Engineering bio-molecular device with biocompatible sensor via symmetric encryption–decryption of spectroscopic signals towards F− detection and Zn2+ recognition by the imine hydrolysis pathway

Abstract

A small molecular probe was synthesized and its response towards biologically significant ions such as Zn²⁺ and F⁻ with low detection threshold (Zn²⁺: 50 nM and F⁻: 3 μM) was investigated in the present work. The recognition event was appreciably utilized towards designing a biomolecular logic device. ¹H-NMR and ESI-MS analyses suggested a chemodosimetric recognition pathway of the probe in the existence of Zn²⁺ that was thoroughly explored by theoretical (DFT-D3) analysis. In DFT-D3, to ensure the character of the minimum structures obtained from the geometry optimization, the vibrational frequency was analysed, which further confirmed the absence of imaginary mode of vibration for the substrate, intermediate and product geometries. The presence of only one imaginary mode of vibration for the transition state geometries confirmed the behaviour of the first-order saddle point. The zero-point vibrational energy and thermal correction to the enthalpy and entropy at 298.15 K were also derived at the same level of theory. In case of F⁻, the pathway follows a supramolecular non-covalent type of interaction. The in vitro recognition of Zn²⁺ and F⁻ was explored in different cells (Pollens and Candida albicans), which, in turn, establishes the cell permeability and bioapplicability of the present chemosensor. The reversible spectroscopic response of the probe was utilized to design multi logic gate-based circuitry and a biomolecular device with versatile applications that open up new avenues in the realm of supramolecular functional world.