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AbstractHuman Papillomavirus (HPV) is the principal cause of cervical cancer, which is still a prime universal health concern, especially in underdeveloped nations where access to advanced screening techniques is often restricted. Herein, we propose an electrochemical immunosensor for the determination of HPV 16 L1 protein, a key biomarker associated with cervical carcinogenesis. The developed immunosensor, employing glassy carbon electrode (GCE) enhanced with gold nanoparticles, provides a highly sensitive, specific, and cost-effective approach for early screening of cervical cancer. An optimized stepwise fabrication process which includes electrode surface modification and antibody immobilization, was used to enhance sensor performance. Characterization studies confirmed the effective modification of electrodes and the selectivity of immunoreactions. With an impressive limit of detection (LOD) of 0.033 fg mL−1, the immunosensor showed a linear response to L1 protein concentrations ranging from 0.1 fg mL−1 to 1 ng mL−1. Additionally, the immunosensor exhibits excellent specificity, stability, reproducibility, and regeneration capabilities. The performance of the immunosensor was compared with the enzyme-linked immunosorbent assay (ELISA) by analyzing clinical samples (positive: n = 12; healthy: n = 5) showed satisfactory results. The findings indicated that the proposed sensing platform has the potential to be utilized for the early diagnosis of cervical cancer. [ABSTRACT FROM AUTHOR]

Copyright of Food & Fermentation Industries is the property of Food & Fermentation Industries and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

For the detection of ferritin, this work engineered an electrochemical immunosensor by functionalizing multi-walled carbon nanotubes (MWCNTs) and integrating them into a screen-printed carbon electrode (SPCE) platform. Under optimal conditions (pH 7.4, antibody concentration 10 μg/mL, incubation time 30 min), the developed immunosensor exhibited a linear relationship between the electrochemical signal and ferritin concentrations spanning 1–500 ng/mL. Notably, it demonstrated an impressive ability to detect ferritin at exceptionally low levels, with a limit of detection reaching 0.3 ng/mL. The immunosensor demonstrated high selectivity, good reproducibility (RSD = 3.2 %, n = 5), and stability (87.3 % of initial response after 14 days at 4°C). The immunosensor was used to sensing ferritin in serum and good agreement with the commercial ELISA method (relative error < 5 %). The proposed sensor shows promise as a analytical approach for early diagnosis of lymphoma and point-of-care testing. [ABSTRACT FROM AUTHOR]

Vertically ordered mesoporous silica films (VMSF) are a class of porous materials composed of ultrasmall pores and ultrathin perpendicular nanochannels, which are attractive in the areas of electroanalytical sensors and molecular separation. However, VMSF easily falls off from the carbonaceous electrodes and thereby impacts their broad applications. Herein, carbon nitride nanosheets (CNNS) were served as an adhesive layer for stable growth of VMSF on the glassy carbon electrode (GCE). CNNS bearing plentiful oxygen-containing groups can covalently bind with silanol groups of VMSF, effectively promoting the stability of VMSF on the GCE surface. Benefiting from numerous open nanopores of VMSF, modification of VMSF's external surface with carbohydrate antigen 15-3 (CA15-3)-specific antibody allows the target-controlled transport of electrochemical probes through the internal silica nanochannels, yielding sensitive quantitative detection of CA15-3 with a broad detection range of 1 mU/mL to 1000 U/mL and a low limit of detection of 0.47 mU/mL. Furthermore, the proposed VMSF/CNNS/GCE immunosensor is capable of highly selective and accurate determination of CA15-3 in spiked serum samples, which offers a simple and effective electrochemical strategy for detection of various practical biomarkers in complicated biological specimens. [ABSTRACT FROM AUTHOR]

Copyright of Food Research & Development is the property of Food Research & Development Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A novel sandwich-type electrochemical immunosensor for the detection of the liver cancer marker alpha-fetoprotein (AFP) in human serum is proposed. The two-dimensional MXene material Ti3C2Tx was first prepared using etching and ultrasonic stripping, and then Ti3C2Tx was used to reduce chloroauric acid to form Ti3C2Tx/AuNP composites which were modified on the surface of the glassy carbon electrodes to form probe-type sensors. The Ti3C2Tx/AuNPs provide a large number of binding sites for the AFP capture antibody (Ab1) and increase the electrochemical reaction active site. The Ti3C2Tx/copper metal–organic frameworks HKUST-1 composite was also prepared by solvothermal method and combined with toluidine blue (TB) and AFP detection antibody (Ab2) to form a labeled sandwich-type electrochemical immunosensor. The sensor achieved trace detection of AFP from 0.1 to 100 ng/mL with a detection limit of 0.073 pg/mL and possesses good selectivity, stability, and reproducibility. The sensor performs well in clinical samples and has good potential for clinical applications. [ABSTRACT FROM AUTHOR]

For the detection of ferritin, this work engineered an electrochemical immunosensor by functionalizing multi-walled carbon nanotubes (MWCNTs) and integrating them into a screen-printed carbon electrode (SPCE) platform. Under optimal conditions (pH 7.4, antibody concentration 10 μg/mL, incubation time 30 min), the developed immunosensor exhibited a linear relationship between the electrochemical signal and ferritin concentrations spanning 1–500 ng/mL. Notably, it demonstrated an impressive ability to detect ferritin at exceptionally low levels, with a limit of detection reaching 0.3 ng/mL. The immunosensor demonstrated high selectivity, good reproducibility (RSD = 3.2 %, n = 5), and stability (87.3 % of initial response after 14 days at 4°C). The immunosensor was used to sensing ferritin in serum and good agreement with the commercial ELISA method (relative error < 5 %). The proposed sensor shows promise as a analytical approach for early diagnosis of lymphoma and point-of-care testing.

Objective To prepare a high performance electrochemical immunosensor for detecting Brucella abortus (B. abortus). Methods Prussian blue (PB), multi walled carbon nanotubes (MWCNTs) and gold nanoparticles (GNPs)(PB-MWCNTs-GNPs) nanocomposites were prepared, and appropriate antibody was used to construct the immunosensor for detecting B. abortus samples. The optimal conditions were clarified by examining the key factors in sensor construction, and then the performance of the sensor was evaluated. Results The optimal construction conditions were determined as follows: the ratio of MWCNTs-PB was 1 ∶5, the drying temperature was 37 ℃, the pH value of buffer system was 7.5, and the incubation time of antibody and sample was 1 h and 30 min, respectively. B. abortus exhibited a good linear relationship, when ranging from 10 to 1×105 CFU/mL. The sensor had good anti-interference ability, repeatability, stability and high accuracy. Conclusion Our prepared PB-MWCNTs GNPs nanomaterials modified electrochemical immunosensor for detecting B. abortus is easy to prepare, has good performance, and can provide reference for the early clinical diagnosis of brucellosis.

