Excised pig colon backgrounds, mean, and first two principal components.

<p>Excised pig colon backgrounds, mean, and first two principal components.</p

Color background results.

<p>(a) Phantom, (b-d) log2 of S440 concentrations by LS-3P, HLA, and HLP, (e-f) example fitted spectra and residuals by LS-3P, HLA and HLP, (g) histogram of the Durbin-Watson statistic for all pixels, and (h-i) quantification of concentration estimation accuracy. ‘True’ in (h) plots the theoretical linear relationship between the estimated and true concentrations of S440. The concentration estimate by LS-3P for the lowest true concentration was negative and hence not shown in the logarithmic plot in (h).</p

Background signals of the printed colors: mean and first two principal components.

<p>Background signals of the printed colors: mean and first two principal components.</p

Excised pig colon results.

<p>Excised pig colon results.</p

Simulation results.

<p>(a) Example of fitted spectra, (b) corresponding residuals, (c) histograms of Durbin-Watson statistics produced by each method, (d) estimated concentrations, and (e-f) mean and standard deviation of fractional errors generated by the LS-3P, HLA and HLP algorithms.</p

Acquired signals, mean signal, and the first two principal components of the S440 nanoparticle (left) and the paraffin background (right).

<p>Acquired signals, mean signal, and the first two principal components of the S440 nanoparticle (left) and the paraffin background (right).</p

A Real-Time Clinical Endoscopic System for Intraluminal, Multiplexed Imaging of Surface-Enhanced Raman Scattering Nanoparticles

<div><p>The detection of biomarker-targeting surface-enhanced Raman scattering (SERS) nanoparticles (NPs) in the human gastrointestinal tract has the potential to improve early cancer detection; however, a clinically relevant device with rapid Raman-imaging capability has not been described. Here we report the design and <i>in vivo</i> demonstration of a miniature, non-contact, opto-electro-mechanical Raman device as an accessory to clinical endoscopes that can provide multiplexed molecular data via a panel of SERS NPs. This device enables rapid circumferential scanning of topologically complex luminal surfaces of hollow organs (e.g., colon and esophagus) and produces quantitative images of the relative concentrations of SERS NPs that are present. Human and swine studies have demonstrated the speed and simplicity of this technique. This approach also offers unparalleled multiplexing capabilities by simultaneously detecting the unique spectral fingerprints of multiple SERS NPs. Therefore, this new screening strategy has the potential to improve diagnosis and to guide therapy by enabling sensitive quantitative molecular detection of small and otherwise hard-to-detect lesions in the context of white-light endoscopy.</p></div

Imaging device and system.

<p>(a) Photographs of the components of the distal end of the device adjacent to a quarter (diameter = 24 mm) for scale. All the components shown, less the motor, were custom designed and fabricated for this device. (b) Close-up photograph of the distal end of the fully functional device. The fiber bundle was enclosed and sealed within a flexible extrusion sheath. The window was placed between the scan mirror and the tissue in order to seal the inner mechanisms of the device from fluids in the surrounding environment. The use of a toroidal mirror compensates for beam distortion from the curvature of the glass window in order to maintain a collimated beam. Utilization of a 50-degree inclination angle of the toroidal mirror effectively eliminates back reflections from the window into the fiber bundle detector. (c) System overview. A continuous wave (CW) laser at 785 nm was used and the Raman-scattered light is collected through the multi-mode fibers of the fiber bundle. At the proximal end of the fiber bundle, the multimode fibers are arranged into a vertical array for efficient coupling to the spectrometer. A long-pass filter at the entrance of the spectrometer filters out the illumination light. A function generator signal controls a motor control board to finely tune the rotational speed of the motor to the desired speed of 1 rev/s. (d) Photograph of the completed fully functional system.</p

Hollow lumen phantom multiplexing study.

<p>(a) Photograph of the paper phantom laid flat. Each letter and the spot beneath was pipetted on to paper using different SERS nanoparticle flavors (‘S’ = S493,‘P’ = S440, ‘E’ = S482, ‘C’ = S420, ‘T’ = S481, ‘R’ = S421). The ‘A’ and spot below were composed of an equal mixture of all six flavors at one-fifth the concentration; thus appearing dimmer than the other letters. The spots under each letter were below 1 mm in diameter, which is less than the size detectable with white-light endoscopy. (b) Photograph of the phantom with a radius set to 25 mm to mimic the average human colon radius. (c) Image of signal intensities of S493, S440, S482, S420, S481, and S421 shown as 2-D images. (d) Cylindrical three-dimensional reconstruction of the data acquired with the device showing a 5-cm segment of the phantom lumen. (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0123185#pone.0123185.s002" target="_blank">S2 Video</a>). There are a total of 5,000 pixels (50 rev x 100 pix/rev) acquired, which was obtained in a period of 50 seconds (1 rev/s). Each of the SERS flavors was assigned a specific color.</p

Schematic of Raman-imaging system being used in parallel with white-light endoscopy.

<p>(a) The device is designed such that it can be inserted through the accessory channel of a clinical endoscope. As the endoscope is being retracted in the GI tract, the device simultaneously scans the lumen. The collected Raman-scattered light is analyzed, and an image is displayed to the user (also see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0123185#pone.0123185.s001" target="_blank">S1 Video</a>). (b) Expanded schematic of the distal end of the device. The schematic illustrates the position of the device relative to the end of the endoscope. A brushless DC motor that rotates a mirror causing the collimated beam to sweep 360 degrees, enabling luminal imaging of the colon wall. The device is not required to be in contact with the tissue, which is enabled through the use of the collimated illumination beam. A custom, miniature, concentrically segmented, air-spaced doublet lens having a non-reciprocal optical path consists of a plano-convex lens and an adjacent plano-concave lens with a central hole. The doublet lens increases collection efficiency at longer, clinically relevant working distances.</p