Alginate/porous silica matrices for the encapsulation of living organisms: tunable properties for biosensors, modular bioreactors, and bioremediation devices

Abstract

Abstract:The encapsulation of living cells within inorganic silica hydrogels is a promising strategy for the design of biosensors, modular bioreactors, and bioremediation devices, among other interesting applications, attracting scientific and technological interest. These hostguest multifunctional materials (HGFM) combine synergistically specific biologic functions of their guest with those of the host matrix enhancing their performance. Although inorganic immobilization hosts present several advantages over their (bio)polymer-based counterparts in terms of chemical and physical stability, the direct contact of cells with silica precursors during synthesis and the constraints imposed by the inorganic host during operating conditions have proved to influence their biological response. Recently, we proposed an alternative two-step procedure including a pre-encapsulation in biocompatible polymers such as alginates in order to confer protection to the biological guest during the inorganic and more cytotoxic synthesis. By means of this procedure, whole cultures of microorganisms remain confined in small liquid volumes generated inside the inorganic host, providing near conventional liquid culture conditions.Moreover, the fact of protecting the biological guest during the synthesis of the host, allows extending the synthesis parameters beyond biocompatible conditions, tuning the microstructure of the matrix. In turn, the microstructure (porosity at the nanoscale, radius of gyration of particles composing the structure, and fractal dimension of particle clusters) is determinant of macroscopic parameters, such as optical quality and transport properties that govern the encapsulation material’s performance. Here, we review the most interesting applications of the two-step procedure, making special emphasis on the optimization of optical, transport and mechanical properties of the host as well as in the interaction with the guest during operation conditions.

Metal–Organic Frameworks for Cell and Virus Biology: A Perspective

“…We have previously shown that protein films can seed MOF growth. 31 Similarly, protein-coated cells can be used to trigger biomimetic mineralization (Figure 3e-f). By means of stable electrostatic interactions, or covalent bonding, enzymes can be deposited on the outer surface of the cell and then exposed to MOF precursors.…”

“…29 This field is now attracting trans-disciplinary research groups who are working in areas such as the design of biosensors, bioreactors, and biomedical devices. 24, [30][31][32] Metal-organic Frameworks (MOFs) 33 represent a class of materials that are now being investigated as coatings for cells and other complex bio-entities such as viruses. MOFs are constructed via a molecular building block approach, from organic links and inorganic nodes (metal ions or clusters), that offers a high level of control over their chemical composition and functionality, structure topology, pore size and shape as well as crystal morphology.…”

Nanoarchitectonics of Biofunctionalized Metal–Organic Frameworks with Biological Macromolecules and Living Cells

“…Apart from this, generally protein size will also play a significant role in the formation of functional protein materials. In this regard, biomimetic postreplication may play a vital role in promoting the growth of MOF on protein. Nevertheless, future development in this area will require better understanding of the nature of interactions between proteins and MOFs.…”

Angiogenesis-promoted bone repair with silicate-shelled hydrogel fiber scaffolds

“…Thus, the scaffold was designed to be a core-shell structure that has the merits of both shape-formability of alginate hydrogel and proangiogenic and bone-bioactive capacity of silicate [35][36][37][38] . Even though alginatesilica matrices have been investigated with their easy methodology for improved/tunable mechanical or biological properties for a variety of applications, including cell-free or cell-laden regeneratives for (bone) tissue repair, organ on a chip, and biosensing [26][27][28][29] , the detail investigation of indirect effect from alginatesilica core-shell composite was not performed yet, especially with the focus on the released ions (calcium and silicate) and their therapeutic efficacy 30,31 .…”

“…Surface silicate coating, --which is a simple yet versatile method to introduce silicate ions into biomaterials, was applied on alginate hydrogel as a model biomaterial. Previously, alginatesilica matrices, fabricated by currently addressed two-step silicate coating on alginate or direct incorporation of bioactive silica-based-nanoparticles, have been investigated with their easy methdology for improved/tunable mechanical and biological properties for a variety of applications, including cell-free or cell-laden regeneratives for (bone) tissue repair, organ on a chip, and biosensing [26][27][28][29] .…”