Evaluation of the hemocompatibility and rapid hemostasis of (RADA)4 peptide-based hydrogels.

(RADA)4 peptides are promising biomaterials due to their high degree of hydration (<99.5% (w/v)), programmability at the molecular level, and their subsequent potential to respond to external stimuli. Interestingly, these peptides have also demonstrated the ability to cause rapid (∼15s) hemostasis when applied directly to wounds. General hemocompatibility of (RADA)4 nanofibers was investigated systematically using clot formation kinetics, C3a generation, and platelet activation (morphology and CD62P) studies. (RADA)4 nanofibers caused a rapid clot formation, but yielded a low platelet activation and low C3a activation. The study suggests that the rapid hemostasis observed when these materials are employed results principally from humoral coagulation, despite these materials having a net neutral charge and high hydration at physiological conditions. The observed rapid hemostasis may be induced due to the available nanofiber surface area within the hydrogel construct. In conclusion, our experiments strongly support further development of (RADA)4 peptide based biomaterials. STATEMENT OF SIGNIFICANCE: Biomedicine based applications of (RADA)4 peptides are being extensively studied for the purpose of improving drug carriers, and 3D peptide nanofiber scaffolds. However, this peptide's biocompatibility has not been investigated till now. One particular study has reported a revolutionary and very desirable ability of (RADA)4 peptide to achieve complete and rapid hemostasis, nevertheless, the literature remains inconclusive on the underlying molecular mechanism. In this manuscript we bridge these two main knowledge gaps by providing the much needed systematic biocompatibility analysis (morphology analysis, platelet and C3a activation) of the (RADA)4 based hydrogels, and also investigate the underlying hemostatic mechanism of this peptide-induced hemostasis. Our work not only provides the much-needed biocompatibility of the peptide for applicative research, but also explores the molecular mechanism of hemostasis, which will help us design novel biomaterials to achieve hemostasis.