This Small Business Innovation Research (SBIR) Phase I project aims to develop the first-in-class microwell array plates for dual optical and MS imaging of bead libraries comprising up to one million members. As a cost-effective alternative to the traditional flow cytometry-based screening, optical imaging of planar bead arrays has the potential to become a preferred method of analysis in a variety of multiplexed bead-based bioassays. The preliminary experimental data shows that the beads arrayed on optically transparent glass microchips also can be measured with high sensitivity by MALDI TOF MS. The microchips evaluated in this project will be fabricated from fused optic fibers, micro-structured glass and thermoplastics to determine the optimal supports. The unique 3D structure of the microwells will be utilized to perform highly specific elution of selected compounds from individual beads and their localization in tightly focused microspots near the surface of the microwell plate. Fluorescence imaging performed at varying focus distance will provide quantitative detection of the bead-bound and eluted analytes while the mass spec imaging will enable structural characterization of the eluted compounds.
The broader impact/commercial potential of this project, if successful, will be the availability of microchips with dual optical and mass spec readout that will facilitate development of new methods of high-throughput screening (HTS), and enable the use of mass spectrometry in various HTS-based applications. Such ability will be particularly important in the field of biomarker discovery given the need for detailed characterization of proteomic biomarkers including identification of the protein sequence variants. This technology also will significantly benefit the field of drug discovery, which relies heavily on the HTS assays. The high-resolution microarray scanning techniques that will be developed in the course of this project are expected to make significant contribution to the rapidly growing field of mass spectrometry imaging, which so far has been focused primarily on measuring distribution of various analytes within biological tissues. Overall, the proposed work will accelerate progress toward a single analytical platform that seamlessly integrates fluorescence and mass spectrometry for the analysis of diverse libraries of microbeads including peptide, protein and antibody bead arrays.
The SBIR project supported by this award was designed to demonstrate feasibility of combining two major bioanalytical technologies, namely mass spectrometry and fluorescence imaging on a single microarray-type platform. Justification for undertaking such project was that the dual detection option would provide the life science researchers with an ability to develop significantly more powerful tools compared to the existing conventional assays, which rely primarily on a single analytical method. We studied arrays of beads fabricated on specialized microwell plates, which are known as picotiter plates. The picotiter plates, which can be made from glass, polymers or fused optic fibers, have dimensions of a standard microscope slide and contain tens of thousands of miniature microwells, each microwell capable of holding a single bead. These plates have been previously extensively evaluated for fluorescence imaging applications, as well as massively parallel DNA sequencing but not for mass spectrometry. We have accomplished our research objectives by identifying several materials and surface coatings, which enabled acquisition of high quality mass spectra from individual beads while maintaining compatibility with the fluorescence readout. The knowledge acquired while working on this project has allowed us to move toward the technology commercialization by developing several customizable user-friendly assay kits tailored to research applications in the areas of drug discovery, clinical diagnostics and environmental monitoring. We have also established several novel experimental protocols related to the acquisition, storage and analysis of the bead array imaging data, which will be implemented in the custom software that is currently under development.
