Special Poster Session Biofabrication
Hydrogels display highly attractive properties for their use in the field of biofabrication and tissue engineering. With a water content above 80%, they form 3D network structures that can resemble parts of the extracellular matrix of native tissue and are therefore predestined to be used as bioinks in 3D printing processes including living cells. They can be prepared from various polymers, either synthetic or biological, to match the requirements of the targeted tissue that must be replaced. To enable sufficient resolutions in the printing process, high polymer concentrations are generally required resulting in increased shear forces on the incorporated cells upon printing. Unfortunately, this is commonly known to be at the expense of cell viability. To simultaneously enable good printing resolutions and maintain high cell viability, it is important to trigger the rheological properties of bioinks towards low internal shear forces upon-, and high shape fidelity after printing. Filler materials such as fibers and spheres provide a widely used strategy to change rheological properties of solutions and melts and can further be applied to reinforce matrix materials. In this work, we developed a systematic approach to adapt the flow behavior of bioinks upon printing and increase the mechanical performance of the printed constructs. Electrospinning was applied to produce micro-fiber fragments made from poly-ε-caprolactone (PCL), providing good mechanical properties and biodegradability. Thermo-responsive gelatin methacrylate (GelMa) hydrogels were used as the matrix material promoting cell adhesion and proliferation. Pluronic was applied as an additional test system to systematically investigate the influence of fragment concentration in a shear thinning system. The resulting composite systems should provide adjustable rheological properties that can be triggered by particle size and filling density. This systematic study includes electrospinning of PCL fiber fragments and SEM analysis thereof, surface modification of PCL particles by plasma treatment and oscillatory rheology to determine the effects of size, concentration and surface modification on the rheological properties of the resulting composite hydrogels.