Algae–silica systems as functional hybrid materials

Hybrid and biohybrid silicate based materials: molecular vs. block-assembling bottom–up processes

“…The biohybrids may be easily processed as thin coatings on electrode surfaces and applied in the electroanalytical determination of heavy metal ions in aqueous solution. 317,318 The algae could be also removed from the polysiloxane network leaving only a trace of the algal cells (Fig. 16C-E), resulting in imprinted materials prepared by a soft lithographic approach that could be potentially used as artificial receptors for electrochemical sensing of algae target species.…”

“…16C-E), resulting in imprinted materials prepared by a soft lithographic approach that could be potentially used as artificial receptors for electrochemical sensing of algae target species. 318 Aqueous silicates may be more suitable silica precursors for encapsulation of living biological entities due to their biocompatibility and the low ecological impact of silicate chemistry, but they show several disadvantages such as the lack of diversity, flexibility, and processability. 332 Thus, silicon alkoxides are preferred for processing the biohybrids as thin films, for instance in biosensing applications, while the aqueous silicates and colloidal silica lead to bulk gel materials with potential application as bioreactors, for instance photobioreactors based on the immobilization of photosynthetic cyanobacterial strains.…”

“…Non-living biomass associated to silica or silicates is employed as biosorbent for removal of pollutants 315,316 or for electroanalytical purposes. 317,318 However, many other applications require biohybrids with encapsulated living cells and microorganisms, for use as bioreactors profiting from their metabolic activity for production of beneficial compounds, [319][320][321] as well as in other interesting applications within the biomedical field. [322][323][324] Selected examples of the possible applications of these materials are summarized in Table 7.…”

“…332 Thus, silicon alkoxides are preferred for processing the biohybrids as thin films, for instance in biosensing applications, while the aqueous silicates and colloidal silica lead to bulk gel materials with potential application as bioreactors, for instance photobioreactors based on the immobilization of photosynthetic cyanobacterial strains. 333 Porous materials processed by freeze-cast techniques from silica nanosols, resulting in the so-called biocers, 334 or by freeze-drying of silicate-based nanocomposites 335 may be a novel alternative to sol-gel technologies for entrapment of microorganisms such as yeasts, bacteria and algal cells. These open structures facilitate the accessibility of nutrients, and in the case of macroporous nanocomposites, the growth and proliferation of cells inside the pores was confirmed, 335 which has not been reported in the case of cells encapsulated in silica-based matrices.…”

“…333 Porous materials processed by freeze-cast techniques from silica nanosols, resulting in the so-called biocers, 334 or by freeze-drying of silicate-based nanocomposites 335 may be a novel alternative to sol-gel technologies for entrapment of microorganisms such as yeasts, bacteria and algal cells. These open structures facilitate the accessibility of nutrients, and in the case of macroporous nanocomposites, the growth and proliferation of cells inside the pores was confirmed, 335 which has not been reported in the case of cells encapsulated in silica-based matrices.…”