Studies of how molecules are released from nanoparticles when they encounter cancer cells and of how the nanoparticles break down prematurely while circulating in the blood point toward ways to improve the nanotech delivery of therapeutic drugs into cancer cells. From “Imaging yields insights into ‘nanomedicine’ for cancer treatment“, a Purdue University news release written by Emil Venere, via Nanowerk News:
Researchers at Purdue University have discovered a possible new pathway for anti-tumor drugs to kill cancer cells and proposed how to improve the design of tiny drug-delivery particles for use in “nanomedicine.”
The synthetic “polymer micelles” are drug-delivery spheres 60-100 nanometers in diameter, or roughly 100 times smaller than a red blood cell. The spheres harbor drugs in their inner core and contain an outer shell made of a material called polyethylene glycol.
Purdue researchers showed for the first time how this shell of polyethylene glycol latches onto the membranes of cancer cells, allowing fluorescent probes mimicking cancer drugs to enter the cancer cells, said Ji-Xin Cheng, an assistant professor in the Weldon School of Biomedical Engineering and Department of Chemistry.
…New findings are detailed in two research papers. One paper appears this week in Proceedings of the National Academy of Sciences [abstract], and another paper also will appear in May in the journal Langmuir [abstract].
The researchers used an imaging technique called Förster resonance energy transfer imaging, or FRET, to make two key discoveries: how fluorescent molecules mimicking the cancer drug paclitaxel enter tumor cells and how the micelles break down in the blood before they have a chance to deliver the drug to cancer cells.
A critical feature of micelles is that they combine two types of polymers, one being hydrophobic and the other hydrophilic, meaning they are either unable or able to mix with water. The hydrophobic core was loaded with a green dye and the hydrophilic portion labeled with a red dye.
Experiments showed that “core-loaded” fluorescent molecules mimicking the drug entered cancer cells within 15 minutes, suggesting a new drug-delivery pathway to kill tumor cells, Cheng said.
…”So this technique provides a system to monitor in real time how well anti-cancer drug delivery is working,” Cheng said.