Interplay of Electronic Delocalization and Aggregation Dynamics in Decoding Metabolic Disease Biomarkers: Application to Screening of Biological Fluids and Intracellular Imaging

Herein, we report the design and comparative evaluation of two hydrazone-based fluorogenic probes incorporating distinct polyaromatic scaffolds, anthracene (compound 1) and pyrene (compound 2), for the selective detection of the metabolic biomarker α-ketoglutaric acid (KGA). The novelty of this work lies in correlating fluorophore architecture with reactivity, electronic delocalization, and aggregation dynamics toward KGA sensing (LOD: 1.09 μM). Spectroscopic, morphological, and computational analyses revealed that compound 1, with its planar anthracene framework and accessible -NH₂ donor, forms a Schiff-base (C═N) adduct with KGA, accompanied by a controlled aggregation process that leads to the formation of larger colloidal particles and a ∼ 4.0-fold fluorescence enhancement (K = 1.16 × 10⁴ M⁻¹). In contrast, the pyrene analogue (compound 2) exhibited limited response due to preaggregation and steric hindrance. The probe efficiently quantified KGA in diluted human urine (93-105% recovery) and demonstrated bright intracellular fluorescence in HeLa cells, confirming its biocompatibility and diagnostic potential for real-time metabolic biomarker monitoring.