Abstract Earlier access to patients’ biomarker status could transform disease management. However, gold-standard techniques such as enzyme-linked immunosorbent assays (ELISAs) are typically not deployed at the point-of-care due to their cumbersome instrumentation and complexity. Electrochemical immunosensors can be disruptive in this sector with their small size and lower cost but, without further modifications, the performance of these sensors in complex media (e.g., blood) has been limited. This paper presents a low-cost fluidic accessory fabricated using widely accessible materials and processes for boosting sensor sensitivity through confinement of the detection media next to the electrode surface. Liquid confinement first highlighted a spontaneous reaction between the pseudoreference electrode and ELISA detection substrate 3,3’,5,5’-tetramethylbenzidine (TMB) that decreases the amount of oxTMB available for detection. Different strategies are investigated to limit this and maximize reliability. Next, flow cell integration during the signal amplification step of sensor preparation was shown to substantially enhance the detection of cytokine interleukin-6 (IL-6) with the best sensitivity boost recorded for fresh human plasma (x7 increase compared to x5.8 in purified serum and x5.5 in PBS). The flow cell requires no specialized equipment and can be seamlessly integrated with commercial sensors, making an ideal companion for electrochemical signal enhancement.

Root rot is a highly infectious disease in traditional Chinese medicine (TCM) that spreads quickly and significantly affects the yield and quality of TCM. Therefore, there is an urgent need for accurate and convenient early warning technology to guide root rot control. The root rot of TCM is mainly caused by Fusarium fungi infecting plants. After plants have been infected with fungi, zearalenone (ZEN), fumonisin (FB), fusarium acid (FA), and other compounds will produce duo to Fusarium infects plants to promote metabolism. And the trace expression of these compounds in plants is used as root rot early warning markers (RREWM). Herein, an electrochemical immunosensor was developed for the rapid, convenient, and sensitive detection of zearalenone (ZEN), an early warning marker for Radix isatidis root rot. The immunosensor utilizes Fe3O4@g-C3N4 composite ITO electrode. Initially, the ITO conductive films were modified with Fe3O4@g-C3N4 and gold nanoparticles (AuNPs) through droplet coating and chemical deposition, respectively. Subsequently, the AuNPs were conjugated with zearalenone antibody (ZEN-Ab) to generate high affinity sulfhydryl-bound recognition elements. Under the optimized condition, the sensor demonstrates a linear wide range of 10.00 pg mL−1 to 1.20 × 104 pg mL−1 with a LOD of 3.86 pg mL−1. Additionally, the sensor showed good reproducibility and stability. This study exhibits a convenient, accurate, and low-cost method for detecting early warning markers of root rot in TCM cultivation, which was expected to provide a reliable warning technology for the early warning and prevention of diseases in the planting process of TCM. [ABSTRACT FROM AUTHOR]

Interferon gamma (IFN‐γ) released by T lymphocytes, plays an important role in immune regulation and is also an important biomarker for the early diagnosis of bovine tuberculosis. In this work, an electrochemical immunosensor based on gold nanoparticles (AuNPs)/chitosan composite was developed for highly sensitive determination of bovine IFN‐γ. AuNPs/chitosan composite shows high surface area and good hydrophilicity. The bovine IFN‐γ immunosensor was prepared by immobilizing IFN‐γ antibody on AuNPs/chitosan composite‐modified glassy carbon electrode. The immunosensors were characterized by scanning electron microscopy, electrochemical impedance spectroscopy, and cyclic voltammetry (CV). Using horseradish peroxidase (HRP)‐labeled IFN‐γ antibody as amplification probe, the concentration of bovine IFN‐γ can be monitored via the increasing current signal, which can be attributed to the specific immune binding between bovine IFN‐γ antigen and HRP‐labeled IFN‐γ antibody, as well as the efficient catalysis reaction between thionine and HRP with the presence of H2O2. The developed electrochemical immunosensor exhibited a wide linear range of 0.01 to 30 ng/mL, and low detection limit of 0.003 ng/mL with good specificity and stability. This study provides a simple and promising method for diagnosis of bovine tuberculosis, which can be expanded to determine other biomarkers. [ABSTRACT FROM AUTHOR]

A novel immunodetection sensing platform for Salmonella based on a CoFe-MOF-carbon nanotube composite was developed. The CoFe-MOF-CNT composite exhibited excellent electrochemical performance, providing a highly conductive and stable matrix for antibody immobilization and signal amplification. Under optimized conditions, the immunosensor demonstrated a wide linear range of 102 to 107 CFU/mL, with a low detection limit of 37 CFU/mL and a high sensitivity of 6.061 µA/log(CFU/mL). The immunosensor showed excellent specificity towards Salmonella, with a relative response of 100% for Salmonella and less than 10% for non-target bacteria. The immunosensor exhibited good reproducibility (RSD of 4.2%) and stability, retaining 88.7% of its initial response after 30 days of storage at 4 °C. The practical applicability of the immunosensor was demonstrated by analyzing spiked milk samples, with recoveries ranging from 96.7% to 105.2% and RSD less than 6.5%. [ABSTRACT FROM AUTHOR]

