TY - JOUR T1 - Electricity-free amplification and detection for molecular point-of-care diagnosis of HIV-1. JF - PLoS One Y1 - 2014 A1 - Singleton, Jered A1 - Osborn, Jennifer L A1 - Lillis, Lorraine A1 - Hawkins, Kenneth A1 - Guelig, Dylan A1 - Price, Will A1 - Johns, Rachel A1 - Ebels, Kelly A1 - Boyle, David A1 - Weigl, Bernhard A1 - LaBarre, Paul AB -

In resource-limited settings, the lack of decentralized molecular diagnostic testing and sparse access to centralized medical facilities can present a critical barrier to timely diagnosis, treatment, and subsequent control and elimination of infectious diseases. Isothermal nucleic acid amplification methods, including reverse transcription loop-mediated isothermal amplification (RT-LAMP), are well-suited for decentralized point-of-care molecular testing in minimal infrastructure laboratories since they significantly reduce the complexity of equipment and power requirements. Despite reduced complexity, however, there is still a need for a constant heat source to enable isothermal nucleic acid amplification. This requirement poses significant challenges for laboratories in developing countries where electricity is often unreliable or unavailable. To address this need, we previously developed a low-cost, electricity-free heater using an exothermic reaction thermally coupled with a phase change material. This heater achieved acceptable performance, but exhibited considerable variability. Furthermore, as an enabling technology, the heater was an incomplete diagnostic solution. Here we describe a more precise, affordable, and robust heater design with thermal standard deviation <0.5°C at operating temperature, a cost of approximately US$.06 per test for heater reaction materials, and an ambient temperature operating range from 16°C to 30°C. We also pair the heater with nucleic acid lateral flow (NALF)-detection for a visual readout. To further illustrate the utility of the electricity-free heater and NALF-detection platform, we demonstrate sensitive and repeatable detection of HIV-1 with a ß-actin positive internal amplification control from processed sample to result in less than 80 minutes. Together, these elements are building blocks for an electricity-free platform capable of isothermal amplification and detection of a variety of pathogens.

VL - 9 IS - 11 U1 - http://www.ncbi.nlm.nih.gov/pubmed/25426953?dopt=Abstract ER - TY - JOUR T1 - Field evaluation of a prototype paper-based point-of-care fingerstick transaminase test. JF - PLoS One Y1 - 2013 A1 - Pollock, Nira R A1 - McGray, Sarah A1 - Colby, Donn J A1 - Noubary, Farzad A1 - Nguyen, Huyen A1 - Nguyen, The Anh A1 - Khormaee, Sariah A1 - Jain, Sidhartha A1 - Hawkins, Kenneth A1 - Kumar, Shailendra A1 - Rolland, Jason P A1 - Beattie, Patrick D A1 - Chau, Nguyen V A1 - Quang, Vo M A1 - Barfield, Cori A1 - Tietje, Kathy A1 - Steele, Matt A1 - Weigl, Bernhard H KW - Alanine Transaminase KW - Blood Chemical Analysis KW - Developing Countries KW - Drug Monitoring KW - Drug-Induced Liver Injury KW - Humans KW - Liver Function Tests KW - Microfluidics KW - Observer Variation KW - Paper KW - Point-of-Care Systems KW - Vietnam AB -

Monitoring for drug-induced liver injury (DILI) via serial transaminase measurements in patients on potentially hepatotoxic medications (e.g., for HIV and tuberculosis) is routine in resource-rich nations, but often unavailable in resource-limited settings. Towards enabling universal access to affordable point-of-care (POC) screening for DILI, we have performed the first field evaluation of a paper-based, microfluidic fingerstick test for rapid, semi-quantitative, visual measurement of blood alanine aminotransferase (ALT). Our objectives were to assess operational feasibility, inter-operator variability, lot variability, device failure rate, and accuracy, to inform device modification for further field testing. The paper-based ALT test was performed at POC on fingerstick samples from 600 outpatients receiving HIV treatment in Vietnam. Results, read independently by two clinic nurses, were compared with gold-standard automated (Roche Cobas) results from venipuncture samples obtained in parallel. Two device lots were used sequentially. We demonstrated high inter-operator agreement, with 96.3% (95% C.I., 94.3-97.7%) agreement in placing visual results into clinically-defined "bins" (<3x, 3-5x, and >5x upper limit of normal), >90% agreement in validity determination, and intraclass correlation coefficient of 0.89 (95% C.I., 0.87-0.91). Lot variability was observed in % invalids due to hemolysis (21.1% for Lot 1, 1.6% for Lot 2) and correlated with lots of incorporated plasma separation membranes. Invalid rates <1% were observed for all other device controls. Overall bin placement accuracy for the two readers was 84% (84.3%/83.6%). Our findings of extremely high inter-operator agreement for visual reading-obtained in a target clinical environment, as performed by local practitioners-indicate that the device operation and reading process is feasible and reproducible. Bin placement accuracy and lot-to-lot variability data identified specific targets for device optimization and material quality control. This is the first field study performed with a patterned paper-based microfluidic device and opens the door to development of similar assays for other important analytes.

VL - 8 IS - 9 U1 - http://www.ncbi.nlm.nih.gov/pubmed/24098705?dopt=Abstract ER - TY - JOUR T1 - Instrument-free nucleic acid amplification assays for global health settings. JF - Proc SPIE Int Soc Opt Eng Y1 - 2011 A1 - LaBarre, Paul A1 - Boyle, David A1 - Hawkins, Kenneth A1 - Weigl, Bernhard AB -

Many infectious diseases that affect global health are most accurately diagnosed through nucleic acid amplification and detection. However, existing nucleic acid amplification tests are too expensive and complex for most low-resource settings. The small numbers of centralized laboratories that exist in developing countries tend to be in urban areas and primarily cater to the affluent. In contrast, rural area health care facilities commonly have only basic equipment and health workers have limited training and little ability to maintain equipment and handle reagents.(1) Reliable electric power is a common infrastructure shortfall. In this paper, we discuss a practical approach to the design and development of non-instrumented molecular diagnostic tests that exploit the benefits of isothermal amplification strategies. We identify modular instrument-free technologies for sample collection, sample preparation, amplification, heating, and detection. By appropriately selecting and integrating these instrument-free modules, we envision development of an easy to use, infrastructure independent diagnostic test that will enable increased use of highly accurate molecular diagnostics at the point of care in low-resource settings.

VL - 8029 U1 - http://www.ncbi.nlm.nih.gov/pubmed/25089171?dopt=Abstract ER - TY - PAT T1 - United States Patent: 7011791 - Microfluidic devices for rotational manipulation of the fluidic interface between multiple flow streams Y1 - 2006 A1 - Weigl, Bernhard H. A1 - Bardell, Ronald L. A1 - Kamholz, Andrew A1 - Munson, Matthew A1 - Schilling, Eric A1 - Hawkins, Kenneth AB - Microfluidic devices and methods are provided for enhancing detection of a diffusion pattern formed by particles diffusing between at least two fluid streams in parallel laminar flow such that an interface is formed between them by increasing the dimension of the streams in the diffusion direction. This may be accomplished by flowing the streams through a transforming turn, or by flowing the streams through a channel having diverging walls. Devices and methods are also provided for enhancing diffusion between two streams comprising changing the interface between said streams from a narrow interface to a broad interface. UR - http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=17&f=G&l=50&co1=AND&d=PTXT&s1=%22Weigl%3B+Bernhard%22.INNM.&OS=IN/%22Weigl;+Bernhard%22&RS=IN/%22Weigl;+Bernhard%22 ER -