Hybrid gelation processes in enzymatically gelled gelatin: impact on nanostructure, macroscopic properties and cellular response

Abstract

Physical, chemical and hybrid tilapia fish gelatin hydrogels were investigated by small-angle neutron scattering (), molecular dynamic simulations and their biological effect in cell cultures studied; results from the different experimental techniques were then correlated and linked to the rheological properties of the gels (F. Bode et al., Biomacromolecules, 2011, 12, 3741-3752). Hydrogels were obtained by cross-linking with the microbial enzyme transglutaminase (mTGase) under two conditions: above and below gelatin physical temperature (ca. 23 °C). Hydrogels cross-linked at 37 °C, from the sol-state, are referred to as 'chemical' gels (C); hydrogels cross-linked at 21 °C, thus with concurrent physical , are referred to as 'physical-co-chemical' gels (PC). The data were appropriately described by a combination of a Lorentzian and a power law model. For physical gels, the correlation length (ξ) obtained from the fits decreased linearly with gelatin concentration, from 42 to 26 Å for 3.5 to 10% w/w gelatin, respectively. Independently of temperature, all physical gels at a given concentration showed a similar correlation length ξ (26 ± 2 Å), with no significant difference with the sol-state (23 ± 2 Å). In both C and PC gels, ξ increased with mTGase concentration over the range studied: 40 to 167 Å for 10 and 40 U mTGase per g gelatin in C gels (after 120 min cross-linking) and 40 to 82 Å for 10 and 40 U mTGase per g gelatin for PC gels. ξ reached a plateau at the highest mTGase concentration studied for both types of gels. In addition, kinetic studies on C gels revealed that ξ increased linearly with time in the first two hours and grew faster with increasing mTGase concentration. ξ values in the PC gels were smaller than in the corresponding C gels. Cell proliferation studies showed that the gels were compatible with cell growth and indicated no statistically relevant dependence on mTGase concentration for C gels. For PC gels, cell proliferation decreased with increases in mTGase concentration, by approximately 80% from 10 to 40 U mTGase per g gelatin. With the exception of the highest mTGase concentration studied, PC gels overall showed a slightly (but statistically significant) higher cell proliferation than the corresponding chemical gels.

Assessing the Potential of Folded Globular Polyproteins As Hydrogel Building Blocks

“…The first is a correlation length (ξ), which in the case of cross-linked hydrogels can be described as the length of the scattering center. 47,51 The second is the Lorentzian exponent, which carries information about the dimensionality of the scattering center. 53 …”

Enzymatically Cross‐Linked Gelatin/Chitosan Hydrogels: Tuning Gel Properties and Cellular Response

“…The gelatin solution in the Chirascan took approximately 2 min to reach the target temperature. The optical rotation angle calibration and correction has been described elsewhere …”

“…They reported a higher storage modulus ( G ′) for chemical gels obtained in the presence of the physical network. Recently, we reported an extensive investigation on the enzymatically‐cross‐linked gels of tilapia fish gelatin . A combination of rheology, small‐angle neutron scattering and optical rotation revealed that the presence of the physical network drastically affects the rheological and microstructural properties of the gels.…”

“…In this work, we explore the gelation kinetics and equilibrium rheological properties of mixed gels of chitosan and gelatin, where both biopolymers participate to the network. Our objective is to assess the impact of the chitosan/gelatin blend compared to the single‐component gels (gelatin alone), the effect of a hybrid gelation protocol on the network characteristics, and how these parameters affect cellular response, in view of developing these gels for tissue repair applications …”

Precise patterning of biopolymers and cells by direct write technique

“…However, physical cross-linking by single strand to triple helix transition is homogeneously distributed throughout the mass. 10 For this reason, we first induced sol-gel transition and then covalently cross-linked gelatin filaments using EDC and NHS.…”