A near-infrared fluorescent heptamethine indocyanine dye with preferential tumor accumulation for in vivo imaging

Herceptin functionalized polyhedral oligomeric silsesquioxane - conjugated oligomers - silica/iron oxide nanoparticles for tumor cell sorting and detection

Sorting and detection of circulating tumor cells (CTC) in peripheral blood as an efficient and non-invasive method to diagnose cancer have recently attracted much attention. In this article, we developed a multiply-engineered nanoparticle system for CTC sorting and detection, which consists of (1) conjugated oligomer (CO) as fluorescence signal source, (2) polyhedral oligomeric silsesquioxanes (POSS) scaffold for CO localization for better fluorescent effects, (3) silica nanoparticles (SiNPs) as formulation matrix of the POSS containing CO, (4) iron oxide (IO) layer on the silica nanoparticles (IO-SiNPs) for magnetic collection, and (5) herceptin surface functionalization of the IO-SiNPs to target cancer cells of HER2 overexpression. Such a multiply-engineered structure can be used for either traditional immunomagnetic methods or microfluidic devices for CTC sorting and detection.

Multimodal image-guided photothermal therapy mediated by 188Re-labeled micelles containing a cyanine-type photosensitizer

Multifunctional micelles loaded with the near-infrared (NIR) dye and labeled with the radionuclide rhenium-188 ((188)Re) have been developed to provide multimodalities for NIR fluorescence and nuclear imaging and for photothermal therapy (PTT) of cancer. The NIR dye, IR-780 iodide, allowed the micelles to have dual functions in cancer NIR imaging and PTT. The (188)Re-labeled IR-780 micelles enabled imaging by NIR fluorescence and by microSPECT to guide the delivery of drugs and to monitor in real-time the tumor accumulation, intratumoral distribution, and kinetics of drug release, which serve as a basis of specific photothermal injury to the targeted tissue. We also investigated the biodistribution, generation of heat, and photothermal cancer ablation of IR-780 micelles of both in vitro and in vivo xenografts. Histopathology observed irreversible tissue damage, such as necrotic features, decreased cell proliferation, increased apoptosis of cells, and increased expression of heat shock proteins in the PTT-treated tumors. The (188)Re-labeled IR-780 micelles offer multifunctional modalities for NIR fluorescence and nuclear imaging and for PTT of cancer.

A review of NIR dyes in cancer targeting and imaging

The development of multifunctional agents for simultaneous tumor targeting and near infrared (NIR) fluorescence imaging is expected to have significant impact on future personalized oncology owing to the very low tissue autofluorescence and high tissue penetration depth in the NIR spectrum window. Cancer NIR molecular imaging relies greatly on the development of stable, highly specific and sensitive molecular probes. Organic dyes have shown promising clinical implications as non-targeting agents for optical imaging in which indocyanine green has long been implemented in clinical use. Recently, significant progress has been made on the development of unique NIR dyes with tumor targeting properties. Current ongoing design strategies have overcome some of the limitations of conventional NIR organic dyes, such as poor hydrophilicity and photostability, low quantum yield, insufficient stability in biological system, low detection sensitivity, etc. This potential is further realized with the use of these NIR dyes or NIR dye-encapsulated nanoparticles by conjugation with tumor specific ligands (such as small molecules, peptides, proteins and antibodies) for tumor targeted imaging. Very recently, natively multifunctional NIR dyes that can preferentially accumulate in tumor cells without the need of chemical conjugation to tumor targeting ligands have been developed and these dyes have shown unique optical and pharmaceutical properties for biomedical imaging with superior signal-to-background contrast index. The main focus of this article is to provide a concise overview of newly developed NIR dyes and their potential applications in cancer targeting and imaging. The development of future multifunctional agents by combining targeting, imaging and even therapeutic routes will also be discussed. We believe these newly developed multifunctional NIR dyes will broaden current concept of tumor targeted imaging and hold promise to make an important contribution to the diagnosis and therapeutics for the treatment of cancer.

Staining of mitochondria with Cy5-labeled oligonucleotides for long-term microscopy studies

Labeling of organelles for microscopy is achieved generally by specific dyes that either accumulate in a cellular compartment such as cyanine dyes in mitochondria or are only fluorescent under specific conditions such as the low pH in the lysosome. Here we demonstrate that Cy5--a fluorescent molecule that does not enter cells by itself--can be loaded into cells by attaching a short oligonucleotide. This very inexpensive labeling procedure can be done in the presence of serum. Therefore, very sensitive cell types should also be amenable to this procedure, and longer observations can be achieved compared to other commercially available dyes as the labeling reagent does not need to be washed out. This also points to the pitfall of using fluorescently labeled oligonucleotides for live cell imaging where the oligonucleotide is supposed to detect a specific target sequence in its subcellular distribution.