Electrospun PEO/gelatin nanofibers for pDNA and mRNA delivery

Electrospun nanofiber mats are a versatile delivery system that can be applied locally at a target site, making them attractive for localized gene delivery. Although some studies reported electrospinning of nucleic acids, polyethylene oxide (PEO) was primarily used as a co-spinnable additive rather than as a standalone carrier in previous studies. In this study, PEO and gelatin nanofiber mats were prepared via blend and coaxial electrospinning to encapsulate pDNA and mRNA polyplexes prepared with a commercial transfection reagent. Notably, mRNA complexes were directly encapsulated within electrospun nanofibers through blend electrospinning, an approach not previously reported for mRNA delivery from fiber matrices. The results showed that PEO fiber mats exhibit higher encapsulation efficiency (∼60% for pDNA), transfection performance (∼75% of the free-complex level), and maintenance of polyplex integrity than gelatin, blend, and coaxial fibers for both types of nucleic acids. Stability studies over time have shown that encapsulation within electrospun fibers significantly increased the functional lifetimes of both polyplexes compared with non-electrospun (free) polyplexes. Free pDNA polyplexes lost ∼95% of their activity within 24 h, whereas PEO fiber-encapsulated pDNA retained most of its activity, losing only ∼35% over the same period. Cytotoxicity analysis showed that all fiber mats maintained cell viability above 70% at low-to-moderate electrospinning polymer amounts. It was thus shown that PEO electrospun nanofibers can serve as efficient standalone carriers for nucleic acid delivery, with polymer selection influencing encapsulation, transfection, and stability.