Visible Light Cross-Linking of Gelatin Hydrogels Offers an Enhanced Cell Microenvironment with Improved Light Penetration Depth

Khoon S. Lim, Barbara J. Klotz, Gabriella C. J. Lindberg, Ferry P. W. Melchels, Gary J. Hooper, Jos Malda, Debby Gawlitta, Tim B. F. Woodfield

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In this study, the cyto-compatibility and cellular functionality of cell-laden gelatin-methacryloyl (Gel-MA) hydrogels fabricated using a set of photo-initiators which absorb in 400-450 nm of the visible light range are investigated. Gel-MA hydrogels cross-linked using ruthenium (Ru) and sodium persulfate (SPS), are characterized to have comparable physico-mechanical properties as Gel-MA gels photo-polymerized using more conventionally adopted photo-initiators, such as 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one (Irgacure 2959) and lithium phenyl(2,4,6-trimethylbenzoyl) phosphinate (LAP). It is demonstrated that the Ru/SPS system has a less adverse effect on the viability and metabolic activity of human articular chondrocytes encapsulated in Gel-MA hydrogels for up to 35 days. Furthermore, cell-laden constructs cross-linked using the Ru/SPS system have significantly higher glycosaminoglycan content and re-differentiation capacity as compared to cells encapsulated using I2959 and LAP. Moreover, the Ru/SPS system offers significantly greater light penetration depth as compared to the I2959 system, allowing thick (10 mm) Gel-MA hydrogels to be fabricated with homogenous cross-linking density throughout the construct. These results demonstrate the considerable advantages of the Ru/SPS system over traditional UV polymerizing systems in terms of clinical relevance and practicability for applications such as cell encapsulation, biofabrication, and in situ cross-linking of injectable hydrogels.

Original languageEnglish
Article number1900098
JournalMacromolecular Bioscience
Issue number6
Early online date26 Apr 2019
Publication statusPublished - Jun 2019


  • cell encapsulation
  • gelatin-methacryloyl (Gel-MA)
  • hydrogels
  • light penetration depth
  • transdermal crosslinking
  • visible light

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Biomaterials
  • Polymers and Plastics
  • Materials Chemistry


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