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Multiwalled carbon nanotubes (MWNT) reinforced epoxy composite thin films were prepared by a microfabrication process and their elastic modulus was determined using a shaft-loaded blister test and linear and nonlinear elasticity models. Compared to net resin thin films, a 20% increase in elastic modulus was seen when 0.1 wt % MWNTs were added, suggesting MWNT alignment by spin coating. Electron microscopic observations of the fracture surfaces suggested high interfacial shear stress between MWNTs and the epoxy matrix, a result supported by both molecular mechanics simulation and micromechanics calculations.

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Transdermal drug delivery TDD systems have many advantages but are conventionally limited by the low permeability of skin. The idea of using microneedles to painlessly penetrate the topmost impermeable stratum corneum has previously been put forward. In this paper, the fabrication of solid and hollow silicon microneedles with straight side-walls and with the following dimensions: 20-100 microm in diameter and 100-150 microm in length is described. In vitro tests demonstrate that with prior solid microneedle application, transdermal drug transport is significantly increased by 10-20 times, with the degree of enhancement being related to needle diameter. In vivo tests in diabetic animals, however, were unable to demonstrate any delivery of insulin through the hollow microneedles. It is proposed that two factors, microneedle length and tip sharpness, have to be improved for systemic drug delivery to be seen in vivo.

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