Near infrared-emitting carbon dots for the detection of glial fibrillary acidic protein (GFAP): a non-enzymatic approach for the early identification of stroke and glioblastoma†

Immunoassay techniques are widely recognized for their sensitivity and selectivity in biomarker detection; however, their high cost, time-consuming protocols and limited stability often pose significant limitations. In this study, we address these challenges by developing an antibody-free fluorescent platform for the detection of glial fibrillary acidic protein (GFAP), a biomarker released from astrocytes, which plays a critical role in neurological diseases such as ischemic stroke and glioblastoma (GBM). Glutamic acid (GA), a neurotransmitter prevalent in the brain, was selected to quench a near-infrared (NIR) emitting carbon dot-based probe, exploiting the potential interaction between GA and GFAP. The probe demonstrated a turn-on response towards GFAP in the presence of various co-existing biomolecules and ions with a detection limit of 1.8 pg mL⁻¹. A real sample assay conducted in human serum further validated the performance of the probe, achieving a recovery rate of 85% to 97%, underscoring the potential of the probe as a reliable and cost-effective tool for GFAP detection in clinical settings.