. Author manuscript; available in PMC: 2020 Aug 18.

Published in final edited form as: J Biophotonics. 2020 Apr 20;13(7):e202000005. doi: 10.1002/jbio.202000005

TABLE 1.

Wavenumber peaks and corresponding biomolecules

Observed peak	Assignment
(1,3) ≈859 cm⁻¹	Collagen, tyrosine
(3) 975 cm⁻¹	=C—H out-of-plane deformation (collagen)
(1) 1004 cm⁻¹	Symmetric CC aromatic ring breathing (phenylalanine)
(3) 1080 cm⁻¹	Typical phospholipids
(1) 1131 cm⁻¹	Fatty acid, phospholipid structural change, etc.
(1) 1172 cm⁻¹	CH3 rocking
(1) 1211 cm⁻¹	C—C₆H₅ stretching mode in tyrosine and phenylalanine
(3) ≈1272 cm⁻¹	Amide III, CHα′ rocking
(3) 1306 cm⁻¹	Amide III (N—H), α-helix, C—C stretching, and C—H bending
(1) 1338 cm⁻¹	Tryptophan, CH2/CH3 wagging, twisting, and bending mode of collagens and lipids
(3) 1441 cm⁻¹	CH₂ scissoring and CH₃ bending (lipids)
(1) 1607 cm⁻¹	CO stretching, C=C bending (tyrosine, phenylalanine ring vibration
(3) 1656 cm⁻¹	Amide I unordered
(1) ≈1686 cm⁻¹	Amide I (disordered structure; nonhydrogen bonded)

Note: The numbers in parentheses before the wavenumber values notate the NMF-extracted spectra (Figure 5B) in which they are most present. The “≈” symbol notates a broad region of peaks around the maximum value listed [19, 58].

Abbreviations: NMF, nonnegative matrix factorization.