Although amelogenin comprises the vast majority of the matrix that templates calcium phosphate nucleation during enamel formation, other proteins, particularly enamelin, are also known to play an important role in the formation of enamel's intricate architecture. However, there is little understanding of the interplay between amelogenin and enamelin in controlling processes of mineral nucleation and growth. Here, we used an in vitro model to investigate the impact of enamelin interaction with amelogenin on calcium phosphate nucleation for a range of enamelin-toamelogenin ratios. We found that amelogenin alone is a weak promoter of nucleation, but addition of enamelin enhanced nucleation rates in a highly nonlinear, nonmonotonic manner reaching a sharp maximum at a ratio of 1:50 enamelin/amelogenin. We provide a phenomenological model to explain this effect that assumes only isolated enamelin proteins can act as sites of enhanced nucleation, while enamelin oligomers cannot. Even when interaction is random, the model reproduces the observed behavior, suggesting a simple means to tightly control the timing and extent of nucleation and phase transformation by amelogenin and enamelin.

Colloidal assembly of silica (nano)particles is a powerful method to design functional materials across multiple length scales. Although this method has enabled the fabrication of a wide range of silica‐based materials, attempts to design and synthesize porous materials with a high level of tuneability and control over pore dimensions have remained relatively unsuccessful. Here, the colloidal assembly of silica nanoparticles into mesoporous silica microspheres (MSMs) is reported using a discrete set of silica sols within the confinement of a water‐in‐oil emulsion system. By studying the independent manipulation of different assembly parameters during the sol–gel process, a design strategy is outlined to synthesize MSMs with excellent reproducibility and independent control over pore size and overall porosity, which does not require additional ageing or post‐treatment steps to reach pore sizes as large as 50 nm. The strategy presented here can provide the necessary tools for the microstructural design of the next generation of tailor‐made silica microspheres for use in separation applications and beyond.

Controlling nucleation and growth is crucial in biological and artificial mineralization and self-assembly processes. The nucleation barrier is determined by the chemistry of the interfaces at which crystallization occurs and local supersaturation. Although chemically tailored substrates and lattice mismatches are routinely used to modify energy landscape at the substrate/nucleus interface and thereby steer heterogeneous nucleation, strategies to combine this with control over local supersaturations have remained virtually unexplored. Here we demonstrate simultaneous control over both parameters to direct the positioning and growth direction of mineralizing compounds on preselected polymorphic substrates. We exploit the polymorphic nature of calcium carbonate (CaCO) to locally manipulate the carbonate concentration and lattice mismatch between the nucleus and substrate, such that barium carbonate (BaCO) and strontium carbonate (SrCO) nucleate only on specific CaCO polymorphs. Based on this approach we position different materials and shapes on predetermined CaCO polymorphs in sequential steps, and guide the growth direction using locally created supersaturations. These results shed light on nature's remarkable mineralization capabilities and outline fabrication strategies for advanced materials, such as ceramics, photonic structures, and semiconductors.