In 1966 , when UC San Diego was little more than a patchwork of Quonset huts and former military barracks , theaters across America premiered the science fiction movie Fantastic Voyage . In it , a submarine and its crew are shrunk to microscopic size and injected into the body of a scientist suffering from an inoperable blood clot in his brain . The mission : repair the blood clot and save his life .
The concept was truly fantastic for the time ; so much so that any researcher peering into a microscope at then-UC La Jolla may have justly relegated it to science fiction forever . How could they have known that decades later , researchers would strive to master that fantastic frontier — to save not only one life , but impact the lives of millions ?
ROCKET TO THE STOMACH
The lab of Joseph Wang , a nanoengineering professor at UC San Diego ’ s Jacobs School of Engineering , is the first stop on UC San Diego ’ s own fantastic voyage . There , you ’ ll find a team creating tube-shaped micromotors — smaller than the width of a human hair — that could one day be used to efficiently deliver drugs to specific locations in the body , or even perform surgeries and conduct biopsies on hard-to-reach tumors . Wang recently teamed up with Liangfang Zhang , a nanoengineering professor affiliated with the cross-disciplinary Institute of Engineering in Medicine , to demonstrate how micromotors could be deployed inside a mouse ’ s stomach and deliver cargo to the stomach wall . “ This is the first example of loading and releasing a cargo in vivo ,” says Wang . “ We thought it was the logical extension of the work we have done , to see if these motors might be able to swim in stomach acid .”
Not only are they able to swim in stomach acid , the acid is a major factor in their ability to swim at all . Made primarily of zinc , these tubular micromotors react with stomach acid to generate a stream of hydrogen bubbles that propel the motors like miniature rockets . This propulsive burst allows the motors to swim around and lodge themselves and their cargo firmly in the stomach wall . As a bonus feature , the zinc micromotors are biodegradable — they gradually dissolve in stomach acid , disappearing within a few days with no toxic traces left behind .
As part of their experiment , Wang , Zhang and their cohorts tested the ability of micromotors to deliver a cargo of gold nanoparticles to the stomach wall of mice . The mice ingested tiny drops of solution containing hundreds of these gold-loaded micromotors , which became active as soon as they hit the stomach acid and propelled themselves toward the stomach wall . Remarkably , the researchers found that more than three times as many gold nanoparticles ended up in the stomachs of mice when delivered by the micromotors , compared to when the gold nanoparticles alone were ingested normally .
The experiment shows the promise of micromotors to safely and efficiently deliver cargo in living animals , a prospect that could one day revolutionize drug delivery . Yet there is much to be explored before that day comes — elements like navigation capabilities and more precise targeting will be crucial .
A DRUG IN CANCER ’ S CLOTHING
BY SUSAN BROWN
The key to destroying cancer cells may be in the very enzymes that make them dangerous . Known as matrix metalloproteinases ( MMP ), these enzymes chew through membranes and let cancer cells colonize other regions of the body , often with deadly consequences . UC San Diego chemists have recently designed nanoparticles that release drugs strictly in the presence of these enzymes , focusing the effects of medicine where it ’ s most needed .
A team led by Nathan Gianneschi , professor of chemistry and biochemistry , has taken tiny spheres of anti-cancer drugs , or nanospheres , and coated them with a protective shell made of peptides — the very membrane proteins that MMPs love to chew through . Yet when the cancer cells tear up the shell and release the drug , the shredded shell forms a ragged mesh that entangles the drug particles , keeping them near the tumor .
22 TRITON | WINTER 2016