Momentum - The Magazine for Virginia Tech Mechanical Engineering Vol. 4 No. 1 Spring 2019 | Page 22

22
NanoBEADS agents are constructed by conjugating poly(lactic‐co‐glycolic acid) nanoparticles with tumor‐targeting Salmonella typhimurium.
NanoBEADS enhance retention and distribution of nanoparticles in solid tumors by up to a remarkable ≈100‐fold, through intercellular (between cells)
self‐replication and translocation. This transport enhancement is achieved autonomously, without the need for any externally applied driving force or
control input.
passively diffuse on its own?”
Trial and error
"Its (salmonella’s) job as a patho-
gen to penetrate through the
tissue,” Behkam said. “What we
thought is if bacteria are so good
at moving through the tissue, how
about coupling nanomedicine with
the bacterium to carry that med-
icine much farther than it’d pas-
sively diffuse on its own?”
Bahareh Behkam
Although Behkam had a vision for the new
drug delivery system, it took several years for
it to become reality.
“The process of creating nanoparticles and
then attaching them to bacteria in a robust
and repeatable manner was challenging, but
add on top of that ensuring the bacteria stay
alive, discovering the mechanism of bacteria
transport in cancerous tissue, and devising
ways to quantitatively describe the effective-
ness of NanoBEADS, and this was a difficult
project,” Davis said.
SeungBeum Suh, Behkam’s former Ph.D.
student, and Amy Jo, Davis’ former Ph.D.
student, worked together on attaching
nanoparticles while keeping the bacteria alive.
It wasn’t until their fourth attempt that they
started finding success.
“We collaborated to make these particles,
and we attached them to the bacteria,” Be-
hkam said. “Then the question was what is
the mechanism of their translocation in the
tumor? How far do they go into the tumor?
How do we present a quantitative measure of
their performance?”
Behkam along with Suh and current doctoral
student Ying Zhan tested their nanoparti-
cle-attached salmonella in lab-grown tumors.