Single Chain Variable Fragment (scFv), a small fragment of antibody can be used to substitute the monoclonal antibody for diagnostic purposes. Production of scFv in Escherichia coli host has been a challenge due to the potential miss-folding and formation of inclusion bodies. This study aimed to express anti-CHIKV E2 scFv which previously designed specifically for Asian strains by co-expression of three chaperones that play a role in increasing protein solubility; GroEL, GroES, and Trigger Factor. The scFv and chaperones were expressed in Origami B E. coli host under the control of the T7 promoter, and purified using a Ni-NTA column. Functional assay of anti-CHIKV-E2 scFv was examined by electrochemical immunosensor using gold modified Screen Printed Carbon Electrode (SPCE), and characterized by differential pulses voltammetry (DPV) using K3[Fe(CN)6] redox system and scanning microscope electron (SEM). The experimental condition was optimized using the Box-Behnken design. The results showed that co-expression of chaperone increased the soluble scFv yield from 54.405 μg/mL to 220.097 µg/mL (~5×). Furthermore, scFv can be used to detect CHIKV-E2 in immunosensor electrochemistry with a detection limit of 0.74048 ng/mL and a quantification limit of 2,24388 ng/mL. Thus, the scFv-anti-CHIKV-E2 can be applied as a bioreceptor in another immunoassay method. [ABSTRACT FROM AUTHOR]

A sandwich-type voltammetric immunosensor based on conjugates of gold nanoparticles (AuNP) with specific immunoglobulins (IgG) against ovalbumin (IgG@AuNP) is developed for the determination of ovalbumin in some immunobiological preparations. The IgG@AuNP conjugate is synthesized by passive adsorption. A carbon-containing planar printed electrode modified by laser reduced graphene oxide is used as a substrate electrode for immobilizing the receptor layer of specific immunoglobulins. A possibility of the catalytic reduction of silver nitrate with a mixture of reducing agents, citric acid and metol, is considered in order to enhance the signal of AuNP. Conditions for the voltammetric recording of the electrochemical signal of silver on an immunosensor, which has been successfully tested in determining ovalbumin residues in some immunobiological drugs, are selected. Enzyme-linked immunosorbent assay is used as a reference method. [ABSTRACT FROM AUTHOR]

An electrochemical immunoassay system was developed to detect CA-125 using a glassy carbon electrode (GCE) modified with MXene, graphene quantum dots (GQDs), and gold nanoparticles (AuNPs). The combined MXene-GQD/AuNPs modification displayed advantageous electrochemical properties due to the synergistic effects of MXene, GQDs, and AuNPs. The MXene-GQD composite in the modified layer provided strong mechanical properties and a large specific surface area. Furthermore, the presence of AuNPs significantly improved conductivity and facilitated the binding of anti-CA-125 on the modified GCE, thereby enhancing sensitivity. Various analytical techniques such as FE-SEM and EDS were utilized to investigate the structural and morphological characteristics as well as the elemental composition. The performance of the developed immunosensor was assessed using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), square wave voltammetry (SWV), and differential pulse voltammetry (DPV). Under optimized conditions in a working potential range of −0.2 to 0.6 V (vs. Ag/AgCl), the sensitivity, linear range (LR), limit of detection (LOD), and correlation coefficient (R2) were determined to be 315.250 µA pU.mL−1/cm2, 0.1 to 1 nU/mL, 0.075 nU/mL, and 0.9855, respectively. The detection of CA-125 in real samples was investigated using the developed immunoassay platform, demonstrating satisfactory results including excellent selectivity and reproducibility. [ABSTRACT FROM AUTHOR]

Nanosized sodium bismuth perovskite titanate (NBT) was synthesized and first used as the electrochemical immune sensing platform for the sensitive detection of carcinoembryonic antigen (CEA). Gold nanoparticles (Au NPs) grew on the surface of NBT through forming Au-N bond to obtain Au@NBT, and a label-free electrochemical immunosensor was proposed using Au@NBT as an immunosensing recognizer towards CEA. The well-ordered crystal structure of NBT was not changed at all after the modification of Au NPs outside, but significantly improved the conductivity, catalytic activity, and biocompatibility of the Au@NBT-modified electrode. The unique cubic crystal nanostructure of NBT offered a large active area for both Au NP modification and the subsequent immobilization of biomolecules over the electrode surface, triggering the effective generation of promising properties of the proposed Au@NBT-based electrochemical immunosensor. As expected, favorable detection performances were achieved using this immunosensor towards CEA detection, where a good linear relationship between the current response and CEA concentration was obtained in the concentration range 10 fg mL−1 to 100 ng mL−1 with a low detection limit (LOD) of 13.17 fg mL−1. Also, the significantly enhanced selectivity, and stability guaranteed the promising electrochemical properties of this immunosensor. Furthermore, the analysis of real serum samples verified the high feasibility of this new method in clinical CEA detection. This work opens a new window for the application of nanoperovskite in the early detection of CEA. [ABSTRACT FROM AUTHOR]

An efficient electrochemical transducer matrix for immunosensing must possess a variety of specialized characteristics, comprised of stability, quick electron transport, biocompatibility, having a large electroactive surface area, and exhibiting certain functional groups, to facilitate biomolecule attachment. For sensitive detection of CA 15-3 and to provide higher electroactive surface area, CS–ZnO–CeO2 nanocomposites were synthesized to modify the electrode surface and characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR), and X-ray diffraction (XRD). The immunosensor shows a sensitive response with a sensitivity of 15.79 µAmUmL−1 and a linear range of 0.1–20 mUmL−1 with 1.24 mUmL−1 limit of detection (LOD) (S/N = 3) for CA 15-3 detection. The immunosensor developed as a result was utilized to detect CA 15-3 in human serum samples without any pretreatment, only dilution, and recovery rates ranging from 91 to 95%. As a result, the immunosensor displays the proper fabrication of the electrochemical biosensors to detect the CA 15-3 in actual sample analysis and exhibits excellent stability, sensitivity, repeatability, and reproducibility. [ABSTRACT FROM AUTHOR]

Because of the possible harm that drugs may cause to the environment and public health, the discovery of pharmaceuticals in drinking water sources has drawn increasing attention. Pharmaceuticals such as atezolizumab (ATZ), a monoclonal antibody used to treat liver cancer, can enter water sources through a number of different routes. The design and development of a new electrochemical sensor for the detection of ATZ in water sources are presented in this research study. Gold nanoparticles (Au NPs) and an anti-Atezolizumab antibody (Ab) on a glassy carbon electrode (GCE) were used to develop the immunosensor. Differential pulse voltammetry was used to comprehensively examine the immunosensor's electrochemical characteristics. The immunosensor showed a broad concentration range of 0.001 to 2000 µg/mL and a low detection limit of 0.6 ng/mL. When the performance of the sensor was compared to other documented ATZ immunoassays, it demonstrated better performance because of its wide analytical range and low detection limit. The immunosensor's repeatability and stability were assessed as well; results revealed a significant 40-day stability period and a relative standard deviation of 4.13%. The immunosensor's distinct capacity to recognize ATZ validated its selectivity. Recovery experiments using human serum, urine, and drinking water samples were used to assess the immunosensor's feasibility; the range of recoveries was 90.00 to 99.40%. The results showed a strong correlation with the ATZ ELISA Assay Kit that is sold commercially. All things considered, the creation of this unique electrochemical sensor marks a substantial breakthrough in the fields of drug detection and environmental monitoring. This sensor could be used to quickly and accurately identify ATZ in water sources, assisting in maintaining the security of our water supply and safeguarding public health and the environment. [ABSTRACT FROM AUTHOR]

