Nanoparticle growth via concentration gradients generated by enzyme nanopatterns
De La Rica R., Bat E., Herpoldt KL., Xie HN., Bertazzo S., Maynard HD., Stevens MM.
Biomineralizing organisms can grow nanomaterials with unexpected morphologies in an organic matrix where temporal and vectorial gradients of crystal growth precursors are established. Here, concentration gradients for the crystallization of gold nanoparticles are generated and applied on silicon substrates. Gradients of crystal growth precursors are generated by enzymes patterned as lines that are separated by distances ranging from the micro- to the nanoscale. The concentration of crystallization precursors around the lines separated by nanometric distances is not only determined by mass transport and enzyme activity but also by the nanoscale organization of biocatalysts. This nanoscale organization favors non-classical crystal growth conditions that lead to the formation of nanoparticle clusters containing nanocrystals that are highly crystallographically aligned. The combination of bottom-up crystal growth with top-down electron beam lithography enables the fabrication of micrometric patterns containing gold nanoparticles of different size, shape, and surface density. These are all critical parameters that determine the physical properties of these nanomaterials. Concentrations gradients generated by enzyme patterns guide the growth of gold nanostructures with programmable size, shape, and state of aggregation. When the patterns are separated by nanometric distances, clusters of highly crystallographically aligned gold nanoscrystals are obtained, which suggests that the nanoparticles grow via biomimetic non-classical crystal growth conditions. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.