The plasmon resonance of noble metal nanoparticles (NP) manifests itself in a variety of extraordinary optical properties.
Resonant excitation of the conduction electrons by incident radiation generates a localized surface plasmon resonance
(LSPR) that is responsible for a variety of surface enhanced optical phenomena. This unique optical property coupled
with well-established surface chemistry allows us to utilize both Ag and Au NP as optical contrasting agents to probe
and monitor the surface receptors of cells. We have employed two plasmon-assisted optical techniques (namely, surface
enhanced Raman scattering, and resonant Rayleigh scattering) to monitor the adrenergic receptors in mammalian
cardiomyocyte cells that have been labeled with functionalized Ag NPs. In this study, a unique Raman reporter
molecule, 4-(mercaptomethyl)benzonitrile, was developed to provide an easily identifiable vibration, the C≡N stretch, in
a spectral window free from Raman bands of cell constituents and other biomolecules used in receptor crosslinking and
surface passivation. Successfully labeled cells were then monitored with both optical techniques. Both techniques are
related through the plasmonic properties of the noble metal NP and combined with high resolution imaging techniques;
we outline the importance that different NP architectures play in the different imaging techniques. Furthermore, we will
discuss the instrumentation and plasmonic implications in the design of NP best suited for such multimodal imaging
Multi-modal sensing scheme significantly improves the detection accuracy but can also introduce
extra complexity in the overall design of the sensor. We overcome this difficulty by utilizing the
plasmonic properties of metallic nanoparticles. In this study, we will present a simple dual optical
sensing mechanism which harvests signals of the resonantly excited metallic nanostructure in the
form of surface enhanced Raman scattering (SERS) and resonant Rayleigh scattering. Silver and
gold nanoparticles labeled with appropriate antibodies act as signal transduction units and upon
exposure to the targeted pathogen render the targeted species optically active. We demonstrate that
detection of a single pathogen cell is easily attainable with the dual detection scheme. Furthermore,
we explore the markedly different SERS intensity observed from the use of two very different
antibody recognition units during the pathogen labeling process.
Semiconductor devices that are not generally thought of as light sources do emit radiation in the visible and the near infrared as they operate. Observation of this electroluminescence furnishes insight into the operation of the devices and of the circuitry that they constitute but it requires an extremely sensitive light detector and picosecond time resolution. This can be achieved using a Mepsicron photodetector system that enables single photon counting time-correlated imaging with a spatial resolution of about 1 µm and a time resolution approaching 10 ps. Information extracted from the time-resolved imagery can be compared with circuit layout and topology and individual device structures and with electrical measurements that are performed concurrently. These time-correlated measurements allow signal waveforms to be determined optically, much as the waveforms measured electronically with an oscilloscope and microprobing, but with the advantage that the acquisition is entirely non-invasive. Images can be dissected in both space and time to provide information for individual components of a circuit or regions of a device. This imaging equipment has been used in our laboratory for measurements on Si, GaAsP and GaN technologies and analyses will be presented.