*2.1. Antibacterial Activity*

A desirable wound dressing should have certain antimicrobial functions to minimize pathogens to reduce inflammatory response and tissue fluid exudation at the wound site and accelerate the healing process [32]. Figure 1 shows zones of inhibition of CS, GT, and CS-GT against *S. aureus* and *P. aeruginosa*, respectively. CS samples were dissolved with 1% glacial acetic acid (HAc). As a result of adding dropwise 1% HAc alone onto paper discs (6.0 mm in diameter), zones of inhibition were all 6.0 mm in size, and, therefore, HAc solvent has no inhibitory effect against both test strains. Measurement of inhibition zones shows that diameters of the zones of inhibition of CS, GT, and CS-GT against *S. aureus* were 7.0 ± 1.0, 17.7 ± 1.2, and 20.0 ± 1.0 mm, respectively, and diameters of the zones of inhibition of CS, GT, and CS-GT against *P. aeruginosa* were 7.0 ± 1.0, 21.3 ± 0.6, and 20.3 ± 0.6 mm, respectively (Table 1). The results sugges<sup>t</sup> that GT and CS-GT have comparable antibacterial activity against *P. aeruginosa*. However, these two samples have significant differences in the diameter of the zones of inhibition of *S. aureus* (*p* < 0.05). Compared with the results of CS, diameters of zones of inhibition of CS-GT against both test strains increased by 13.0 and 13.3 mm due to the introduction of GT, respectively, indicative of superior antimicrobial activity.

**Figure 1.** Zones of inhibition of glacial acetic acid (HAc), chitosan (CS), gentamicin (GT), and chitosan-gentamicin conjugate (CS-GT) against *S. aureus* and *P. aeruginosa*.

**Table 1.** Diameters of zones of inhibition in various groups (unit: mm, mean ± SD, *n* = 3). Note: versus CS group, \* *p* < 0.01; versus GT group, # *p* < 0.05.

