The central theme of our research efforts is to measure and control single biomolecules and biologically inspired nanostructures at interfaces.

Directional molecular motion:

A fascinating and important question in nanotechnology is: can we create molecular -scale machines capable of sophisticated motion? These machines have implications in areas ranging from drug delivery to information storage and processing.  Such nanomachines also hold the promise to bring new capabilities to bottom-up nanoscale assembly in a fashion similar to biological motors.  We will combine molecular design, nanoscale fabrication, scanning probe microscopy characterization, and other surface chemistry tools  to engineer molecules and their nanoscale environments for programmable linear motions. 

Nanoscale biomolecular surfaces:

Biosensors have the potential to revolutionalize medical diagnostics. However, significant improvements in sensitivity, selectivity, dynamic range and costs must be achieved before the potential can become reality. For many biosensors, they can only as sensitive and selective as the ability of the surface immobilized probes in recognizing and binding analytes. The inhibition of target binding due to the inter-probe interactions and surface-probe interactions has been a bottleneck in surface-based biosensing. Due to the localized nature of these interactions and the heterogeneity of practical sensor surfaces, understanding and controlling of such interactions necessitates the characterization of the probe surfaces at the nanoscale and single molecule level. While existing studies have mostly relied on ensemble techniques, recently we developed a new approach that allows atomic force microscopy to characterize an important class of sensor surfaces at the nanoscale and single molecule level. Our single molecule level investigation of the dynamic conformational changes of tethered DNAs revealed extreme sensitivities to the nanoscale local environment and highlight the critical importance of the fundamental understanding of such interfaces in biotechnological devices.

Controlling the spatial organization of biomolecules is of fundamental importance in a number of biotechnology applications such as microarrays.Spatially organizing biomolecules is also essential for a number of biophysical studies. So far, most methods can only pattern bundles that contain hundreds to millions of molecules. Molecules in these bundles tend to have heterogeneous conformations and reactivities. We have pioneered a novel method that allows one to pattern single DNA molecules in arbitrary two dimensional nanoscale spatial arrangements.  Such isolated molecules allow us to perform chemistry of these biomolecules with single molecule precision for the first time.

Building on the progress, we are building more complex biomolecular structures with molecular precision using the principle of self-assembly. We are developing a versatile nanoscale lab-bench that allow the interrogation and manipulation of biomolecules with unprecedented precision and control. Our lab-bench is based on gold mciroplates supported on indium tin oxide.