Hybrid material for ferric ion detection & remediation: Exceptional selectivity & adsorption capacity with biological applications

Abstract

In this work, naphthalimide derived functionalized silica material SiO2@NAPIA (2,2‘((((propylazanediyl)bis(methylene))bis(2,1-phenylene))bis(oxy))bis(N-(1,3-dioxo-1H-benzo[de]isoquinoline-2(3H)-yl)acetamide)) was constructed as a dual signaling and remediation material for ferric ions from a pool of 35 common ions (cations and anions) in the aqueous system. The material Cubic SiO2 shows a high surface area (1104 m2/g, pore volume (1.510 cm3/g), and pore diameter (6.3 nm) in the mesoporous range, which reduces further on functionalization to get the final material SiO2@NAPIA. The ferric ion selectivity through fluorescence quenching displays a Stern-Volmer quenching constant (Ksv) of 7.8 × 108 M−1 with a LOD (Limit of detection) value of 0.11 μM for ferric-ion, which is 48 times lower than the USEPA (United States Environmental Protection Agency) maximum contaminant level (5.35 μM) in drinking water. This material also shows a very high adsorption capacity (664 mg/g) for ferric ions fitting the Langmuir model isotherm with R2 = 0.99, which can be easily stripped out, and the material can be recycled. This material was also used as a sensory probe material for biosensing of ferric ions through fluorescence imaging in living organisms like Artemia salina and quantification in the real environmental sample. Furthermore, the antibacterial activity inspired by the ferric ion chelating affinity shows good potency against several Gram-negative and Gram-positive bacterial strains. The Minimum Inhibitory Concentration (MIC) & Minimal Bactericidal Concentration (MBC) of the material against these pathogens were found to be 100 & 200 μg/mL respectively. This material signifies superior activity with respect to the ferric-ion selective materials known in the literature.