Removing Nanoparticles from your Blood

Nanoparticles — tiny objects 1,000 times smaller than the width of a human hair — are gaining popularity as vehicles for delivering drugs to targeted sites in the body. However, removing these nanoparticles from the bloodstream for further study is a time-con-suming and challenging task. Nanoengineers at the Jacobs School have developed an electric chip that separates drug-delivery nanoparticles from blood within minutes.

The new technology will enable research-ers to study what happens to drug-delivery nanoparticles circulating in a patient’s blood-stream and determine whether these parti-cles are compatible with a patient’s blood.

“We were interested in a fast and easy way to take these nanoparticles out of blood plasma so we could find out what’s going on at their surfaces and redesign them to work more effectively in blood,” said Michael Heller, a nanoengineering professor at UC San Diego and senior researcher on the project.

The electric chip used to isolate drug-de-livery nanoparticles was manufactured by Biological Dynamics, a Jacobs School spin-


Nanoparticle removal from blood

out which licensed the original technology from Heller’s lab. The chip is the size of a dime and contains hundreds of tiny electrodes that generate a rapidly oscillating electric field that selectively pulls nanoparticles out of a plasma sample. After inserting a drop of blood plas-ma spiked with nanoparticles into the electric chip, researchers demonstrated nanoparticle recovery within seven minutes.

The technology works on different types of drug-delivery nanoparticles. Moreover, the technique doesn’t require any modifications to the nanoparticles or plasma samples — an advantage over other nanoparticle separation methods.

The chip’s ability to pull nanoparticles out of plasma is based on differences in material properties between the nanoparticles and plasma components. When the chip’s elec-trodes apply an oscillating electric field, the nanoparticles’ positive and negative charges re-orient at a speed different from the charges in the surrounding plasma. This mo-mentary charge imbalance creates an attrac-tive force between the nanoparticles and the electrodes. As the electric field oscillates, the nanoparticles gravitate toward the electrodes while plasma stays behind. The electric field is designed to oscillate at just the right frequen-cy to do this: 15,000 times per second.

Slow Eating

In a pilot study, researchers investigate whether pausing between bites can help kids to avoid overeating.

Getting children to wait 30 seconds between bites of food just might allow them to realize early on that they’re no longer hungry. And this could help keep them from overeating.

“To lose weight, you need to stop eating. But it’s not that simple for most people,” said bioengineering professor Marcos Intaglietta, a co-author on the new study. “So we decided to investigate how effective eating slowly would be.”

The study’s goal was to minimize the amount of food children ate before their stomach told their brain that they’re no longer hungry — the so-called “satiety reflex,” which takes about 10 minutes to kick in. “You can adopt this slow eating approach for yourself and keep it up for the rest of your life,” said Jacobs School bioengineer and co-author Geert Schmid-Schönbein. “You can teach this approach to your children.”


The study, a collaboration with physicians and researchers at higher education institutions in Mexico, showed that children didn’t gain excessive weight when chewing slowly. The team would like to conduct further studies with a larger sample size both in Mexico and in Southern California.

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