Cellular Imaging Agents Research Articles

Photodynamic Effect in Near‐IR Light by a Photocytotoxic Iron(III) Cellular Imaging Agent

Photodynamic Effect in Near‐IR Light by a Photocytotoxic Iron(III) Cellular Imaging Agent

Photodynamic Effect in Near‐IR Light by a Photocytotoxic Iron(III) Cellular Imaging Agent

A red light for cancer cells: an iron(III) complex (1, see picture) that contains an anthracenyl fluorophore moiety and a catecholate ligand is a potent, metal-based PDT agent that efficiently photocleaves DNA in near-infrared light, has significant nuclear uptake, and high photocytotoxicity in red light by an apoptotic pathway in HeLa and MCF-7 cancer cells.

Photophysical and biological investigation of novel luminescent Ru(ii)-polypyridyl-1,8-naphthalimide Tröger's bases as cellular imaging agents

The synthesis and photophysical properties of 1 and 2, two Ru(II)-polypyridyl based-1,8-naphthalimide Tröger's bases, are described; these were found to stabilize double stranded DNA, undergo rapid cellular uptake, displaying good luminescence without affecting cell viability even after 24 hours of incubation.

Remarkable photocytotoxicity of curcumin in HeLa cells in visible light and arresting its degradation on oxovanadium(iv) complex formation

Curcumin (Hcur) as a cellular imaging and PDT agent shows remarkable photocytotoxicity in HeLa cells in visible light of 400-700 nm giving IC(50) = 8.2 ± 0.2 μM and its degradation is arrested on formation of photocytotoxic dipyridophenazine (dppz) complex [VO(cur)(dppz)Cl] (IC(50) = 3.3 ± 0.4 μM), while both are less toxic in the dark.

Luminescent Ruthenium(II) Polypyridyl Functionalized Gold Nanoparticles; Their DNA Binding Abilities and Application As Cellular Imaging Agents

The synthesis and photophysical and biological investigation of Ru(II)-polypyridyl stabilized water-soluble, luminescent gold nanoparticles (AuNPs) are described. These structures bind to DNA and undergo rapid cellular uptake, being localized within the cell cytoplasm and nucleus within 4 h.

Functionalization of Inorganic Nanoparticles for Bioimaging Applications

Modern biomedical imaging technologies have led to significant advances in diagnosis and therapy. Because most disease processes occur at the molecular and cellular levels, researchers continue to face challenges in viewing and understanding these processes precisely and in real time. The ideal imaging resolution would be in nanometers, because most biological processes take place on this length scale. Therefore, the functionalization of nanoparticles (NPs) and their use in therapeutic and diagnostic applications are of great interest. Molecular and cellular imaging agents made from inorganic NPs have been developed to probe such biological events noninvasively. The conjugation of tiny NPs with specific biomolecules allows researchers to target the desired location, reduce overall toxicity, and boost the efficiency of the imaging probes. In this Account, we review recent research on the functionalization of NPs for bioimaging applications. Several types of NPs have been employed for bioimaging applications, including metal (Au, Ag), metal oxide (Fe(3)O(4)), and semiconductor nanocrystals (e.g. quantum dots (QDs) and magnetic quantum dots (MQDs)). The preparation of NPs for bioimaging applications can include a variety of steps: synthesis, coating, surface functionalization, and bioconjugation. The most common strategies of engineering NP surfaces involve physical adsorption or chemisorption of the desired ligands onto the surface. Chemisorption or covalent linkages are preferred, and the coated NPs should possess high colloidal stability, biocompatibility, water solubility, and functional groups for further bioconjugation. Many of the functionalization techniques that have been reported in the literature suffer from limitations such as complex synthesis steps, poor biocompatibility, low stability, and hydrophobic products. Coating strategies based on chemisorption and ligand exchange often provide a better way to tailor the surface properties of NPs. After conjugation with the appropriate targeting ligands, antibodies, or proteins, the NPs may exhibit highly selective binding, making them useful for fluorescence imaging, magnetic resonance imaging (MRI), positron emission tomography (PET) imaging, and multimodal imaging.

