Hybrid nanoparticles have great potential for biotechnological and biomedical applications. It was recently proposed that biopolymer/silica nanomaterials could be easily obtained by adapting traditional routes used in pharmaceutical science to design polymer nanoparticles. In this paper, we demonstrate that core–shell gelatine/silica nanoparticles can be obtained using a nano-emulsion route, taking advantage of the thermal gelation properties of the biopolymer and of its strong “biomimetic” affinity for silicates. The formation of the silica coating could be ascertained by SEM, TEM, EDAX, FTIR and DLS/zeta potential measurements. Silica coating was also performed on microparticles, allowing us to investigate in more detail the mechanism of silica deposition on the gelatine surface, which bears some relevance for the understanding of biosilicification processes. Finally, the possible internalization and intracellular degradation of these hybrid nanoparticles by fibroblast cells was demonstrated. A comparison with previously described silica/alginate nanoparticles is provided in the context of drug-delivery system design.

The sol-gel process is an inorganic polymerization process taking place in mild conditions, allowing the association of mineral phases with organic or biological systems. The possibility to immobilize drugs, enzymes, antibodies and even whole cells without loss of their biological activity led to the development of diagnostic tools, drug delivery carriers as well as new hosts for artificial organ design. These systems take profit from the wide variety of chemical compositions, dimensions and forms that can be achieved via sol-gel chemistry. Recent advances involve multifunctional "smart" devices combining biocompatibility, biological activity and stimuli-responsive materials. The design of such novel devices with significant added value when compared to current products is probably a key factor when foreseeing industrial developments of sol-gel materials in medicinal science.

Bioencapsulation in silica gels has become a very popular field of research, leading to the design of biosensors and bioreactors. If pure silica gels appear suitable to maintain the biological activity of entrapped enzymes, there are many cases where hybrid materials are necessary to reach the long-term preservation of biomolecular or cellular species and/or to provide new functionalities. This review focuses on the design of such nanocomposite materials combining silica with biopolymers. In the first part, the synthesis and characterization of these bio-hybrid materials are described, emphasizing the importance of the polymer influence on the reactivity of silica precursors. In the second part, the benefits of biopolymer incorporation in silica gels are illustrated in the context of biotechnological devices. As a conclusion, a parallel is drawn between biohybrids and biominerals, opening new perspectives for the design of multi-component biologically-active materials.

Several methods have already been developed for the design of (bio)polymer micro- and nanoparticles used in pharmaceutical science. In this paper, we demonstrate that some of these approaches can be easily adapted for the design of hybrid nanocapsules. A microgel route can be used for the synthesis of poly-L-lysine/alginate microparticles, that are further coated with silica, leading to micron sized core shell composites. Alternatively, a spray-drying technique is used for the one-pot synthesis of silica/poly-L-lysine/alginate nanocomposites that exhibit a homogeneous structure. As a consequence, the in situ reduction of Co²⁺ ions leads to the intra-capsular formation of magnetic cobalt silicates. When added to fibroblast cells, nanoparticles enter the intracellular space where they are degraded, suggesting that these new nanocomposites should be suitable for targeted drug delivery applications.