Method of measuring diffusion in a medium
Methods for measuring diffusion in a medium. One method includes dissolving a fluorescent sample in a medium, imaging the fluorescent sample with a patterned illumination Fluorescence Recovery After Photobleaching (FRAP) technique, and analyzing a set of microscope images of the photobleached dissolved fluorescent sample with the patterned illumination using a Fourier Transform (FT) FRAP technique.
1. A method for measuring diffusion in a medium, comprising:
dissolving a fluorescent sample into the medium;
imaging the fluorescent sample with a patterned illumination Fluorescence Recovery After Photobleaching (FRAP) technique, wherein the imaging the fluorescent sample with the patterned illumination FRAP technique comprises:
recording images of a dissolved fluorescent sample into the medium;
photobleaching the dissolved fluorescent sample using a patterned illumination with a laser, wherein the patterned illumination comprises at least one of periodic patterned illumination or repeating patterned illumination; and
recording images of a photobleached dissolved fluorescent sample with the patterned illumination;
analyzing a set of microscope images of the photobleached dissolved fluorescent sample with the patterned illumination using a Fourier Transform (FT) FRAP technique, wherein the analyzing the set of microscope images of the photobleached dissolved fluorescent sample with the patterned illumination using the FT FRAP technique comprises:
performing a two-dimensional spatial Fourier transform on the set of microscope images;
fitting at least one Fourier transform peak to a diffusion model, thereby producing a fitted curve; and
calculating diffusion properties of the fitted curve.
2. The method of claim 1 , wherein the laser has power ranging from 300 milliwatts (mW) to 500 milliwatts (mW).
3. The method of claim 1 , wherein the using the patterned illumination with the laser comprises using patterned laser beam scanning; or using diffractive optical elements.
4. The method of claim 1 , wherein the at least one Fourier peak corresponds to a frequency of the patterned illumination.
5. The method of claim 1 , wherein the diffusion model comprises Fick's Law of Diffusion model or continuous-time random walk fractional diffusion model.
6. The method of claim 1 , wherein the fitting the at least one Fourier transform peak to the diffusion model, thereby producing the fitted curve comprises fitting the at least one Fourier transform peak to the diffusion model using a least-squares methodology, thereby producing the fitted curve.
7. The method of claim 1 , wherein the diffusion properties comprises at least one of diffusion coefficient, recoverable fraction, subdiffusive exponent, or Lévy flight exponent.