Ruthenium(II) Metallo‐intercalators: DNA Imaging and Cytotoxicity

Dead or alive: We report the successful cellular uptake of two ruthenium polypyridyl DNA light switch complexes that function as multifunctional cellular DNA imaging agents and display potent cytotoxicity against cancer cells. The cytotoxic properties of one complex are of great interest as it offers a potential lead for the development of a new class of anticancer drug in addition to its use as a cellular DNA imaging agent.

Update on Probe Discovery World Congress 2009

The conference was the first of its kind in a series of trend-setting conferences conceived and organized by Select Biosciences. The word 'probe' is a broad term that can be interpreted to mean any one of a wide variety of agents. These include active chemistries discovered in academic screening laboratories or in government organizations (Molecular Libraries Probe Production Centers Network or the US NIH), commercially available probes (i.e., dyes, antibodies or fluorescent proteins), failed drug candidates from the pharmaceutical industry, whole-body or cellular imaging agents, specific biomarkers or tool molecules from chemogenomics and/or systems biology efforts. The conference attendees represented academia, biotech and pharma, the speaker list was stellar, and the conference organizers succeeded in bringing together all of the various incarnations of probe hunters in order to share their experiences and to network with a common purpose.

Carbon nanotube-based magnetic-fluorescent nanohybrids as highly efficient contrast agents for multimodal cellular imaging

We developed a simple and novel layer-by-layer (LBL) assembly in combination with covalent connection strategy for the synthesis of multifunctional carbon nanotubes (CNTs)-based magnetic-fluorescent nanohybrids as multimodal cellular imaging agents for detecting human embryonic kidney (HEK) 293T cells via magnetic resonance (MRI) and confocal fluorescence imaging. Superparamagnetic iron oxide nanoparticles (SPIO) and near-infrared fluorescent CdTe quantum dots (QDs) were covalently coupled on the surface of CNTs in sequence via LBL assembly. It was indicated that the SPIO layer acted not only as a contrast agent for MRI, but also as a spacer between CdTe QDs and CNTs for prohibiting fluorescence quenching of QDs on the surface of the CNTs. The multifunctional CNT-based magnetic-fluorescent nanohybrids showed an enhanced MRI signal as contrast agent for detecting 293T cells in comparison with the pure SPIO. This is due to the magnetic coupling between the orderly arrayed SPIO, the function of CNTs for lowering the transverse relaxation and the ability of CNTs for penetrating into cells. Moreover, the multifunctional CNT-based magnetic-fluorescent nanohybrids exhibited the higher intracellular labeling efficiency due to the ability of CNTs for penetrating into cells in comparison with pure SPIO-CdTe nanoparticles.

Simple conjugated polymer nanoparticles as biological labels

The use of nanoparticles in biology, especially in cellular imaging, is extremely promising and offers numerous advantages over existing organic dye systems. There are, however, constraints that need to be addressed before the use of such materials in mainstream clinical applications can be realized. One of the main concerns is the use of metal-containing particles that are potentially toxic or interfere with other diagnostic processes. Here, we present the use of simple conjugated polymer nanoparticles as alternative photostable cellular optical imaging agents.

In Vivo Cellular Imaging for Translational Medical Research

Personalized treatment using stem, modified or genetically engineered, cells is becoming a reality in the field of medicine, in which allogenic or autologous cells can be used for treatment and possibly for early diagnosis of diseases. Hematopoietic, stromal and organ specific stem cells are under evaluation for cell-based therapies for cardiac, neurological, autoimmune and other disorders. Cytotoxic or genetically altered T-cells are under clinical trial for the treatment of hematopoietic or other malignant diseases. Before using stem cells in clinical trials, translational research in experimental animal models are essential, with a critical emphasis on developing noninvasive methods for tracking the temporal and spatial homing of these cells to target tissues. Moreover, it is necessary to determine the transplanted cell's engraftment efficiency and functional capability. Various in vivo imaging modalities are in use to track the movement and incorporation of administered cells. Tagging cells with reporter genes, fluorescent dyes or different contrast agents transforms them into cellular probes or imaging agents. Recent reports have shown that magnetically labeled cells can be used as cellular magnetic resonance imaging (MRI) probes, demonstrating the cell trafficking to target tissues. In this review, we will discuss the methods to transform cells into probes for in vivo imaging, along with their advantages and disadvantages as well as the future clinical applicability of cellular imaging method and corresponding imaging modality.

