Fig. 1

FTIR spectra of CS-NPs () showed a broad band at 3393 cm − 1 corresponds to intermolecular hydrogen bond stretching vibrations of (O–H and N–H) groups. The peaks at 1507 cm − 1 is attributed to CH bending and 1392 cm^− 1 are attributed to the CH2 stretching vibration; and peak at 907 cm^− 1 characteristic to P = O stretching vibration. FTIR of phage encapsulated CS-NPs (), the peak at 3393 cm − 1 (–NH2 groups stretching vibration) was shifted to 3477 cm^− 1 attributing to the occurrence of phage encapsulated. In addition, the peaks at 1507 and 1392 cm^− 1 in CS-NPs were shifted to 1602 and 1476 cm − 1 in CS-NPs, with the presence of a peak at 1665 cm^-1 is typically associated with the C = O (carbonyl) stretching vibration