Highly efficient, long life, reusable and robust photosynthetic hybrid core-shell beads for the sustainable production of high value compounds

An efficient one-step process to synthesize highly porous (Ca-alginate–SiO2–polycation) shell: (Na-alginate–
SiO2) core hybrid beads for cell encapsulation, yielding a reusable long-life photosynthetically
active material for a sustainable manufacture of high-value metabolites is presented. Bead formation is
based on crosslinking of an alginate biopolymer and mineralisation of silicic acid in combination with
a coacervation process between a polycation and the silica sol, forming a semi-permeable external membrane.
The excellent mechanical strength and durability of the monodispersed beads and the control of
their porosity and textural properties is achieved by tailoring the silica and alginate loading, polycation
concentration and incubation time during coacervation. This process has led to the formation of a
remarkably robust hybrid material that confers exceptional protection to live cells against sheer stresses
and contamination in a diverse range of applications. Dunaliella tertiolecta encapsulated within this
hybrid core–shell system display high photosynthetic activity over a long duration (>1 year). This sustainable
biotechnology could find use in high value chemical harvests and biofuel cells to photosynthetic
solar cells (energy transformation, electricity production, water splitting technologies). Furthermore the
material can be engineered into various forms from spheres to variable thickness films, broadening its
potential applications.
2015 Elsevier Inc. All rights reserved.