Bulletin of the American Physical Society
76th Annual Meeting of the Southeastern Section of APS
Volume 54, Number 16
Wednesday–Saturday, November 11–14, 2009; Atlanta, Georgia
Session JA: Biophotonics |
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Chair: Gary Hastings, Georgia State University Room: Brussels |
Friday, November 13, 2009 1:30PM - 2:00PM |
JA.00001: Sensing Plasmon-Resonant Nanorods in Tissue with Optical Coherence Tomography Invited Speaker: Gold nanoparticles (GNPs) are of high interest for biomedical imaging and photothermal therapy due to their plasmon-resonant nature. However, their utility is limited by transport and targeting to the disease of interest after administration in the living body. Optical coherence tomography can image the distribution of GNPs on the micro- to meso-scale, leading toward a better understanding of these limiting factors. Plasmon-resonant nanorods provide strong optical absorption at near-infrared wavelengths, and are studied using an optical coherence tomography system based on a broadband laser centered at 800nm. The ability to sense GNPs against a biological tissue background is treated as a sensing problem with parameters including the nanorod volume and aspect ratio, optical detection metrics including extinction, a new backscattering albedo metric based on the ratio of backscattering to extinction, and spectroscopic analysis. A key element of this analysis is determining the native tissue optical response, optical signal noise, and spatial heterogeneity before addition of the GNPs. Experiments are performed in skin-like tissue phantoms where a sensitivity of 30ppm is found. Experiments in excised human mammary tumors reveal additional challenges for imaging in real tissues, and the results of various processing techniques are compared. [Preview Abstract] |
Friday, November 13, 2009 2:00PM - 2:30PM |
JA.00002: Imaging of Breast Cancer and Epilepsy using Diffuse Optical Tomography Invited Speaker: In this talk, I will describe the fundamental principles of the emerging near-infrared diffuse optical tomography. In my laboratory this imaging technology has been developed for imaging of breast cancer, osteoarthritis, epilepsy and drug delivery/gene therapy. I will report on our most recent clinical and preclinical studies in breast cancer and epilepsy. [Preview Abstract] |
Friday, November 13, 2009 2:30PM - 3:00PM |
JA.00003: Biophysical Studies of the Cell Coat Invited Speaker: Many mammalian cell types are enveloped by a coat of polysaccharides and proteins. This coat influences vital biological processes such as cell adhesion, proliferation, motility and embryogenesis. The constitution and thickness of this layer, referred to as the pericellular coat (PCC), pericellular matrix or glycocalyx, can vary considerably. Despite its significance, the macromolecular organization of the cell coat remains speculative. Here we focus on cell coats whose vital structural backbone is hyaluronan (HA), a highly-hydrated polysaccharide that anchors the coat to the cell membrane. The molecular interaction of HA with different HA-binding proteins determines the architecture of the PCC. The resultant mesoscopic arrangement of the different PCC components influences the cell's perception of the extracellular environment and its ability to withstand compression. The stress transduction through the PCC is especially important for chondrocytes, cells located in the load-bearing cartilage. The molecular structure of some PCC components, especially the HA-binding protein aggrecan, changes with age or osteoarthritis. These changes alter the viscoelasticity of the PCC and may also affect its molecular architecture. We employ a combination of passive microrheology and optical force probe microscopy on the PCC of living rat chondrocytes (RCJ-P) cells, which serve as a well-established model system for HA-rich coats. We establish the first micromechanical map of the PCC which reveals an increase in both the viscosity and elasticity of the PCC towards the cell surface. Further, we characterize the distribution of HA and observe a linear increase in fluorescence intensity towards the cell membrane. Comparing the results of these approaches using polymer theory sheds light on the macromolecular architecture of the PCC. Our data indicate that the structure of PCC is far more complex than expected from a pure end-grafted polymer brush. [Preview Abstract] |
Friday, November 13, 2009 3:00PM - 3:30PM |
JA.00004: The Development of Combined Raman Spectroscopy-Optical Coherence Tomography and Application for Skin Cancer Diagnosis Invited Speaker: Optical spectroscopy and imaging have shown promise for performing rapid, non-invasive disease detection and diagnosis \textit{in vivo}. Independently, Raman Spectroscopy (RS) has demonstrated the ability to perform diagnosis of epithelial cancers such the cervix with excellent overall classification accuracy due to the inherent biochemical specificity of the technique, however relating features of tissue morphology with techniques such as Raman mapping is clinically impractical due to the weak nature of the scattering phenomena resulting in prohibitively long acquisition times. Optical Coherence Tomography (OCT), on the other hand, has demonstrated the ability to perform real-time, high-resolution, cross-sectional imaging of the microstructural characteristics of disease, but typically lacks molecularly specific information that can assist in classifying pathological lesions. We present the development of a combined Raman Spectroscopy-OCT (RS-OCT) instrument capable of compensating for the limitations of each technique individually and performing both biochemical and microstructural evaluation of tissues. We will include the design and development of benchtop RS-OCT implementations based on independent 785 nm Raman and 1310 nm time-domain OCT system backbones, as well as with a 785nm Raman / 850nm spectral-domain OCT setup employing an integrated detection arm. These systems motivated the ultimate design of a clinical RS-OCT system for application in dermatology. In order to aid in the development of our Raman spectral processing and classification methods, we conducted a simultaneous pilot study in which RS alone was used to measure basal and squamous cell carcinomas. We will present the initial results from our clinical experiences with the combined RS-OCT device, and include a discussion of spectral classification and the ultimate potential of combined RS-OCT for skin cancer diagnosis. [Preview Abstract] |
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