Role of Raman spectroscopy and surface enhanced Raman spectroscopy in colorectal cancer

Abstract

Colorectal cancer (CRC) is the fourth most common cancer in the United Kingdom and is the second largest cause of cancer related death in the United Kingdom after lung cancer. Currently in the United Kingdom there is not a diagnostic test that has sufficient differentiation between patients with cancer and those without cancer so the current referral system relies on symptomatic presentation in a primary care setting. Raman spectroscopy and surface enhanced Raman spectroscopy (SERS) are forms of vibrational spectroscopy that offer a non-destructive method to gain molecular information about biological samples. The techniques offer a wide range of applications from in vivo or in vitro diagnostics using endoscopic probes, to the use of micro-spectrometers for analysis of biofluids. The techniques have the potential to detect molecular changes prior to any morphological changes occurring in the tissue and therefore could offer many possibilities to aid the detection of CRC. The purpose of this review is to look at the current state of diagnostic technology in the United Kingdom. The development of Raman spectroscopy and SERS in clinical applications relation for CRC will then be discussed. Finally, future areas of research of Raman/SERS as a clinical tool for the diagnosis of CRC are also discussed.

Keywords: Colorectal cancer; Detection; Raman; Spectroscopy; Surface enhanced Raman spectroscopy.

Figure 1

Energy shifts involved in light scattering interactions. Adapted from Lin et al[23].

Figure 2

Example Raman spectrum of dried human serum. Spectrum of dried droplet of human serum taken with 785 nm laser excitation, 10 s acquisition time with an InVia Raman spectrometer (Renishaw, United Kingdom).

Figure 3

An example spectrum of a surface enhanced Raman spectroscopy response vs Raman response of human blood plasma. Raman spectrum and SERS spectrum of dried human plasma droplet at 10% laser power with 785 nm laser excitation, 10 s acquisition time with an InVia Raman spectrometer (Renishaw, United Kingdom). SERS response gained by 1:1 mixing with 40 nm raw gold nanoparticles (Nanocs, United States). Purple: SERS response of plasma; Blue: Raman response of plasma. SERS: Surface enhanced Raman spectroscopy.

Figure 4

Different methods of producing a surface enhanced Raman spectroscopy response with biological samples. A: Mixing based methods with both non-labeled mixing and labeled or “aggregation” based mixing; B: Labeled surface enhanced Raman spectroscopy based immunoassay. SERS: Surface enhanced Raman spectroscopy.