The Effect of Mixing on the Mechanical Properties of Hyaluronan‐Based Injectable Hydrogels

Abstract

A method for determining the correlation between the mixing of two reactive polymers and the structural and mechanical properties of the formed hydrogels is presented. Rheological measurements show that insufficient mixing gives rise to soft and not fully crosslinked hydrogels while excessive mixing beyond gel point results in weaker hydrogels due to potential breakage of their 3D network. Furthermore, the hydrogels swell significantly more in cell culture medium than in phosphate‐buffered saline, attributed to interactions with additional molecules such as proteins. Thus, moderate mixing gives rise to the most homogenous and mechanically stable hydrogels and the choice of medium e.g., for release experiments, should be consistent in order to avoid unnecessary variations in the data caused by different swelling profiles.

Characterization of recombinant human bone morphogenetic protein-2 delivery from injectable hyaluronan-based hydrogels by means of125I-radiolabelling

“…PBS was chosen as the release medium for the in vitro experiments, due to its neutral pH. The swelling of HAA/PVAH hydrogels in PBS has previously been shown to be less than, for example, in cell culture medium (Piskounova et al ., ). However, since PBS lacked the protective features of the formulation buffer, protein loss due to adsorption to surfaces was of concern.…”

“…The first phase in vitro correlated to the swelling of the hydrogels, which had been previously shown to take place during this period (Piskounova et al ., ). Other delivery systems, discussed in the literature, showed similar initial release profiles, which correlated to water absorption and implant swelling (Costache et al ., ; Kempen et al ., ).…”

Critical assessment of rhBMP-2 mediated bone induction: An in vitro and in vivo evaluation

“…This significantly higher storage modulus than the loss modulus (G′ >G″) implies that the material is elastic and has a typical gel like characteristics. This storage modulus also corresponds to an average molecular weight between crosslinks of~20 kg/mol forming stable networks [19] (Scheme 1).…”

Hydrogel-Based Controlled Release Formulations: Designing Considerations, Characterization Techniques and Applications

“…4) [23,[38][39][40][41][42] . These physical interactions are reversible in nature, i.e., the physical interactions breakdown causing a loss of structural integrity when suitable energy (e.g., mechanical stress and thermal energy) is provided and regain the original structure when the energy is withdrawn [43] .…”