School of Humanities and Sciences


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  • Hongjie Dai

    Hongjie Dai

    The J.G. Jackson and C.J. Wood Professor in Chemistry

    BioProfessor Dai’s research spans chemistry, physics, and materials and biomedical sciences, leading to materials with properties useful in electronics, energy storage and biomedicine. Recent developments include near-infrared-II fluorescence imaging, ultra-sensitive diagnostic assays, a fast-charging aluminum battery and inexpensive electrocatalysts that split water into oxygen and hydrogen fuels.

    Born in 1966 in Shaoyang, China, Hongjie Dai began his formal studies in physics at Tsinghua U. in Beijing (B.S. 1989) and applied sciences at Columbia U. (M.S. 1991). His doctoral work under Dr. Charles Lieber at Harvard U. (Ph.D. 1994) focused on charge-density waves and superconductivity. During postdoctoral research at Rice U. with Dr. Richard Smalley, he developed carbon nanotube probes for atomic force microscopy. He joined the Stanford faculty in 1997, and in 2007 was named Jackson–Wood Professor of Chemistry. Among many awards, he has been recognized with the ACS Pure Chemistry Award, APS McGroddy Prize for New Materials, Julius Springer Prize for Applied Physics and Materials Research Society Mid-Career Award. He has been elected to the American Academy of Arts and Sciences, AAAS and National Academy of Sciences.

    The Dai Laboratory has advanced the synthesis and basic understanding of carbon nanomaterials and applications in nanoelectronics, nanomedicine, energy storage and electrocatalysis.

    Nanomaterials
    The Dai Lab pioneered some of the now-widespread uses of chemical vapor deposition for carbon nanotube (CNT) growth, including vertically aligned nanotubes and patterned growth of single-walled CNTs on wafer substrates, facilitating fundamental studies of their intrinsic properties. The group developed the synthesis of graphene nanoribbons, and of nanocrystals and nanoparticles on CNTs and graphene with controlled degrees of oxidation, producing a class of strongly coupled hybrid materials with advanced properties for electrochemistry, electrocatalysis and photocatalysis. The lab’s synthesis of a novel plasmonic gold film has enhanced near-infrared fluorescence up to 100-fold, enabling ultra-sensitive assays of disease biomarkers.

    Nanoscale Physics and Electronics
    High quality nanotubes from his group’s synthesis are widely used to investigate the electrical, mechanical, optical, electro-mechanical and thermal properties of quasi-one-dimensional systems. Lab members have studied ballistic electron transport in nanotubes and demonstrated nanotube-based nanosensors, Pd ohmic contacts and ballistic field effect transistors with integrated high-kappa dielectrics.

    Nanomedicine and NIR-II Imaging
    Advancing biological research with CNTs and nano-graphene, group members have developed π–π stacking non-covalent functionalization chemistry, molecular cellular delivery (drugs, proteins and siRNA), in vivo anti-cancer drug delivery and in vivo photothermal ablation of cancer. Using nanotubes as novel contrast agents, lab collaborations have developed in vitro and in vivo Raman, photoacoustic and fluorescence imaging. Lab members have exploited the physics of reduced light scattering in the near-infrared-II (1000-1700nm) window and pioneered NIR-II fluorescence imaging to increase tissue penetration depth in vivo. Video-rate NIR-II imaging can measure blood flow in single vessels in real time. The lab has developed novel NIR-II fluorescence agents, including CNTs, quantum dots, conjugated polymers and small organic dyes with promise for clinical translation.

    Electrocatalysis and Batteries
    The Dai group’s nanocarbon–inorganic particle hybrid materials have opened new directions in energy research. Advances include electrocatalysts for oxygen reduction and water splitting catalysts including NiFe layered-double-hydroxide for oxygen evolution. Recently, the group also demonstrated an aluminum ion battery with graphite cathodes and ionic liquid electrolytes, a substantial breakthrough in battery science.

  • Laura M.K. Dassama

    Laura M.K. Dassama

    Assistant Professor of Chemistry

    BioThe Dassama laboratory at Stanford performs research directed at understanding and mitigating bacterial multidrug resistance (MDR). Described as an emerging crisis, MDR often results from the misuse of antibiotics and the genetic transfer of resistance mechanisms by microbes. Efforts to combat MDR involve two broad strategies: understanding how resistance is acquired in hopes of mitigating it, and identifying new compounds that could serve as potent antibiotics. The successful implementation of both strategies relies heavily on an interdisciplinary approach, as resistance mechanisms must be elucidated on a molecular level, and formation of new drugs must be developed with precision before they can be used. The laboratory uses both strategies to contribute to current MDR mitigation efforts.

    One area of research involves integral membrane proteins called multidrug and toxin efflux (MATE) pumps that have emerged as key players in MDR because their presence enables bacteria to secrete multiple drugs.The genes encoding these proteins are present in many bacterial genomes. However, the broad substrate range and challenges associated with membrane protein handling have hindered efforts to elucidate and exploit transport mechanisms of MATE proteins. To date, substrates identified for MATE proteins are small and ionic drugs, but recent reports have implicated these proteins in efflux of novel natural product substrates. The group’s approach will focus on identifying the natural product substrates of some of these new MATE proteins, as well as obtaining static and dynamic structures of the proteins during efflux. These efforts will define the range of molecules that can be recognized and effluxed by MATE proteins and reveal how their transport mechanisms can be exploited to curtail drug efflux.

    Another research direction involves the biosynthesis of biologically active natural products. Natural products are known for their therapeutic potential, and those that derive from modified ribosomal peptides are an important emerging class. These ribosomally produced and post-translationally modified peptidic (RiPP) natural products have the potential to substantially diversify the chemical composition of known molecules because the peptides they derive from can tolerate sequence variance, and modifying enzymes can be selected to install specific functional groups. With an interest in producing new antimicrobial and anticancer compounds, the laboratory will exploit the versatility of RiPP natural product biosynthesis. Specifically, efforts in the laboratory will revolve around elucidating the reaction mechanisms of particular biosynthetic enzymes and leveraging that understanding to design and engineer new natural products with desired biological activities.