title: Design, optimization and characterisation of polymeric microneedle arrays prepared by a novel laser-based micromoulding technique.
abstract: OBJECTIVE
  Design and evaluation of a novel laser-based method for micromoulding of microneedle arrays from polymeric materials under ambient conditions. The aim of this study was to optimise polymeric composition and assess the performance of microneedle devices that possess different geometries.
  
  
  METHODS
  A range of microneedle geometries was engineered into silicone micromoulds, and their physicochemical features were subsequently characterised.
  
  
  RESULTS
  Microneedles micromoulded from 20% w/w aqueous blends of the mucoadhesive copolymer Gantrez® AN-139 were surprisingly found to possess superior physical strength than those produced from commonly used pharma polymers. Gantrez® AN-139 microneedles, 600 μm and 900 μm in height, penetrated neonatal porcine skin with low application forces (>0.03 N per microneedle). When theophylline was loaded into 600 μm microneedles, 83% of the incorporated drug was delivered across neonatal porcine skin over 24 h. Optical coherence tomography (OCT) showed that drug-free 600 μm Gantrez® AN-139 microneedles punctured the stratum corneum barrier of human skin in vivo and extended approximately 460 µm into the skin. However, the entirety of the microneedle lengths was not inserted.
  
  
  CONCLUSIONS
  In this study, we have shown that a novel laser engineering method can be used in micromoulding of polymeric microneedle arrays. We are currently carrying out an extensive OCT-informed study investigating the influence of microneedle array geometry on skin penetration depth, with a view to enhanced transdermal drug delivery from optimised laser-engineered Gantrez® AN-139 microneedles.
authors.affiliation: School of Pharmacy, Queen's University Belfast Medical Biology Centre, 97 Lisburn Road, Belfast, BT9 7BL, UK. r.donnelly@qub.ac.uk
authors.forename: Ryan F
authors.initials: RF
authors.lastname: Donnelly
authors.forename: Rita
authors.initials: R
authors.lastname: Majithiya
authors.forename: Thakur Raghu Raj
authors.initials: TR
authors.lastname: Singh
authors.forename: Desmond I J
authors.initials: DI
authors.lastname: Morrow
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Garland
authors.forename: Yusuf K
authors.initials: YK
authors.lastname: Demir
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Migalska
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Ryan
authors.forename: David
authors.initials: D
authors.lastname: Gillen
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Scott
authors.forename: A David
authors.initials: AD
authors.lastname: Woolfson
mesh_terms: D000818:Animals; D016503:Drug Delivery Systems / Q000295:instrumentation / Q000379:methods; D004867:Equipment Design; D006801:Humans; D066298:In Vitro Techniques; D007271:Injections, Intradermal; D007834:Lasers; D008845:Microinjections / Q000295:instrumentation / Q000379:methods; D008954:Models, Biological; D009339:Needles; D011108:Polymers / Q000737:chemistry; D012828:Silicones / Q000737:chemistry; D012867:Skin / Q000378:metabolism / Q000648:ultrastructure; D012995:Solubility; D013552:Swine; D013678:Technology, Pharmaceutical / Q000379:methods*; D041623:Tomography, Optical Coherence
chemical_list: D011108:Polymers; D012828:Silicones