpressed in tumour cells and is a potential tumour marker, thus the detection of which is of great importance. This work proposes a novel and highly sensitive electrochemical immunosensor based on nucleic acid aptamer recognition and silver deposition for EGFR detection. The key novelty of this work is the use of SiO2 nanospheres to enhance the sensitivity. First, SiO2 nanospheres were synthesized and modified on the surface of a gold electrode using a self-assembly process. This provided a large surface area to allow high loading of capture antibodies. The antibody was then immobilized on the SiO2 nanosphere modified electrode surface to form an immunosandwich complex with the antigen and biotin-labelled nucleic acid aptamer. Afterwards, the affinity-labelled alkaline phosphatase was immobilized onto the electrode with the specific reaction of biotin and affinity. The obtained product was subjected to silver deposition in the substrate solution. The large surface area provided by the SiO2 nanospheres allowed significantly improved sensitivity. Experiments were performed to optimize the concentration of immobilized antibodies and biotin-labelled nucleic acid aptamer. The experimental results show a good linearity of EGFR concentration in the range of 1 to 1000 ng/mL, with the lowest detection limit up to 0.06 ng/mL. This method has high sensitivity and stability, which allows it to have a broad application prospects in the clinical field.

Reduced graphene oxide-gadolinium oxide-functionalized paper based immunosensor for electrochemical detection of gentamicin

Excessive consumption of antibiotics like gentamicin (GEN) can lead to hostile effects as antibiotic resistance. Therefore, the detection is important for which, reduced graphene oxide-Gadolinium oxide nanocomposite (rGO@Gd2O3 NC) was composed through co-precipitation method for the detection of GEN. The structural, morphological and functional group characterizations were done using XRD, FT-IR, SEM and TEM techniques. The cyclic voltammetry (CV) showed excellent electrocatalytic activity and superior performance towards GEN detection. Through the use of GEN monoclonal antibodies (anti-GEN) on a screen-printed electrode (SPE), a very sensitive electrochemical immunosensor was fabricated. Covalent interactions were employed to construct the electrochemical immunosensor, while bovine serum albumin (BSA) was employed as a blocking agent on the anti-GEN/rGO@Gd2O3/SPE electrode surface. The analysis of the CV response of the BSA/anti-GEN/rGO@Gd2O3/SPE bioelectrode demonstrated linear detection range from 1 pM – 100 μM, along with limit of detection (LOD) of 0.424 pM and sensitivity of 44.87 μA pM-1 cm− 2. Additionally, rGO@Gd2O3 immunosensor, exhibited a good level of linearity with R2 value of 0.978. These findings indicate the excellent potential of the rGO@Gd2O3 electrochemical immunosensor for accurately detecting GEN in spiked milk samples at different concentrations.

Sensitive electrochemical gold nanoparticle-based immunosensor for norovirus detection in food samples.

Norovirus (NoV) infection is one of the most common non-bacterial causes of gastroenteritis among the population worldwide. From the point of view of medical diagnostics, it is important to develop a system that would sensitively and selectively detect norovirus from a patient's sample in order to control and limit its spread. In this paper, we present a stable and sensitive NoV (mouse model) detection matrix in infected food samples. The bio-platform was made of a modified gold electrode with a self-assembled l-cysteine monolayer, covered with gold nanoparticles, a linker and an antibody specific to the VP1 surface protein of the virus. Binding of the VP1 protein to the antibody caused a decrease in the current strength confirmed by electrochemical techniques - cyclic voltammetry (CV) and differential pulse voltammetry. The reduction of the current was proportional to the concentration of NoV sample. The biosensors showed high sensitivity and linearity in a range from 1 × 10-9 to 1 × 10-18 TCID50, with the detection limit of 1 × 10-18 TCID50. CV showed a diffusion-controlled process. In addition, each modification step was confirmed by scanning electron microscopy, electrochemical impedance spectroscopy, and CV. The described immunosensor showed excellent recovery values, good linearity and long-term stability, crucial parameters for biosensor construction.

Highly sensitive electrochemical immunosensor based on electrodeposited platinum nanostructures confined in silica nanochannels for the detection of the carcinoembryonic antigen.

In this study, we report a highly sensitive electrochemical immunosensor for carcinoembryonic antigen (CEA) detection based on the electrodeposited platinum nanoparticles (Pt NPs) confined in the ultrasmall nanochannels of vertically ordered mesoporous silica film (VMSF). VMSF bearing amine groups (NH2-VMSF) can be prepared on the indium tin oxide electrode surface via a one-step co-condensation route using an electrochemically assisted self-assembly method, which renders a strong electrostatic effect for [PtCl6]2- and leads to the spatial confinement of Pt NPs inside the silica nanochannels after electrodeposition. The external surface of NH2-VMSF is functionalized with CEA antibodies using glutaraldehyde as a coupling agent, resulting in an electrochemical immunosensing interface with good specificity for CEA detection. Under optimal experimental conditions, high affinity between the CEA antibody and CEA produces a steric hindrance effect for the accessibility of the electrochemical probe ([Fe(CN)6]3-) in the bulk solution to the underlying indium tin oxide surface, eventually resulting in the attenuated electrochemical signal and enabling the detection of the CEA with a wide linear range of 0.01pg/mL∼10ng/mL and a pretty low limit of detection of 0.30fg/mL. Owing to the signal amplification ability of Pt NPs and the anti-biofouling property of NH2-VMSF, the as-prepared electrochemical immunosensor based on the Pt NPs@NH2-VMSF displays an accurate analysis of the CEA in human serum samples, holding significant promise for health monitoring and clinical diagnosis.

A Methylene Blue-Enhanced Nanostructured Electrochemical Immunosensor for H-FABP Myocardial Injury Biomarker.

A sensitive electrochemical immunosensor for the detection of the heart-type fatty acid binding protein (HFABP), an earlier biomarker for acute myocardial infarction than Troponins, is described. The sensing platform was enhanced with methylene blue (MB) redox coupled to carbon nanotubes (CNT) assembled on a polymer film of polythionine (PTh). For this strategy, monomers of thionine rich in amine groups were electrosynthesized by cyclic voltammetry on the immunosensor's gold surface, forming an electroactive film with excellent electron transfer capacity. Stepwise sensor surface preparation was electrochemically characterized at each step and scanning electronic microscopy was carried out showing all the preparation steps. The assembled sensor platform combines MB and PTh in a synergism, allowing sensitive detection of the H-FABP in a linear response from 3.0 to 25.0 ng∙mL-1 with a limit of detection of 1.47 ng∙mL-1 HFABP that is similar to the clinical level range for diagnostics. H-FABP is a newer powerful biomarker for distinguishing between unstable angina and acute myocardial infarction.