One-Pot Avidin Functionalization of Reduced Graphene Oxide Yields Label-Free Electrochemical Biosensor

Researchers in Argentina have developed a one-pot, ultrasound-assisted method that simultaneously partially reduces and biofunctionalizes graphene oxide, using L-tyrosine and ascorbic acid as mild, complementary reducing agents. The approach, described in Frontiers in Sensors, incorporates avidin directly during the reduction process, eliminating post-synthetic modification steps and producing an avidin-functionalized reduced graphene oxide (rGO) interface for electrochemical biosensing.

According to the team from the Instituto de Investigaciones en Fisicoquímica de Córdoba and the Universidad Nacional de Córdoba, the synergistic combination of the two reducing agents enables controlled partial restoration of the sp2 carbon framework while preserving the oxygen functionalities required for biomolecular anchoring.

The resulting material provides a functional electrochemical interface for the oriented immobilization of biotinylated recognition elements through the avidin-biotin affinity interaction. Because avidin is incorporated in situ, the platform avoids separate surface-engineering steps, and the authors conceived the immobilization strategy to allow different biosensing interfaces to be assembled without re-engineering the underlying transducer.

The platform was implemented as a label-free electrochemical interface and characterized by electrochemical impedance spectroscopy, a technique used to monitor both the interfacial assembly and the biorecognition events as they occur.

As a proof of concept, the team validated the immobilization strategy using the thrombin-binding aptamer as a representative biotinylated recognition element for the detection of human α-thrombin.

The platform exhibited a linear response from 1.34 × 10−9 M to 2.67 × 10−6 M, with a coefficient of determination (R2) of 0.987, and a detection limit of 4.4 × 10−10 M. The authors report that the sensor demonstrated a selective response in the presence of potentially interfering proteins and in enriched human serum samples, indicating that the avidin-biotin assembly can retain function in a biologically relevant matrix.

The study is explicitly framed as a proof of concept. The authors note that the approach was experimentally validated using a single aptamer-target pair, and that broader claims about modularity remain a design goal rather than a demonstrated result. Nevertheless, the authors note that the immobilization strategy may enable the future development of adaptable electrochemical biosensing platforms employing different biotinylated recognition elements without modifying the underlying transducer.

The authors describe the strategy as environmentally responsible, and the one-pot format reduces the number of synthesis and functionalization steps required to reach a working biointerface.

The findings establish, in the authors’ words, a sustainable one-pot strategy for producing avidin-functionalized rGO and a proof of concept for an avidin-based electrochemical biointerface.

Subject of Research: A one-pot avidin functionalization of reduced graphene oxide for label-free electrochemical aptamer biosensing

Article Title: Toward a modular label-free electrochemical biosensing platform based on a one-pot avidin functionalization of reduced graphene oxide

Article References: Reartes, D. F., Rivas, G. A., Rubianes, M. D., & Rodríguez, M. C. (2026). Toward a modular label-free electrochemical biosensing platform based on a one-pot avidin functionalization of reduced graphene oxide. Frontiers in Sensors, 7, Article 1864839. https://doi.org/10.3389/fsens.2026.1864839

Image Credits: AI Generated

DOI: 10.3389/fsens.2026.1864839

Keywords: reduced graphene oxide, graphene oxide, avidin-biotin interaction, electrochemical biosensor, label-free detection, electrochemical impedance spectroscopy, thrombin-binding aptamer, human α-thrombin, ascorbic acid, L-tyrosine, one-pot synthesis, biosensing platform