Earlier access to patients' biomarker status could transform disease management. However, gold-standard techniques such as enzyme-linked immunosorbent assays (ELISAs) are typically not deployed at the point-of-care due to their cumbersome instrumentation and complexity. Electrochemical immunosensors can be disruptive in this sector with their small size and lower cost but, without further modifications, the performance of these sensors in complex media (e.g., blood) has been limited. This paper presents a low-cost fluidic accessory fabricated using widely accessible materials and processes for boosting sensor sensitivity through confinement of the detection media next to the electrode surface. Liquid confinement first highlighted a spontaneous reaction between the pseudoreference electrode and ELISA detection substrate 3,3',5,5'-tetramethylbenzidine (TMB) that decreases the amount of oxTMB available for detection. Different strategies are investigated to limit this and maximize reliability. Next, flow cell integration during the signal amplification step of sensor preparation was shown to substantially enhance the detection of cytokine interleukin-6 (IL-6) with the best sensitivity boost recorded for fresh human plasma (x7 increase compared to x5.8 in purified serum and x5.5 in PBS). The flow cell requires no specialized equipment and can be seamlessly integrated with commercial sensors, making an ideal companion for electrochemical signal enhancement. [ABSTRACT FROM AUTHOR]

Early diagnosis of cancer can be achieved by detecting associated biomarkers before the appearance of symptoms. Herein, we have developed an electrochemical immunosensor of ionic liquid tailored to molybdenum trioxide‐reduced graphene oxide (MoO3‐rGO‐IL) nanocomposite to detect carcinoembryonic antigen (CEA), a cancer biomarker. The MoO3‐rGO‐IL nanocomposite has been synthesized in situ via the hydrothermal method. The functionalization of 1‐butyl‐3‐methylimidazolium tetrafluoroborate IL with MoO3‐rGO synergistically improves the electrochemical and surface properties of the nanocomposite. The characterization studies revealed that the MoO3‐rGO‐IL nanocomposite is a highly appropriate material for the construction of immunosensors. The material exhibits exceptional electrical conductivity, surface properties, stability, and a large electrochemical effective surface area (13.77×10−2 cm2) making it ideal for fabricating immunosensors. The quantitative outcome showed that the developed immunosensor (BSA/anti‐CEA/MoO3‐rGO‐IL/GCE) possesses excellent sensitivity, broad linearity from 25 fg mL−1 to 100 ng mL−1, and a low detection limit of 1.19 fg mL−1. Moreover, the remarkable selectivity, repeatability, and efficiency of detecting CEA in serum specimens demonstrated the feasibility of the immunosensor. Thus, the projected electrochemical immunosensor can potentially be utilized for the quantification of CEA in clinical specimens. [ABSTRACT FROM AUTHOR]

Copyright of Micronanoelectronic Technology is the property of Micronanoelectronic Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Since the p53 protein is an important promising biomarker of lung tumor and colorectal tumor, it is very essential to design a highly effective mean to monitor the degree of p53 for the early clinical analysis/therapy of the related tumors. In this work, a sandwich-type electrochemical immunosensing (SES) platform is proposed for the first time to detect p53 via synthesizing Ti3C2Tx MXene nanoribbons (Ti3C2Tx Nb) and ferrocene/gold nanoparticles (Fc/Au) respectively as the sensing substrate and signal-amplifier. The superior electrical property and large surface area of Ti3C2Tx Nb are beneficial to assemble the initial p53-antibodies (Ab1), while the synthesized Fc/Au is devoted to assemble the secondary p53 antibodies (Ab2) and gives a magnified signal. By adopting the Fc molecules as the probes, the experiments reveal the response current of Fc resulted from the SES structure increases along with the p53 increase from 1.0 to 200.0 pg mL−1. A considerable low detection limit (1.0 pg mL−1) is achieved after optimizing several key conditions, it is thus confirmed the as-proposed SES mean exhibits significant application in the detection of p53 protein and other targets.

Abstract Cancer stands as one of the most impactful illnesses in the modern world, primarily owing to its lethal consequences. The fundamental concern in this context likely stems from delayed diagnoses in patients. Hence, detecting various forms of cancer is imperative. A formidable challenge in cancer research has been the diagnosis and treatment of this disease. Early cancer diagnosis is crucial, as it significantly influences subsequent therapeutic steps. Despite substantial scientific efforts, accurately and swiftly diagnosing cancer remains a formidable challenge. It is well known that the field of cancer diagnosis has effectively included electrochemical approaches. Combining the remarkable selectivity of biosensing components—such as aptamers, antibodies, or nucleic acids—with electrochemical sensor systems has shown positive outcomes. In this study, we adapt a novel electrochemical biosensor for cancer detection. This biosensor, based on a glassy carbon electrode, incorporates a nanocomposite of reduced graphene oxide/Fe3O4/Nafion/polyaniline. We elucidated the modification process using SEM, TEM, FTIR, RAMAN, VSM, and electrochemical methods. To optimize the experimental conditions and monitor the immobilization processes, electrochemical techniques such as CV, EIS, and SWV were employed. The calibration graph has a linear range of 102–106 cells mL−1, with a detection limit of 5 cells mL−1.

