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Core-Shell Structures of Upconversion Nanocrystals Coated with Silica for Near Infrared Light Enabled Optical Imaging of Cancer Cells

School of Basic Sciences and Advanced Materials Research Center, Indian Institute of Technology Mandi, Kamand, Mandi 175005, Himachal Pradesh, India
Pharmaceutical Sciences Laboratory, Faculty of Sciences and Engineering, Åbo Akademi University, 20520 Turku, Finland
Authors to whom correspondence should be addressed.
Micromachines 2018, 9(8), 400;
Received: 3 July 2018 / Revised: 8 August 2018 / Accepted: 9 August 2018 / Published: 14 August 2018
(This article belongs to the Special Issue Nanostructures for Bioimaging)
PDF [3593 KB, uploaded 14 August 2018]


Optical imaging of cancer cells using near infrared (NIR) light is currently an active area of research, as this spectral region directly corresponds to the therapeutic window of biological tissues. Upconversion nanocrystals are photostable alternatives to conventional fluorophores. In our work, we have prepared upconversion nanocrystals of NaYF4:Yb/Er and encapsulated them in silica to form core-shell structures. The as-prepared core-shell nanostructures have been characterized for their structure, morphology, and optical properties using X-ray diffraction, transmission electron microscopy coupled with elemental mapping, and upconversion luminescence spectroscopy, respectively. The cytotoxicity examined using cell viability assay indicated a low level of toxicity of these core-shell nanostructures. Finally, these core-shell nanostructures have been utilized as photostable probes for NIR light enabled optical imaging of human breast cancer cells. This work paves the way for the development of advanced photostable, biocompatible, low-toxic core-shell nanostructures for potential optical imaging of biological cells and tissues. View Full-Text
Keywords: core-shell structures; upconversion nanocrystals; NIR imaging; cancer cells core-shell structures; upconversion nanocrystals; NIR imaging; cancer cells

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Lingeshwar Reddy, K.; Prabhakar, N.; Rosenholm, J.M.; Krishnan, V. Core-Shell Structures of Upconversion Nanocrystals Coated with Silica for Near Infrared Light Enabled Optical Imaging of Cancer Cells. Micromachines 2018, 9, 400.

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