Search

This work focuses on fabricating poly(2-aminobenzylamine)-modified screen-printed carbon electrode as an electrochemical immunosensor for the label-free detection of human immunoglobulin G. To selectively detect immunoglobulin G, the anti-immunoglobulin G antibody with high affinity to immunoglobulin G was covalently linked with the amine group of poly(2-aminobenzylamine) film-deposited screen-printed carbon electrode. The selectivity for immunoglobulin G was subsequently assured by being challenged with redox-active interferences and adventitious adsorption did not significantly interfere the analyte signal. To obviate the use of costly secondary antibody, the [Fe(CN)6]4-/3- redox probe was instead applied to measure the number of human immunoglobulin G through the immunocomplex formation that is quantitatively related to the level of the differential pulse voltammetric current. The resulting immunosensor exhibited good sensitivity with the detection limit of 0.15 ng mL−1, limit of quantitation of 0.50 ng mL−1 and the linear range from 1.0 to 50 ng mL−1. Given those striking analytical performances and the affordability arising from using cheap screen-printed carbon electrode with label-free detection, the immunosensor serves as a promising model for the next-step development of a diagnostic tool. [ABSTRACT FROM AUTHOR]

Sometimes, smaller size is not always better, and looking for nanomaterials that offer better device performance requires consideration of their properties at the first stage. In this study, the effects of the size of polyethylenimine-capped AuNPs (PEI-AuNPs) and proteins on the immunosensor performances, namely, sensitivity and limit of detection, are examined. The size-effect investigation of PEI-AuNPs involves their modification on the surface of disposable screen-printed carbon electrodes to support primary antibodies and their ability to load secondary antibodies and redox probes to perform amplification in the immunosensor. The correlation of the average size, electrochemical activities, protein size, and device property of PEI-AuNPs is investigated. The synthesized PEI-AuNPs with different average diameters ranging from 4.7 to 44.9 nm are employed for the investigation. When the sensor surface forms a sandwich architecture, the detection employs the current response of Ag + ions on the PEI-AuNPs bioconjugate, which greatly increases by increasing the protein concentration. In addition, the best electrochemical signal of PEI-AuNPs or their antibody complexes with a unique AuNPs' average size allows superior signal amplification. The effect of using different sizes of target proteins on their devices is not significantly observed. Although in general small-sized nanomaterials offer high active surface areas, which can improve the electrode surface, reactivity, and device performance, we observe that the medium size of PEI-AuNPs (16.3 nm) gives the best sensitivity and detection limit of this sensor type. Therefore, the finding is useful for considering and optimizing their sizes for tunable voltammetric properties and acquiring a superior sensor., Competing Interests: The authors declare no competing financial interest., (© 2025 The Authors. Published by American Chemical Society.)