Abstract We present an advanced electrochemical immunosensor designed to detect the vascular endothelial growth factor (VEGF) precisely. The sensor is constructed on a modified porous gold electrode through a fabrication process involving the deposition of silver and gold on an FTO substrate. Employing thermal annealing and a de-alloying process, the silver is eliminated from the electrode, producing a reproducible porous gold substrate. Utilizing a well-defined protocol, we immobilize the heavy-chain (VHH) antibody against VEGF on the gold substrate, facilitating VEGF detection through various electrochemical methods. Remarkably, this immunosensor performs well, featuring an impressive detection limit of 0.05 pg/mL and an extensive linear range from 0.1 pg/mL to 0.1 µg/mL. This emphasizes it’s to measure biomarkers across a wide concentration spectrum precisely. The robust fabrication methodology in this research underscores its potential for widespread application, offering enhanced precision, reproducibility, and remarkable detection capabilities for the developed immunosensor.

An ultrasensitive electrochemical immunosensor using boron nitride nanosheet/gold nanoparticle (BNNS/AuNP) hybrids was developed for exhaled breath condensate (EBC) interleukin-6 (IL-6) quantification. BNNS were synthesized by chemical vapor deposition and decorated with AuNPs. The BNNS/AuNP hybrids were characterized by SEM, TEM, XRD, Raman, XPS, etc., and deposited on screen-printed carbon electrodes. Anti-IL-6 antibodies were immobilized via EDC/NHS crosslinking. The immunosensor detected IL-6 by differential pulse voltammetry technique with a linear range of 0.01–200 ng/mL and a limit of detection of 5 pg/mL. The sensor showed high reproducibility and selectivity. Validation with spiked EBC samples demonstrated good accuracy (relative error

Rapid and precise detection of SARS‐CoV‐2 antibodies is paramount for effective outbreak monitoring and vaccine efficacy assessment. While existing approaches for antibody detection often rely on complex electrochemical immunosensing with nanomaterial functionalization targeting S‐protein antibodies, their limitations in sensitivity and complexity have hindered widespread application. Here, we present a simplistic immunosensing platform designed for the rapid, and precise detection of SARS‐CoV‐2 specific IgG and Nucleocapsid antibodies. Notably, this study marks only the second exploration of SARS‐CoV‐2 N‐protein antibody detection. The platform utilizes traditional self‐assembled monolayers to establish selective bio‐affinity between SARS‐CoV‐2 specific Nucleocapsid antibodies and a gold electrode functionalized with the N‐protein antigen. Interestingly, despite the absence of nanomaterial functionalization, the developed platform achieves sensitivity comparable to existing sensors across a wide detection range (0.025 to 1 ng/mL) with an impressive limit of detection (0.019 ng/mL). The simplicity of the approach, relying solely on immunocomplex reactions, underscores that effective binding efficiency may be achieved in the absence of complex functionalization and determines its affordability, specificity, and high sensitivity. By eliminating the need for additional functionalization steps, the platform offers a streamlined solution for SARS‐CoV‐2 antibody detection and demonstrates the possibility of N‐protein antibody detection as a promising avenue for widespread application in SARS‐CoV‐2 outbreak monitoring and vaccine efficacy assessment particularly in underdeveloped regions. [ABSTRACT FROM AUTHOR]

In this study, a labeled electrochemical immunosensor was developed to determine gliadin protein. Herein, the glassy carbon electrode (GCE) surface was modified by the graphene oxide (GO) dispersion followed by electrochemical deposition of silver nanoparticles (AgNPs). Anti‐gliadin antibody (Gli‐Ab1) was immobilized on this electrode (GCE/GO/AgNPs); subsequently, this platform was incubated with bovine serum albumin (BSA) to prevent non‐specific interactions. Gliadin antigen (Gli) followed by horseradish peroxidase‐labeled secondary antibody (HRP−Ab2) solutions were added to the GCE/GO/AgNPs/Gli‐Ab1/BSA immunosensor surface. Scanning Electron Microscope (SEM) was utilized to investigate the surface properties of the prepared electrodes, and cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV) techniques were utilized to investigate their electrochemical properties. The experimental conditions have been optimized to form the appropriate immunosensor structure. The gliadin antigen was determined using DPV after the HRP enzyme substrates (hydroquinone and hydrogen peroxide) were added to the electrochemical cell. The gliadin protein′s linear working range was 0.5–200 μg mL−1. The subjected immunosensor displayed convenient reproducibility and selectivity to the possible interfering substances. [ABSTRACT FROM AUTHOR]

To accurately detect tumor marker carbohydrate antigen 72-4 (CA72-4) of serum samples is of great significance for the early diagnosis of malignant tumors. In the present study, MnO2/hollow nanobox metal-organic framework (HNM)-AuPtPd nanocomposites were prepared via multi-step synthesis and superposition method and a series of characterizations were carried out. A highly sensitive immunosensor Ab/MnO2/HNM-AuPtPd/GCE based on the composite nanomaterial was further prepared and used to detect the tumor marker CA72-4. The constructed immunosensor achieved signal amplification by increasing the electrocatalytic activity to H2O2 by means of the synergistic effect of MnO2 ultra-thin nanosheets (MnO2 UNs) and HNM-AuPtPd. At the same time, the electrochemical properties of the immunosensor were analyzed using cyclic voltammetry, electrochemical impedance, amperometry (with the test voltage of −0.4 V), and differential pulse voltammetry. The experimental results showed that the MnO2/HNM-AuPtPd nanocomposites were successfully prepared, and the immunosensor Ab/MnO2/HNM-AuPtPd/GCE demonstrated an excellent electrochemical performance. The electrochemical immunosensor had the highest detection sensitivity under the optimal experimental conditions, such as incubation pH of 7.0, incubation time of 60 min, with the addition of 15 μL of H2O2, and in the concentration range 0.001–500 U/mL. It had a low detection limit of 1.78×10−5 U/mL (S/N = 3). Moreover, the serum sample recovery were in the range from 99.38 to 100.52%. This study provides a new method and experimental basis for the detection of tumor markers in clinical practice. [ABSTRACT FROM AUTHOR]

