Polymer particle-based micromolding to fabricate novel microstructures.

Conventional micromolding provides rapid and low-cost methods to fabricate polymer microstructures, but has limitations when producing sophisticated designs. To provide more versatile micromolding techniques, we developed methods based on filling micromolds with polymer microparticles, as opposed to polymer melts, to produce microstructures composed of multiple materials, having complex geometries, and made using mild processing conditions. Polymer microparticles of 1 to 30 microm in size were made from PLA, PGA and PLGA using established spray drying and emulsion techniques either with or without encapsulating model drug compounds.

Microinfusion using hollow microneedles.

Purpose: The aim of the study is to determine the effect of experimental parameters on microinfusion through hollow microneedles into skin to optimize drug delivery protocols and identify rate-limiting barriers to flow.

Methods: Glass microneedles were inserted to a depth of 720-1080 microm into human cadaver skin to microinfuse sulforhodamine solution at constant pressure. Flow rate was determined as a function of experimental parameters, such as microneedle insertion and retraction distance, infusion pressure, microneedle tip geometry, presence of hyaluronidase, and time.