Protein encapsulation in polymeric microneedles by photolithography.
BACKGROUND
Recent interest in biocompatible polymeric microneedles for the delivery of biomolecules has propelled considerable interest in fabrication of microneedles. It is important that the fabrication process is feasible for drug encapsulation and compatible with the stability of the drug in question. Moreover, drug encapsulation may offer the advantage of higher drug loading compared with other technologies, such as drug coating.


RESULTS
In this study, we encapsulated a model protein drug, namely, bovine serum albumin, in polymeric microneedles by photolithography. Drug distribution within the microneedle array was found to be uniform. The encapsulated protein retained its primary, secondary, and tertiary structural characteristics. In vitro release of the encapsulated protein showed that almost all of the drug was released into phosphate buffered saline within 6 hours. The in vitro permeation profile of encapsulated bovine serum albumin through rat skin was also tested and shown to resemble the in vitro release profile, with an initial release burst followed by a slow release phase. The cytotoxicity of the microneedles without bovine serum albumin was tested in three different cell lines. High cell viabilities were observed, demonstrating the innocuous nature of the microneedles.


CONCLUSIONS
The microneedle array can potentially serve as a useful drug carrier for proteins, peptides, and vaccines.
Department of Pharmacy, National University of Singapore, Singapore.
Jaspreet Singh
JS
Kochhar
Shui
S
Zou
Sui Yung
SY
Chan
Lifeng
L
Kang
D000818:Animals; D002214:Capsules / Q000008:administration & dosage / Q000737:chemistry / Q000493:pharmacokinetics; D045744:Cell Line, Tumor; D016503:Drug Delivery Systems / Q000295:instrumentation*; D004355:Drug Stability; D005456:Fluorescent Dyes / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D008845:Microinjections / Q000295:instrumentation*; D055616:Microtechnology / Q000295:instrumentation* / Q000379:methods*; D009339:Needles; D011092:Polyethylene Glycols / Q000008:administration & dosage / Q000737:chemistry* / Q000493:pharmacokinetics; D011506:Proteins / Q000008:administration & dosage / Q000737:chemistry* / Q000493:pharmacokinetics; D051381:Rats; D012710:Serum Albumin, Bovine / Q000008:administration & dosage / Q000737:chemistry / Q000493:pharmacokinetics; D012869:Skin Absorption; D013678:Technology, Pharmaceutical; D014966:Xanthenes / Q000737:chemistry
D002214:Capsules; D005456:Fluorescent Dyes; D011506:Proteins; D014966:Xanthenes; C437167:poly(ethylene glycol)diacrylate; D012710:Serum Albumin, Bovine; D011092:Polyethylene Glycols; C034657:Texas red