Bacterial cellulose in biomedical applications: A review.

Bacterial cellulose (BC) derived materials represents major advances to the current regenerative and diagnostic medicine. BC is a highly pure, biocompatible and versatile material that can be utilized in several applications - individually or in the combination with different components (e.g. biopolymers and nanoparticles) - to provide structural organization and flexible matrixes to distinct finalities. The wide application and importance of BC is described by its common utilization as skin repair treatments in cases of burns, wounds and ulcers. BC membranes accelerate the process of epithelialization and avoid infections. Furthermore, BC biocomposites exhibit the potential to regulate cell adhesion, an important characteristic to scaffolds and grafts; ultra-thin films of BC might be also utilized in the development of diagnostic sensors for its capability in immobilizing several antigens. Therefore, the growing interest in BC derived materials establishes it as a great promise to enhance the quality and functionalities of the current generation of biomedical materials.

Lysozyme-triggered epidermal growth factor release from bacterial cellulose membranes controlled by smart nanostructured films.

A novel wound-dressing biodevice, sensitive to lysozyme, an enzyme commonly found at infected skin wounds, was assembled by the layer-by-layer deposition of nanopolymeric chitosan and alginate films onto oxidized bacterial cellulose membranes incorporated with epidermal growth factor (EGF). Distinct EGF release profiles were obtained according to specific stimuli caused by infection. In in vitro conditions simulating noninfected wounds, the EGF rate and burst release effect were reduced by three deposited layers (Mt /M∞ of 0.25 at 3 h) in a process dependent on the porosity of the compact chitosan-alginate complex. The importance of the organized structure was revealed when an infected wound was simulated by adding lysozyme to the release medium, thus inducing the formation of a loosely polyelectrolyte architecture that caused rapid EGF diffusion (Mt /M∞ of 0.75 at 30 min). The results indicate that the nanopolymeric layers were capable of slowly releasing EGF as required for normal wound repair and rapidly undergoing architectural transitions that allow the diffusion of massive amounts of drug to enhance the process of re-epithelialization. In summary, the proposed system comprises the roles of both wound dressing and local delivery mechanism to recognize infections and respond with a burst of EGF release.

Bioactive nanocomposites of bacterial cellulose and natural hydrocolloids.

The aim of this work was to develop bioactive films from bacterial cellulose and hydrocolloids (guar gum and hyaluronic acid), coated or not with collagen. After mechanical treatment, a suspension of cellulose nanofibres was obtained which, combined with the dispersions of hydrocolloids, was used to produce bionanocomposite films by wet casting. The materials were stable in physiological solution and presented better swelling capacity than that of the bacterial cellulose. The films were coated with collagen by dipping. Cell adhesion tests and surface analysis by tensiometry, X-ray photoelectron spectroscopy and atomic force microscopy showed that the surface properties of the films can be adjusted by changing the proportions of the components. The collagen coating presented a self-assembling pattern resembling that of living tissues. The materials developed in this work showed potential for applications in the medical field as bioactive wound dressings, scaffolds for cellular growth and sustained drug release systems. The films were obtained by simple production and purification methods, including the use of low toxicity solvents. Thus, in addition to potential cost saving, the development of these bionanocomposites is in accordance with green chemistry principles.