Bioinspired self-assembly supramolecular hydrogel for ocular drug delivery

Based on a recent report concerning endogenous agents(i.e., pyridoxal phosphate, adenosine triphosphate, adenosine monophosphate, folinic acid) that modulate the oligomerization of apoptosis-associated speck-like protein(ASC) via the peptide epitope of KKFKLKL, we rationally designed and synthesized a nonapeptide(Nap FFKKFKLKL), which can co-assemble with dexamethasone sodium phosphate(Dexp) to generate a Nap FFKKFKLKL/Dexp supramolecular hydrogel for ocular drug delivery.The Nap FFKKFKLKL/Dexp hydrogel formed instantly after the complexation of Nap FFKKFKLKL with Dexp in aqueous solution. The formed supramolecular hydrogels were thoroughly characterized by transmission electron microscopy(TEM), fluorescent spectrum, circular dichroism(CD) spectra and rheology. The peptide concentration significantly affected the in vitro release behavior of Dexp from the supramolecular hydrogel, and the higher peptide concentration resulted in the slower drug release.Following a single intravitreal injection, the proposed Nap FFKKFKLKL/Dexp hydrogel displayed good intraocular biocompatibility without having an adverse impact on the retinal architecture and eyesight functions during one month of follow-up. Using an experimental autoimmune uveitis(EAU) rat model,we demonstrated that the resulting Nap FFKKFKLKL/Dexp hydrogel had potent capacity to alleviate the intraocular inflammation and retain the morphology of retinal architecture. Overall, the resulting Nap FFKKFKLKL/Dexp hydrogel may be a promising drug carrier system to treat various posterior disorders(i.e., uveitis).