Antimicrobial activity of a bacterial nanocellulose film functionalized with Nisin Z for prospective burn wounds treatment

Burn wounds can lead to numerous severe complications including bacterial infections causing patient morbidity and mortality, mostly in low- and middle-income countries. The considerable increase of the microbial resistance against traditional antibiotics is leading towards alternative strategies to treat bacterial infections. Nisin Z is an antimicrobial peptide which exhibits a significant antibacterial activity against Gram-positive bacteria. Its efficacy against Gram-negative bacteria is limited, nonetheless it can be improved with the addition of surfactants, such as ethylenediaminetetraacetic acid (EDTA). The incorporation of peptide and other biomolecules within a biopolymer matrix provides protection maintaining their antimicrobial potential. Bacterial nanocellulose (BNC) has been widely used as wound dressings. Its impressive water retention capacity (> 99 %) and porosity are beneficial to manage wounds due to its potential to absorb exudates, providing a breathable and humid environment. In this work, the functionalization of BNC with Nisin Z (BNC-NZ) via vacuum filtration is reported. The entrapment of the peptide inside the BNC films was confirmed through morphological characterization using Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectrometry. Typical absorbance peaks of Nisin Z are easily identifiable at 1647 cm^-1 (amide group) and 1520 cm^-1 (bending of primary amines). Thermal Gravimetric Analysis (TGA) suggested that Nisin Z did not interfere with the BNC matrix. The antimicrobial activity of Nisin Z against five of the most common bacteria found in burn wounds was verified by Minimum Bactericidal Concentration (MBC) ranging 8.0-256.0 µg/mL. Agar Diffusion and Shake Flask methods revealed the potential of BNC-NZ for prospective applications in burn wound dressings.