Preparation of fluorescent bimodal probe coupled with ultra-small superparamagnetic iron oxide particles

Abstract

To prepare USPIO-PEG-Cy5.5 targeted bimodal probe for noninvasive diagnosis of thyroid cancer. The characterization was verified, and the physical and chemical properties were discussed. Fe3O4 was used as the carrier. Fluorescent Cy5.5 was linked with polyethylene glycol (PEG). A small amount of Cy5.5-NHS fluorescent powder were dissolved in dimethyl sulfoxide solution. PEG-Fe3O4 nanoparticles were centrifuged and ultra-filtrated. The nanoparticles were resuspended with phosphate buffer to change the pH. The Cy5.5 fluorescence was added to the Fe3O4 particles and incubated at 37 °C for 2 h. Characterization test of Cy5.5-PEG-Fe3O4 and relaxation rate measurement were performed. Fro cells were used to perform cell imaging experiment. CCK-8 assay was carried out to detect the cytotoxicity. The bimodal molecular probe Cy5.5-PEG-Fe3O4 was synthesized successfully. Transmission electron microscopy showed that the particle size of the probe was 18.8 ± 3.5 nm, the water and particle size of the nanoparticles was 35.7 ± 18.6 nm, and the zeta potential was −18.0 mv. The relaxation rate was 0.044 and the slope was 0.97. The cytotoxicity test showed that the bimodal molecular probe had slight toxicity to fro cells with a concentration-dependent manner. The synthesized Cy5.5-PEG-Fe3O4 probe has low toxicity, good biocompatibility, stable particle size, which can be used for cell imaging for noninvasive diagnosis of thyroid cancer.

Keywords

• Ultra-small superparamagnetic iron oxide particles
• Fluorescent bimodal probe
• Cell imaging
• Thyroid cancer
• Fe3O4