Imaging of QDs-labeled tumors in small animals by fluorescence diffuse tomography

Abstract

Quantum dots (QD) are a new class of fluorescence labels with properties and biomedical applications that are not available with traditional organic dyes and fluorescent proteins. The unique optical properties of QDs (high absorption, quantum yield and emission spanning to near IR) make them attractive as in vivo markers for deep-tissue imaging. Different types of optical tomography allow imaging of fluorescent-labeled tumors located deep in human or animal tissue. In this work, preliminary results of the fluorescent diffuse tomography (FDT) method in application to CdTe/CdSe-core/shell fluorescing nanocrystals are reported. In our experiments we utilized low-frequency amplitude modulation (1 kHz) of the second harmonic of Nd:YAG laser (532 nm). The transilluminative configuration was used in the setup. Results of post mortem experiments with capsules containing QDs placed into esophagus of small animals to simulate labeled tumor are shown. An algorithm of processing fluorescent image based on calculating zero of maximum curvature has been applied to detect fluorescent inclusions boundaries on the image. This work demonstrates potential capabilities of the FDT method for imaging of deep fluorescent tumors in human tissue or animal models of human cancer.Intensity, a.u.

Frequency-domain diffuse optical tomography with single source-detector pair for breast cancer detection

“…DFT is now available for small animal imaging using different fluorophores, such as fluorescent proteins, organic dyes and quantum dots bound to specific molecules for selective delivery [20][21][22][23]. Concentration of these markers in tumor is much higher than in surrounding tissues.…”

“…There are several ways to improve efficacy of DOT technique: by using fluorescent markers as contrast agents (Diffuse Fluorescent Tomography (DFT)) or providing information about tissue components composition by employing illumination at different wavelengths. DFT is now available for small animal imaging using different fluorophores, such as fluorescent proteins, organic dyes and quantum dots bound to specific molecules for selective delivery [20][21][22][23]. Concentration of these markers in tumor is much higher than in surrounding tissues.…”

Fluorescence diffuse tomography technique with autofluorescence removal based on dispersion of biotissue optical properties

“…The epi-illumination image of deep seated tumors is considerably blurred because of strong light scattering in biological tissues. Trans-illumination imaging systems [9,10] are usually made in a raster-scanning configuration and require a significantly longer time (a few minutes) to acquire a single image (projection) of the investigated animal. As distinct from epi-illumination images, trans-illumination images are more sensitive to deep seated tumors.…”

Evaluation of emission cross section of CdSe quantum dots for laser applications

“…Semiconductor quantum dots (QDs) are nanoscale materials with size-dependent optical, physical and chemical properties compared with bulk materials. Cadmium selenide (CdSe) QDs have been a subject of intense study over the past two decades due to unique effects of quantum confinement and potential application in chemical and biological areas [1]. Narrowband stimulated emission at room temperature was demonstrated and the stimulated emission is spectrally tunable with dot size due to strongly quantum confinement [2], which provides a proof that QDs can be employed as new optical gain medium and QDs-based optical amplifiers and lasers over a broad spectral range are achievable.…”