Development of Chitosan/Bacterial Cellulose Composite Films Containing Nanodiamonds as a Potential Flexible Platform for Wound Dressing

Abstract

Chitosan/bacterial cellulose composite films containing diamond nanoparticles (NDs) with potential application as wound dressing are introduced. Microstructural studies show that NDs are uniformly dispersed in the matrix, although slight agglomeration at concentrations above 2 wt % is seen. Fourier transform infrared spectroscopy reveals formation of hydrogen bonds between NDs and the polymer matrix. X-ray diffraction analysis indicates reduced crystallinity of the polymer matrix in the presence of NDs. Approximately 3.5-fold increase in the elastic modulus of the composite film is obtained by the addition of 2 wt % NDs. The results of colorimetric analysis show that the composite films are transparent but turn to gray-like and semitransparent at high ND concentrations. Additionally, a decrease in highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) gap is also seen, which results in a red shift and higher absorption intensity towards the visible region. Mitochondrial activity assay using L929 fibroblast cells shows that the nanocomposite films are biocompatible (>90%) after 24 h incubation. Multiple lamellapodia and cell-cell interaction are shown. The results suggest that the developed films can potentially be used as a flexible platform for wound dressing.

Keywords: bacterial cellulose; chitosan; nanocomposite; nanodiamond; wound dressing.

Figure 1

Scanning electron microscopy (SEM) micrographs of the composite films containing (a) 0, (b) 1, (c) 2, (d) 3 and (e) 4 wt % diamond nanoparticles. The scale bar is 300 nm. (f) Transmission optical micrographs of chitosan/bacterial cellulose (CS/BC) film.

Figure 2

(a,b) Fourier transform infrared (FTIR) spectra of composite films. (c) Schematic illustration of possible interactions between the polymer matrix and functional groups of NDs.

Figure 3

(a) Transmission profile of composite films containing different amounts of ND. (b) Digital images show the appearance of the composite films.

Figure 4

(a) Differential scanning calorimetric traces of CS/BC composite films containing different amounts of NDs. (b) X-ray diffraction (XRD) pattern of (1) CS/BC and (2) CS/BC/ND (4wt%). Note the disappearance of the green circles and the appearance of purple squares after ND addition.

Figure 5

SEM images show the fracture surface of CS/BC films containing (wt %) (a) 0, (b) 2 and (c) 4 NDs. (d) Digital image illustrates the flexibility of the nanocomposite films.

Figure 6

Viability of L929 mouse fibroblast cells incubated on the surface of the composite films.

Figure 7

Representative SEM images of composite films. The films were prepared by freeze drying. (a) The film surface before cell incubation shows the porous structure of the freeze-dried specimen. Cell morphology on (b,c) CS/BC and (d–f) CS/BC/ND (4 wt %) films.

Figure 8

The antibacterial activity of the compounds against (a) American Type Culture Collection (ATCC) 25923 Escherichia coli and (b) American Type Culture Collection ATCC 25922 Staphylococcus aureus.