A porous electrochemical immunosensor was fabricated for the sensitive determination of ractopamine (RAC) based on a cMWCNT–Ag–CS matrix film with a working bare screen-printed carbon electrode (SPCE). At the same time, the amine groups of chitosan interacted with the cMWCNT and silver nanoparticles, which was examined in detail by XPS. Cyclic voltammetry (CV) was employed to investigate the electrochemical characteristics of the immunosensor. Under optimal conditions, the logarithmic value of CRAC was positively correlated with the △Ipa of the RAC immunosensor, from 0.01 to 100 ng mL−1 (correlation coefficient R2 = 0.998). The limit of detection (LOD, 3σ) was 0.001 ng mL−1. The relative standard deviation (RSD) for Ipa current was 3.78%. These results suggested that the cMWCNT–Ag–CS matrix film provides a microenvironment beneficial for the coupling probability of anti-RAC, promotes electron transfer, and improves the sensitivity of the immunosensor. This strategy based on a cMWCNT–Ag–CS substrate may offer a new approach for the sensitive and selective detection of other lean meat powders via only changing the corresponding antibodies. [ABSTRACT FROM AUTHOR]

An ultrasensitive electrochemical immunosensor using boron nitride nanosheet/gold nanoparticle (BNNS/AuNP) hybrids was developed for exhaled breath condensate (EBC) interleukin-6 (IL-6) quantification. BNNS were synthesized by chemical vapor deposition and decorated with AuNPs. The BNNS/AuNP hybrids were characterized by SEM, TEM, XRD, Raman, XPS, etc., and deposited on screen-printed carbon electrodes. Anti-IL-6 antibodies were immobilized via EDC/NHS crosslinking. The immunosensor detected IL-6 by differential pulse voltammetry technique with a linear range of 0.01–200 ng/mL and a limit of detection of 5 pg/mL. The sensor showed high reproducibility and selectivity. Validation with spiked EBC samples demonstrated good accuracy (relative error <5%). The sensor was successfully applied to analyze IL-6 in EBC samples. The BNNS/AuNP hybrid immunosensor provides a sensitive platform for non-invasive EBC biomarker quantification in respiratory diseases. [ABSTRACT FROM AUTHOR]

Protein tumor marker (PTM) analysis is of great significance for the early diagnosis and process monitoring of tumors. However, the clinical reference value of a single PTM is restricted, and existing tests for multiple PTMs majorly suffer from complex processes and poor sensitivity. Herein, a cancerous inhibitor of protein phosphatase 2A (CIP2A) and protein c-Myc (AGc‑Myc) with a positive feedback path in oral squamous cell carcinoma (OSCC) was chosen as a dual PTM, and a magnetic electrochemical immunosensor (MEI) for their simultaneous detection was successfully established. Fe3O4 coated with a gold nanoparticle (MAu)-functionalized magnetic electrode (f-MGE) was of benefit to immobilize two capture antibodies (CAb) through internal forces and external magnetic fields. By a mechanical alloying (MA) method, two photoelectric materials osmosed bimetallic-matrix nanospheres (Bi-MPE), including luminol and Ru-(bpy)32+ osmosed AuNPs–AgNPs nanoalloy (Lu@AuAg and Ru@AuAg), were prepared as innovative signal probes. Lu@AuAg and Ru@AuAg not only exhibit superior electrochemical properties than photoelectric material osmosed monometallic-matrix nanospheres but can directly label detection antibodies (DAb) without complex reaction conditions and additional functionalization. After immunological reactions, the distinguishable differential voltammetry pulse signals were obtained at +0.48 and +1.13 V, corresponding to AGc‑Myc and CIP2A, respectively. The proposed assay showed a good linear response range from 5 pg L–1 to 5 ng L–1 for AGc‑Myc and 50 pg L–1 to 50 ng L–1 for CIP2A, and a low limit of detection of 2.5 pg L–1 and 25 pg mL–1, respectively. The MEI also exhibited satisfactory selectivity, stability, and reproducibility. Moreover, when the proposed method and the ELISA kit were simultaneously applied to saliva samples of OSCC patients, the obtained results were completely consistent, reflecting the clinical practicability of this work. [ABSTRACT FROM AUTHOR]

We reported a highly efficient electrochemical immunosensor utilizing chitosan–graphene nanosheets (CS-GNs) nanocomposites for the detection of aflatoxin B1 (AFB1) in corn samples. The CS-GNs nanocomposites, serving as a modifying layer, provide a significant specific surface area and biocompatibility, thereby enhancing both the electron transfer rate and the efficiency of antibody immobilization. The electrochemical characterization was conducted utilizing both differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). Moreover, the antibody concentration, pH, antibody immobilization time, and immunoreaction time, were optimized. The results showed that the current change ( Δ I ) before and after the immunoreaction demonstrated a strong linear relationship ( R 2 = 0.990 ) with the AFB1 concentration, as well as good specificity and stability. The linear range extended from 0.05 to 25 ng/mL, with a detection limit of 0.021 ng/mL ( S / N = 3 ). The immunosensor exhibited a recovery rate ranging from 97.3% to 101.4% in corn samples, showing a promising performance using an efficient method, and indicating a remarkable prospect for the detection of fungal toxins in grains. [ABSTRACT FROM AUTHOR]

A ratiometric assay was designed to improve the sensitivity and reliability of electrochemical immunosensors for deoxynivalenol (DON) detection. The indicator signal caused by the Fe-based metal–organic framework nanocomposites loaded with gold nanoparticles and the internal reference signal from the [Fe(CN)6]3−/4− in the electrolyte came together at the immunosensor. When immunoreactivity occurred, the indicator signals decreased as the concentration of DON increased, while the internal reference signals increased slightly. The ratio of the indicator signal to the internal reference signal was available for reproducible and sensitive monitoring of DON. The prepared immunosensor showed excellent performance in the range from 0.5 to 5000 pg mL−1, and the detection limit was 0.0166 pg mL−1. The immunosensor achieved satisfactory detection toward DON in spiked and actual samples and has a promising application in the control of DON in grain products. [ABSTRACT FROM AUTHOR]

