Raman Spectroscopy For Comprehensive Serum Analysis And Gastric Cancer Diagnosis

INTRODUCTION

The traditional methods for analyzing blood serum composition are often time-consuming and require sample preparation and multiple reagents. Recently, there's been interest in alternative techniques that are rapid, non-invasive, and reagent-free. Raman spectroscopy has emerged as a promising option, allowing real-time, non-destructive analysis of serum constituents. Moreover, Raman spectroscopy has been developed for gastric cancer diagnosis.

This application note showcases Raman spectroscopy's ability to quantify serum components and distinguish between healthy and gastric cancer samples.

METHODOLOGY

Raman spectroscopy was employed to obtain spectra from serum samples, utilizing a setup featuring a 532 nm excitation laser and an objective lens, then the Raman spectrum was detected with a high-performance Ocean Optics QE Pro spectrometer.

Statistic analysis was then utilized to establish the relationship between Raman spectra and serum component concentrations. This approach facilitated robust correlations between Raman and enzymatic tests for glucose, cholesterol, and HDL as illustrated in Figure 1.

Figure 1. The predicted concentrations obtained from the statistical model based on the Raman data and the concentrations obtained from the enzymatic test belonged to (a) CHO, (b) FBS, and (c) HDL of 40 serum samples.

In addition to quantitative analysis, researchers investigated the potential of Raman spectroscopy as a diagnostic tool for gastric cancer. Figure 2 demonstrates the application of statistical methods to differentiate serum samples from those of healthy individuals and gastric cancer patients. Through multivariate statistical techniques, classification models were developed to accurately determine the health status of the samples.

Figure 2. The shadow curves show the Raman spectra of all healthy and gastric cancer subjects which are separated by an offset.

RAMAN EXPERIMENT

In every measurement, a laser beam with a specific excitation wavelength is utilized along with an optical system to transmit the light. Subsequently, the Raman spectrum is captured using a high-performance spectrometer.

Take advantage of Ocean Insight application-ready systems, comprising spectrometers, lasers, accessories, and software tailored for Raman measurements. INTINS offers comprehensive bundles encompassing all necessary components for probe-based Raman measurements.

These packages cater to Raman excitation wavelengths of 532 nm, 638 nm, 785 nm, and 1064 nm, providing versatility to suit various experimental requirements:

• 532 nm This wavelength is the workhorse for inorganic materials, offering maximum signal for samples that do not suffer from autofluorescence.
• 638 nm –  Often used for most biomedical applications, which need to balance the risk of sample damage with fluorescence generation.
• 785 nm – Yields quality Raman spectra for most chemicals, with limited interference from fluorescence. Also offers good spectral resolution.
• 1064 nm – Is popular for pigment-rich tissues and materials. Though the Raman signal is much weaker, the near absence of fluorescence permits spectra to be obtained with a reasonable SNR.

Figure 3. Raman measurement packages.

CONCLUSION

The study demonstrates Raman spectroscopy's versatility and potential in serum analysis and disease diagnosis. High correlation coefficients (over 94%) between Raman spectra and enzymatic test results validate its accuracy for quantitative measurements. This suggests it could replace traditional enzymatic tests, reducing time and resources.

Moreover, Raman spectroscopy accurately distinguishes between healthy and gastric cancer subjects (87.5% accuracy), making it a promising screening tool for earlier cancer detection. Its non-invasive nature also allows for frequent monitoring, easing the burden on patients and healthcare systems.