Microneedle/nanoencapsulation-mediated transdermal delivery: mechanistic insights
Yasmine A Gomaa1, Martin J Garland2, Fiona J McInnes3
1Strathclyde Institute of Pharmacy and Biomedical Sciences (SIPBS), University of Strathclyde, Scotland, UK; Department of Pharmaceutics, Faculty of Pharmacy, Alexandria University, Alexandria, Egypt.
Summary
This study reveals how nanoparticle characteristics and dye properties influence transdermal delivery through microneedle-treated skin. Smaller, hydrophilic nanoparticles with negative charge enhance dye permeation, aiding drug delivery strategies.
Area of Science:
- Materials Science
- Biomedical Engineering
- Pharmaceutics
Background:
- Transdermal drug delivery offers a non-invasive route for administering therapeutics.
- Microneedle (MN) arrays enhance skin permeability, but the precise mechanisms for nanoencapsulated payloads remain unclear.
- Understanding nanoencapsulation transport is crucial for optimizing MN-mediated drug delivery systems.
Purpose of the Study:
- To elucidate the mechanism of transdermal delivery for nanoencapsulated dyes across microneedle-treated skin.
- To investigate the influence of nanoparticle physicochemical properties and encapsulated dye characteristics on skin permeation.
- To provide mechanistic insights for developing advanced MN-mediated nano-delivery formulations.
Main Methods:
- Model hydrophilic (Rhodamine B) and hydrophobic (FITC) dyes were encapsulated in poly lactic-co-glycolic acid (PLGA) nanoparticles (NPs).
- Nanoparticle-loaded dyes were delivered across full-thickness porcine skin pretreated with microneedle arrays.
- Confocal laser scanning microscopy was employed to visualize and verify dye distribution and permeation.
Main Results:
- Dye permeation was significantly enhanced by smaller NP size, increased hydrophilicity, and negative zeta potential.
- For encapsulated dyes, solubility at physiological pH and protein interaction were more critical than molecular weight for skin penetration.
- Confocal imaging confirmed NP influx into MN channels, forming dye-rich reservoirs and subsequent molecular diffusion.
Conclusions:
- The mechanism involves NP entry into MN channels, creating localized depots for sustained dye release.
- Subsequent molecular diffusion of the dye is governed by its intrinsic properties, not solely by NP characteristics.
- These findings are vital for designing effective transdermal and intradermal delivery systems for nanoencapsulated therapeutics using microneedles.
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