Cross-Linkable Gelatins with Superior Mechanical PropertiesThrough Carboxylic Acid Modification: Increasing the Two-Photon PolymerizationPotential

摘要

The present work reports on the development of photo-cross-linkable gelatins sufficiently versatile to overcome current biopolymer two-photon polymerization (2PP) processing limitations. To this end, both the primary amines as well as the carboxylic acids of gelatin type B were functionalized with photo-cross-linkable moieties (up to 1 mmol/g) resulting in superior and tunable mechanical properties (G′ from 5000 to 147000 Pa) enabling efficient 2PP processing. The materials were characterized in depth prior to and after photoinduced cross-linking using fully functionalized gelatin-methacrylamide (gel-MOD) as a benchmark to assess the effect of functionalization on the protein properties, cross-linking efficiency, and mechanical properties. In addition, preliminary experiments on hydrogel films indicated excellent in vitro biocompatibility (close to 100% viability) both in the presence of MC3T3 preosteoblasts and L929 fibroblasts. Moreover, 2PP processing of the novel derivative was superior in terms of applied laser power (≥40 vs ≥60 mW for gel-MOD at 100 mm/s) as well as post-production swelling (0–20% vs 75–100% for gel-MOD) compared tothose of gel-MOD. The reported novel gelatin derivative (gel-MOD-AEMA)proves to be extremely suitable for direct laser writing as both superiormimicry of the applied computer-aided design (CAD) was obtained whilemaintaining the desired cellular interactivity of the biopolymer.It can be anticipated that the present work will also be applicableto alternative biopolymers mimicking the extracellular environmentsuch as collagen, elastin, and glycosaminoglycans, thereby expandingcurrent material-related processing limitations in the tissue engineeringfield.