Array-Based High-Throughput Analysis of Silk-Elastinlike Protein Polymer Degradation and C-Peptide Release by Proteases

The objective of this study was to utilize an on chip degradation assay to evaluate polymer depots and the predicted drug release from the depots. We conjugated four silk-elastinlike protein (SELP) polymers including SELP-815K, SELP-815K-RS1, SELP-815K-RS2, and SELP-815K-RS5 with a Cy5-NHS ester and fabricated SELP arrays by immobilizing the conjugated polymers onto well-type amine arrays. SELP polymer degradation rates were investigated by calculating the half maximal effective concentration (EC50). Eight cleavage enzymes were applied, all of which exhibited distinctive EC50 values for SELP-815K and its three analogues. We successfully utilized this assay to study the in vitro release of the Cy5-conjugated C-peptide from SELP-815K hydrogel arrays. Additionally, cumulative C-peptide release from the SELP-815K depots was also demonstrated using repetitive elastase treatments. Therefore, this array-based on-chip degradation assay could potentially be used for evaluating depot degradation and controlled drug, release from polymer depots at the molecular level.