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

Franziska Bode, Marcelo Alves Da Silva, Paul Smith, Christian D. Lorenz, Seth McCullen, Molly M. Stevens, Cécile A. Dreiss

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Abstract

Physical, chemical and hybrid tilapia fish gelatin hydrogels were investigated by small-angle neutron scattering (SANS), 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 gelation 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 gelation, are referred to as 'physical-co-chemical' gels (PC). The SANS 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 gelation 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.

Original languageEnglish
Pages (from-to)6986-6999
Number of pages14
JournalSoft Matter
Volume9
Issue number29
Early online date24 Apr 2013
DOIs
Publication statusPublished - 7 Aug 2013

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics

Cite this

Bode, F., Da Silva, M. A., Smith, P., Lorenz, C. D., McCullen, S., Stevens, M. M., & Dreiss, C. A. (2013). Hybrid gelation processes in enzymatically gelled gelatin: Impact on nanostructure, macroscopic properties and cellular response. Soft Matter, 9(29), 6986-6999. https://doi.org/10.1039/c3sm00125c