A sensitive electrochemical strategy for carcinoembryonic antigen 15–3 (CA15-3) detection is reported using CTAB-Co-MOFs@AuPt NPs as signal probes. The electrochemical strategy was designed as follows: First, the graphene aerogel@gold nanoparticles (GA@Au NPs) nanocomposites were employed to modify the sensing surface for promoting electron transfer rate and primary antibody (Ab1) immobilization due to GA possesses a large specific surface area, eminent conductivity, and a 3D network structure. Cobalt metal–organic frameworks (CTAB-Co-MOFs) synthesized were then used as a carrier for AuPt NPs and secondary antibody (Ab2) immobilization (notes: labelled-Ab2). With sandwich immunoreaction, the labelled-Ab2 was captured on the surface of the GA@Au NPs nanocomposites. Finally, differential pulse voltammetry (DPV) was employed to register the electrochemical signal of the immunosensor at the potential of − 0.85 V (vs SCE) in phosphate buffer saline (PBS) containing 2.5 mM H2O2. It was verified that the electrochemical reduction signal from Co3+ to Co2+ was recorded. The AuPt NPs could catalyze the reaction of H2O2 oxidizing Co2+ to Co3+, resulting in the amplification of the electrochemical signal. Under the selected conditions, the immunosensor can detect CA15-3 in the range 10 µU/mL to 250 U/mL with a low detection limit of 1.1 µU/mL. In the designed strategy, the CTAB-Co-MOFs were not only employed as carriers for AuPt NPs, but also acted as signal probes. The CTAB-Co-MOFs were investigated including SEM, TEM, XPS, and XRD. The application ability of the immunosensor was evaluated using serum sample, demonstrating the immunosensor can be applied to clinic serum analysis. [ABSTRACT FROM AUTHOR]

The screen-printed carbon electrode (SPCE) is a useful technology that has been widely used in the practical application of biosensors oriented to point-of-care testing (POCT) due to its characteristics of cost-effectiveness, disposability, miniaturization, wide potential window, and simple electrode design. Compared with gold or platinum electrodes, surface modification is difficult because the carbon surface is chemically or physically stable. Oxygen plasma (O2) can easily produce carboxyl groups on the carbon surface, which act as scaffolds for covalent bonds. However, the effect of O2-plasma treatment on electrode performance remains to be investigated from an electrochemical perspective, and sensor performance can be improved by clarifying the surface conditions of plasma-treated biosensors. In this research, we compared antibody modification by plasma treatment and physical adsorption, using our novel immunosensor based on gold nanoparticles (AuNPs). Consequently, the O2-plasma treatment produced carboxyl groups on the electrode surface that changed the electrochemical properties owing to electrostatic interactions. In this study, we compared the following four cases of SPCE modification: O2-plasma-treated electrode/covalent-bonded antibody (a); O2-plasma-treated electrode/physical adsorbed antibody (b); bare electrode/covalent-bonded antibody (c); and bare electrode/physical absorbed antibody (d). The limits of detection (LOD) were 0.50 ng/mL (a), 9.7 ng/mL (b), 0.54 ng/mL (c), and 1.2 ng/mL (d). The slopes of the linear response range were 0.039, 0.029, 0.014, and 0.022. The LOD of (a) was 2.4 times higher than the conventional condition (d), The slope of (a) showed higher sensitivity than other cases (b~d). This is because the plasma treatment generated many carboxyl groups and increased the number of antibody adsorption sites. In summary, the O2-plasma treatment was found to modify the electrode surface conditions and improve the amount of antibody modifications. In the future, O2-plasma treatment could be used as a simple method for modifying various molecular recognition elements on printed carbon electrodes. [ABSTRACT FROM AUTHOR]

This research is focused on enhancing the capabilities of scanning electrochemical impedance microscopy (SEIM) for detecting gold nanoparticle-labelled antibodies using electrochemically modified platinum ultramicroelectrode. The primary objective was to address the high resistance issue encountered in previous measurements with SEIM via the utilization of SEIM probes based on micro-electrodes modified by platinum microstructures, which improved the sensitivity and precision of the detection of targeted biomolecules. The modified probe resulted in a lowered charge transfer resistance by over ten times and a decrease in detection to around 100 fg/mL. We suggest potential applications in various biotechnological and biomedical fields, with future research expected to further refine this technique. [ABSTRACT FROM AUTHOR]

Atherosclerotic coronary heart disease (CHD) is ischemic and a worldwide health issue. The soluble suppression of tumorigenicity 2 (sST2) is a novel biomarker for atherosclerotic coronary heart disease. This work develops an immunosensor with a nanocomposite consisting of polyaniline (PANI) and MXene-Nafion for the specific and sensitive determination of sST2. PANI was first electropolymerized on a glassy carbon electrode (GCE) to enhance electron transfer. Subsequently, MXene-Nafion dispersion was drop cast on the PANI/GCE substrate to further increase the electrical conductivity and immobilize anti-sST2 which captures sST2 for detection. The current response as a function of sST2 concentration was measured by differential pulse voltammetry (DPV). Under the optimal conditions, this immunosensor demonstrates a linear range from 1 pg mL−1 to 1 μg mL−1 and a detection limit of 0.149 pg mL−1. The device offers high sensitivity, excellent specificity, satisfactory reproducibility, good stability, and has significant potential for detecting clinical biomarkers. In addition, the immunosensor is able differentiate between serum of healthy people and CHD patients. [ABSTRACT FROM AUTHOR]

The research aims to develop an electrochemical immunosensing assay using gold nanoparticles (AuNPs) on screen printed carbon electrode (SPCE) for the specific detection of Apolipoprotein A1 (ApoA1) proteins in chicken blood plasma (CBP). The biotin anti-ApoAI antibody was first immobilized on magnetic beads (MBs), while antibody ApoA1 was then conjugated with AuNPs. After a series of sandwich-type immunoreaction complexes was performed on the screen-printed carbon electrode, AuNPs were quantified by subjecting the immunocomplex to a peroxidation process of high potential at 1.2 V for 330 s and immediately reduced and scanned by differential pulse voltammetry (DPASV). This study obtained a linear relationship between reduction peak current signals and ApoA1 concentration from 0 to 100% (correlation coefficient of 0.996 with a detection limit of 5% of chicken blood plasma (CBP). The efficacy of our immunosensor is predicated on the seamless integration of antibodies with MBs to the target analyte, which provide ample surface area, biocompatibility, and user-friendliness. This breakthrough improves preliminary food fraud detection's sensitivity, reliability, and usability. It could improve diagnostic food safety, leading to a worldwide health breakthrough. [ABSTRACT FROM AUTHOR]

