An integrated, minimally invasive approach will be developed toward the detection, diagnosis, and treatment of cells and tissues in diseased states, using emerging biomedical imaging methods (optical coherence tomography, or OCT) and novel contrast agents (functionalized gold nanorods). OCT is capable of cellular-resolution imaging in the near infrared (NIR) and has the potential to diagnose abnormal cells and tissues at an early stage of disease, given sufficient contrast. Anisotropic gold nanorods exhibit tunable plasmon responses and can be engineered for strong absorption or scattering at select NIR frequencies, thereby enhancing the sensitivity and scope of OCT and related technologies. New OCT methods will be developed based on the enhanced optical contrast of anisotropic nanorods in isolated or aggregate forms. Gold nanorods with strong and selective NIR extinction will be functionalized with biomolecular ligands for selective targeting of tissues with abnormal biomarker expression. These will serve as site-directed optical labels by binding to cell-surface markers or by cell uptake. Nanorods with magnetic tips may provide additional positional and orientational control within the tissue, and enhance the development of a novel, dynamic OCT method. Metal nanorods can also support extremely large absorption cross-sections and generate highly localized thermal gradients, and can be used to enhance optically-induced hyperthermia at low radiation power. The proposed nanorod-enhanced OCT imaging system will first be applied toward tissue phantoms, then toward the in vivo detection and treatment of tumor cells by local hyperthermia using a hamster cheek pouch model. The OCT-nanorod technology is anticipated to have broad application as an integrated, noninvasive system for medical concerns which require image-guided intervention.
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