Affinity Directed Surface Functionalization of Two\nDifferent Metal Nanoparticles by a Natural Ionophore: Probing and\nRemoval of Hg2+ and Al3+ Ions from Aqueous Solutions

In this work, we\nreport affinity controlled surface modifications of two different\nmetal nanoparticles (MNPs) using a hydrophilic natural ionophore (microbial\nchelator) aeruginic acid (abbreviated as H2L) that possesses\ntwo different types of binding pockets viz. O/O from carboxylic acid\ngroup and N/O from a phenol–thiazole moiety. Preferred binding\nof the former donor set (i.e., O/O) on to the surface of silver nanoparticles\n(AgNPs) has resulted in a colorimetric nanomaterial HL@AgNPs, which\nshowed naked eye observable easy detection of Hg2+ in aqueous\nHEPES buffer at pH 7.4, even in the presence of other metal ions.\nOn the other hand, excellent affinity of the phenol–thiazole\nmoiety (i.e., N/O) for iron nanosurfaces (FeNPs) develops a fluorogenic\nnanomaterial HL@FeNPs. Brilliant emission behavior of this nanomaterial\nenabled it to be useful for highly selective recognition of Al3+ under identical experimental conditions. Remarkable fluorescence\nenhancement (122-folds) of HL@FeNPs upon addition of Al3+ remain unchanged even in the presence of other competing metal ions.\nThe nanomaterials HL@AgNPs and HL@FeNPs could even detect the target\nanalytes instantly offering lower detection limits of 2 and 80 nM,\nrespectively. Presence of toxic metal ions as environmental pollutant\ndemands for dual-functional materials capable of performing the task\nof probing cum removal. Surface functionalizations of the nanomaterials\nof silver and iron with H2L have also resulted two removal\nagents that can efficiently and easily extract Hg2+ and\nAl3+ ions from contaminated water, respectively. We are\nnot aware of any work that highlights the manifold utilization of\na microbial chelator (i.e., natural ionophore) in the facile construction\nof different metal nanoparticles for environmental applications such\nas detection cum removal of toxic metal ions from aqueous solutions.