Wheat gliadin is thought to be the main cause of wheat allergy leading to celiac disease. In this study, we reported an electrochemical immunosensor based on AuNPs/Zn/Ni-ZIF-8-800@graphene for simple, efficient, and sensitive detection of gliadin. A monoclonal antibody against gliadin were prepared by hybridoma technique. Zn/Ni-ZIF-8-800 with high stability was prepared by using zinc–nickel bimetallic organic framework MOFs, and graphene and gold nanoparticles with large surface area and excellent conductivity were introduced. Chitosan was used as a binder to fixed the composite on the surface of glassy carbon electrode. The fabricated materials and the corresponding sensors were comprehensively characterized by X-ray diffractometer, scanning electron microscope, transmission electron microscopy, Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller, and cyclic voltammetry analyses. Under the optimal conditions, the linear range of the electrochemical immunosensor was 0.1–100 μg mL−1, and the detection limit was 0.950 μg mL−1. In addition, the fabricated sensor exhibited high selectivity and long-term stability. The recovery test showed that the prepared sensor was suitable for the detection of gliadin in real food and feed, exhibiting great promising of the developed sensor in practical application. [ABSTRACT FROM AUTHOR]

An ultrasensitive sandwich-type electrochemical immunosensor for pro-gastrin-releasing peptide (ProGRP) detection was constructed based on PtCu nanodendrites functionalized Au/polyaniline nanospheres (Au/PANI@PtCu). The prepared Au/PANI@PtCu nanocomposites not only possessed excellent electro-catalytic activity of H2O2 reduction due to the synergistic effect between the Au/PANI and PtCu NDs but also provided large specific surface area for detection of antibodies (Ab2) immobilization. In addition, Au nanoparticles encapsulated multi-wall carbon nanotubes (AuNPs@MWCNTs) were also applied to modify the glassy carbon electrode interface for loading numerous capture antibodies (Ab1). In the presence of target ProGRP, a sandwich-type electrochemical immunosensor showed a strong current response from the electro-catalysis of Au/PANI@PtCu toward H2O2 reduction. Benefiting from the exceptional electro-catalytic performance of Au/PANI@PtCu and the high conductivity of AuNPs@MWCNTs, the sandwich-type immunoassay exhibited remarkable sensitivity in detection. The linear range extended from 100 fg/mL to 10 ng/mL, while achieving an impressively low limit of detection of 77.62 fg/mL. [ABSTRACT FROM AUTHOR]

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.

An ultrasensitive electrochemical immunosensor was developed for detection of the cervical squamous cell carcinoma antigen (SCCA) biomarker using graphene-chitosan nanocomposites. Graphene oxide (GO) synthesized by a modified Hummer’s method was functionalized with chitosan biopolymer (CS) to produce CS-GO nanocomposites. Characterization by SEM, FTIR, Raman, XPS confirmed successful grafting of CS onto GO by electrostatic interactions. The CS-GO composite exhibited improved conductivity and biocompatibility. After optimizing the GO:CS ratio to 1:1, the nanocomposite was deposited on glassy carbon electrodes (GCE). Anti-SCCA antibodies were then immobilized covalently using pyrenebutyric acid crosslinker. The immunosensor fabrication was analyzed by EIS, CV, and DPV electrochemical techniques. The conditions including CS-GO ratio, antibody concentration, incubation time, pH, and voltage parameters were systematically optimized using orthogonal experimental design. Under optimal conditions, the immunosensor showed a linear detection range from 1 pg/mL to 100 ng/mL with a sensitivity of 196 μA/(ng/mL/cm2). The low limit of detection of 1 pg/mL was attributed to the high surface area and conductivity of the CS-GO transducer. Analysis of human serum samples spiked with SCCA demonstrated the reliability of the immunosensor for clinical applications. The graphene-nanocomposite electrochemical biosensing platform provides a rapid, low-cost, and ultrasensitive alternative to ELISA for SCCA detection in cervical cancer diagnostics.

This work created a simple electrochemical cortisol sensing method based on ZnO nanostructures to track high-performance athletes' stress levels and recuperation times. ZnO nanorods (ZnO NRs) were deposited on the surface of a glassy carbon electrode (ZnO/GCE) using an electrodeposition technique. Subsequently, 3-aminopropyltriethoxysilane (APTES) was applied to the electrode surface in order to improve cortisol antibody (C-M ab) immobilization and stability (C-M ab/APTES/ZnO/GCE). Successful immobilization of C-M ab on APTES/ZnO/GCE and electrodeposition of ZnO NRs on GCE were confirmed by structural investigations conducted using XRD, FT-IR, and FE-SEM. Cortisol was detected using an electrochemical immunosensor (C-M ab/APTES/ZnO/GCE) by monitoring the change in DPV and CV currents following cortisol binding to C-M ab. According to electrochemical experiments, the immunosensor exhibited a steady, selective, and sensitive response when it detected cortisol at concentrations between 10−6 nM and 106 nM, with a detection limit of 2 × 10−4 nM. It was assessed if the C-M ab/APTES/ZnO/GCE combination could identify cortisol in human serum. The samples' relative standard deviation (RSD) values range from 3.63% to 4.30%, and their recovery rates range from 90.00% to 98.50%, according to the analytical study. These findings imply that the C-M ab/APTES/ZnO/GCE offers accurate evaluations for cortisol detection in human serum samples.

Vertically ordered mesoporous silica films (VMSF) are a class of porous materials composed of ultrasmall pores and ultrathin perpendicular nanochannels, which are attractive in the areas of electroanalytical sensors and molecular separation. However, VMSF easily falls off from the carbonaceous electrodes and thereby impacts their broad applications. Herein, carbon nitride nanosheets (CNNS) were served as an adhesive layer for stable growth of VMSF on the glassy carbon electrode (GCE). CNNS bearing plentiful oxygen-containing groups can covalently bind with silanol groups of VMSF, effectively promoting the stability of VMSF on the GCE surface. Benefiting from numerous open nanopores of VMSF, modification of VMSF’s external surface with carbohydrate antigen 15-3 (CA15-3)-specific antibody allows the target-controlled transport of electrochemical probes through the internal silica nanochannels, yielding sensitive quantitative detection of CA15-3 with a broad detection range of 1 mU/mL to 1000 U/mL and a low limit of detection of 0.47 mU/mL. Furthermore, the proposed VMSF/CNNS/GCE immunosensor is capable of highly selective and accurate determination of CA15-3 in spiked serum samples, which offers a simple and effective electrochemical strategy for detection of various practical biomarkers in complicated biological specimens.