Preparation and physical properties of hyaluronic acid‐based cryogels

Abstract

Macroporous hydrogels based on hyaluronan (HA), a natural polysaccharide occurring in extracellular matrix, have attracted interest over many years owing to their numerous applications in the biomedical area. However, HA hydrogels produced so far suffer from low mechanical strength and slow rate of response against external stimuli, which limit their applications. Here, we prepared macroporous HA cryogels of high mechanical stability and fast responsivity from aqueous HA solutions at subzero temperatures using ethylene glycol diglycidyl ether as a crosslinking agent. HA cryogels are squeezable and no crack development was exhibited when compressed up to 80% strain. Depending on the synthesis parameters, the cryogels exhibit an elastic modulus between 0.2 and 2 kPa, and show fast swelling/deswelling behavior. The microstructure of the cryogels consists of large, interconnected pores on the order of 100 mm separated by thick pore walls, as observed by scanning electron microscopy and confocal scanning laser microscopy.

Microstructure and mechanical properties of arabinoxylan and (1,3;1,4)-β-glucan gels produced by cryo-gelation

“…Similar microstructures have been previously reported for cryogels of different materials such as chitosan (Berillo, Mattiasson & Kirsebom, 2014), hemicelluloses/PVA/chitin nanowhiskers (Guan, Bian, Peng, Zhang & Sun, 2014), silk fibroin (Ak, Oztoprak, Karakutuk & Okay, 2013) and hyaluronic acid (Strom, Larsson & Okay, 2015). Phase separation between two polysaccharides can occur depending on their molecular and structural properties; phase separation between highly substituted arabinoxylan (Ara:Xyl = 0.73) but not lower substitutions (Ara:Xyl = 0.53 or 0.33) and β-glucan has been reported when composite films were cast (Ying, Saulnier, Bouchet, Barron, Ji & RondeauMouro, 2015).…”

Studies on Novel Methods for Formulating Novel Cross-Linked Hydrogel Films of Hyaluronic Acid

“…For instance, HA exhibits suboptimal efficacy due to its inability to form physical (Type 2) hydrogels over a wide range of pH conditions. Additionally, it has a short half-life of about 12 h as it undergoes rapid degradation by the hyaluronase enzymes present in body tissues [5,6]. Therefore, cross-linked (Type 1) HA hydrogel films can overcome the above limitations and provide a robust cosmetic platform.…”

“…The hydroxyl (-OH), carboxylic (-COOH), and amide (-NHCOCH 3 ) functional groups in HA are available for crosslinking via an ether bond (R-O-R), ester linkage (R-COO-R), and carbodiimide, respectively. Therefore, HA has been successfully cross-linked using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC), glutaraldehyde (GTA), poly (ethylene glycol) diglycidil ether (PEGDE), ethylene glycol diglycidil ether (EGDE), and divinyl sulfonate (DVS) among others as crosslinkers [6]. To maintain the biocompatibility of cross-linked HA, the effective proportion of a cross-linker should be as low as possible.…”

“…In contrast to other reported methods [6], our approach is intended to avoid additional functionalisation of the HA prior to or during the cross-linking reaction, which avoids the use of organic solvents and multiple reaction steps. As such, our overall aim is to provide a simple and robust one-step crosslinking method for high MW HA.…”

Removal of organic water pollutant using magnetite nanomaterials embedded with ionic copolymers of 2‐acrylamido‐2‐methylpropane sodium sulfonate cryogels

“…The thawing of the gels at room temperature can be used to produce a highly interconnected porous cryogel system. 23,24 The important parameters affecting the cryogel characteristics, such as pore size distribution and wall thickness, can be controlled by variation of the monomer concentration, pH, ionic strength, amounts of water and organic co-solvents, cooling rate and polymerization conditions. 25,26 It has been reported that functional monomers based on N-methacrylamide and acrylamides form cryogel polymers due to their strong ability to form strong polar, hydrogen, coordination bonds and van der Waals forces in cryogel matrices.…”