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. Author manuscript; available in PMC: 2011 Jul 1.
Published in final edited form as: Analyst. 2010 May 25;135(7):1569–1578. doi: 10.1039/c0an00112k

Table 1.

Assignment of IR spectral features in skin. Results are reported from compilations in the literature [ref. 43–45], from other studies referenced here and from analysis of this study’s skin samples, including both clinical and engineered tissue a

Mode Origin Literature Human skin
 Engineered skin
Epidermis Dermis Epidermis Dermis
Amide A (N–H stretching) Peptide, protein 3300 3298 3298 3292 3292
Amide B (N–H stretching) Peptide, protein 3080 3078 3078 3080 3082
C–H stretching of alkenes Phospholipid, glycolipid, fatty acid, ceramide, triglyceride 3010 3010 3010 3012 3012
Asymmetric CH3 stretching Phospholipid, glycolipid, fatty acid, ceramide, triglyceride 2957 2960 2960 2962 2958
Asymmetric CH2 stretching Phospholipid, glycolipid, fatty acid, ceramide, triglyceride 2920 2920 2920 2916 2918
Symmetric CH3 stretching Phospholipid, glycolipid, fatty acid, ceramide, triglyceride 2872 2868 2868 2874 2874
Symmetric CH2 stretching Phospholipid, glycolipid, fatty acid, ceramide, triglyceride 2851 2850 2850 2850 2850
CO stretch Phospholipid 1738 1740 1740 1738 1738
Amide I (80% CO stretch) Peptide, protein, ceramide 1655 1654 1654 1664 1664
Amide II (60% N–H in plane bend, 40% C–N stretch) Peptide, protein, ceramide 1545 1548 1548 1552 1550
CH2 scissoring Phospholipid, glycolipid, fatty acid, triglyceride 1468 1468 1468 1454 1460
CO stretch of COO– Fatty acid ~1395 1400 1400 1402 1392
CH3 symmetric bend Phospholipid, fatty acid, triglyceride 1378 1384 1384 1392 1390
CH2 wagging Phospholipid, fatty acid, triglyceride 1343–1370 1344 1338 1344 1336
Amide III (40% C–N stretch, 30% N–H in plane bend, 20% methyl–C stretch) Collagen 1283 1284 1284 1284 1284
Asymmetric PO2–stretch Phosphate salt, nucleic acid, DNA, RNA ~1245 1242 1240 1240 1238
Amide III (40% C–N stretch, 30% N–H in plane bend, 20% methyl–C stretch) Collagen 1236 1236 1234 1236 1236
Asymmetric PO2–stretch Phosphate salt, nucleic acid, DNA, RNA 1223 1224 1226 1224 1226
Amide III (40% C–N stretch, 30% N–H in plane bend, 20% methyl–C stretch) Collagen 1204 1204 1204 1204 1204
Ester C–O asymmetric stretch Ester 1170 1170 1168 1160 1170
Symmetric PO2–stretch Phosphate salt, nucleic acid, DNA, RNA ~1080 1082 1082 1082 1082
C–OP stretch Phosphate ester 1047 1056 1058 1034 1030
a

Results are reported from compilations in the literature [ref. 43–45] and from analysis of this study’s skin samples, including both clinical and engineered tissue.