THESIS
2013
xvi, 140 pages : illustrations (some color) ; 30 cm
Abstract
The skin is an effective barrier against the invasion of noxious chemicals and harmful
pathogens. The rigidity of the outermost layer of skin, stratum corneum, hinders the
transdermal delivery of drugs especially those with large molecular weight and low
lipophilicity. A pathway across the skin barrier is needed for drug delivery. Microneedles
primarily made of silicon, metals or polymers can be used to breach the skin barrier and
facilitate transdermal drug administration.
This study explores zeolite, microporous aluminosilicate structure, as a material for
microneedle. A back-side exposure technique for forming the SU-8 into template needle
structure was developed for fabrication of various zeolite microneedle shapes including
cylindrical, hollow and tapered structure. Fa...[
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The skin is an effective barrier against the invasion of noxious chemicals and harmful
pathogens. The rigidity of the outermost layer of skin, stratum corneum, hinders the
transdermal delivery of drugs especially those with large molecular weight and low
lipophilicity. A pathway across the skin barrier is needed for drug delivery. Microneedles
primarily made of silicon, metals or polymers can be used to breach the skin barrier and
facilitate transdermal drug administration.
This study explores zeolite, microporous aluminosilicate structure, as a material for
microneedle. A back-side exposure technique for forming the SU-8 into template needle
structure was developed for fabrication of various zeolite microneedle shapes including
cylindrical, hollow and tapered structure. Fabrication parameters for controlling the length
and shape of zeolite microneedles were investigated. The mechanical properties of the
fabricated zeolite microneedles were measured and analyzed. The axial fracture force, shear
fracture force and insertion force for excised porcine skin model were obtained. The
relationship of the zeolite microneedle geometry to its axial fracture force was determined,
and a safety factor of 3.2 to 4.3 were obtained for zeolite microneedles for skin insertion due
to the sharp edge of zeolite crystals on the tip. Finally, in vivo transdermal drug delivery by
zeolite microneedles was illustrated for influenza vaccination of mice model. The serum IgG
level of mice by conventional vaccination and vaccination by zeolite microneedles were
found to be comparable indicating successful vaccination by microneedles.
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