Fluorescent gold nanoclusters (AuNCs) with emission in near infrared (NIR) range have drawn wide attention due to its bright fluorescence, good biocompatibility and photostability. In this work, AuNCs with emission at 800 nm were synthesized through a simple glutathione reduction method through heating. Cyclic RGD peptide will be conjugated through thiol-PEG-amine as targeting ligand. The AuNCs are then used for two photon fluorescent imaging, due to the wide stokes shift. In vivo NIR fluorescent study showed the accumulation of the AuNCs in tumor areas. Moreover, the AuNCs also showed brain uptake, which indicates possible applications in brain imaging.
LS301 is a promising NIR fluorescence probe for targeting brain glioma cancer. The co-localization of LS31 and 5-ALA induced PpIX in vitro and in vivo enables LS301 to guide PpIX fluorescence image surgery. Moreover, LS301 showed no negative impact on 5-ALA-PpIX PDT outcome in brain glioma cells and mouse tumor model. Therefore, the implementation of LS301 and PpIX has potential to improve tumor resection surgery and PDT treatment for better tumor outcomes.
The large size of many near infrared (NIR) fluorescent nanoparticles prevents rapid extravasation from blood vessels and subsequent diffusion to tumors. This confines in vivo uptake to the peritumoral space and results in high liver retention. We developed a viscosity modulated approach to synthesize ultrasmall silver sulfide quantum dots (QDs) with distinct tunable light emission from visible to near-infrared in spectrum and a QD core diameter between less than 5 nm. Further functionalization of these Ag2S QDs with different type of molecules such as targeting peptides, retains monodisperse, relatively small water soluble QDs without loss of the functionality of the peptide’s high binding affinity to cancerous tumor. Fluorescence and electron microscopy showed that selective integrin-mediated internalization was observed only in cancer cells treated with the peptide-labeled QDs, demonstrating that the unlabeled hydrophilic nanoparticles exhibit characteristics of negatively charged fluorescent dye molecules, which typically do not internalize in cells. The biodistribution profiles of intravenously administered QDs in different mouse models of cancer reveal an exceptionally high tumor-to-liver uptake ratio, suggesting that the small sized QDs evaded conventional opsonization and subsequent high uptake in the liver and spleen. The seamless tunability of the QDs over a wide spectral range with only a small increase in size, as well as the ease of labeling the bright and non-cytotoxic QDs with biomolecules, provides a platform for multiplexing information, tracking the trafficking of single molecules in cells, and selectively targeting disease biomarkers in living organisms without premature QD opsonization in circulating blood.
The era of molecular medicine has ushered in the development of microscopic methods that can report molecular processes in thick tissues with high spatial resolution. A commonality in deep-tissue microscopy is the use of near-infrared (NIR) lasers with single- or multiphoton excitations. However, the relationship between different NIR excitation microscopic techniques and the imaging depths in tissue has not been established. We compared such depth limits for three NIR excitation techniques: NIR single-photon confocal microscopy (NIR SPCM), NIR multiphoton excitation with visible detection (NIR/VIS MPM), and all-NIR multiphoton excitation with NIR detection (NIR/NIR MPM). Homologous cyanine dyes provided the fluorescence. Intact kidneys were harvested after administration of kidney-clearing cyanine dyes in mice. NIR SPCM and NIR/VIS MPM achieved similar maximum imaging depth of ∼100 μm . The NIR/NIR MPM enabled greater than fivefold imaging depth (>500 μm ) using the harvested kidneys. Although the NIR/NIR MPM used 1550-nm excitation where water absorption is relatively high, cell viability and histology studies demonstrate that the laser did not induce photothermal damage at the low laser powers used for the kidney imaging. This study provides guidance on the imaging depth capabilities of NIR excitation-based microscopic techniques and reveals the potential to multiplex information using these platforms.
The spectral changes of native fluorophores among normal fibroblasts and cancer cell lines of different metastatic ability are investigated by fluorescence spectroscopy. The normal (fibroblast), moderately metastatic (DU-145), and advanced metastatic (PC-3) cell lines were each selectively excited at 300 nm, and their fluorescence emission spectra are analyzed using principal component analysis to explore the differences of the relative contents of tryptophan and reduced nicotinamide adenine dinucleotide in these cell lines. The results show that the tryptophan emission featured predominantly in the fluorescence spectra of the advanced metastatic cancer cells in comparison with the moderately metastatic cancer and normal cells.
KEYWORDS: Luminescence, Goggles, Imaging systems, Signal to noise ratio, Near infrared, Signal detection, Liver, Surgery, CMOS technology, Optical sensors
We have developed a near-infrared (NIR) fluorescence goggle system based on the complementary metal–oxide–semiconductor active pixel sensor imaging and see-through display technologies. The fluorescence goggle system is a compact wearable intraoperative fluorescence imaging and display system that can guide surgery in real time. The goggle is capable of detecting fluorescence of indocyanine green solution in the picomolar range. Aided by NIR quantum dots, we successfully used the fluorescence goggle to guide sentinel lymph node mapping in a rat model. We further demonstrated the feasibility of using the fluorescence goggle in guiding surgical resection of breast cancer metastases in the liver in conjunction with NIR fluorescent probes. These results illustrate the diverse potential use of the goggle system in surgical procedures.
The alteration of native fluorophores among different types of cancer cell lines was investigated by the fluorescence spectroscopy. Different types of cancer cell lines with different risk levels, such as moderate metastatic (DU-145) and advanced metastatic (PC-3) cell lines as well as normal cell line (Fibroblast), were excited by the selective excitation wavelength of 300 nm to explore changes of the relative contents of tryptophan and NADH using principal component analysis (PCA). The higher relative content of tryptophan was observed in the advanced metastatic cancer cell lines in comparison with the moderate metastatic and non aggressive cell lines.
The clinical diagnosis of most cancers is based on evaluation of histology microscopic slide to view the size and shape of
cellular nuclei, and morphological structure of tissue. To achieve this goal in vivo and in deep tissue, near infrared (NIR)
dyes-bovine serum albumin (BSA) and immunoglobulin G (IgG) conjugates were synthesized. The spectral study show
that the absorption and fluorescence of the dye-conjugates are in the “tissue optical window” between 650 nm and 1100
nm. The internalization and pinocytosis of the synthesized compound were investigated in cell level using fluorescence
microscopy to obtain the optimal concentration and staining time scale.
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