A turn on fluorescent sensor for detecting Al3+ and colorimetric detection for Cu2+: Synthesis, cytotoxicity and on-site assay kit

Abstract A new rhodamine-fluorene based sensor, RFC has been synthesized for selective detection of Al3+ and Cu2+ with detection limit as low as 0.12 μM and 1.14 μM respectively. The “off-on’’ colorimetric changes of RFC upon binding with the metal ions was differentiated by UV-light. Furthermore, the possible sensing mechanism was proposed from FTIR and 1H NMR spectrum, while the binding stoichiometry was determined from Benesi-Hildebrand and Job’s plot. From these studies, a 1:1 stoichiometry of sensor-metal complex for both RFC-Al3+ and RFC-Cu2+ was recorded. On-site virtual detection of these metal ions by RFC was done by using filter paper as test strips. MTT assay indicated that RFC have no significant cytotoxicity to the cultured human colorectal adenocarcinoma (HT-29) and normal (CCD-18Co) cells.