The overall research area in the laboratory is the creation of Smart Bandage Biomaterial Engineering and Skin Disease. This laboratory investigates the fundamental optical, morphological, and surface chemical properties of bioengineered nanoporous silicon (PSi) in developing a platform of Smart Bandage technologies targeting biosensors for point of care diagnosis of cutaneous disease, transdermal drug delivery, and tissue engineering for wound healing. PSi is fabricated from single crystal silicon wafers using an electrochemical etch process. The pore diameter, porosity (surface area and internal void volume), bioerosion, and interferometric optical properties can be tailored over a wide range to suit the application.
Ongoing projects involve developing a refractive index sensitive biosensor for detection of Candida ablicans for which we've developed methods to site direct the immobilization of phage display scFv antibody receptors. Tests are underway to evaluate detection sensitivity relative to nonspecifically immobilized whole IgG aCandida antibody receptor employing commercial antigen. Fundamental insights into the factors (pore size, steric crowding, operating frequency, device architecture, blocking agent, operation protocol, etc.) that impact detection sensitivity are being explored. Biosensor tests are typically conducted on devices attached to the silicon wafer. Recently, we developed methods to detach the sensor and mount it in a polymer support. We are conducting studies to characterize the diffusion characteristics of small molecules though hydrogel films (40 micron) cast over porous silicon sensor (4 um) by monitoring changes in the optical response that result when molecules diffuse in or out of the porous silicon layer. This work will enable us to develop models for designing transdermal drug delivery systems where the optical response can be measured, while applied to the skin, to monitor the time released delivery of therapeutics concentrated within the porous reservoir. We are interested in developing a smart bandage to deliver antifungal locally to the nail matrix where nail progenitor cells live. We are also investing the morphology and phenotype dermal human fibroblast and immortalized keratinocytes (HaCaT) cells cultured on chemically modified PSi and flat silicon wafer surfaces. The goal is systematically engineer the surface chemistry, energy and topography of biomaterial scaffolds to mimic the fetal reepithelialization process. Our hypothesis is that by controlling differential cell proliferation (keratinocyte vs. fibroblast) and cell phenotype, such as integrin and metalloproteinase expression profiles or the magnitude of actin fiber extensions, novel therapies will result that can accelerate the healing of chronic wounds (ulcers) and burns with reduced scarring. A unique aspect of this research program is the melding of cross-disciplinary skills in surface science, physical chemistry, microfluidic device engineering, optics, and biological and medical sciences. This interdisciplinary approach provides a firm basis for the investigation and fabrication of new biomedical devices, while enabling a broader perspective on quantifying biological efficacy and establishing clinical utility.