Selective Chromo-Fluorogenic Chemoprobe for nM Al³⁺ Recognition: Experimental and Living-Cell Applications

A rhodamine based chemoprobe BESN was engineered and employed as a selective ''OFF-ON'' chromo-fluorogenic sensor for Al³⁺ in H₂O:MeOH (1:9, v:v). Notable changes in the absorption and emission spectra of BESN were clearly detectable upon the addition of Al³⁺. Sensitivity and binding mechanism studies demonstrated a good sensing performance of BESN with nanomolar detection limit (130 nM), and it was found to be highly selective towards interfering metal ions. Besides, the binding constant between BESN and Al³⁺ was found to be 3.19 × 10³ M^-1. Then, the validation study of BESN for Al³⁺ was performed based on significant analytical parameters and statistical tests. The binding of Al³⁺ with BESN (1:1) was probed via infrared, high-resolution mass and emission (Job's plot) spectroscopy measurements. The sensing performance of BESN could make it ideal chemosensor for real applications including vegetable, tuna fish and water samples, also for Smartphone and test-kit applications. The recovery values of the BESN to Al³⁺ were estimated within a range from 95.13% to 105.30% for water, 94.63% to 109.62% for tuna fish and 94.80% to 109.80% for vegetable samples. Additionally, the BESN has very low cytotoxicity and was triumphantly utilized for the recognition of Al³⁺ in living-cells.