Photophysical Study and Biological Applications of Synthetic Chalcone-Based Fluorescent Dyes

Abstract

A chalcone series (<b>3a</b>-<b>f</b>) with electron push-pull effect was synthesized via a one-pot Claisen-Schmidt reaction with a simple purification step. The compounds exhibited strong emission, peaking around 512-567 nm with mega-stokes shift (∆λ = 93-139 nm) in polar solvents (DMSO, MeOH, and PBS) and showed good photo-stability. Therefore, <b>3a</b>-<b>f</b> were applied in cellular imaging. After 3 h of incubation, green fluorescence was clearly brighter in cancer cells (HepG2) compared to normal cells (HEK-293), suggesting preferential accumulation in cancer cells. Moreover, all compounds exhibited higher cytotoxicity within 24 h toward cancer cells (IC₅₀ values ranging from 45 to 100 μM) than normal cells (IC₅₀ value >100 μM). Furthermore, the antimicrobial properties of chalcones <b>3a</b>-<b>f</b> were investigated. Interestingly, <b>3a</b>-<b>f</b> exhibited antibacterial activities against <i>Escherichia coli</i> and <i>Staphylococcus aureus</i>, with minimum bactericidal concentrations (MBC) of 0.10-0.60 mg/mL (375-1000 µM), suggesting their potential antibacterial activity against both Gram-negative and Gram-positive bacteria. Thus, this series of chalcone-derived fluorescent dyes with facile synthesis shows great potential for the development of antibiotics and cancer cell staining agents.