Highly Stable and Sensitive Nucleic Acid Amplification and Cell-Phone-Based Readout

ACS Nano. 2017 Mar 28;11(3):2934-2943. doi: 10.1021/acsnano.6b08274. Epub 2017 Mar 2.


Key challenges with point-of-care (POC) nucleic acid tests include achieving a low-cost, portable form factor, and stable readout, while also retaining the same robust standards of benchtop lab-based tests. We addressed two crucial aspects of this problem, identifying a chemical additive, hydroxynaphthol blue, that both stabilizes and significantly enhances intercalator-based fluorescence readout of nucleic acid concentration, and developing a cost-effective fiber-optic bundle-based fluorescence microplate reader integrated onto a mobile phone. Using loop-mediated isothermal amplification on lambda DNA we achieve a 69-fold increase in signal above background, 20-fold higher than the gold standard, yielding an overall limit of detection of 25 copies/μL within an hour using our mobile-phone-based platform. Critical for a point-of-care system, we achieve a >60% increase in fluorescence stability as a function of temperature and time, obviating the need for manual baseline correction or secondary calibration dyes. This field-portable and cost-effective mobile-phone-based nucleic acid amplification and readout platform is broadly applicable to other real-time nucleic acid amplification tests by similarly modulating intercalating dye performance and is compatible with any fluorescence-based assay that can be run in a 96-well microplate format, making it especially valuable for POC and resource-limited settings.

Keywords: intercalating dyes; loop-mediated isothermal amplification; mobile-phone fluorescence microscopy; nucleic acid detection; point-of-care assay.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Bacteriophage lambda / chemistry
  • Cell Phone* / economics
  • DNA / analysis*
  • Fluorescence
  • Intercalating Agents / chemistry*
  • Molecular Structure
  • Naphthalenesulfonates / chemistry*
  • Nucleic Acid Amplification Techniques* / economics
  • Nucleic Acid Amplification Techniques* / instrumentation
  • Point-of-Care Systems* / economics
  • Spectrometry, Fluorescence / economics
  • Spectrometry, Fluorescence / instrumentation


  • Intercalating Agents
  • Naphthalenesulfonates
  • trisodium 3-hydroxy-4-((2Z)-2-(2-oxo-4-sulfonatonaphthalen-1-ylidene)hydrazinyl)naphthalene-2,7-disulfonate
  • DNA