Method and device for single molecule imaging
A device and method for imaging fluorescently labeled molecules (e.g., nucleic acids) includes securing a modular attachment device to the mobile phone with a sample containing stretched, fluorescently labeled nucleic acid molecules and illuminating the sample with excitation light to cause the fluorescently labeled nucleic acid molecules to emit fluorescent light. Images of the nucleic acids are captured using a camera of the mobile phone. The images from the mobile phone are transferred to a remote computer for image processing and analysis. The images are processed by the remote computer to generate analysis data of sample, wherein the analysis data includes the length of nucleic acid molecules contained in the sample or the length of molecular sub-region(s). The mobile phone or another computing device receives from the remote computer the analysis data and displays at least some of the analysis data thereon.
1. A device for imaging fluorescently labeled nucleic acid molecules in a sample comprising:
a mobile phone having a camera therein;
a modular attachment device configured to mount to the mobile phone and position a fluorescently labeled nucleic acid sample contained therein within a field of view of the camera, the modular attachment device comprising:
an excitation light source;
a sample holder configured to hold the sample containing the fluorescently labeled nucleic acid compressed between two optically transparent substrates, wherein fluorescently labeled nucleic acid molecules are stretched or extended in response to a compression force applied to the two optically transparent substrates;
a lens or set of lenses for magnifying the image of the sample;
a filter interposed between the lens and the camera of the mobile phone and configured to reject scattered background light from the excitation light source and transmit fluorescent light through the filter;
a moveable stage for moving the excitation light source and sample holder relative to the camera of the mobile phone; and
wherein the mobile phone comprises software executed thereon to identify molecules of fluorescently labeled nucleic acid in the sample along with their respective lengths or lengths of sub-regions of the nucleic acid molecules.
2. The device of claim 1 , wherein the mobile phone comprises at least one processor configured to transmit one or more images obtained from the mobile phone camera to a remote or local computer for image processing and analysis, the mobile phone configured to receive analysis results from the remote computer including the length of nucleic acid molecules in the sample.
3. The device of claim 1 , wherein the mobile phone comprises at least one processor configured for processing images obtained of the sample with the mobile phone and output an analysis of the sample including the length of nucleic acid molecules in the sample or specific sub-regions of nucleic acid molecules.
4. The device of claim 1 , wherein the sample holder comprises first and second optically transparent substrates and the sample of interest is interposed there between.
5. The device of claim 1 , wherein the excitation light source comprises at least one of a laser diode, light emitting diode, or an array of the same.
6. The device of claim 2 , wherein the mobile phone transmits a plurality of images to the remote or local computer, wherein the remote computer subjects the plurality of images to image averaging to form a higher SNR image.
7. The device of claim 6 , wherein the remote or local computer processes the higher SNR image to retain one or two colors of pixels from the higher SNR image.
8. The device of claim 7 , wherein the remote or local computer rotates the retained pixels in the image by about 45 degrees.
9. The device of claim 8 , wherein the remote computer generates an object mask of the molecules of fluorescently labeled nucleic acid in the rotated image.
10. The device of claim 9 , wherein the remote computer generates a line or skeleton of the fluorescently labeled nucleic acid molecules or a specific sub-region of the nucleic acid molecules through fitting a function that estimates or mimics the point spread function (PSF) of the mobile phone camera.
11. The device of claim 10 , wherein the remote computer generates a length measurement for the fluorescently labeled nucleic acid molecules or a specific sub-region of nucleic acid molecules based on the PSF fitting.