Development of laser ablation-compliant hydrogels for Tissue Engineering

One of the main areas of focus in the Tissue Engineering field is the development of three-dimensional (3D) matrices to support cells and their activity, mimicking the native extracellular matrix (ECM). Hydrogels, especially the ones made from ECM proteins, have shown great promise to fit this role due to their similarity with native ECM in terms of chemistry, water content and mechanical properties. These and other properties can be tuned by varying the hydrogels’ components or their concentrations. This tunability is very important in the development of efficient methods for their structural modification (e.g. micropatterning) to improve and control cell behaviour. Laser ablation is an emerging tool for creating user-defined architectures with high resolution control in hydrogel-based 3D matrices. This technique is very sensitive to the optical properties of hydrogels. In fact, turbidity, a common outcome in hydrogels based on ECM proteins such as collagen, impedes efficient ablation. The objective of this work was to investigate the compliance of several gelatin- and collagen-based hydrogels with the laser ablation process. For that, the optical and rheological properties of several formulations of gelatin, collagen and collagen-gelatin hydrogels were assessed. The same hydrogels were then subjected to different laser ablation protocols. Data showed that only highly transparent hydrogels could be successfully ablated. A certain degree of stiffness was needed for the hydrogels to maintain the ablated 3D structures. Crosslinked gelatin hydrogels were shown to be the easiest to ablate, demanding less laser intensity to create hollow structures inside the 3D matrix. This work provides a starting point to better define hydrogel formulations for efficient laser ablation.  

Acknowledgements: EU Horizon 2020 research and innovation programme under the ERC grant CapBed (805411), IF/00347/2015