A simple, inexpensive device for nucleic acid amplification without electricity-toward instrument-free molecular diagnostics in low-resource settings

• Published in: PloS one 2011-05, Vol.6 (5), p.e19738-e19738
• Main Authors: LaBarre, Paul, Hawkins, Kenneth R, Gerlach, Jay, Wilmoth, Jared, Beddoe, Andrew, Singleton, Jered, Boyle, David, Weigl, Bernhard
• Format: Article
• Language: English
• Subjects: Acids; Amplification; Analysis; Assaying; Biology; Chemical reactions; Chemistry; Cold storage; Communicable diseases; Deoxyribonucleic acid; Developed countries; Developing Countries; Diagnostic equipment (Medical); Diagnostic systems; Diagnostic tests; DNA; Electricity; Engineering; Exothermic reactions; Hot Temperature; Infectious diseases; Innovations; Instrumentation; Malaria; Medical diagnosis; Medicine; Methods; Molecular Diagnostic Techniques - economics; Molecular Diagnostic Techniques - instrumentation; Molecular Diagnostic Techniques - standards; Nuclear electric power generation; Nucleic Acid Amplification Techniques - economics; Nucleic Acid Amplification Techniques - instrumentation; Nucleic Acid Amplification Techniques - standards; Nucleic acids; Orientia tsutsugamushi; Penaeus monodon; Phase change materials; Plasmodium falciparum; Plasmodium falciparum - genetics; Polymerase chain reaction; Reagents; Reference Standards; Sample preparation; Temperature profiles
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0019738

Molecular assays targeted to nucleic acid (NA) markers are becoming increasingly important to medical diagnostics. However, these are typically confined to wealthy, developed countries; or, to the national reference laboratories of developing-world countries. There are many infectious diseases that are endemic in low-resource settings (LRS) where the lack of simple, instrument-free, NA diagnostic tests is a critical barrier to timely treatment. One of the primary barriers to the practicality and availability of NA assays in LRS has been the complexity and power requirements of polymerase chain reaction (PCR) instrumentation (another is sample preparation). In this article, we investigate the hypothesis that an electricity-free heater based on exothermic chemical reactions and engineered phase change materials can successfully incubate isothermal NA amplification assays. We assess the heater's equivalence to commercially available PCR instruments through the characterization of the temperature profiles produced, and a minimal method comparison. Versions of the prototype for several different isothermal techniques are presented. We demonstrate that an electricity-free heater based on exothermic chemical reactions and engineered phase change materials can successfully incubate isothermal NA amplification assays, and that the results of those assays are not significantly different from ones incubated in parallel in commercially available PCR instruments. These results clearly suggest the potential of the non-instrumented nucleic acid amplification (NINA) heater for molecular diagnostics in LRS. When combined with other innovations in development that eliminate power requirements for sample preparation, cold reagent storage, and readout, the NINA heater will comprise part of a kit that should enable electricity-free NA testing for many important analytes.