"We use the quantum dots to create a set of beads that are unique and can be distinguished from each other. It’s similar to bar-coding -- once you barcode the beads and put them in the urine or blood sample, you can remove them and decode what proteins or viruses have attached to individual beads based on their spectral signature," explained Sathe.
The process of creating these beads is quite simple, according to Sathe. The surface of the beads contains a long-chain carbon molecule that makes the beads hydrophobic, meaning they repel water. The beads are dissolved in butanol and washed several times. Then the beads are counted and optical and magnetic nanocrystals are added to the suspension either simultaneously or sequentially. __IMAGE_3
After 15-20 minutes, the butanol is removed to get rid of any remaining nanoparticles that didn’t get incorporated into the beads and the beads are washed with ethanol. Then the beads are coated with a polymer that creates a hydrophilic surface on the beads. This allows the beads to be functionalized by adding antibodies or DNA molecules to the surface that will capture the target molecules.
These beads are dual-function -- both optical and magnetic -- but according to Sathe, more functions can be added to the beads. "Adding them is as easy as adding the nanoparticles into the solution. You just have to make sure the nanoparticle surface is hydrophobic so that it interacts with the beads," said Sathe.
The primary biomedical applications for this new technology will be to detect cancer and neurological diseases by identifying certain molecules present in human blood or urine that indicate specific diseases, according to Nie, who is also professor of biomedical engineering, chemistry, materials sc
Source:Georgia Institute of Technology Research News