On-chip assessment of the protein-release profile from 3D hydrogel arrays

As the formation of healthy tissue and the treatment of several diseases are often dependent on an effective and prolonged action of bioactive agents, the delivery of molecules for therapeutic or induction purposes in a tissue is a common procedure. The correct administration of those agents is often dependent on tailored delivery mechanisms from hydrogel or polymeric matrixes. To the best of our knowledge, methods for the high-throughput monitoring of bioactive agent delivery are nonexistent. The methods for the in vitro monitoring of molecule release are expensive and laborious. As a simple alternative to these methods, we propose the imprinting of superhydrophobic biomimetic surfaces with ring-shaped transparent spots with concentric superhydrophobic millimetric regions to be used as bioactive agent release study platforms. We designed an array where polymeric precursors mixed with a growth-factor model protein labeled with a fluorescent tag could be dispensed in the concentric highly repellent regions and cross-linked afterward, generating a polymeric protein-loaded sphere. The ring-shaped region was then filled with a physiological-like fluid that covered the polymeric sphere. The acquisition of sequential images of each spot over time using microscopy methods allowed one to easily monitor the protein release by image-based fluorescence quantification. As the platform is easily adaptable and amenable for future automation in order to mimic standardized organ dynamics, we concluded that the device shows applicability for rapid and efficient in vitro bioactive agent release studies.