Fluorescein-labeled fluoroapatite nanocrystals codoped with Yb(III) and Ho(III) for trimodal (downconversion, upconversion and magnetic resonance) imaging of cancer cells

详细信息    查看全文

• 作者：Sasidharanpillai S. Syamchand ; George Sony
• 关键词：FITC ; Fluorescence imaging ; Upconversion luminescence imaging ; Multimodal imaging ; Receptor targeted imaging ; Folate receptor ; T2 contrast agents
• 刊名：Microchimica Acta
• 出版年：2016
• 出版时间：December 2016
• 年：2016
• 卷：183
• 期：12
• 页码：3209-3219
• 全文大小：
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Nanochemistry; Nanotechnology; Characterization and Evaluation of Materials; Analytical Chemistry; Microengineering;
• 出版者：Springer Vienna
• ISSN：1436-5073
• 卷排序：183

文摘

The authors report on upconversion nanocrystals (NCs) based on a fluoroapatite (FAp) support that was engineered to enable multimodal imaging by fluorescence imaging (FI), magnetic resonance imaging (MRI), and upconversion luminescence imaging. A fluorescein based fluorophore (FITC) was incorporated into the FAp nanocrystals and then doped with Yb(III) and Ho(III) by microwave-assisted solution combustion synthesis. The hexagonal phase nanocrystals (FITC-FAp:Yb/Ho) exhibit spindle like morphology with an average diameter and length of 15 nm and 196 nm, respectively. The doping concentration of the Yb (5 %) and Ho (0.6 %) was determined by ICP-MS. The nanocrystals exhibit upconversion luminescence when irradiated with NIR light of wavelength 980 nm. The emission spectrum consists of two bands centered at 542 nm (green emission) and 654 nm (red emission) corresponding to two transitions of Ho(III). The pump power dependence of upconversion luminescence intensity confirmed the 2-photon process. The presence of FITC in the nanocrystal imparts green fluorescence (peaking at 521 nm) by a conventional downconversion process. The presence of Ho(III) endows the NCs with paramagnetism. The magnetization is 21.063 emu∙g−1 at room temperature. The NCs exhibit a longitudinal relaxivity (r1) of 0.12 s−1∙mM−1, and a transverse relaxivity (r2) of 29 s−1∙mM−1, which makes the system suitable for developing T2 MRI contrast agents. The nanocrystals are surface aminized using polyethyleneimine (PEI) and covalently conjugated to folic acid (FA) in order to target the folate receptors that are overexpressed in many cancer cells. The FA-conjugated nanocrystals have been tested for their applicability in fluorescence imaging of HeLa cells. Their biocompatibility, upconversion and downconversion luminescence, and magnetism render these NCs potentially powerful nanoprobes for trimodal imaging.