Browsing by Author "Abraham, A"

Now showing 1 - 8 of 8
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    Biokinetics and In Vivo Distribution Behaviours of Silica-Coated Cadmium Selenide Quantum Dots
    (BIOLOGICAL TRACE ELEMENT RESEARCH, 2011) Vibin, M; Vinayakan, R; John, A; Raji, V; Rejiya, CS; Abraham, A
    Recently, quantum dots derived from trace elements like cadmium and selenium have attracted widespread interest in biology and medicine. They are rapidly being used as novel tools for both diagnostic and therapeutic purposes. In this report, we evaluated the distribution of silica-coated cadmium selenide (CdSe) quantum dots (QDs) following intravenous injection into male Swiss albino mice as a model system for determining tissue localization using in vivo fluorescence and ex vivo elemental analysis by inductively coupled plasma optical emission spectroscopy (ICP-OES). Trioctylphosphine oxide-capped CdSe quantum dots were synthesized and rendered water soluble by overcoating with silica, using aminopropyl silane (APS) as silica precursor. ICP-OES was used to measure the cadmium content to indicate the concentration of QDs in blood, organs and excretion samples collected at predetermined time intervals. Meanwhile, the distribution and aggregation state of QDs in tissues were also investigated in cryosections of the organs by fluorescence microscopy. We have demonstrated that the liver and kidney were the main target organs for QDs. Our systematic investigation clearly shows that most of the QDs were metabolized in the liver and excreted via faeces and urine in vivo. A fraction of free QDs, maintaining their original form, could be filtered by glomerular capillaries and excreted via urine as small molecules within 5 days.
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    Cellular uptake and subcellular localization of highly luminescent silica-coated CdSe quantum dots - In vitro and in vivo
    (JOURNAL OF COLLOID AND INTERFACE SCIENCE, 2011) Vibin, M; Vinayakan, R; John, A; Rejiya, CS; Raji, V; Abraham, A
    With excellent optical properties, quantum dots (QDs) have been made as attractive molecular probes for labeling cells in biological research. The purpose of the present work is to explore the possible role of silica-coated cadmium selenide (CdSe) QDs in the in vitro and in vivo cellular uptake and their subcellular localization. The in vitro uptake characteristics of silica-coated CdSe QDs were performed in cultured New Zealand rabbit adipose tissue-derived mesenchymal stem cells (RADMSCs) and Human cervical cancer cells (HeLa) using fluorescence microscopy after staining with 4,6-diamidino-2-phenylindole (DAPI). The in vitro results showed that the silica-coated CdSe QDs were efficiently taken up by the cells and it was localized in the intracellular vesicles giving strong fluorescence from the cytoplasm and nearby nucleus. Subsequently, the in vivo localization and distribution of QDs were studied by the hematoxilin stained semithin cryosections of tissues (similar to 15 mu m thickness) under fluorescence microscopy and ultrathin sections of tissues (similar to 100 nm thickness) under confocal laser scanning microscopy at the distribution maxima. Our in vivo results confirmed the effective cellular uptake and even distribution pattern of QDs in tissues. Overall, these in vitro and in vivo results are represented with focus on internalization, subcellular localization and distribution of the QDs, in view of their potential applications in biomedical field. (C) 2011 Elsevier Inc. All rights reserved.
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    Cytotoxicity and fluorescence studies of silica-coated CdSe quantum dots for bioimaging applications
    (Journal of Nanoparticle Research., 2011) Vibin, M; Vinayakan, R; John, A; Raji, V; Rejiya, CS; Abraham, A
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    Effective cellular internalization of silica-coated CdSe quantum dots for high contrast cancer imaging and labeling applications.
    (Cancer Nanotechnology., 2015-01) Vibin, M; Vinayakan, R; John, A; Fernandez, FB; Abraham, A
    The possibility of developing novel contrast imaging agents for cancer cellular labelling and fluorescence imaging applications were explored using silica-coated cadmium selenide (CdSe) quantum dots (QDs). The time dependent cellular internalization efficiency study was carried out using Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) and Confocal Laser Scanning Microscopy (cLSM) after exposing QDs to stem cells and cancer cells. The strong fluorescence from the cytoplasm confirmed that the QDs were efficiently internalized by the cells. The internalization maxima were observed at the fourth hour of incubation in both stem and cancer cells. Further, the in vitro fluorescence imaging as well as localization study of QDs were performed in various cells. Moreover, high contrast in vivo tumor imaging efficiency of silica-coated CdSe QDs was performed in ultrathin sections of tumor mice, and the results confirmed its effective role in cellular imaging and labelling in cancer and other diseases.
