Gelatin-Based Highly Stretchable, Self-Healing, Conducting, Multiadhesive, and Antimicrobial Ionogels Embedded with Ag₂O Nanoparticles

Abstract

The polyionic nature of gelatin (G), derived from partial hydrolysis of collagen, is utilized to prepare ionogels (IGs) in conjunction with aqueous mixtures of a polar ionic liquid (IL), 1-ethyl-3-methylimidazolium ethylsulfate, [C 2 mim][C 2 OSO 3 ]. The highly polar nature of IL−H 2 O mixture (50/50 v/v %) supported the high solubility of G, where the IGs are prepared by dissolving equal amount of G to IL−H 2 O mixture (50/50 v/v %) in a stepwise manner at 45 °C while stirring. The combination of IGs with Ag 2 O nanoparticles (NPs) prepared in situ, via photoreduction of AgNO 3 led to induction of antimicrobial activity in IGs, while enhancing the mechanical properties. The prepared IGs show fast self-healing (<1 min) and multiadhesive nature along with reversible stretching efficiency and high conductivity. The conductivity (2 mS cm −1 ) of prepared IG is highest among all biopolymer-based IGs reported, until date. The multiadhesive and highly conducting nature, transparency, inherent shapememory effect, and mechanical stability of the prepared the IGs are expected to be utilized in various electrical and bioelectronic applications. Moreover, these properties can be controlled by tuning the morphology of Ag 2 O NPs and water content in IGs. The method used for preparation of IGs provides a new way for easy, green, and economical preparation of antimicrobial IGs at a reduced temperature, where no harmful reducing agent or UV light is used for in situ preparation of Ag 2 O NPs.

Marine-Derived Polymers in Ionic Liquids: Architectures Development and Biomedical Applications

“…In Figure 5 is presented the model structure of gelatin. Gelatin has a high solubility in water, as well as in many ILs [31]. The dissolution of gelatin in water occurs after the polypeptide strands in its structure undergo a coil-helix transition, and it happens at 30-35 • C [93].…”

“…The dissolution of gelatin in water occurs after the polypeptide strands in its structure undergo a coil-helix transition, and it happens at 30-35 • C [93]. Gelatin's amino acid content, which includes positively charged (lysine and Arg, 7.5%); negatively charged (Glu and aspartic acid, 12%); neutral (Gly, Pro, and Hyp, 58%); and hydrophobic (leucine, isoleucine, methionine, and valine, 6%) amino acid residues, promotes a different set of interactions with solvents or electrolytes [31]. This polymer is inexpensive, biocompatible, and biodegradable and interacts strongly with molecules that are soluble in aqueous media [93].…”

“…ILs can provide different physical-chemical properties and, also, change the gelatin microenvironment, being able to address one of gelatin's limitations, which concerns the entrapment of poorly water-soluble molecules [93]. The combination of ILs with gelatin is often used for the production of ion gels (IGs) [31,93,94]. This is mainly possible due to the expected set of electrostatic, hydrophobic, and H-boding interactions between the biopolymer and ILs, which lead to the formation of IGs [31].…”

“…The combination of ILs with gelatin is often used for the production of ion gels (IGs) [31,93,94]. This is mainly possible due to the expected set of electrostatic, hydrophobic, and H-boding interactions between the biopolymer and ILs, which lead to the formation of IGs [31]. This gelation process is based on a good compromise between the retention of the IL and its fluidity inside the polymeric network [93].…”

“…The produced IGs are usually simpler than the common solid polymer electrolytes and exhibit improved conductivities, which boosts its use as substitutes for the existing solid-state polyelectrolytes in energy devices [94]. Moreover, these electrolytes may often be used as printable "inks" [31,94]. Several authors have been using these IGs for the development of biosensing devices, namely for the immobilization of oxidoreductases, such as glucose oxidase (GOD) and horseradish peroxidase (HRP) [93,95,96].…”