Translational Molecular Imaging Group

Singapore, Singapore

Translational Molecular Imaging Group

Singapore, Singapore
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Krishnan M.V.,Nanyang Technological University | Matham M.V.,Nanyang Technological University | Krishnan S.,Nanyang Technological University | Parasuraman P.,Translational Molecular Imaging Group | And 2 more authors.
Journal of Biomedical Optics | Year: 2012

Identification of abnormal pathology in situ remains one of the challenges of medicine. The interpretation of tissue conditions relies mainly on optical assessment, which can be difficult due to inadequate visual differences or poor color delineation. We propose a methodology to identify regions of abnormal tissue in a targeted area based on red, green, blue (RGB) shift analysis employing a simple CCD color camera and light-emitting diode illumination in a whole-field-imaging scheme. The concept involves analysis of RGB components in an image with respect to a reference set of RGB values under different illumination wavelengths. The magnitude of the gray value shift is estimated by calculating the Euclidean distance between their normalized RGB coordinates. The shift values obtained using these concepts are thereafter used to construct pseudo-colored images with high contrast, enabling easy identification of abnormal areas in the tissue. Images processed from experiments conducted with excised Wistar rat colon sample (lightly doped with Alexafluor 488) and with simulated tumor (cancer cell pellet placed on colon) showed clear localization of tumor region. This proposed approach and methodology is expected to find potential applications for the in vivo diagnosis of disease. © 2012 Society of Photo-Optical Instrumentation Engineers (SPIE).

Das G.K.,Nanyang Technological University | Heng B.C.,Nanyang Technological University | Ng S.-C.,Nanyang Technological University | White T.,Nanyang Technological University | And 6 more authors.
Langmuir | Year: 2010

We demonstrate a simple synthetic strategy for the fabrication of single-phase rare earth (RE) doped gadolinium oxide (Gd2O 3:RE where RE = terbium (Tb), ytterbium (Yb), and erbium (Er)) nanorods (NRs) as multimodal imaging probes. The NRs are ultranarrow and exhibit both emission and magnetic characteristics. The Tb-doped and Yb/Er-codoped Gd2O3 NRs exhibit down- and up-conversion fluorescence respectively, and also exhibit paramagnetism. Importantly, these codoped NRs possess excellent magnetic characteristics, as shown in their longitudinal relaxation time (T1) -weighted image contrast, which is closer to that of commercial Gadovist for magnetic resonance imaging (MRI) applications. This property opens up new avenues in the development of contrast agents. © 2010 American Chemical Society.

Zhang Y.,Nanyang Technological University | Das G.K.,Nanyang Technological University | Vijayaragavan V.,Translational Molecular Imaging Group | Vijayaragavan V.,Virginia Commonwealth University | And 6 more authors.
Nanoscale | Year: 2014

The current work reports a type of "smart" lanthanide-based theranostic nanoprobe, NaDyF4:Yb3+/NaGdF4:Yb3+,Er3+, which is able to circumvent the up-converting poisoning effect of Dy3+ ions to give efficient near infrared (980 nm) triggered up-conversion fluorescence, and offers not only excellent dark T2-weighted MR contrast but also tunable bright and T1-weighted MR contrast properties. Due to the efficient up-converted energy transfer from the nanocrystals to chlorin e6 (Ce6) photosensitizers loaded onto the nanocrystals, cytotoxic singlet oxygen was generated and photodynamic therapy was demonstrated. Therefore, the current multifunctional nanocrystals could be potentially useful in various image-guided diagnoses where bright or dark MRI contrast could be selectively tuned to optimize image quality, but also as an efficient and more penetrative near-infrared activated photodynamic therapy agent. © 2014 the Partner Organisations.

Das G.K.,Nanyang Technological University | Zhang Y.,Nanyang Technological University | D'Silva L.,Translational Molecular Imaging Group | Padmanabhan P.,Translational Molecular Imaging Group | And 5 more authors.
Chemistry of Materials | Year: 2011

Ultrasmall terbium ions (Tb3+) doped dysprosium oxide (Dy 2O3) nanocrystals (NCs) of ∼3 nm diameter have been synthesized and applied as a single-phase dual modality contrast agent for high field magnetic resonance imaging (MRI) and optical imaging. The NCs show excellent positive contrast at 7.0 T MRI in phantom and in vivo imaging in a mouse breast tumor model (MCF-7 cells) injected with NCs. In vitro confocal fluorescence microscopy images show the staining of cultured human bronchial epithelial cells (BEAS-2B) with green fluorescent NCs. In vitro cytotoxicity studies in BEAS-2B and L929 cells indicate that the bifunctional NCs have no appreciable toxicity at a concentration of up to 1000 μg/mL. These results suggest the potential application of these NCs as dual modality contrast agents in a combined high field MRI and fluorescence imaging. © 2011 American Chemical Society.

Mohankumar V.K.,Nanyang Technological University | Padmanabhan P.,Translational Molecular Imaging Group | Sathiyamoorthy K.,Nanyang Technological University | Murukeshan V.M.,Nanyang Technological University | And 2 more authors.
Journal of Medical Imaging and Health Informatics | Year: 2011

This paper illustrates high-resolution bio-imaging using a miniaturized fiber based probe system which offers axial and lateral resolutions 16 μm and 144 lp/mm, respectively. The capability of imaging cellular structures is illustrated by imaging cancerous epithelium and neuronal cells. Furthermore, this study depicts a new imaging protocol, that has the potential to avoid many of the difficulties linked with quantitative fluorescence microscopy and imaging. The proposed concepts and, the flexibility and miniaturization of the probe system are explored for single cell imaging. Further the proposed probe system is found to enable imaging of fluorescent microspheres incorporated in a micro-channel. These are expected to find potential applications in pathological and physiological assessment, as well as live-cells cultured in customized live-cell imaging chambers such as perfusion chambers, flow cells and biochips. Copyright © 2011 American Scientific Publishers.

Janczewski D.,Institute of Materials Research and Engineering of Singapore | Zhang Y.,Nanyang Technological University | Das G.K.,Nanyang Technological University | Yi D.K.,Gachon University | And 4 more authors.
Microscopy Research and Technique | Year: 2011

Fluorescent optical probes have been intensively used in the area of bio-imaging. In this review article, we describe the recent advancements in the synthesis and application of bimodal magnetic-fluorescent probes for bioimaging. The bimodal probes consist of fluorescent [semiconducting quantum dots (e.g., CdSe/ZnS) or rare-earth doped (e.g., NaYF4:Yb, Er)] nanoparticles (NPs) and magnetic (iron oxide or gadolinium based) NPs for optical and magnetic resonance (MR) imaging. © 2010 Wiley-Liss, Inc.

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