Microfabricated Nanoporous Silicon Membranes for Drug Delivery Applications
Ketul Popat, Physiology/Bioengineering, University of California, San Francisco, 1700-4th Street, Box 2520, QB3 203, Mission Bay Campus, San Francisco, CA 94143-2520 and Tejal Desai, Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, 1700-4th Street, Box 2520, QB3 203, Mission Bay Campus, San Francisco, CA 94143-2520.
In recent years, rapid advancements have been made in the biomedical applications of micro- and nanotechnology. While the focus of such technology has primarily been on in vitro analytical and diagnostic tools, more recently, in vivo therapeutic and sensing applications have gained attention. In this work, monodisperse, nanoporous, and biocompatible silicon membranes are fabricated using microfabrication techniques. The goal is to use these membranes as a platform for the drug delivery. Microfabrication technology offers unique opportunities to precisely engineer nanopores that will allow sustained release of drugs through the tissues. The pore size can be engineered depending on the desired delivery rate. The drug can be loaded in its liquid or lyophilized form into a biocapsule with nanoporous membranes at the end, which will allow the diffusion of drugs. Diffusive properties of these membranes were characterized by studying short-term and long-term diffusion of different size biomolecules. Further, these membranes may suffer from biofouling due to non-specific protein interactions with the silicon surface, ultimately clogging the pores and reducing the flux through the membrane. We have covalently coupled silicon nanoporous membranes with poly (ethylene glycol) (PEG) to avert this limitation. Diffusion of different biomolecules through PEG modified membranes was also investigated and compared to that from unmodified.