In the Nanoreactors cluster, use of micro- and nanofluidic technologies will be explored to synthesize and analyze both individual catalytic nanoparticles as well as self-assembled supraparticle aggregates. A consortium of experts in the fields of nanoparticle synthesis and self-assembly, micro- and nanofluidics, nanosensing and spectroscopy will work together in five projects to develop new strategies for catalyst optimization. Micro- and nanofabrication and micro/nanofluidic technologies will enable realization of X-ray transparent nanoconfinements for in-situ spectroscopic nanoparticle analysis, while a microfluidic microdroplet platform will enable high-throughput creation of nanoliter environments with varying reaction conditions to study performance of individual catalyst particles. Using integrated nanosensing structures we will be able to select those catalyst particles with highest efficiency for further analysis. In addition, microfluidic structures will be designed and used to create locally well-defined conditions (shear forces, electrical and magnetic forces, temperature, chemical and/or pressure gradients) that determine supraparticle self-assembly parameters.