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.