Novel bioactive membranes in devices

Combining the natural talent of bacteria to create porous membranes and of sponges to produce metal oxide nanostructures, EU-funded scientists are devising novel sensors, water purification devices and more.

Membranes have long played an important role in chemical processes for separation, distillation and purification. With advances in nanotechnology, their use has been extended to sensors and catalytic surfaces for chemical synthesis, diagnostics and drug discovery.

Scientists recently discovered two new groups of proteins in bacteria and sponges with the unique property - self-assembly of functionalised nanoporous membranes. The EU-funded project MEM-S was initiated to exploit these proteins in industrial membranes.

Surface layer (S-layer) proteins in the cell envelope of certain bacteria form lattice-type structures through a process of self-assembly. Silacateins, a group of enzymes forming the inorganic skeleton of siliceous sponges, catalyse the condensation of silica (silicon dioxide (SiO2)), forming silica nanospheres. The silicateins can also catalyse condensation of a variety of metal oxides on various surfaces under mild conditions.

MEM-S scientists are using biocatalytic formation of silica nanospheres to reinforce self-assembled S-layer structures and encapsulate biologically active molecules (e.g. antibodies and enzymes) in a silica shell. Together, this will enable environmentally friendly bottom-up manufacture of novel functionalised membranes.

To date, scientists have isolated, expressed and purified S-layer proteins, S-layer fusion proteins (important in self-assembly) and silicateins. Investigation of silicatein has led to new understanding of biosilica formation and the discovery of two facilitators of silicatein activity. Using this knowledge, scientists produced functionalised membranes through self-assembly of S-layer proteins and biocatalytic formation of silica to reinforce the S-layer.

Methods were developed to encapsulate enzymes or antibodies. This enabled the production of enzymatic biosensors, silica-based microchips for optical detection, and preliminary work on water purification membranes that adsorb bacteria that cause pneumonia. Up-scaling of production processes and optimisation of yield are underway.

MEM-S is well on its way to developing nano-functionalised porous membranes based on biological systems and produced under mild environmentally friendly conditions for various applications. Potential market volume is quite promising, environmental impact is low, and benefits for industry and society are enormous.

Related link:
http://cordis.europa.eu