Preparation of Biomolecular Gradients on Patterned Hydrogel Surfaces

Gradients of chemotactic biomolecules, present in extracellular environments, have been shown to provide biochemical cues needed to initiate cellular migration. If these cellular response mechanisms to chemotactic gradients can be reproduced within an in-vitro setting it can lead to substantial implications on regenerative medicine studies involved in cell guidance and differentiation. Hydrogels are commonly used as a tool to mimic extracellular matrix conditions and serve as promising candidates for biomolecular gradient fabrication. Recently, successful fabrication of such gradients onto biomimetic hydrogels was reported via high precision bioprinting of molecular reagents; nevertheless, this approach is fairly time consuming and the bioprinter technology utilized in the process can be rather expensive. This study demonstrates a facile and inexpensive approach to creating time dependent biomolecular gradients through patterned agarose-based hydrogel surfaces and investigates the effect of gel pore size on the gradient profiles established using this process. By means of this method, successful production of biomolecular diffusion gradients of fluorescently labeled Tetramethylrhodamine-Dextran (70,000 MW) through patterned agarose gel stamps have been achieved. Comparison of pore size effect on diffusion for 2, 3, and 5 percentages of agarose hydrogels were also analyzed. Recently, our lab has been applying this method in conjunction with electropolymerization of patterned biocompatible conductive polymer (CP) films with the intention of functionalizing these CP films with chemotactic gradients for future use in cell culture, microdevices, and in-vitro chemotaxis studies.