Self-limiting electrospray deposition to create bioactive coating*

Electrospray deposition (ESD) is a well-established technique for thin film creation from the spray of highly charged droplets loaded with the material to be deposited. Recently, we have characterized self-limiting electrospray deposition (SLED). In SLED, manipulation of electrostatic repulsion, hydrodynamic forces and evaporation kinetics can conformally cover 3D architectures with microcoatings. The coatings are hierarchical, possessing nanoshell or nanoparticle microstructure. Initial demonstrations of SLED used single glassy polymers as the solutes and simple cm-scale geometries as substrates. Here, I will discuss opportunities to create bioactive conformal coatings on medically-relevant architectures with blending, self-assembly, and complex geometries. We explore coating transdermal microneedles with blends of DNA vaccines and rapid-dissolving matrixes as a high-efficiency, scalable alternative to dip or inkjet coating. We demonstrate that we can deposit up to 70wt% viable coatings of DNA in a sugar matrix that quickly dissolve upon insertion into the skin and show expression of GFP(pEGFP-N1). This method is compatible with rapid continuous manufacturing and provides a shelf-stable, low-training vaccination for the current and future pandemic crises.