A Novel Upconversion/MRI Nanoprobe For Cell Labeling And In Vivo Imaging

In the field of biomedical research,there are many imaging methods could be applied to different areas with variety of different characteristics.But a single imaging method cannot fully meet the medical imaging technology requirements.At present,most multimodal imaging probes have difficulties in preparing,characterizing and further modifying.In addition to its inherent excellent optical properties,the upconversion nanoparticles(UCNPs)with pulsed manganese element doped exhibit good dual-mode imaging capabilities,which are easy to synthesize and facilitate further modification.In order to make better use of the advantages of fluorescence and magnetic resonance dual-mode imaging for get a better solution and biology information in biomedical research.In this paper,a kind of UCNPs with paramagnetic element manganese ion doped(?-NaYF4:20%Yb,2%Er,30%Mn)were prepared.It is better than the general UCNPs in the optical performance,but also has excellent magnetic resonance imaging performance.The UCNPs were modified and characterized by different reaction mechanisms.The potential of UCNPs in cell labeling and in vivo imaging were discussed.The aim of the present research includes:1.Preparation and characterization of hydrophilically modified UCNPsThe oleic acid on the surface of the UCNPs prepared by conventional methods limits their application in the biological system.Conventional modification methods,such as silica encapsulation and organic macromolecule treatment,usually increase the overall size of nanoparticles.The modification processes are also complex.In this paper,DNA chain and phosphorylated cell membrane peptides were used to treat oleic acid-coated UCNPs with hydrophilic treatment Compared with the traditional silica coating method,the experiments show the DNA chain and phosphorylated cell perforation peptide hydrophilic modification is feasible and convenient.At the same time,the UCNPs treated by three modification methods exhibit excellent upconversion luminescence properties and magnetic resonance imaging properties in aqueous solution.2.UCL/MRI nanoprobe for cell labeling and in vivo imagingAn excellent fluorescence/magnetic resonance dual mode imaging probe requires a good biocompatibility and a sufficiently strong signal intensity to distinguish the background signal from in vivo complex biological environments.In order to investigate the excellent dual-mode imaging performance of the UCNPs,the cell-penetrating peptide-modified UCNPs were selected after detecting the cytotoxicity and cellular ability of the three UCNPs.The sensitivity of the probe in cell labeling imaging was investigated by cell counting experiments after incubation UCNPs with cells.The ability of this probe for in vivo imaging and distribution were investigated through live and tissue slice imaging experiments.