Table 3 FTIR characteristic peaks for chitosan, methacrylated chitosan, Eosin Y, triethanolamine, and dithiothreitol.

Chitosan (Cs)

ν_as(C–O–C), 1150 cm^{− 1 69} – ν(C–N) for amide III, ~ 1317 cm^{− 1 69} – ν(C = O) for amide I, 1650–1655 cm^{− 1 69,70} – δ(N–H) for amide II in the N-acetyl-D-glucosamine (GlcNAc) units, ~ 1555–1560 cm^{− 1 71,72} – CO–NH for amide III, 1320 cm^{− 1 70}

Methacrylated chitosan (MECs)

C = CH₂, 804 cm^{− 1 11} – ν(C–N) for amide I, 1625 cm^{− 1 11} – CH₃ 1404–1409 cm^{− 1 71} – CONH, 3100 cm^{− 1 11} – ester bond, ~1710 cm^{− 1 11}

Eosin Y (EY)

ν(C–C), 1260 cm^{− 1 73} – ν(C–O–C), 1215,1330 cm^{− 1 73} – ν(C–C), 1317–1348 cm^{− 1 74} – ν(C–O), 1200–1260 cm^{− 1 75} – ν(C–C), ν_s(COO⁻), ~1395 cm^{− 1 73} – ν(C–C), ν_s(COO⁻), ~1460 cm^{− 1 73} – lactone conformation or ν(C = O), ~1750 cm^{− 1 76} – ν_s (C–H) ~ 2848 cm^{− 1 77} – ν_as (C–H), 2922 cm^{− 1 77}

Triethanolamine (TEOA)

ν(C–N), ~1450 cm^{− 1 77} – δ(–CH₂–), ~1468 cm^{− 1 78}– ν (–CH₂–), 2845–2925 cm^{− 1 78}– ν (C–H), ~2950 cm^{− 1 77}

Dithiothreitol (DTT)

–SH, 2550–2600 cm^{− 1 79} – ν(monomers), ~2545 cm^{− 1 80} – ν(dimmers), ~2564 cm^{− 1 81} –R₁–S–S–R₂–, 730–750 cm^{− 1 82} – R₁–S–R₂, 760–785 cm^{− 1 82}