We present a lookup table (LUT)-based inverse model for determining the optical properties of turbid media from steady-state diffuse reflectance spectra that is valid for fiber-based probe geometries with close source-detector separations and tissue with low albedo. The lookup table is based solely on experimental measurements of calibration standards. We used tissue-simulating phantoms to validate the accuracy of the LUT inverse model. Our results show excellent agreement between the expected and extracted values of the optical parameters. In addition, the LUT represents a significant improvement in accuracy at short source-detector separations (300 microm) and low albedo (approximately 0.35). We also present in vivo data from clinically normal and malignant nonmelanoma skin cancers fit to the LUT-based model.
We report noninvasive modulation of in vivo tumor radiation response using gold nanoshells. Mild-temperature hyperthermia generated by near-infrared illumination of gold nanoshell-laden tumors, noninvasively quantified by magnetic resonance temperature imaging, causes an early increase in tumor perfusion that reduces the hypoxic fraction of tumors. A subsequent radiation dose induces vascular disruption with extensive tumor necrosis. Gold nanoshells sequestered in the perivascular space mediate these two tumor vasculature-focused effects to improve radiation response of tumors. This novel integrated antihypoxic and localized vascular disrupting therapy can potentially be combined with other conventional antitumor therapies.
Gold nanoshells (dielectric silica core/gold shell) are a novel class of hybrid metal nanoparticles whose unique optical properties have spawned new applications including more sensitive molecular assays and cancer therapy. We report a new photo-physical property of nanoshells (NS) whereby these particles glow brightly when excited by near-infrared light. We characterized the luminescence brightness of NS, comparing to that of gold nanorods (NR) and fluorescent beads (FB). We find that NS are as bright as NR and 140 times brighter than FB. To demonstrate the potential application of this bright two-photon-induced photoluminescence (TPIP) signal for biological imaging, we imaged the 3D distribution of gold nanoshells targeted to murine tumors.