Table 1 FTIR bands of histidine, histidine–GNPs, histamine, and histamine–GNPs

νH₂O/νNH/νNH₂ and νCOOH

νamine-HCl

ν_asyCOO⁻, δ_asyNH, and δNH₃ ⁺

ν_sym COO⁻, δ_sym NH, and νC=N