Superhydrophobic patterned chips for the combinatorial and rapid study of 3D biomaterials-cells interactions and protein delivery systems

The development of optimized products in the tissue engineering (TE) field is a time and resource consuming process due to the unpredictable influence of the combination of variables such as biomaterials, cells and soluble factors. As multiple combinations can be considered highthroughput (HT) methods were suggested as a way to master complexity in TE. Usually, HT systems test cell-2D biomaterials interactions and, more recently, cell-3D hydrogels interactions. Using a chip consisting of superhydrophobic surfaces patterned with wettable regions we tested cells-hydrogels interactions in three-dimensional environment [1]. The versatility of the chip allowed its use for the first time on-chip combinatorial study of 3D miniaturized porous scaffolds. Arrays of biomaterials were dispensed and processed in situ as porous scaffolds with distinct composition, surface characteristics, porosity/pore size and mechanical properties. Those characteristics were assessed by adapting microcomputed tomography equipment and a dynamic mechanical analyzer. The interactions between cell types of two distinct origins – osteoblast-like and fibroblasts - and the scaffolds modified with distinct amounts of fibronectin were studied by image-based methods and validated by comparison with conventional destructive methods. Physical and biological on-chip results were coherent with conventional measures, and conclusions about the most favorable media for the growth of both cell types were taken. Growth factors (GF) proved to play an important role in TE approaches, mainly for determining cell fate in applications containing stem cells. We developed a chip based on wettability contrast with torus-shaped hydrophilic transparent regions disposed in an array matrix. Concentrically to these wettable regions a superhydrophobic circle was maintained, so the hydrogels could be processed as protein-loaded spheres with minimum protein loss [2] and fixed with an indentation. A combinatorial system of BSA-FITC – a commonly used GF model – encapsulated in alginate hydrogels was designed. The protein release from the hydrogels could be studied by image analysis, avoiding manipulation and protein loss. The results were compared with conventional protein release tests and similar tendencies were observed. We believe that the proposed innovative uses for the superhydrophobic chip and their upgrade in future applications may constitute a promising breakthrough in integrated technologies for the rapid development of TE systems