Water soluble perylene bisimide and its turn off/on fluorescence are used to detect cysteine and homocysteine

Perylene derivatives (P) in the presence of melamine (M) are envisioned as novel fluorescent probe for mercury ions and form a selective complex (PMHg) with mercury ions in neutral medium (pH = 7). This chemo-sensing ensemble probe exhibits high selectivity and sensitivity for thiol-containing amino acids and detects cysteine and homocysteine from healthy to abnormal levels under physiologically-relevant conditions.