Surface-enhanced Raman spectroscopy of blood serum based on gold nanoparticles for tumor stages detection and histologic grades classification of oral squamous cell carcinoma

Figures & data

Table 1 Detailed information of the subjects in this study

Case information	Patients (%)
Age
Range from 39–70 years
Mean age 62.3 years
Gender
Male	75 (56)
Female	60 (44)
Tumor site
Bucca	40 (30)
Tongue	50 (37)
Floor of mouth	45 (33)
Human papillomavirus infection
Yes	0 (0)
No	135 (100)
Total	135 (100)

Figure 1 (A) The scanning electron microscopy images of the gold nanoparticles. (B) The UV–visible absorption of the gold nanoparticles and the gold nanoparticles with serum. (C) SERS spectrum of serum, regular Raman spectrum of serum, and Raman spectrum of the gold nanoparticles. (D) Enlarged figure of regular Raman spectrum of serum. (E) Enlarged figure of Raman spectrum of the gold nanoparticles.

Abbreviations: Abs, absorbance; au, arbitrary unit; SERS, surface-enhanced Raman spectroscopy; SE (U), secondary electron (U); UV, ultraviolet.

Table 2 The assignments of the different peaks in the Raman spectra

Raman shift (cm^−1)	Peak assignment
294–296	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 α-helix in proteins
1,084	C-C band in lipids
1,094	C-C stretch in lipids
1,261–1,264	CH bending in lipids
1,326–1,329	CH vibration in DNA/RNA, CH2 twisting in lipids
1,368–1,373	Guanine in DNA, tryptophan in proteins
1,441–1,445	CH2, CH3 bending in proteins and lipids
1,541–1,542	C-N stretching, Amide II
1,586	C-C stretch in phenylalanine or acetoacetic acid
1,602–1,607	C=C band in phenylalanine or tyrosine
1,698–1,699	Amide I

Table 3 The results of the classification of different T stage groups

Method	Class	Predicted group				Total
		T1	T2	T3	T4
PCA-LDA count (%)	T1	8 (80.0)	2 (20.0)	0 (0)	0 (0)	10 (100)
	T2	1 (2.2)	33 (71.7)	6 (13.0)	6 (13.0)	46 (100)
	T3	1 (4.0)	2 (8.0)	20 (80.0)	2 (8.0)	25 (100)
	T4	1 (1.9)	4 (7.4)	7 (13.0)	42 (77.8)	54 (100)

Abbreviations: LDA, linear discriminant analysis; PCA, principal component analysis.

Figure 2 (A) The normalized average SERS spectra of the T1, T2, T3, and T4 groups. (B) The two-dimensional scatter plot diagram of the T1, T2, T3, and T4 groups. (C) The normalized average SERS spectra of T1–2 and T3–4, and the subtracted spectrum of T1–2 and T3–4. (D) The histogram of discrimination scores of T1–2 and T3–4.

Abbreviation: SERS, surface-enhanced Raman spectroscopy.

Table 4 The results of the classification of T1–2 and T3–4 stage groups

	Class	Predicted group		Total
		T1–2	T3–4
PCA-LDA count (%)	T1–2	49 (87.5)	7 (12.5)	56 (100)
	T3–4	6 (7.6)	73 (92.4)	79 (100)

Abbreviations: LDA, linear discriminant analysis; PCA, principal component analysis.

Figure 3 (A) The normalized average SERS spectra of N0, N1, and N2 groups and the subtracted spectra of different N groups. (B) The two-dimensional scatter plot diagram of the N0, N1, and N2 groups.

Abbreviations: au, arbitrary unit; SERS, surface-enhanced Raman spectroscopy.

Table 5 The results of the classification of different N stage groups

Method	Class	Predicted group			Total
		N0	N1	N2
PCA-LDA count (%)	N0	40 (75.5)	2 (3.8)	11 (20.8)	53 (100)
	N1	2 (6.3)	30 (93.8)	0 (0)	32 (100)
	N2	3 (6.0)	1 (2.0)	46 (92.0)	50 (100)

Abbreviations: LDA, linear discriminant analysis; PCA, principal component analysis.

Figure 4 (A) The normalized average SERS spectra of the SCC-I, SCC-II, and the SCC-III groups and the subtracted spectra of different SCC groups. (B) The two-dimensional scatter plot diagram of the SCC-I, SCC-II, and the SCC-III groups.

Abbreviations: SCC, squamous cell carcinoma; SERS, surface-enhanced Raman spectroscopy.

Table 6 The results of the classification of different histologic grade groups

Method	Class	Predicted group			Total
		SCC-I	SCC-II	SCC-III
PCA-LDA count (%)	SCC-I	36 (92.3)	1 (2.6)	2 (5.1)	39 (100)
	SCC-II	2 (4.1)	44 (89.8)	3 (6.1)	49 (100)
	SCC-III	1 (2.1)	4 (8.5)	42 (89.4)	47 (100)

Abbreviations: LDA, linear discriminant analysis; PCA, principal component analysis; SCC, squamous cell carcinoma.