Experimental approach to the chemical and physical impact on in vitro polycationic peptide-mediated silica biomineralization

The world now stands at the brink of a technological revolution, where micro- and nano-engineering will ultimately change the very nature of most human-made structures leading to unprecedented breakthroughs in a wide range of applications. The design and fabrication of micro- and nano-devices faces many challenges due to the small-scale nature of the devices to be engineered. Numerous examples of nanopattering and nanostructures are commonly found in nature, i.e. diatoms. Therefore, biology can provide valuable insight into the development of micro- and nano-devices.; The present research demonstrates that in vitro polycationic peptide-mediated silica biomineralization morphologies can be influenced chemically and physically to create complex 2-D and 3-D silica networks. These structures are shown to differ from the typical sphere-like disperse silica particulate normally obtained in vitro.; Silica particles characteristic size were observed to decrease over 10 fold—from 500 nm to less than 50 nm, when—OH group molar concentrations in alcohol and carbohydrates additives were increased. Furthermore, overall morphologies are observed to shift from a characteristic dispersed sphere-like silica morphology to a sheet-like structure in the presence—OH groups, and to sharp edged plate-like structures in the presence of larger polycationic peptide organic matrices.; Hydrodynamic fields are shown to have the most dramatic impact on overall silica morphology. Orchestrating a biomineralization reaction in a capillary tube in which a slug volume was present, yielded a two-way slug flow which produced fiber-like structures ranging from 1.6 μm to 10 μm in diameter, and from 100 μm to 1400 μm in length. Likewise, when the biomineralization reaction is perturbed by shear flows in the vicinity of a spinning electrode, platelike and dendrite-like structures are observed to form. In this case, dendrite-like main branches measuring in length ca. 3.5 μm, with secondary branches averaging 900 nm and 300 nm in length and diameter respectively. Localized high shear stresses and surface tension gradients are suggested as being key in the formation of the fiber-like, plate-like, and dendrite-like silica network structures.; The present research has demonstrated that in vitro polycationic peptide-mediated silica biomineralization can indeed be profoundly influenced chemically and physically. These findings could lead to the future development of biomimetic inspired complex 2-D and 3-D silica micro- and nano-devices.