Conversion of Nanocrystals to Water Soluble Forms for the Life Sciences
Owing to the excellent optical and electronic properties of nanocrystals coupled with stability under relatively harsh environment, these have been targeted for various biomedical applications. Biomedical applications require high-quality water-soluble nanocrystals. Quantum dots produced in organic solvents at high temperature are monodisperse with narrow size distribution, very wide emission color ranging from ultraviolet to near infrared (300–2500 nm) by simply changing the size, composition and/or structure. But, these quantum dots synthesized in organic solvents are insoluble in water. The same thing can be said for iron oxide magnetic nanocrystals. Using Ocean’s proprietary method, most hydrophobic, organic ligand-coated nanocrystals can be made soluble in water through the monolayer polymer coating strategy. Due to the compact nature of this coating, only one polymer layer is coated on the nanocrystal surface. The organic layer (surface ligand and polymer coating) is less than 4 nm (Figure 1) in thickness and keeps the nanocrystals highly stable. Figure 2 shows the electrophoresis gel picture of Ocean’s quantum dots at emission wavelength of 550, 580, 600, and 620 nm representing the colors green to red. Figure 3 demonstrates that the iron oxide nanoparticles show size dependent migration during an agarose gel electrophoresis.