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    Fluorescence Imaging of Stem Cells, Cancer Cells and Semi-Thin Sections of Tissues using Silica-Coated CdSe Quantum Dots
    (JOURNAL OF FLUORESCENCE, 2011) Vibin, M; Vinayakan, R; John, A; Raji, V; Rejiya, CS; Abraham, A
    Trioctylphosphine oxide capped cadmium selenide quantum dots, synthesized in organic media were rendered water soluble by silica overcoating. Silanisation was done by a simple reverse microemulsion method using aminopropyl silane as the silica precursor. Further, the strong photoluminescence of the silica-coated CdSe quantum dots has been utilized to visualize rabbit adipose tissue-derived mesenchymal stem cells (RADMSCs) and Daltons lymphoma ascites (DLA) cancerous cells in vitro. Subsequently the in vivo fluorescence behaviours of QDs in the tissues were also demonstrated by intravenous administration of the QDs in Swiss albino mice. The fluorescence microscopic images in the stem cells, cancer cells and semi-thin sections of mice organs proved the strong luminescence property of silica-coated quantum dots under biological systems. These results establish silica-coated CdSe QDs as extremely useful tools for molecular imaging and cell tracking to study the cell division and metastasis of cancer and other diseases.
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    Rate and risk of all cause mortality among people with known hypertension in a rural community of southern Kerala, India:The resutls for the prolife cohort.
    (International journal of preventive medicine., 2014) Kuriakose, A; Anish, TSN; Soman, B; Varghese, RT; Sreelal, TP; Mendez, AM; Abraham, A
    Background: Hypertension is one of the most important determinants of death due to vascular damage and is fast emerging as a high burden disease in India. However, its documentation is poor in the country. This study aims to estimate the rate and the causal pattern of mortality in a cohort of people with high blood pressure as compared to normotensives. Methods: The study setting is Varkkala, a rural village in southern Kerala, India, and the study design was that of a prospective cohort. A total of 77,881 participants of age 20 years and above were considered for analysis. The rate and risk of all cause mortality (death due to any cause) among hypertensives were quantified and compared against the normotensives. The causes of death were also analyzedin both the groups. Cox proportional hazard models were created to estimate the hazard ratios of death among hypertensives adjusted for sociodemographic factors, behaviors, and comorbidities. Results: The incidence proportion of deaths in the study was 4.28% during the follow‑up period of 6 years. The relative risk of mortality was 3.13 (CI: 2.91‑3.37) in the high BP group. The age‑adjusted hazard ratio of all cause mortality for the high BP group was 2.96 (2.56‑3.42). Coronary artery disease was the major cause of death among the subjects with high BP. Conclusions: The study revealed high prevalence of hypertension in the study population. A person with hypertension is at three times higher risk of death due to any cause compared to a normotensive individual even after adjustment for age.
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    Synthesis, characterisation and biocompatibility of surface-functionalised gold nanoparticles
    (JOURNAL OF EXPERIMENTAL NANOSCIENCE, 2012) Raji, V; Kumar, J; Rejiya, CS; Vibin, M; John, A; Abraham, A
    Understanding and controlling the interactions between nanoparticles and living cells are of great importance in the diagnosis and therapeutic applications of nanosized materials. This article describes the synthesis, characterisation and interactions of gold nanoparticles (AuNPs) with different in vitro and in vivo experimental models. Preliminary cytotoxicity studies were carried out in tumour ascites (Dalton's lymphoma ascites and Ehrlich's ascites carcinoma) and normal peritoneal cells for different concentrations and it was found that AuNPs did not cause any cell death or morphological changes even at 100 mu M concentrations. The tissue distribution and toxicity of intravenously administered AuNPs were investigated in mice because of the fundamental importance of obtaining information about the localisation and biocompatibility of this material. Tissue distribution of AuNPs was studied in normal as well as skin tumour-induced Swiss albino mice using inductively coupled plasma-atomic emission spectrophotometer and transmission electron microscopy. Acute cytotoxicity and histopathology were carried out for toxicity evaluation in AuNP-injected normal mice and found that AuNPs did not cause any significant metabolic change. The health and behaviour of animals were normal throughout the study. The biocompatibility assessment of AuNPs both in vitro and in vivo confirmed that triethylene glycol-functionalised AuNPs are compatible to the biological system and can be used as a safe material for various biological applications.
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    Synthesis, characterisation and biocompatibility of surface-functionalized gold nanoparticles
    (Journal of Experimental Nanoscience., 2012) Raji, V; Kumar, J; Rejiya, CS; Vibin, M; John, A; Abraham, A