As part of the MEM-S (Bottom-up design and fabrication of industrial bio-inorganic nano-porous membranes with novel functionalities based on principles of protein self-assembly and biomineralization) project, scientists worked on combining these technologies to cost-effectively produce bio-inorganic functionalised membranes on an industrial scale. Major MEM-S scientific breakthroughs led to the development of the surface layer (S-layer) technology, methods for obtaining porous silica, and the use of biocatalysts and a sol-gel technique to immobilise important biomolecules. MEM-S exploited the inherent ability of S-layer proteins to self-assemble and obtained highly organised membrane structures of desired pore size. The enzyme silicatein was used to deposit inorganic silica material and strengthen this organic membrane as well as enclose important biomolecules. Optically transparent silica matrices and innovative titania thin films were produced using either the silicatein enzymes or the sol-gel techniques. Biomolecules-of-interest such as enzymes (for biocatalytic activity) and antibodies (for bio-sensing pathogens such as Legionella) were successfully immobilised on these surfaces. Important milestones were achieved during the course of the project, starting with the successful functionalisation of S-layer–coated surfaces. MEM-S then designed and developed prototype functionalised membranes as well as enzymatic- and bacterial antigen-based biosensors. Absorbance-based detection chips prepared during the project were used in multiple project tasks and the resulting platform was frequently used as a demonstration kit. Moreover, scientists demonstrated proof-of-concept for the removal of Legionella from drinking water systems with an integrated membrane–biosensor platform having functionalised silicon nitride micro-sieves. Use of micro ring resonator (MRR)-sensing platforms enhanced performance by a factor of 10-100. Several dissemination activities were carried out including about 30 publications in peer-reviewed international journals, leaflets, mass media communication, exhibitions, a summer school and workshops. MEM-S members were also winners of the national competition 'Germany – Land of Ideas', initiative '365 sites'. To protect intellectual property, 10 patents were filed and their marketing potential was assessed. Project partners exploited these technologies for commercial application in microfluidics-based sample processing and micro-array development. A few noteworthy applications are the lab-on-chip systems using TriPleX-based MRR biosensor chips for water purification and the use of industrial micro-/nano-sieves for the food industry. Future areas of application include environment monitoring, drug delivery, medical diagnostics, dental products, orthopaedic implants and recombinant silicatein technology.
Bio-functionalised, S-layer technology, porous silica, biocatalyst, sol-gel, silicatein, titania, biosensor, micro-sieve, micro ring resonator