Systematic engineering of Layer-by-Layer anti-miR coated wound dressings with tunable release kinetics

The Layer-by-Layer (LbL) technique enables conformal coating of commercial wound dressings with oligonucleotide therapeutics and polymeric excipients to achieve controlled delivery to non-healing wounds. We previously demonstrated a proof-of-concept LbL dressing containing miRNA inhibitors (anti-miRs); however, release occurred on a single time scale. Because wound healing is dynamic, temporally tuning anti-miR delivery to the wound may alter therapeutic effects. Here, we provide an approach to modulate oligonucleotide release kinetics from coated wound dressings, exploring the design space of excipients, formulation parameters, and oligonucleotide structure. Incorporation of Laponite nanoclay prolonged release, while poly(acrylic acid) accelerated release kinetics. Hydrolyzable poly(β-amino esters) with varying hydrolysis rates were also used to further tune release kinetics. A fast-release formulation demonstrated 40% release over 4 h, while a slow-release formulation took 24 h to release the same amount. We evaluated these dressings in an excisional chronic wound model in diabetic (db/db) mice using anti-miR-92a (92ai), selected for its ability to enhance angiogenic signaling and promote wound closure. Dressings coated with 92ai accelerated healing compared to non-targeting scramble anti-miR (Scr) controls, with closure rates accelerated at times corresponding to release kinetics. Although ultimate wound closure was similar across release conditions, analyses of gene expression, cellular composition, histology, and immunofluorescence suggested distinct underlying mechanisms. Differences were particularly evident in macrophage phenotype and angiogenesis, suggesting that release timing influences biological pathways active during repair. Overall, these findings demonstrate that LbL dressings can be engineered for temporally controlled oligonucleotide delivery and that release kinetics may shape mechanisms driving wound closure.