Lanthanum mediated rutin yellow-fluorescent carbon dots as multifaceted sensing probes for the detection of calcium ions in melanoma and plant cells.

Calcium (Ca2 +) as a signaling ion and intracellular second messenger plays a crucial role in living organisms for various cellular functions. In the present work, we have designed a novel yellow-fluorescent carbon dots (LERCDs) using lanthanum, ethylenediaminetetraacetic acid (EDTA), and rutin as precursors for the sensing of Ca2 + ions. In this sense, a combination of hydrothermal and reflux methods was adopted. The as-designed LERCDs display bright yellow color emission in the aqueous solutions with a high quantum yield (23.8%). The LERCDs showed excitation-independent emission property along with magnificent photostability and time stability. The LERCDs show potential fluorescence quenching response towards the Ca2+ ions in the concentration range of 0-25 µM with a detection limit of 2.19 µM. The LERCDs have studied for extracellular sensing of Ca2 + ions in both melanoma cell lines (A375) and onion epidermal cells by employing fluorescence microscopy. The LERCDs facilitate low cytotoxicity and superior biocompatibility features in A375 cells. The practicality of LERCDs was studied in biological samples like the human serum.