Table 1.

Surface enhanced Raman spectroscopy (SERS) assignments in Gram-negative and Gram-positive bacteria. NAG—N-acetylglucosamine; PDMS—polydimethylsiloxane.

	E. coli (cm−1)	S. epidermidis (cm−1)	Proposed Assignment	References
1	621		C–C twisting mode of phenylalanine	[23]
2	643	650	Guanine ring breathing	[17,19]
3		660	Guanine, thymine ring breathing	[23]
4	665	670	NAG	[27,29]
5	702	706	PDMS	[54]
6	725		Adenine ring breathing	[4,19,31,32]
7	744		B1g heme vibration (cytochrome c)	[35,37,38,39,40]
8	755		Tryptophan ring breathing	[37,43]
9	778	780	DNA/RNA ring breathing (cytosine/thymine)	[17,27,29,31]
10		800	DNA/RNA ring breathing	[27,29]
11	826		νa(O‒P‒O) str.	[19,44]
12	851	848	Thymine	[19,48]
13	955	950	ν(CH3) of proteins (a-helix)	[19]
14	1003	1002	Phenylalanine	[19,27,29,31,37]
15	1032	1030	Phenylalanine C–H in plane bending	[19]
16		1040	ν (CC) aromatic ring	[29]
17	1096	1097	νs (PO2)	[19,44]
18	1124		ν(PO2)	[19]
19		1165	Tyrosine, phenylalanine, amide III	[29]
20	1204	1208	Phenylalanine	[37]
21	1241	1230	ν(PO2−), amide III	[19]
22		1257	amide III	[19]
23		1277	PDMS	[54]
24	1319	1314	Guanine, CH2 twist (lipids)	[19,29]
25	1335	1342	Protein twisting (CH2 and CH3), ν(NH2) Adenine	[29,37]
26	1386		δ(CH3) symmetrical	[19]
27	1399		C‒O‒O‒ stretching in amino acids	[29]
28	1449	1446	Scissoring (fatty acids, phospholipids, and mono- and oligo-saccharides); CH2CH3 deformation	[19,29]
29		1495	δ (CH2)	[29]
30	1533	1529	Amide II of proteins, N-acetyl related bands (amide II)	[29]
31		1538	Amide II of proteins	[29]
32	1553	1564	Amide II of proteins, guanine/adenine (only S. epidermidis)	[17,19,29]
33	1579		Guanine, adenine, tryptophane (proteins)	[19]
34	1651	1648	Amide I of proteins (α—helix), cytosine/thymine	[17,19,29,46]
35	1667	1657	Amide I of proteins (random coils)	[46]
36	1694	1665	Amide I of proteins (β—sheet)	[46]