Hierarchical self-assembly in ionic liquid crosslinked polyelectrolyte gels as a citric acid sensor

Abstract

The design of an enzyme-free biocompatible electrochemical platform for the detection of citric acid is discussed. We have studied sol-gel transition in DNA ionic liquid solution triggered by the ionic liquid (IL), (1-Octyl-3-methylimidazolium Chloride [C8mim][Cl]; concentration= 0.1 to 1.0% (w/v)). Rheology and Small-angle neutron scattering (SANS) studies characterized their viscoelastic and microstructural properties. The gel modulus was found to vary from 10 to 60 Pa concomitant with a tunable temperature of gelation. SANS data yielded the persistence length of DNA (50 ± 12 nm) and the mesh size of these gels (ξ = 2.5±0.5 nm). Remarkably, this ionogel served as an excellent electrochemical sensor for citric acid detection in the application window of 0.02-0.08 mM analyte concentration with a detection limit of 1.510-8 molL-1. Yet another non-trivial application of the versatile DNA gel is demonstrated here.