Effect of microneedle treatment on the skin permeation of a nanoencapsulated dye

Objectives The aim of the study was to investigate the effect of microneedle (MN) pretreatment on the transdermal delivery of a model drug (Rhodamine B, Rh B) encapsulated in polylactic-co-glycolic acid (PLGA) nanoparticles (NPs) focusing on the MN characteristics and application variables. Methods Gantrez MNs were fabricated using laser-engineered silicone micro-mould templates. PLGA NPs were prepared using a modified emulsiondiffusionevaporation method and characterised in vitro. Permeation of encapsulated Rh B through MN-treated full thickness porcine skin was performed using Franz diffusion cells with appropriate controls. Key findings In-vitro skin permeation of the nanoencapsulated Rh B (6.19 +/- 0.77 mu g/cm2/h) was significantly higher (P < 0.05) compared with the free solution (1.66 +/- 0.53 mu g/cm2/h). Mechanistic insights were supportive of preferential and rapid deposition of NPs in the MN-created microconduits, resulting in accelerated dye permeation. Variables such as MN array configuration and application mode were shown to affect transdermal delivery of the nanoencapsulated dye. Conclusions This dual MN/NP-mediated approach offers potential for both the dermal and transdermal delivery of therapeutic agents with poor passive diffusion characteristics.