Biocers, Industrial Applications

Abstract

After 20 years of research, the inorganic sol–gel process can now be considered as a suitable technological alternative for the encapsulation of living cells. Strategies have been developed and optimized that allow the formation of glasses and ceramics in conditions compatible with the preservation of cell membrane integrity and metabolic activity over several weeks. These biocer(amic)s can be prepared as gels, coatings, films, and capsules, which can host a wide variety of organisms including bacteria, protists, yeasts, and plant and animal cells. It was demonstrated that biocers can be used for the design of bioreactors, biosensors, as well as for bioremediation systems, at least at the laboratory scale. Moreover, hybrid materials associating biopolymers and silica were shown to be suitable for the elaboration of bioartificial organs that have been patented and are currently under clinical evaluation. The biocer technology has now reached its maturity, suggesting that industrial developments can now be foreseen in the near future.

Microorganism mediated biosynthesis of metal chalcogenides; a powerful tool to transform toxic effluents into functional nanomaterials

“…To be useful for the encapsulation of MC biosynthetic microorganisms, the encapsulating matrix need to fulfill some conditions: (i) biocompatible synthesis to ensure the survival of a significant fraction of microorganisms; (ii)the porosity of the network has to be tuned to allow the diffusion of nutrients and pollutants, but avoiding the escape of the produced nanoparticles; (iii)the matrix has to maintain its properties through changes in the operation conditions such as temperature, pH or humidity; (iv) the microorganisms have to remain biologically active. Known encapsulation matrices range from biopolymers (Muralidhar et al, 2001;Murua et al, 2008) to ceramics (Böttcher et al, 2004;Coradin and Livage, 2007;Coradin et al, 2009). Biopolymers such as alginate, quitosan and pectines are useful only for short-term operation for being biodegradable and macroporous.…”

Living materials from sol–gel chemistry: current challenges and perspectives

“…13 In parallel, efforts were made to extend the variety of living organisms that could be entrapped in solgel based materials, including almost all types of cells from prokaryotes (bacteria, cyanobacteria but not archaebacteria) to eukaryotes (protists, fungi, vegetal and animal cells). 14 In parallel, the range of targeted applications is now covering major fields of materials science at its interface with living systems, from energy production to medicine. 15…”

“…Whereas yeasts and bacteria have long been successfully encapsulated in silica gels, significant efforts have been made over the recent years to enlarge the diversity of living organisms that could survive within sol-gel based materials. 14 One particular type of cells that was extensively studied are photosynthetic organisms, due to their potential applications for hydrogen production, 31 CO 2 sequestration, 32 production of specific metabolites 33 and biosensor design. 34 A great deal of work has been achieved to adapt the sol-gel protocols to the specificities of these organisms.…”