Biocompatibility of bacterial cellulose based biomaterials

Abstract

Some bacteria can synthesize cellulose when they are cultivated under adequate conditions. These bacteria produce a mat of cellulose on the top of the culture medium, which is formed by a three-dimensional coherent network of pure cellulose nanofibers. Bacterial cellulose (BC) has been widely used in different fields, such as the paper industry, electronics and tissue engineering due to its remarkable mechanical properties, conformability and porosity. Nanocomposites based on BC have received much attention, because of the possibility of combining the good properties of BC with other materials for specific applications. BC nanocomposites can be processed either in a static or an agitated medium. The fabrication of BC nanocomposites in static media can be carried out while keeping the original mat structure obtained after the synthesis to form the final nanocomposite or by altering the culture media with other components. The present article reviews the issue of biocompatibility of BC and BC nanocomposites. Biomedical aspects, such as surface modification for improving cell adhesion, in vitro and in vivo studies are given along with details concerning the physics of network formation and the changes that occur in the cellulose networks due to the presence of a second phase. The relevance of biocompatibility studies for the development of BC-based materials in bone, skin and cardiovascular tissue engineering is also discussed.

Figure 1

SEM micrograph of a bacterial cellulose sample showing a coherent 3-D network formed by cellulose fibers connected by physical joints [22].

Figure 2

Scheme of the BC-starch Bottom-Up process: (a) Starch granules are in suspension in the culture medium; (b) After autoclaving, starch is partially gelatinized, amylose leaches and granules swell; (c) BC nanofibrils grow in presence of the partially gelatinized starch; (d) After hot-pressing, the nanocomposite shows interpenetrating networks of amylose and cellulose [23].

Figure 3

Optical micrographs of HEK cells for one day of culture in a composite of BC-Hidroxyapatite [12].