Bacterial nanocellulose: A natural biopolymer for controlled drug delivery

Bacterial nanocellulose (BNC) is an innovative biofabricated material, generated in a biotechnological process by Komagataeibacter bacteria strains from glucose and consisting of about 1% cellulose and 99% water. Although the chemical formula is identical to plant cellulose, the material favours totally different, but outstanding material characteristics due to the three-dimensional network of nano-sized fibres. The interest in BNC as drug delivery system dramatically increased during the last years, as BNC is expected to hold a large amount of active ingredients due to the nano-sized 3D network resulting in an enormous surface area-to-volume ratio. However, the highly hydrophilic character limited a broad application, especially for the delivery of lipophilic drugs as well as for long-term applications. We developed different loading techniques to accomplish a controlled immediate and sustained drug release from several hours to weeks using BNC produced under lab-scale as well as under high throughput conditions. Native BNC, hybrid systems with thermo-responsive block-copolymers Poloxamers, as well as lipid-modified BNC were established. Depending on the type of modification, not only the drug release profile, but also superior material properties such as high compression stability and water binding could be achieved. Using the antiseptic octenidine as model drug for wound dressings, the antimicrobial activity against Staphylococcus aureus and Pseudomonas aeruginosa was not changed by the use of the modified BNC. The release of natural lipophilic active ingredients like coenzyme Q10, curcumin or frankincense could be controlled for dermal BNC applications. Excellent biocompatibility of the loaded BNC could be demonstrated in vitro in keratinocytes as well as ex ovo in a shell-less hen’s egg model.
In conclusion, BNC can be tailored as immediate and sustained drug release system for ready-to-use and patient-designed bedside applications e.g. for dermal wound treatment, cosmetics or the use as implant.