The UV-visible absorption spectra of RNA (curve a), pure Ag sol (curve d), the mixture of Ag colloidal and RNA (curve c), and the mixture of Ag colloidal, MgSO4, and RNA solution (curve b). The inserted picture shows SEM images of MgSO4-aggregated Ag colloids on the surface of aluminum substrate.
(a) Comparison of the normalized mean spectra of serum RNA samples obtained from 31 gastric cancer patients versus 34 healthy volunteers. The shaded areas represent the standard deviations (SD) of the means spectra. The stripe shadow represents the standard deviations of the gastric cancer mean spectra, while the gray shaded area indicates the standard deviations of the normal mean spectra. Also shown at the bottom is the difference spectrum. (b) Comparison of the mean intensities and standard deviations of selected peaks with the most distinguishable differences between gastric cancer and normal serum RNA.
(a) Principal component analysis of all serum RNA samples: a 3D mapping of the PCA result for gastric caner and healthy volunteer group. (b) LDA scores: gastric cancer versus healthy subject. The solid line represents the classification cut-value (y = 0.3130).
The ROC curve of the discrimination result for using PCA-LDA-based SERS spectral classification with leave-one-out, cross validation method. The integrated area under the ROC curve was 0.989.
SERS peak positions and vibrational mode assignments.
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