A copper-mediated Fenton-like dual-mode optical sensor for sensitive determination of acetylcholinesterase activity in biological fluids

. Applied to spiked serum and erythrocyte samples, the fluorometric and colorimetric modes yielded mean recoveries of 96.50-100.50% and 96.37-102.30%, respectively. The proposed platform offers complementary sensitivity ranges, cross-validated readouts, and practical applicability in complex biological matrices, representing a reliable tool for AChE activity monitoring in clinical and environmental contexts.