Films based on TEMPO-oxidized chitosan nanoparticles: Obtaining and potential application as wound dressings

A series of novel films based on TEMPO-oxidized chitosan nanoparticles were prepared by casting method. Fourier transform infrared spectroscopy (FTIR) was employed to ascertain the chemical structure of TEMPOoxidized chitosan. The surface morphology of the TEMPO-oxidized chitosan nanoparticles was analyzed by atomic force microscopy (AFM). The physicochemical (area density, thickness, iodine sorption, roughness), functional (moisture sorption, liquid absorption capacity, weight loss upon contact with the liquid, and water vapor transmission rate), antibacterial, and antioxidant properties of films based on TEMPO-oxidized chitosan nanoparticles were also investigated. The physicochemical properties of the films varied widely: area density ranged from 77.83 +/- 0.06 to184.46 +/- 0.05 mg/cm2, thickness varied between 80.5 +/- 1.6 and 200.5 +/- 1.6 mu m, iodine sorption spanned from 333.7 +/- 2.1 to166.4 +/- 2.2 mg I2/g, and roughness ranged from 4.1 +/- 0.2 to 5.6 +/- 0.3 nm. Similarly, the functional properties also varied significantly: moisture sorption ranged from 4.76 +/- 0.03 to 9.62 +/- 0.11 %, liquid absorption capacity was between 129.04 +/- 0.24 and 159.33 +/- 0.73 % after 24 h, weight loss upon contact with the liquid varied between 31.06 +/- 0.35 and 45.88 +/- 0.58 % after 24 h and water vapor transmission rate ranged from 1220.10 +/- 2.91to1407.77 +/- 5.22 g/m2 day. Despite the wide variations in physicochemical and functional properties, all films showed maximum bacterial reduction of Staphylococcus aureus and Escherichia coli, although they exhibited low antioxidant activity. The results suggest that the films could be effectively utilized as antibacterial wound dressings.