The polyvinyl alcohol–bacterial cellulose system as a new nanocomposite for biomedical applications

Abstract

Finding materials suitable for soft tissue replacement is an important aspect for medical devices design and fabrication. There is a need to develop a material that will not only display similar mechanical properties as the tissue it is replacing, but also shows improved life span, biocompatibility, nonthrombogenic, and low degree of calcification. Polyvinyl alcohol (PVA) is a hydrophilic biocompatible polymer with various characteristics desired for biomedical applications. PVA can be transformed into a solid hydrogel with good mechanical properties by physical crosslinking, using freeze-thaw cycles. Hydrophilic bacterial cellulose (BC) fibers of an average diameter of 50 nm are produced by the bacterium Acetobacter xylinum, using a fermentation process. They are used in combination with PVA to form biocompatible nanocomposites. The resulting nanocomposites possess a broad range of mechanical properties and can be made with mechanical properties similar to that of cardiovascular tissues, such as aorta and heart valve leaflets. The stress-strain properties for porcine aorta are matched by at least one type of PVA-BC nanocomposite in both the circumferential and the axial tissue directions. A PVA-BC nanocomposite with similar properties as heart valve tissue is also developed. Relaxation properties of all samples, which are important for cardiovascular applications, were also studied and found to relax at a faster rate and to a lower residual stress than the tissues they might replace. The new PVA-BC composite is a promising material for cardiovascular soft tissue replacement applications.

SANS Characterization of an Anisotropic Poly(vinyl alcohol) Hydrogel with Vascular Applications

“…15,17,18 SANS Data Analysis. 2-D patterns of absolute scattering intensity were obtained for each sample and each q range.…”

“…The load vs extension data were converted to engineering stressengineering strain, using the sample thickness and the initial gauge length after preconditioning, as reported previously. 17,18 Neutron Scattering Experiments. PVA-D 2 O samples for neutron scattering were loaded into standard NIST demountable cells with quartz windows.…”

“…15, 16 Wan et al 15 reported PVA samples that matched the circumferential direction in porcine aortic root up to 35% strain. Millon et al 17 reported a PVA-bacterial cellulose nanocomposite that was able to closely match the mechanical properties of porcine aorta in either circumferential or axial directions up to 70% strain as well as a nanocomposite with high composition of both components which fell within the range displayed by heart valve tissues. These PVA gels and PVA-based nanocomposites displayed isotropic behavior.…”

Through-thickness stress relaxation in bacterial cellulose hydrogel

“…and a use as a scaffold material for both BC-based bio-composites (e.g. BC/fibrin composite for artificial blood vessel [10], BC/polyvinyl alcohol composite for artificial heart-valve leaflets [11], etc.) and in-vitro tissue regeneration (e.g.…”

Properties of Polymer Composites with Cellulose Microfibrils

“…PVA has no toxic action on the human body being used to manufacture medicines cachets, yarn for surgery, controlled drug delivery systems (Tang et al, 2009). New fields of application regard cardiovascular devices (Millon and Wan, 2006), dialysis membrane, artificial cartilage, tissue engineering scaffold (Zhou et al, 2010). Development of ecofriendly packaging materials is still a challenging area and many studies are focused on the improvement of PVA mechanical and barrier properties by combination with other polymers or fillers in order to use it in the packaging industry (Sedlarik et al, 2006).…”