Poly(3-hydroxybutyrate- co-3-hydroxyvalerate) (P(3HB- co-3HV))/Bacterial Cellulose (BC) Biocomposites for Potential Use in Biomedical Applications

Abstract

The aim of this study was to obtain biocomposites consisting of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), bacterial cellulose (BC) and α-tocopherol by a melt processing technique for potential use in biomedical applications. The melt processing and roughness of biocomposites were evaluated and compared to sample without BC. The degradation rate of PHBV/BC biocomposites was measured in phosphate buffer saline (PBS) by determining the mass variation and evidencing of thermal and structural changes by differential scanning calorimetry (DSC) and attenuated total reflectance-Fourier transformed infrared spectrometry (ATR-FTIR). The cell viability, cell morphology, cell cycle distribution and total collagen content were investigated on murine NCTC fibroblasts. Overall, the adding of BC to polyester matrix led to an adequate melt processing of biocomposites and increased surface roughness and cytocompatibility, allowing the cells to secrete the extracellular matrix (collagen) and stimulate cell proliferation. Results showed that the PHBV/BC biocomposites were favorable for long-term degradation and could be used for the design of medical devices with controlled degradability.

Keywords: bacterial cellulose; biocomposite; crystallinity; in vitro cytocompatibility; melt processing; poly(hydroxybutyrate-co-valerate).

Figure 1

Atomic force microscopy images of PHBV/BC biocomposite films and PHBV film with scanning size of 40 µm × 40 µm and 80 µm × 80 µm, respectively. PHBV neat (a); PHBV/Vitamin E (b); PHBV/BC1% (c); PHBV/BC2% (d).

Figure 2

Mass loss of PHBV/BC biocomposites immersed in PBS as a function of exposure time (after 30 days in vitro hydrolytic degradation).

Figure 3

DSC curves for biocomposites based on PHBV, BC and vitamin E, first heating (a) initial; (b) after immersion for 30 days in PBS at 37 °C (exo up).

Figure 4

ATR-FTIR normalized spectra for biocomposites based on PHBV, BC and vitamin E. (a) initial; (b) after 30 days immersion in PBS; (c) carbonyl stretching region (–C=O) for initial samples; (d) carbonyl stretching region (–C=O) for degraded samples in PBS.

Figure 5

Viability of mouse NCTC fibroblasts cultivated in the presence of PHBV and BC biocomposites for 24 and 48 h, evaluated by the MTT assay. Samples were reported to the negative control (untreated cells) considered to have a 100% viability. Data were expressed as mean values ± SD (n = 3).

Figure 6

Cell morphology after 48 h treatment with different biocomposites: neat PHBV (a); PHBV/Vitamin E (b); PHBV/BC1% (c); PHBV/BC2% (d). Negative control was represented by untreated cells (e) and positive control by cells cultivated in MEM containing 0.003% H₂O₂ (f). Scale bar = 50 μm (hematoxylin-eosin staining).

Figure 7

Cell cycle histograms of mouse NCTC fibroblasts treated with different PHBV/BC-based biocomposites for 24 h. Control (a); PHBV/Vitamin E (b); PHBV/BC1% (c); PHBV/BC2% (d).