Infection with the spirochete Borrelia burgdorferi leads to Lyme disease, the most common tick-borne disease in North America, Europe, and Asia. Currently, Lyme disease is diagnosed using a two-tiered approach of ELISA/immunofluorescence, followed by Western blot analysis. These assays measure serological immune response to the infection, namely levels of IgG or IgM antibodies that bind to B. burgdorferi antigens. However, the existing approach is non-quantitative, lacks sensitivity, and may contribute to delayed diagnosis. In this study, grating-coupled fluorescence plasmonics (GC-FP) was used for rapid, highly-multiplexed detection of antibodies that bind B. burgdorferi proteins in human and mouse blood serum. GC-FP is an optical plasmonic method that enables quantitative detection of molecular interactions and can be incorporated into microfluidic format for highly multiplexed testing. We have demonstrated that this technique allows us to use only three microliters of blood serum to quantitatively detect multiple target antibodies within 30 minutes. We have also shown that GC-FP is faster and more sensitive than the traditional two-tiered Lyme disease testing scheme, making it attractive for diagnostic purposes. This proof-of-concept study provides foundations to develop GC-FP as a highly sensitive diagnostic tool to enhance the efficiency of assessment for Lyme disease patients, which will ultimately improve treatment outcomes.
Nanotechnology has recently been applied to a wide range of biological systems. In particular, there is a current push to
examine the interface between the biological world and micro/nano-scale systems. Our research in this field has led to
the development of novel strategies for spatial patterning of biomolecules, electrical and optical biosensing,
nanomaterial delivery systems, single-cell manipulation, and the study of cellular interactions with nano-structured
surfaces. Current work on these topics will be presented, including work on novel, semiconductor-based DNA detection
methods and mechanical, atomic force microscopy (AFM)-based characterization of bacterial biofilms in threedimensional
Microfluidic devices are currently being utilized in many types of BioMEMS and medical applications. In
these systems, the interaction between the surface and the biological specimen depends critically on surface properties.
The surface roughness and chemistry as well as the surface area to which the biomolecules or cells are exposed affect
this interaction. Modification of the surface of microfluidic channels can improve the operation of the device by
influencing the behavior of the biological specimens that are flowing through it. SU-8 is an epoxy-based, negative
photoresist that has been previously used to create covered channels. Once cured, it is both chemically and thermally
stable. It is also optically transparent above 360 nm, which allows optical measurements, including fluorescence
imaging, to be taken inside the channel. SU-8 microchannels have been fabricated with a porous layer on the sidewalls
by the photo-lithographic process, which is reproducible with precisely controlled channel dimensions. In order to attain
these porous sidewalls, no additional fabrication steps are required outside the standard photo-lithographic process. The
porosity of the sidewalls is a result of incomplete cross-linking of the polymer. The obtained porous surfaces can be
specially treated to provide conditions preferable for biological interactions. The porous layer increases the internal
surface area available on the sidewalls, which make these microfluidic channels preferable for biological applications.
This paper describes the details of the fabrication process and the experiments that verify the benefit of using SU-8
microchannels with porous sidewalls.
Cancerous tumors are dynamic microenvironments that require unique analytical tools for their study. Better
understanding of tumor microenvironments may reveal mechanisms behind tumor progression and generate new strategies for diagnostic marker development, which can be used routinely in histopathological analysis. Previous studies have shown that cell invasion and intravasation are related to metastatic potential and have linked these activities to gene expression patterns seen in migratory and invasive tumor cells in vivo. Existing analytical methods for tumor microenvironments include collection of tumor cells through a catheter needle loaded with a chemical or protein attractant (chemoattractant). This method has some limitations and restrictions, including time constraints of cell collection, long term anesthetization, and in vivo imaging inside the catheter. In this study, a novel implantable device was designed to replace the catheter-based method. The 1.5mm x 0.5mm x 0.24mm device is designed to controllably release chemoattractants for stimulation of tumor cell migration and subsequent cell capture. Devices were fabricated using standard microfabrication techniques and have been shown to mediate controlled release of bovine serum albumin (BSA) and epidermal growth factor (EGF). Optically transparent indium tin oxide (ITO) electrodes have been incorporated into the device for impedance-based measurement of cell density and have been shown to be compatible with in vivo multi-photon imaging of cell migration.