Quantum Dot to Dye Based Fluorescent Ratiometric Immunoassay for GFAP - a biomarker for Ischaemic Stroke and Glioblastoma Multiforme

Abstract

Ischaemic stroke and glioma; leading causes of mortality and long-term disability presents a critical challenge in healthcare, necessitating innovative approaches for early and economical diagnosis enabling effective intervention. Glial fibrillary acidic protein (GFAP), a protein produced from astrocytes; is much responsive to ischaemic stroke and glioblastoma multiforme; and its levels are correlative to the extent of brain damage. In this study, we present the development of an immunoassay probe for the fluorescence ratiometric detection of glial fibrillary acidic protein (GFAP), employing monoclonal GFAP antibody-conjugated silicon quantum dots (Ab@SiQDs) and rhodamine B dye (RhB) based immunoprobe. The probe exhibited a fluorescence emission shift from 580 nm to 530 nm in response to GFAP, demonstrating a linear detection range from 31.15 pg/mL to 243 pg/mL, with a limit of detection of 0.7 pg/mL. The immunoprobe showed high selectivity towards GFAP, discriminating it from other potential interfering biomolecules and ions. Furthermore, the probe detected GFAP in spiked serum samples, achieving a recovery rate between 83% and 111%. A low-cost paper strip assay was developed that offers significant potential for the visual detection of GFAP under ultraviolet illumination.