Research Areas

Biochemistry, physical chemistry

Research and Teaching Interests

The research program Yan Lui is involved in is highly interdisciplinary which combines chemistry, biology, physics and material science. Their goal is to develop nanoparticle-based multi-component and multi-functional nanostructures using self-assembly and DNA directed self-assembly, to characterize their unique optical properties, and explore their applications in bio-imaging, biosensing, etc.

The nanoparticles used include gold or silver nanoparticles, quantum dots, and magnetic nanoparticles. Surface modification of the nanoparticles by various bioconjugation methods will be explored to generate stable nanoparticles with desirable surface functionalities. Self-assembly of DNA nanostructures form patterned DNA arrays, and the directed assembly of nanoparticles by the DNA templates generate uniquely functional nanodevices. Taking advantage of the precise spatial control of DNA nanostructures, and tunable size-or distance dependence of the properties of nanoparticles, multi-component structures with unique properties can be created. The various tools they use to characterize the nanoparticle-based multi-component structures, include the microscopic imaging techniques of optical microscope, AFM, SEM or TEM, and spectral analysis tools, such as UV-Vis, fluorometer, surface Raman spectroscopy, etc.

Our research is focused on the following three themes:

1. Chemical synthesis and photophysics of quantum materials:   Quantum-size semiconductor building blocks, such as quantum dots, quantum wires, and quantum sheets and the corresponding hetero-structures have broad applications ranging from light-emitting diodes, nanolasers, nanoelectronics, solar cell devices to biological fluorescent labels. Constructing highly tunable building blocks and the corresponding hetero-structures with control over the size, shape, composition, crystalinity, and their hierarchical structures is vitally important to fully exploit these materials. We aim to develop state of the art colloidal chemistry strategy to synthesize and characterize a series of novel quantum materials with unique optical and electronic properties and investigate their applications in functional nanodevices.

2. Physical chemistry of DNA nanotechnology: DNA nanotechnology allows the design and construction of nanoscale objects that have finely-tuned dimensions, orientation, and structure with remarkable ease and convenience. With the increasing complexity of the DNA nanostructural system these days, much fundamental studies are needed to further understand the underlying physical chemistry. First, we aim to systematically investigate the thermodynamics and kinetics of DNA nanostructure formation. These thermodynamics and kinetics studies will shed light on the stability of the DNA nanostructures, push the limit on their application conditions, and improve their performance. Second, we aim to engineer synthetic DNA nanostructures to model or mimic a variety of other molecules and systems. For example, synthetic DNA nanostructures can be designed to serve as models to study the binding behavior of multi-valent molecules and gain insight into how small changes to the ligand/receptor scaffolds, such as conformational flexibility or relative distance or orientation of the multiple ligands, will affect their association equilibrium with the target molecules. This is important in understanding many multi-valent interactions in nature, like pathogen invasion, immunology recognition, cell-cell interaction.

3. DNA directed deterministic positioning of nanophotonic elements: Systematical study of photonic elements interactions with deterministic positioning at nanometer scale is very important for: a) fundamental understanding of the underlying distance-dependent interactions and energy transfer between various photonic elements; b) providing useful models to understand photonic antenna systems existing in nature; c) providing crucial information for constructing artificial biophotonic systems for applications ranging from light harvesting to biosensing. Along this line, we aim to use DNA directed self-assembly to: a) study distance-dependent effects between metallic nanoparticles and organic fluorophores; b) construct molecular antenna systems for efficient light-harvesting; c) construct and understand geometry dependent energy transfers between fluorophores. We are also collaborating with theory group to fully understand these nanostructured photonic systems. Experiments are designed to test theoretical hypothesis and modeling. New models will be developed by taking into account of many experimental parameters resulting from the deterministic positioning of photonic elements.