Polymer-capped fiber-optic Raman probe for non-invasive Raman spectroscopy

Abstract

Advances in fiber optic probe design are moving Raman spectroscopy into the clinic, although there remain important practical problems. While much effort has been devoted to minimizing Raman and fluorescence background from fibers, less attention has been given to the need to generate reference Raman signals that can correct for variations in tissue albedo, which is important in quantifying changes in tissue composition. To address this shortcoming, we have developed a fiber optic probe that incorporates a fluorinated ethylene-propylene copolymer (FEP) cap at the end of each excitation fiber. Transmission of laser light through the transparent cap generates a 732 cm−1 Raman band whose intensity scales linearly with the laser power delivered to the tissue of interest. In our first design, the FEP cap functions as a waveguide with only a small insertion loss (~5%). Laser transmission through 1 mm of the polymer is sufficient to generate a usable reference Raman signal. We show the application of the probe to quantitative non-invasive Raman spectroscopy of animal tissues using rat leg phantoms as models. Ex-vivo Raman spectroscopy of excised rat tibia supports the use of the probe for spectroscopy of various tissues. These results provide proof of principle that the Raman probe can be used in multiple spectroscopic applications.

Burn Injury Enhances Bone Formation in Heterotopic Ossification Model

“…26 Imaging was completed at 3 months after implantation. Briefly, the ossicle was placed on the probe in identical orientations.…”

Label-free Raman monitoring of extracellular matrix formation in three-dimensional polymeric scaffolds

“…The use of a new generation of fluorocarbon fibre-optic Raman probes, which generate a reference Raman band for quantitative Raman spectroscopy, will eliminate silica background signals and possibly lead to well-resolved Raman spectra of ECM [37,53]. If so and as opposed to the conventional Raman setups, which are only able to measure a relatively small volume of the scaffolds, this would allow collection of Raman spectra from multiple pores in tissue-engineered scaffolds with one measurement in parallel.…”

“…Details of the Raman probe design have been previously described [15,37]. Briefly, the fibreoptic Raman probe consisted of 50 collection fibres that were rsif.royalsocietypublishing.org J R Soc Interface 10: 20130464 arranged into 10 branches.…”

Recent advances in the development of Raman spectroscopy for deep non‐invasive medical diagnosis

“…This can be beneficial in tomographic reconstruction or in recovering quantitative information transcutaneously. Okagbare and Morris [54] have recently developed a method for providing such an internal standard. The reference signal is generated from a fluorinated ethylene-propylene copolymer cap provided at the end of each excitation fiber.…”