A highly sensitive fluorescence biosensor based on polylysine functionalized quantum dots for serum GDF-15 detection.

Growth differentiation factor-15 (GDF-15) is a stress-responsive cytokine that increases in tissue injury and inflammatory states. The circulation level of GDF-15 is firmly correlated with cardiovascular diseases. Herein, we constructed a novel quantum dot-based fluorescent immunosensor for the sensitive detection of serum GDF-15. In this proposed platform, green-emission water-soluble carboxyl-capped CdTe quantum dots were synthesized as fluorescent labels, conjugated with lysine-rich biotinylated peptides P16K to amplify fluorescent signals, and then linked to antibodies via a biotin-streptavidin system to obtain the fluorescent detection probes. The probes were then integrated into a fluorescence-linked immunosorbent assay (FLISA) platform for GDF-15 detection, achieving a wide linear range (6-1600 pg/mL) and low limits of detection (0.98 pg/mL). Moreover, our approach has been demonstrated in clinical validation experiments performed on human serum samples, in which the results obtained were consistent with those from commercial ELISA kits. Due to its higher sensitivity in comparison to commercial ELISA kits, the platform shows excellent potential for early diagnosis and risk screening of cardiovascular diseases.