Publications
Ultrasensitive microanalytical diagnostic methods for rickettsial pathogens
A strategic CRADA was established between Sandia National Laboratories (SNL) and the University of Texas Medical Branch (UTMB) at Galveston to address pressing needs for US protection against biological weapons of mass destruction (WMD) and emerging infectious diseases. The combination of unique expertise and facilities at UTMB and SNL enabled interdisciplinary research efforts in the development of rapid and accurate diagnostic methods for early detection of trace priority pathogen levels. Outstanding postdoctoral students were also trained at both institutions to help enable the next generation of scientists to tackle the challenging interdisciplinary problems in the area of biodefense and emerging infectious diseases. Novel approaches to diagnostics were developed and the both the speed of assays as well as the detection sensitivity were improved by over an order of magnitude compared to traditional methods. This is a significant step toward more timely and specific detection of dangerous infections. We developed in situ polymerized porous polymer monoliths that can be used as (1) size exclusion elements for capture and processing of rickettsial infected cells from a sample, (2) photopatternable framework for grafting high densities of functionalized antibodies/fluorescent particles using novel monolith chemistry. Grafting affinity reagents specific to rickettsial particles enables rapid, ultra-sensitive assays by overcoming transport limitations of traditional planar assay approaches. We have selectively trapped particles and bacteria at the cell trap and have also detected picomolar mouse IL-6 captured with only 20 minutes total incubation times using the densely patterned monolith framework. As predicted, the monolith exhibits >10x improvements in both capture speed and capture density compared to traditional planar approaches. The most significant advancements as part of this CRADA is the optimization of techniques allowing the detection of <10 rickettsial cells in a whole blood sample. This detection limit is over 2 orders of magnitude more sensitive that previously reported methods and overcomes a key hurdle in ability to sense dangerous infections before they are too late to treat and contain. We also showed that in the new format, cross-reactivity with interfering species is reduced thereby increasing the specificity of such tests. Promising options to treat whole blood and avoid clogging and non-specific fouling of sensors were also developed.