Robert J. Meagher, Ph.D.

Development of a point-of-care device for detecting exposure to biological toxins

We are developing electrophoretic immunoassays to detect protein biotoxins, including ricin, Shiga toxin, Staphylococcal enterotoxin B, and botulinum. Our goal is to produce a low-cost, portable, diagnostic device suitable for rapidly diagnosing toxin exposure in the case of a bioterror attack.

Team members include Anson Hatch, Greg Sommer, Ying-Chih Wang, Ron Renzi, and Anup Singh.

Purification of proteins by microfluidic two-phase extraction

We have demonstrated a technique for “micropreparative” rapid purification of small amounts of recombinant protein using laminar-flow aqueous two-phase extraction. To extend the range of possible protein targets, the system works with a variety of genetic fusion tags, including aromatic-rich partition tags, as well as common affinity tags (e.g., His-tag). The process is designed for high-throughput protein expression experiments, such as screening enzyme variants for biofuel production.

Team members include Yooli Light and Anup Singh.

Identification of bacteria in complex samples by fluorescent in situ hybridization (FISH)

Many clinically or environmentally relevant species of bacteria are difficult or impossible to cultivate in the laboratory; thus. it is difficult to accurately determine the makeup of complex samples. We are developing a microfluidic device to perform FISH, a common and powerful technique that uses fluorescent probes specific for genetic targets on the 16S rRNA to identify specific types of bacteria. Our microfluidic approach automates the process, reduces analysis time, reduces the use of reagents, and will be integrated with optical cell-sorting techniques developed at Sandia.

Collaborators include Yooli Light, Julie Kaiser, and Anup Singh.

Analysis of cells and biomolecules in picoliter droplets

The field of “droplet microfluidics” or “digital microfluidics” is potentially interesting for high-throughput screening applications, including enzyme engineering and single-cell analysis. Using a T-junction with a microfabricated micropore, we segment an aqueous stream into a series of highly uniform, picoliter-volume droplets or “containers,” which are stabilized with surfactants and are suitable for performing biochemical assays. Applications include mRNA profiling of single bacterial cells, as well as high-throughput expression and screening of cellulose-degrading enzymes.

Collaborators include Yooli Light, Masood Hadi, Suruchi Anand, Thomas Perroud, Ken Patel, and Anup Singh.

Microchannel electrophoresis with single-molecule detection

We have coupled microfluidic protein separations with the unique time-resolved confocal fluorescence microscope developed by Carl Hayden at Sandia’s Combustion Research Facility. The microscope, which uses a picosecond-pulsed laser and custom detection hardware, enables us to determine the fluorescence lifetime and wavelength of each photon collected. The microscope also provides us with the capability to perform fluorescence correlation spectroscopy (FCS), fluorescence cross-correlation spectroscopy (FCCS), and a variety of temporal and spectral gating techniques. These capabilities, which have been used to study protein–protein and antibody–toxin interactions, are expected to be useful for a variety of sophisticated diagnostics.

Collaborators include: Carl Hayden, Thomas Perroud, Anup Singh