The central theme of our research program is functional surfaces and interfaces with specific applications in nanomaterials, nanobiotechnolgoy, and nanoelectronics.

Surfaces as the outmost boundary of a material or device serve as the interface communicating with the physical phase surrounding the material, and play a critical role in the functions of materials and devices. The need of surface engineering for nanomaterials and nanodevices is both inherent, i.e., high surface energy at the nanoscale, and application driven where ligands presented on the surface act as points of contact communicating with external receptors. An intricate balance must be achieved in order to provide the multifaceted functions of the surface ligands in preventing nanomaterials from agglomerating, presenting the necessary molecular recognition functions, and at the same time preserving the physical properties of the nanomaterials needed for translating the molecular recognition events into reliable readouts.

Research in our laboratory focuses on developing effective surface coupling chemistry that is general, efficient, can accommodate ligand diversity, maintain ligand bioaffinity, and give bioactive and stable interfaces. We developed two new techniques for materials surface functionalization and immobilization. One approach employs a heterobifunctional coupling agent to covalently attach a wide range of molecules on surfaces. This photocoupling chemistry is fast, efficient, and allows control over both spatial and topographic features. Current projects focus on the synthesis of bionanomaterials and their applications in bioanalysis.

The second approach is based on the photochemistry of polymers where thin films of polymers can be immobilized on substrates by way of a photochemically initiated process.  By using polymers of defined structures, architecture, and properties, functional surfaces can be created for stimuli-responsiveness, sensing, and nanostructure formation. Current projects focus on mechanistic studies of polymer photochemistry, fabrication of polymer nanostructures by self-assembly and direct writing with nanoprobes.

Self-assembled polymer nanostructures (left), polymer nanostructures by direct writing with nanoprobes (right).