We develop and study new nanomaterials for catalysis, signaling, and active matter. We are interested both in understanding how nanomaterials function, and in developing new and better ones. We also seek new ways to fabricate nanostructures, and novel ways to perform reactions.
Our ultimate goal is to introduce autonomous capabilities to nanomaterials, and create nanobots – nanoscale machines that operate independently, to travel within the body and treat disease and injuries; assemble complex structures; carefully control chemical synthesis to produce non-thermodynamic product distribution; or break down contaminants. To achieve this goal, we must first understand how various nanoscale components interact with one another, and impact each other’s performance.
We combine knowledge and techniques from all sub-fields of chemistry with inspiration from biological systems, and take a physical chemistry approach to analyzing the complex behaviors of dynamic, nanoscale systems. We currently focus on experimental work, but intend to introduce simulation studies in the future.
We currently focus on the following directions:
1. Nanoscale reaction control – metal nanoparticles (NPs) are excellent catalysts, but can we control their activity? What role do the nanoparticles’ stabilizing ligands play? What about their microenvironment? Can we engineer the surroundings of the particle to tune its activity, and even better, its selectivity? We seek to answer these questions, for both static and responsive structures.
The catalytic reduction of 4-NP by gold nanoparticles leads to a reduction in absorption (left), and is a common model reaction for catalytic particles.
2. Surface patterning – biological complexity arise from the interaction of multiple components, which react with one another, modulate one another, process and transmit information, and react to various signals. Crucially, components are present in spatially-distinct locations. To mimic such complexity in synthetic systems, we are developing highly-capable techniques for surface patterning.
Fluorescence image of a single monolayer in the shape of Marquette University’s seal, created using our photopatterning system. Fluorescent dyes serve as easy-to-observe test systems; ultimately, enzymes and other functional molecules will be patterned. The seal is about 500 µm across.
3. Non-equilibrium transport – accurate nanoscale control requires transporting nanobots and cargo. Biological systems use asymmetric structures and potentials to produce transport, using a ratchet mechanism. Synthetic ratchets can transport particles ranging from micron-scale beads to individual electrons, and are a fascinatingly rich and complex field of study. We develop new techniques to explore these systems, and discover how to use them for applications such as energy harvesting and particle sorting.
A flashing ratchet – an asymmetric potential, oscillated at the right frequency, can transport particles, even though there is no overall bias