Investigation of the solubility and dispersion degree of calf skin collagen in ionic liquids

Abstract

The dissolution of collagen in ionic liquids (ILs) was highly dependent on the polarity of ILs, which was influenced by their sorts and concentrations. Herein, the solubility and dispersion degree of collagen in two sorts of ILs, namely 1-ethyl-methylimidazolium tetrafluoroborate ([EMIM][BF 4 ]) with low polarity and 1-ethyl-3methylimidazolium acetate ([EMIM][Ac]) with high polarity in a concentration range from 10% to 70% at 10°C were investigated. When 150 mg of collagen was added to 30 mg of ILs, the minimum soluble collagen concentration was 0.02 mg/mL in 70% [EMIM][BF 4 ] with lowest polarity and the maximum was 3.57 mg/mL in 70% [EMIM][Ac] with highest polarity, which indicates that soluble collagen and insoluble collagen fibers were both present. For insoluble collagens, differential scanning calorimetry showed that the thermal-stability was weakened when increasing the ILs concentration and polarity, and the fiber arrangement was looser with a more uniform lyophilized structure, observed by atomic force microscopy and scanning electron microscopy. For soluble collagens, electrophoresis patterns and Fourier transform infrared spectroscopy showed that no polypeptide chain degradation occurred during dissolution, but the thermal denaturation temperature decreased by 0.26°C~7.63°C with the increase of ILs concentrations, measured by ultra-sensitive differential scanning calorimetry. Moreover, the aggregation of collagen molecules was reduced when ILs polarity was increased as determined by fluorescence measurements and dynamic light scattering, which resulted in an increased loose fiber arrangement observed by atomic force microscopy. If the structural integrity of collagen needs to be retained, then the ILs sorts and concentrations should be considered.

PCL/Col I-based magnetic nanocomposite scaffold provides an osteoinductive environment for ADSCs in osteogenic cues-free media conditions

“…3 , red graph), which is attributed to the stretching vibrations from amide A (Hydrogen-bonded -NH groups), amide B (C–H-bonded –NH groups), polypeptide backbone (C=O stretching), and amide II (N–H bending and C-H stretching), respectively. These results were consistent with FTIR results of calfskin extracted collagen [ 25 ]. FTIR spectra analysis of natural PCL showed four significant peaks around 2940 cm −1 , 2860 cm −1 , and 1720 cm −1 (Fig.…”

Factors affecting thermal stability of collagen from the aspects of extraction, processing and modification

“…As a potential crosslinker, phosphate anion of cDHP was postulated to attached to cationic functional groups of collagen via electrostatic interaction to make collagen chains closer, resulting in the formation of crosslinking among collagen molecules. The aggregation behaviors of collagen molecules (calf skin) in a novel acetic acid/1-ethyl- The dissolution and thermal stability of collagen in ILs of different polarity and concentrations were investigated by Liu et al [150]. were much more sparsely distribution, as shown in Fig.…”

Sustainable dissolution of collagen and the formation of polypeptides in deep eutectic solvents for application as antibacterial agents

“…24 The lyophilized collagen (type I from calf skin) has also been reported to be soluble in concentrated aqueous solutions of imidazolium-based ILs, [C 2 mim][BF 4 ] and [C 2 mim][Ac]; however, the maximum yield of dissolution was quite low (3.57 mg ml −1 ). 27 There are few examples of ILs that can dissolve collagen except for 1-butyl-3-methylimidazolium chloride, [C 4 mim][Cl], which was found to dissolve collagen in good yield by Meng et al 19 The high chloride concentration is effectual in breaking the H-bonds and the ionic bonds in the collagen and thus leads to its dissolution similar to that observed in the case of dissolution of wood, 28 cork, 29 cellulose, 25 wool keratin, 30 and silk fibre 31 in ILs. Therefore, few advancements in the dissolution of collagen utilizing ILs have been reported.…”