Bacterial Cellulose Ionogels as Chemosensory Supports

Abstract

To fully leverage the advantages of ionic liquids for many applications, it is necessary to immobilize or encapsulate the fluids within an inert, robust, quasi-solid-state format that does not disrupt their many desirable, inherent features. The formation of ionogels represents a promising approach; however, many earlier approaches suffer from solvent/matrix incompatibility, optical opacity, embrittlement, matrix-limited thermal stability, and/or inadequate ionic liquid loading. We offer a solution to these limitations by demonstrating a straightforward and effective strategy toward flexible and durable ionogels comprising bacterial cellulose supports hosting in excess of 99% ionic liquid by total weight. Termed bacterial cellulose ionogels (BCIGs), these gels are prepared using a facile solvent-exchange process equally amenable to water-miscible and water-immiscible ionic liquids. A suite of characterization tools were used to study the preliminary (thermo)physical and structural properties of BCIGs, including no-deuterium nuclear magnetic resonance, differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy, and X-ray diffraction. Our analyses reveal that the weblike structure and high crystallinity of the host bacterial cellulose microfibrils are retained within the BCIG. Notably, not only can BCIGs be tailored in terms of shape, thickness, and choice of ionic liquid, they can also be designed to host virtually any desired active, functional species, including fluorescent probes, nanoparticles (e.g., quantum dots, carbon nanotubes), and gas-capture reagents. In this paper, we also present results for fluorescent designer BCIG chemosensor films responsive to ammonia or hydrogen sulfide vapors on the basis of incorporating selective fluorogenic probes within the ionogels. Additionally, a thermometric BCIG hosting the excimer-forming fluorophore 1,3-bis(1-pyrenyl)propane was devised which exhibited a ratiometric (two-color) fluorescence output that responded precisely to changes in local temperature. The ionogel approach introduced here is simple and has broad generality, offering intriguing potential in (bio)analytical sensing, catalysis, membrane separations, electrochemistry, energy storage devices, and flexible electronics and displays.

Nanocellulose films with multiple functional nanoparticles in confined spatial distribution

“…19,20 TiO 2 and Au nanocomposites were applied in catalysis [21][22][23] while sensing applications were also reported for BC-Au. 24 BC with Fe 2 O 3 nanoparticles 25,26 was proposed as radio-frequency shielding materials, 27 anti-counterfeiting papers, 28 ultra-thin loudspeakers 29 or for heavy metal removal. 30 In our approach, metal and metal oxide nanoparticles decorate the bacterial cellulose fibrils.…”

A natural in situ fabrication method of functional bacterial cellulose using a microorganism

“…BC is often functionalized with chemical modification or physical coating based on fermentation products. Commonly used modification methods include nanoparticle coating, metal oxide modification, fluorescent substance modification and ionic liquid replacement 2,23–25 . The physical coating can provide a mild modification condition, but functional moieties potentially suffer from shedding due to weak physical interactions.…”

Elastic and Thermoreversible Iongels by Supramolecular PVA/Phenol Interactions

“…Dynamic supramolecular iongels are typically designed from low molecular weight gelators (LMWG) [20][21][22][23] or biopolymers, encompassing glycolipids, gelatin, carrageenans, guar gum, and cellulose, [24][25][26][27][28] providing materials with biomolecular functions (e.g. biocatalytic activity and biodegradability).…”

“…Dynamic supramolecular iongels are typically designed from low molecular weight gelators (LMWG) [ 20–23 ] or biopolymers, encompassing glycolipids, gelatin, carrageenan, guar gum, and cellulose, [ 24–28 ] providing materials with biomolecular functions (e.g., biocatalytic activity and biodegradability). However, this type of iongels frequently results in materials lacking the sturdiness required for many applications.…”