Dissolvable microneedles offer an attractive delivery system for
transdermal drug and vaccine delivery. They are most commonly formed by
filling a microneedle mold with liquid formulation using vacuum or
centrifugation to overcome the constraints of surface tension and
solution viscosity. Here, we demonstrate a novel microneedle fabrication
method employing an atomised spray technique that minimises the effects
of the liquid surface tension and viscosity when filling molds. This
spray method was successfully used to fabricate dissolvable microneedles
(DMN) from a wide range of sugars (trehalose, fructose and raffinose)
and polymeric materials (polyvinyl alcohol, polyvinylpyrrolidone,
carboxymethylcellulose, hydroxypropylmethylcellulose and sodium
alginate). Fabrication by spraying produced microneedles with amorphous
content using single sugar compositions. These microneedles displayed
sharp tips and had complete fidelity to the master silicon template.
Using a method to quantify the consistency of DMN penetration into
different skin layers, we demonstrate that the material of construction
significantly influenced the extent of skin penetration. We demonstrate
that this spraying method can be adapted to produce novel
laminate-layered as well as horizontally-layered DMN arrays. To our
knowledge, this is the first report documenting the use of an atomising
spray, at ambient, mild processing conditions, to create dissolvable
microneedle arrays that can possess novel, laminate layering.