Jason H. Hafner, Rice University, Houston, Texas—Gold nanostars are asymmetric nanoparticles that show polarization-dependent scattering spectrum. This has been demonstrated to show large surface plasmon resonance (SPR) shifts in single-particle scattering measurements. Dr. Hafner’s group is currently pursuing single-particle, single-binding-event sensing using nanostars (Nehl et al., 2004).
Naomi J. Halas, Rice University, Houston, Texas—Dr. Halas’s group has developed a variety of nanoparticles that exhibit large SPR sensitivities. These include silica core gold nanoshells and “nanorice” particles (Tam et al., 2004; Wang and Mittleman, 2006).
Mikael Käll, Chalmers University of Technology, Göteborg, Sweden—LSPR sensing of single holes in gold films and the ensemble measurements have been used to demonstrate the LSPR sensitivity by functionalizing with alkanethiols of different lengths. Other geometries made by electron-beam lithography have also been developed. The group at Chalmers University has also developed techniques to study surface modifications in the lipid layer and other chemical changes that occur at the hole sites on lipid layers supported on gold films with nanometer-size holes (Rindzevicius et al., 2005).
Nicholas Kotov, University of Michigan, Ann Arbor—Dr. Kotov developed a layer-by-layer assembly technique to fabricate thin films of mixed anisotropic nanoparticles and controlled surface plasmon absorption.
J.R. Sambles, University of Exeter, Exeter, United Kingdom—Dr. Sambles’s group has developed an acoustooptical tunable filter to enhance the SPR sensitivity of gold films used to detect NO gas close to the surface, the binding of biological molecules in solution, and the electrochemical modifications in the films as different molecules attach to the surface (Jory et al., 1995).
Jennifer Shumaker-Parry, University of Utah, Salt Lake City, Utah—Dr. Shumaker-Parry’s group has developed SPR microscopy as a technique for array-based molecular recognition studies. SPR microscopy using an asymmetric particles array (crescent-shaped particles) provides a label-free method for high-throughput, quantitative, real-time kinetic studies of biomolecule interactions (e.g., protein-DNA, protein-protein, protein-vesicle) (Shumaker-Parry et al., 2005).
Richard P. Van Duyne, Northwestern University, Evanston, Illinois—Dr. Van Duyne’s group has used nanosphere lithography silver triangles as localized surface plasmon resonance (LSPR) sensors to study chemical binding and unbinding events. Both ensemble measurements of silver triangle arrays and single-particle measurements have been used to study LSPR shifts that are due to molecules binding to the surface (Malinsky et al., 2001; McFarland and Van Duyne, 2003). This group has also used LSPR sensing to detect biomarkers for Alzheimer’s disease.
Younan Xia, University of Washington, Seattle, Washington—Dr. Xia’s group has developed hollow gold nanoshells, and nanocube particles that show high LSPR sensitivity. Ensemble measurements on the nanoshells and single-particle measurements on the nanocubes have been performed (Sherry et al., 2005; Sun and Xia, 2002).
Louis Brus, Columbia University, New York, New York—Dr. Brus’s group is involved in studies relating to the origin of large enhancement factors in SERS from silver colloid particles (Michaels et al., 2000). The group is also investigating the chemical effect in the SERS enhancement.