Team:NYU Abu Dhabi/Documentation/DOCS 20ee279bfcdc46b09c4fb108851b2757/Engineering 8297e0cf88af4f8fbfe00ad598c6a52f/Case Studies b2be0b8bd13548ac99d3f41e1124dbb2/Paper Microfluidic Extraction and Use of Smartphon c541c5529e69442a8a9dfa8bafebe001

Paper Microfluidic Extraction and Use of Smartphone detection for Pathogenic Nucleic Acids

Paper Microfluidic Extraction and Use of Smartphone detection for Pathogenic Nucleic Acids

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https://pubs.rsc.org/en/content/articlehtml/2014/ra/c3ra47688j?casa_token=4x6BdwOoAxwAAAAA:ybWAl3voKlh1l4sylzMX8gDqU-kHbPVSaTCCQZJhxqi3KijZp7VbsJbQf4KWjHCnFE0Eb84zF-cdJA
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This process provides a rapid method to extract and identify nucleic acids. In this paper the nucleic acids identified are those of Salmonella Typhimurium. The device and process developed is sensitive, portable, low cost and provides quantitative results.

Fabrication of Paper Microfluidic Chips

Microfluidic channels are designed using SolidWorks 2010 and are printed on clear transparency film. They are then coated with cellulose or nitrocellulose depending on the required results. Cellulose is best used if the required result is for high or low concentrations of pathogen DNA whereas nitrocellulose is best for mid-range concentrations of pathogen DNA.

Fig. 1 Top: patterned cellulose channel using modified lithography with equally-spaced elution regions. Bottom: the overall sample preparation is as follows: (a) load sample on paper; (b) add TE lysis buffer and incubate for 3 minutes; (c) add TE elution buffer and Qubit intercalating dye; (d) elute nucleic acids and measure fluorescence reflectance signal with a smartphone fluorescent microscope; optional: (e) excise specific paper regions, rinse the excised papers with TE buffer and load to a PCR reaction mixture. The flow shows theoretical separation of various components within paper.

Direct Fluorescent Detection with A Smartphone Set-u

Fig. 2 A smartphone with a fluorescent miniature microscope attachment directly measures the fluorescent reflectance from a composite chip, consisting of four separate paper chips. Measurements were made separately for each channel. The fluorescent miniature microscope includes two bandpass filters, two 10× objective lenses, a dichroic mirror, and a blue LED (475 nm)

Required Equipment:

  • Smartphone
  • 2 x 10x Objective Lenses
  • 492 nm bandpass filter
  • 520 nm bandpass filter
  • 500 nm dichroic shortpass filter

A sample containing the pathogen DNA and a buffer,in this example the buffer Tris-EDTA was used, are loaded onto the inlets of the microfluidic chip. The buffer is required for lysis. The sample is left to incubate for 3 minutes before the microfluidic chip os eluted in TE buffer. The sample is loaded for conventional PCR and the chip is analysed by fluorescent reflectance detection. Detailed images of the results of the test can be taken using the smartphone and the setup lenses. ImageJ software can be used in the smartphone in order to record real time results of the intensity on the microfluidic chips.

Key Findings

  • Provides a rapid method to extract and identify nucleic acids.
  • Device is sensitive, low cost and portable.
  • Makes use of and explains a real-time, quantitative, smartphone based method of detection.
  • Use a cellulose coating if qualitative results are required and nitrocellulose coating if quantitative results are required.