Delivering quantum dots into cells: strategies, progress and remaining issues

The use of semiconductor quantum dots (QDs) in biological sensing and labeling continues to grow with each year. Current and projected applications include use as fluorescent labels for cellular labeling, intracellular sensors, deep-tissue and tumor imaging agents, sensitizers for photodynamic therapy, and more recently interest has been sparked in using them as vectors for studying nanoparticle-mediated drug delivery. Many of these applications will ultimately require the QDs to undergo targeted intracellular delivery, not only to specific cells, but also to a variety of subcellular compartments and organelles. It is apparent that this issue will be critical in determining the efficacy of using QDs, and indeed a variety of other nanoparticles, for these types of applications. In this review, we provide an overview of the current methods for delivering QDs into cells. Methods that are covered include facilitated techniques such as those that utilize specific peptide sequences or polymer delivery reagents and active methods such as electroporation and microinjection. We critically examine the benefits and liabilities of each strategy and illustrate them with selected examples from the literature. Several important related issues such as QD size and surface coating, methods for QD biofunctionalization, cellular physiology and toxicity are also discussed. Finally, we conclude by providing a perspective of how this field can be expected to develop in the future.

2089 Detecting inflammation in atherosclerosis using protein cage nanoparticles as cellular imaging agents

2089 Detecting inflammation in atherosclerosis using protein cage nanoparticles as cellular imaging agents

Cyanine dye conjugates as probes for live cell imaging

A series of fluorescent compounds suitable for live cell imaging is described. Functionalized forms of four different asymmetric cyanine dyes are reported that are amenable to peptide conjugation. The photophysical properties of the modified dyes and conjugates and the use of the compounds as cellular imaging agents are described. The results obtained indicate that these spectrally versatile compounds, which have absorption and emission profiles spanning the visible spectrum, are useful probes for cellular imaging.

Apport des produits de contraste en IRM pour le diagnostic et le suivi thérapeutique en cancérologie

Numerous and diverse contrast agents are available in MRI. Their use is focused on two directions : microcirculation imaging and cell capture imaging. Microcirculation imaging uses gadolinium chelates and technical advances in MRI. It quantifies perfusion and capillary permeability applying a physiological analysis to the tissue enhancement curve. Cellular imaging uses labeled cells as contrast agents ; the cells can be labeled in vitro or in vivo. The roles of imaging in cancer are numerous. For diagnosis, detection is improved, particularly for liver metastases with the development of cellular imaging and liver-specific contrast agents. Cellular imaging opens promising perspectives for cellular therapy. Microcirculation imaging characterizes tumors more specifically, particularly in breast imaging. Regarding treatment follow-up, the impact of imaging is considerable. Microcirculation imaging predicts treatment response even before initiation of therapy. During treatment, it allows a more complete evaluation taking into account physiological parameters, better adapted to monitor therapies currently in development, such as anti-angiogenic drugs. Therapeutic effects can be detected earlier, before morphological changes. Cellular imaging offers new prospects to monitor cellular therapy. The use of MRI contrast agents is moving towards the coupling of functional to morphological analysis. This constitutes a new approach perfectly adapted to diagnosis and therapy follow-up in oncology.

Synthesis, Characterisation, and Biological Studies of CdTe Quantum Dot–Naproxen Conjugates

The first naproxen–QD conjugates have been synthesised and investigated. These conjugates demonstrated interesting photophysical properties, good stability in an aggressive enzymatic medium, and cellular localisation in macrophage (THP-1) cells. These nanocomposites might have the potential to act as drug delivery and cellular imaging agents.