Peak oil and peak soil, peak water and peak grain – our present marks a crucial transition, from an oil-based economy to a bio-based economy, from exploiting fossil resources to using renewable resources. This transition will need to be knowledge-driven so that it is executed and perceived as a step forward into a future with improved prospects of human and environmental well-being, securing both health and wealth, rather than as a step backwards into a pre-industrial past.
Scientific research, which generates knowledge, will have to play the leading role in this process. Consequently, Nano3Bio aims to strengthen the knowledge-base through the development of advanced technologies for efficient biomass production tailored towards applications in industrial processes. In many areas such as material sciences or renewable energies, this transition to a knowledge-based bio-economy will heavily rely on the large and diverse group of bio-polymers.
The potential of functional bio-polymers is evident, as they combine characteristics that are promising for many application fields. However, these promises are largely unfulfilled today, and the potential of functional bio-polymers so far has been grossly under-exploited:
- Superior material properties
- Excellent bio-compatibility
- Highly versatile biological activities
By developing biotechnological ways of producing well defined polysaccharides and nanotechnological tools for their formulation and functionalization, yielding products with known physico-chemical properties and reliable biological activities, Nano3Bio aims to offer a fresh approach towards realising the ecological and economical potential of functional bio-polymers, opening new opportunities for the knowledge-based development of high added-value products.
By far the most promising and most advanced functional bio-polymer is the polysaccharide chitosan. The term chitosan really refers to a family of polysaccharides derived from one of the most abundant renewable resources on earth, chitin. Chitin is found in the exoskeletons of insects and crustaceans such as shrimp and crab, in the endoskeletons of mollusks such as squid, in many invertebrates as in egg shells of nematodes, as well as in the cell walls of fungi and some diatom algae.
While chitin is a linear polysaccharide built from just one monomeric sugar unit, namely acetylated glucosamin, chitosans are linear co-polymers of acetylated and non-acetylated residues. This partial deacetylation yields free amino groups which at slightly acidic pH values convey positive charges to chitosan, making it the only polycationic polysaccharide. As such, chitosans can easily interact with polyanionic biomolecules such as most proteins and nucleic acids, but also polyanionic phospholipidic membranes and sulphated polysaccharides such as e.g. human glycosaminoglycans at cell surfaces. Such purely electrostatic interactions are partly responsible for the many biological activities reported for chitosans.
Among these biological activities are:
- Amply demonstrated antimicrobial activities
- Plant growth promoting and disease resistance inducing activities
- Mucoadhesive and immunostimulatory activities
- Anti-proliferative and wound healing promotion activities
- The ability to complex and subsequently deliver genetic material in vivo
- Opening of cellular tight junctions in a reversible manner
The crux with all of these, however, so far has been their poor reproducibility. The development of marketable chitosan-based products has lagged far behind expectations due to repeated failures to achieve reliable and predictable biological functionalities. This failure to achieve reproducible bioactivities was at least partly due to the rather poor characterisation and the resulting batch-to-batch differences in commercially available chitosans.
Based on extensive experience the Nano3Bio partners are addressing the objective of developing biotechnological biosynthesis strategies for partially acetylated chitosan polymers with narrowly defined quality.