Metallo-oxide (MO)-based bioinorganic nanocomposites promise unique structures, physicochemical properties, and novel biochemical functionalities, and within the past decade, investment in research on materials such as ZnO, TiO 2 , SiO 2 , and GeO 2 has significantly increased. Besides traditional approaches, the synthesis, shaping, structural patterning, and postprocessing chemical functionalization of the materials surface is inspired by strategies which mimic processes in nature. Would such materials deliver new technologies? Answering this question requires the merging of historical knowledge and current research from different fields of science. Practically, we need an effective defragmentation of the research area. From our perspective, the superficial accounting of material properties, chemistry of the surfaces, and the behavior of biomolecules next to such surfaces is a problem. This is particularly of concern when we wish to bridge between technologies in vitro and biotechnologies in vivo. Further, besides the potential practical technological efficiency and advantages such materials might exhibit, we have to consider the wider long-term implications of material stability and toxicity. In this contribution, we present a critical review of recent advances in the chemistry and engineering of MO-based biocomposites, highlighting the role of interactions at the interface and the techniques by which these can be studied. At the end of the article, we outline the challenges which hamper progress in research and extrapolate to developing and promising directions including additive manufacturing and synthetic biology that could benefit from molecular level understanding of interactions occurring between inanimate (abiotic) and living (biotic) materials.

The controlled synthesis of ZnO at the micro- and nanoscale has been the focus of significant research due to its importance in electrical and optoelectronic applications, and the potential of tuning its properties at the crystal formation stage. We present a detailed study of ZnO growth processes which supports and consolidates previous findings and gives a clearer understanding of the mechanism of ZnO formation. The influence of synthesis conditions on ZnO formation was investigated by comparison of two different growth routes (Zn­(CH3COO)2–NH3 and Zn­(NO3)2·6H2O−HMTA) both known to result in the formation of wurtzite structured, twinned hexagonal rods of ZnO. The identities of the solid phases formed and supernatants were confirmed by data from SEM, XRD, FTIR, XPS, TGA, and ICP-OES analysis; giving insight into the involvement of multistep pathways. In both cases, reaction takes place via intermediates known as layered basic zinc salts (LBZs) which only later transform to the oxide phase. In the ZnAc2–NH3 system, crystal growth evolves as Zn­(CH3COO)2 → LBZA (A: acetate) → ZnO through a dissolution/reprecipitation process, with the formation of an additional product identified as LBZAC (C: carbonate). In contrast, in the Zn­(NO3)2·6H2O−HMTA system, solid-phase transformation occurs as Zn­(NO3)2·6H2O → LBZN (N: nitrate) → ZnO with no evidence of dissolution. Similar comprehensive studies can be applied to other solid-state processes to further advance functional materials design.

ZnO-binding peptides, differing only by Met or Cys at position 5 modify the mechanism of ZnO crystal growth.

In this contribution, the effect of silica particle size (28 and 210 nm) and surface chemistry (i.e., hydroxyl, methyl, or amino groups) on peptide binding response is studied with a specific emphasis on the effect of the extent of functionalization on binding. Exhaustive characterization of the silica surfaces was crucial for knowledge of the chemistry and topography of the solid surface under study and, thus, to understand their impact on adsorption and the conformational ensemble of the peptides. The extent of surface functionalization was shown to be particle-size dependent, a higher level of 3-aminopropyl functionality being obtained for smaller particles, whereas a higher degree of methyl group functionality was found for the larger particles. We demonstrated that peptide interactions at the aqueous interface were not only influenced by the surface chemistry but also by the extent of functionalization where a "switch" of peptide adsorption behavior was observed, whereas the changes in the conformational ensemble revealed by circular dichroism were independent of the extent of functionalization. In addition to electrostatic interactions and hydrogen bonding driving interaction at the silica-peptide interface, the data obtained suggested that stronger interactions such as hydrophobic and/or covalent interactions may moderate the interaction. The insights gained from this peptide-mineral study give a more comprehensive view of mechanisms concerning mineral-peptide interactions which may allow for the design and synthesis of novel (nano)materials with properties tailored for specific applications.