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Dual-labeled compounds containing nuclear and near-infrared fluorescence contrast have the potential to molecularly guide surgical resection of cancer by extending whole-body diagnostic imaging findings into the surgical suite. To simplify the dual labeling process for antibody-based agents, we designed a multimodality chelation (MMC) scaffold which combined a radiometal chelating agent and fluorescent dye into a single moiety. Three dye-derivatized MMC compounds were synthesized and radiolabeled. The IRDye 800CW conjugate, 4, had favorable optical properties and showed rapid clearance in vivo. Using 4, an epithelial cell adhesion molecule (EpCAM) targeting MMC-immunoconjugate was prepared and dual-labeled with (64)Cu. In vitro binding activity was confirmed after MMC conjugation. Multimodal imaging studies showed higher tumor accumulation of (64)Cu-7 compared to nontargeted (64)Cu-4 in a prostate cancer model. Further evaluation in different EpCAM-expressing cell lines is warranted as well as application of the MMC dual labeling approach with other monoclonal antibodies.

Optical imaging has great potential for studying molecular recognitions both in vivo and in vitro, yet nuclear imaging is the most effective clinical molecular imaging modality. The combination of optical and nuclear imaging modalities may provide complementary information for improving diagnosis and management of diseases. In this study we developed an optical and nuclear dual-labeled imaging agent, 111In-DTPA-Bz-NH-SA-K(IR-783-S-Ph-CO)-c(CGRRAGGSC)NH2, called DLIA-IL11Ralpha. 111In-DTPA-Bz-NH-SA is the radiotracer moiety; a near-infrared dye IR-783-S-Ph-COOH serves as the fluorescent emitter; and the cyclic peptide c(CGRRAGGSC), which is known to target interleukin 11 receptor alpha-chain (IL-11Ralpha), delivers the desired imaging agent to its target. Experiments revealed that the cyclic peptide c(CGRRAGGSC) continued to possess the targeting capability to IL-11Ralpha after the conjugation of the optical and nuclear tracers. Furthermore, the presence of the metal isotope chelator did not cause quenching of fluorescence emission. The cross validation and direct comparison of optical and nuclear imaging of a tumor was achieved using a single injection, and the preliminary results show the conjugate has tumor targeting capabilities in vivo.

Time-dependent measurements of multiply scattered light were made using frequency domain photon migration (FDPM) techniques in polystyrene latex as a function of ppm pigment concentration (by weight) in order to determine the wavelength-dependent absorption efficiencies for three different pigment particles. The results demonstrate that the absorption spectra of pigment particles within their dispersing vehicles concur with the complementary color chart. FDPM offers a first-principles method for assessing optical characteristics of pigments within their dispersing vehicles and without the need to resort to conventional measurement of diffuse reflectance from coatings and data analysis using phenomenological theory.

Fluorescence lifetime spectroscopy in the presence of tissuelike scattering is demonstrated from measurements of phase and modulation ratio as a function of modulation frequency using a pH-sensitive dye, Carboxy Seminaphthofluorescein-1 (C-SNAFL-1). From the optical diffusion equation describing the propagation and generation of fluorescence within solutions of 0.5 microM C-SNAFL-1 containing 2.0% (by volume) of Intralipid as a scatterer, the values of the average lifetime of C-SNAFL-1 were determined as the solution pH varied between 5 and 9. Average lifetime values were found to match those measured using traditional phase-modulation measurement in nonscattering media. Furthermore, the robustness of the spectroscopic technique was demonstrated by conducting lifetime measurements at varying scatterer concentrations (1.5-3.0 vol % Intralipid). These results confirm the approach for analytical sensing in scattering media via fluorescence lifetime kinetics in order to track changes in analyte concentrations.

The frequency domain photon migration (FDPM) technique was employed to determine mean particle size of pharmaceutical powders. Results show that the FDPM-measured scattering coefficient increases linearly with reciprocal mean particle size of powdered samples. In contrast to near-infrared spectroscopy techniques, FDPM technique enables determination of scattering and absorption separately so that it does not require data pretreatment and chemometric calibration models. In addition, this unique advantage provides more detailed information about powder samples, which can be used as a potential tool for on-line monitoring of not only variation of active pharmaceutical ingredient concentrations from changes in the absorption coefficient but also variation of particle sizes from changes in the scattering coefficient.

Using probability distribution analysis to describe the propagation of multiply scattered light between a point source and point detector located a known distance apart, mathematical expressions predicting the volume of sampled powder were determined for infinite and semi-infinite powder beds and then compared to experimental measurements of frequency-domain photon migration (FDPM). Our results show that the volume of powder sampled varies with optical properties and, when using FDPM techniques, with modulation frequency. For a typical measurement in lactose powder, the volume of powder sampled by multiply scattered light propagating between a 1000-microm-diameter point source and point detector pair separated by 8 mm is predicted to be 1.8 and 1.5 cm3 at modulated frequencies of 50 and 100 MHz, respectively. Experimental measurements in lactose powder confirm the predictions.