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. 2025 Mar 26;192(4):260.
doi: 10.1007/s00604-025-07103-2.

Fluorescence 'turn-on' sensing of glial fibrillary acidic protein using graphene oxide-quenched copper nanoclusters

Geneva Indongo  1 , Merin K Abraham  2 , Greeshma Rajeevan  2 , Arathy B Kala  2 , Dheyaa Mohammed Dhahir  2 , Sony George  3   4
Affiliations

Fluorescence 'turn-on' sensing of glial fibrillary acidic protein using graphene oxide-quenched copper nanoclusters

Geneva Indongo et al. Mikrochim Acta. .

Abstract

This study introduces a fluorescence based sensing platform made to detect glial fibrillary acidic protein (GFAP), a critical biomarker associated with glioblastoma and other astrocytic malignancies. Leveraging the unique optical properties of copper nanoclusters (CuNCs) functionalized with GFAP antibodies (GFAP Ab), the platform incorporates graphene oxide (GO) as a fluorescence quencher to create a highly sensitive turn on sensor responsive to GFAP antigens. The detection mechanism relies on Förster resonance energy transfer (FRET), wherein the binding of GFAP antigens disrupts the GFAP Ab@CuNCs-GO interaction, effectively restoring fluorescence. The CuNCs stabilized with l-cysteine to enhance biocompatibility and stability, exhibited strong green fluorescence with a quantum yield of 1.0%. Graphene oxide efficiently quenched the fluorescence of GFAP Ab@CuNCs therefore enhancing the platform's sensitivity. The sensor displayed a linear fluorescence response across a GFAP concentration range 0-46 ng/mL, with a detection limit of 32 pg/mL, demonstrating its capability to detect GFAP at clinically relevant levels. Validation of the sensor in biological fluids, including saliva, serum and urine, confirmed its applicability for minimally invasive diagnostics. Situated at the intersection of biosensing and clinical relevance, this study aims to address the need for cost effective and accessible diagnostic and screening tools for glioblastoma.

Keywords: Biosensor; Cancer; Copper nanoclusters; Fluorescence; GFAP biomarker; Immunosensing.

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Conflict of interest statement

Declarations. Ethical approval: All experiments were performed in accordance with the ethical standards set forth by the Indian Council of Medical Research (ICMR). They were conducted in compliance with ICMR guidelines and received approval from the University Level Human Ethical Committee under Order no: ULECRIHS/UOK/2023/108 at the University of Kerala, Thiruvananthapuram. Informed consent was obtained from blood serum donors, towards the study. Declaration of generative AI and AI-assisted technologies in the writing process: During the preparation of this work the authors used Copilot in order to improve readability and language. After using this tool, the authors reviewed and edited the content as needed and take full responsibility for the content of the publication. Conflict of interest: The authors declare no competing interests.

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