Facile Preparation of Biocompatible and Transparent Silica Aerogels as Ionogels Using Choline Dihydrogen Phosphate Ionic Liquid

Abstract

We developed a facile and greener approach for the preparation of silica-aerogel-based ionogels using choline dihydrogen phosphate ionic liquid by the sol–gel approach. A series of silica-based aerogels as ionogels were prepared by varying the ionic liquid concentrations: 0.1, 0.5, 1, 3, 5, and 10 wt %. The as-prepared ionogels were characterized using several analytical techniques, namely, attenuated total reflectance (ATR)/FT-IR, TGA, XRD, and particle size analyses. The role of ionic liquid in the viscoelastic properties of the sol–gel transition was monitored using time-dependent rheological measurements. The addition of ionic liquid to the sol–gel system favored the formation of a more interconnected silica network structure. The formation of a silica network structure during sol–gel hydrolysis and condensation was confirmed from 29Si solid-state CP/MAS NMR spectra. The effect of the ionic liquid on the morphological properties was investigated using SEM and TEM studies. The cell viabilities of the prepared gel samples were clearly evident from the cytotoxicity assay studies using Swiss and HaCaT cells. The main advantages of using biocompatible ionic liquids for the preparation of these aerogels as ionogels are that they may be used for encapsulating biological molecules and retain their conformational stability for a longer duration.

Sustainable Collagen Blends with Different Ionic Liquids for Resistive Touch Sensing Applications

“…For 40­[Ch]­[DHP] films, a broader band appears at around 950 cm –1 , related to the ammonium groups (955 cm –1 ) of choline cation and to the P–OH group (946 cm –1 ) of [DHP] anion . The shoulder at 1080 cm –1 is related to the PO group of [DHP] anion . 40­[Ch]­[TFSI] films also present the characteristic band of choline cation as well as those of the triflate anion, such as those related to −SO 2 at 1342 and 1140 cm –1 , that related to S–N–S at 1050 cm –1 , and that related to −CF 3 at 1192 cm –1 . , 40­[EMIM]­[TFSI] films also show the bands at 1342, 1192, and 1050 cm –1 of TFSI. , The imidazolium cation bands at 2979 cm –1 , related to the ethyl chains (CH), and at 3018 cm –1 , corresponding to the ring (HC–CH and N­(CH)­N), are overlapped with the wide amide A band (Figure c). , …”

“… 49 The shoulder at 1080 cm –1 is related to the P=O group of [DHP] anion. 50 40[Ch][TFSI] films also present the characteristic band of choline cation as well as those of the triflate anion, such as those related to −SO 2 at 1342 and 1140 cm –1 , that related to S–N–S at 1050 cm –1 , and that related to −CF 3 at 1192 cm –1 . 51 , 52 40[EMIM][TFSI] films also show the bands at 1342, 1192, and 1050 cm –1 of TFSI.…”

Unveiling the Rational Development of Stimuli-Responsive Silk Fibroin-Based Ionogel Formulations

“…We select choline dihydrogen phosphate ([Cho]­[DHP]), choline acetate ([Cho]­[OAc]), and choline chloride ([Cho]­[Cl]) as our model ILs. Previously, these ILs have been shown to lower formulation viscosity, increase gel mechanical strength, induce gelation, and modulate the gelation temperature of diverse gel systems. − These ILs have been demonstrated as biocompatible and shown to enhance API solubility and suppress protein aggregation. ,,− Our choice of the silk fibroin biopolymer was premised in that it is biocompatible, biodegradable, and bioresorbable and offers tunable mechanical properties. , However, employing facile methods to prepare silk fibroin-based materials can result in aggregate formation, reduced mechanical strength, insufficient response to environmental stimuli, and limit fabrication to soft tissue medical materials. − Thus, although numerous studies have explored silk fibroin-based platforms for drug delivery applications, − further research is required. Given that low drug solubility is a major issue in formulation development, we were motivated to study the long-acting barbiturate phenobarbital as our model drug, as it would benefit from enhanced solubility. ,, We include proportions of our biocompatible ILs and silk fibroin biopolymer previously found optimal for directing gel self-assembly, exhibiting stimuli-responsive properties, and increasing the mechanical strength and the structural and thermal stability of diverse ionogels and polymer-based platforms. ,− We limit the water content and create formulation buffers comprising tween 20, histidine, trehalose, and sucrose in the absence and presence of glycerol.…”

“… 13 − 18 These ILs have been demonstrated as biocompatible and shown to enhance API solubility and suppress protein aggregation. 13 , 14 , 19 − 22 Our choice of the silk fibroin biopolymer was premised in that it is biocompatible, biodegradable, and bioresorbable and offers tunable mechanical properties. 23 , 24 However, employing facile methods to prepare silk fibroin-based materials can result in aggregate formation, reduced mechanical strength, insufficient response to environmental stimuli, and limit fabrication to soft tissue medical materials.…”