Selective fluorescence sensing of Cu(II) ions using calix[4]pyrrole fabricated Ag nanoparticles: A spectroscopic and computational approach

Abstract

The presence of Cu(II) at excessive levels can cause several undesirable issues to human health and to the environment as well. Hence, a simple, fast and selective method is needed to develop for monitoring the occurrence of Cu(II). In the present study, we report a novel fluorescent sensor for the selective and sensitive detection of Cu(II) using calix[4]pyrrole fabricated nano-Ag particles (CPTH-AgNPs). The selectivity of the method has been evaluated under optimal conditions of pH and temperature. Molecular Dynamics has been performed to understand the coating of calix[4]pyrrole tetrahydrazide around nano-Ag particles. The computational modeling predicts the grafting of CPTH on the surface of AgNPs and unveils the role of non-covalent pi-pi intermolecular and H-bonding interactions. The conjugated features of calix[4]pyrrole and nanoparticles provide deep insights into the ion sensing phenomenon. The non-covalent interaction of Cu(II) with CPTH-AgNPs disturbs the intramolecular hydrogen bonding networks and causes aggregation of the nanoparticles as demonstrated by FT-IR, DLS and TEM analysis. The present work has also been extended for some bio-analytical applications such as antibacterial, and DNA (CT-DNA) binding studies, which indicate the importance of CPTH-AgNPs for designing an efficient drug-target carrier system. Moreover, the in vitro HeLa cell imaging based on fluorescence microscopy predicts the potential application of CPTH-AgNPs for targeted cancer treatment in living systems.