Gellan gum hydrogels as such and ionic-liquid doped as modulable micro-invasive tools for Cultural Heritage studies

Rigid Gellan gel, composed of Gellan gum and calcium acetate, is known to be biocompatible and capable of absorbing water-soluble compounds present on fragile artworks; moreover, when implemented on screen-printed electrodes, it can result in a device providing both absorption and in situ electroanalytical detection of species of interest for Cultural Heritage researchers. In this application, its properties and performances could be modulated by doping with ionic liquids, innovative media consisting of molecular salts with low melting points. In this preliminary investigation, a series of absorbing conductive materials based on Gellan hydrogel, used as such and doped with 1-ethyl-3-methylimidazolium methanesulfonate in various amounts, are paired with screen-printed sensors and tested as tools for the voltammetric detection of lawsone, a red-orange dye found in the leaves of the henna plant (Lawsonia Inermis) and used since the time of Ancient Egypt to dye textiles.