Foam-Height Response in Saccharomyces cerevisiae as a Phenotypic Indicator of Acute Metal Toxicity and Its Modulation by Amino Acid–Derived Carbon Nanodots

This study evaluates foam-height response in Saccharomyces cerevisiae as a rapid phenotypic indicator of acute toxicological stress induced by selected inorganic salts and its modulation by amino acid–derived carbon nanodots (CNDs). Foam height measured after 20 min, reflecting combined fermentative activity and cell surface properties, was used as an integrative proxy of early cellular responses. Clear dose-dependent inhibitory effects were observed for CuSO₄, NaCl, Na₂SeO₃, and Na₂TeO₃. L-ascorbic acid exhibited a biphasic response. Glycine- and lysine-derived CNDs modulated copper toxicity in a concentration-dependent and compound-specific manner, with GLY-CNDs showing predominantly protective effects, while LYS-CNDs displayed variable outcomes. Although the method does not resolve mechanistic pathways or subtle physiological changes, it reliably captures dominant toxicological trends under acute exposure conditions. The results support the applicability of foam-height response as a simple, rapid, and low-cost complementary screening approach for preliminary toxicity assessment of chemical agents and nanomaterials.