Tuning of Mechanical Properties in Photopolymerizable Gelatin-Based Hydrogels for In Vitro Cell Culture Systems

Abstract

The mechanical microenvironment plays a crucial role in the evolution of colorectal cancer, a complex disease characterized by heterogeneous tumors with varying elasticity. Toward setting up distinct scenarios, herein, we describe the preparation and characterization of gelatin methacrylamide (GelMA)-based hydrogels via two different mechanisms: free-radical photopolymerization and photo-induced thiol-ene reaction. A precise stiffness modulation of covalently crosslinked scaffolds was achieved through the application of well-defined irradiation times while keeping the intensity constant. Besides, the incorporation of thiol chemistry strongly increased stiffness with low to moderate curing times. This wide range of finely tuned mechanical properties successfully covered from healthy tissue to colorectal cancer stages. Hydrogels prepared in phosphate-buffered saline or Dulbecco’s modified Eagle’s medium resulted in different mechanical and swelling properties, although a similar trend was observed for both conditions: thiol-ene systems exhibited higher stiffness and, at the same time, higher swelling capacity than free-radical photopolymerized networks. In terms of biological behavior, three of the substrates showed good cell proliferation rates according to the formation of a confluent monolayer of Caco-2 cells after 14 days of cell culture. Likewise, a characteristic apical-basal polarization of cells was observed for these three hydrogels. These results demonstrate the versatility of the presented platform of biomimetic materials as in vitro cell culture scaffolds.

The Mechanical and Biological Performance of Photopolymerized Gelatin‐Based Hydrogels as a Function of the Reaction Media

“…The substrate stiffness affected the polarization of cells displaying a different organization on hydrogels that mimicked the physiological tissue in contrast to stiffer hydrogels simulating tumoral stages. [16] In the same work, remarkably, we found that GelMA-based hydrogels exhibited significantly different properties in terms of gel fraction, mass swelling ratio and stiffness depending on the aqueous media used for hydrogel photopolymerization while keeping the rest of curing conditions the same. In particular, focusing in mechanical properties, GelMA hydrogels showed up to threetimes lower Young's Moduli when prepared in Dulbecco's modified Eagle's Medium (DMEM) than their analogs prepared in phosphate-buffered saline (PBS).…”

“…[13] Besides, an easy-and fine-tuning of the mechanical properties is possible thanks to this control of the photopolymerization conditions, which has a large impact in its biological performance. [10,[14][15][16] In particular, stiffness is a crucial material parameter that influences cellular behavior. According to Daniele et al, a higher spreading of adherent cells was observed with increasing stiffness of GelMA-based hydrogels.…”

“…The substrate stiffness affected the polarization of cells displaying a different organization on hydrogels that mimicked the physiological tissue in contrast to stiffer hydrogels simulating tumoral stages. [ 16 ]…”

“…In particular, focusing in mechanical properties, GelMA hydrogels showed up to three‐times lower Young's Moduli when prepared in Dulbecco's modified Eagle's Medium (DMEM) than their analogs prepared in phosphate‐buffered saline (PBS). [ 16 ] Notably, scarce reports about mechanical characterization of hydrogels prepared in different cell culture media are found in literature. In polysaccharide‐based bioscaffolds undergoing physical crosslinking, [ 18 ] preparations in DMEM yielded superior mechanical properties resulting from a higher concentration of Ca 2+ ions in the media.…”

Enhancing On-Skin Analysis: A Microfluidic Device and Smartphone Imaging Module for Real-Time Quantitative Detection of Multianalytes in Sweat

“…46 One particularly noteworthy attribute of gelatin is its outstanding film-forming characteristics, making it an ideal foundation for integrating CPDs as recognition elements in sensors. 47 Importantly, this integration does not compromise the sensitivity and stability of these CPDs. What sets gelatin hydrogels apart is their remarkable control over the swelling behavior.…”