Label-free blood serum detection by using surface-enhanced Raman spectroscopy and support vector machine for the preoperative diagnosis of parotid gland tumors

Table 2 Raman shifts of peaks and the characteristic assignments [15–18, 25–31]

Raman shift (cm⁻¹)	Peak assignment
292–296	Au-S band
543–548	S-S disulfide stretching in Proteins
723–727	Hypoxanthine
744–747	Thymine in DNA
933	C-C stretching mode, C-C αhelix in proteins
1084	C-C stretching mode in phospholipids
1094	C-N stretching mode in D-Mannos
1127	C-C stretching in lipids, C-N stretching in D-Mannos
1140	Carotenoids
1261–1264	CH bending in lipids
1326–1329	CH vibration in DNA/RNA, CH₂ twisting in lipids
1368–1373	Guanine in DNA, Tryptophan in proteins
1441–1445	CH₂, CH₃ bending in proteins and lipids
1541–1551	C-N stretching, Amide II
1607	C = C band in Phenylalanine or Tyrosine
1698–1699	Amide I

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