Biosensors

The NASA–Ames Research Center tasked us to develop nanosensor⁄NEMS systems for non–invasive, real–time monitoring of radiation–induced illness in space. They identified the need for self–contained, continuous monitoring of astronauts during NASA missions to monitor the biologic effects of space travel. We have developed a non–invasive system that, when placed into the blood cells of astronauts, will provide "moment to moment" information on the astronaut's health status. These molecules should also be able to administer therapeutics in response to the needs of astronauts to ensure their safety.

Accordingly, we developed cellular biosensors based on dendritic polymers, nanoscale structures less than 20 nm in diameter. These sensors are used to target into specific cells of an astronaut and are enabled to monitor health issues such as exposure to radiation. Multiple chemical structures can be assembled on the polymers including target directors, analytical devices (such as molecular probes), and reporting agents. Reporting is accomplished through fluorescence signal monitoring with the use of multispectral analysis for signal interpretation.

These nanosensors could facilitate the success and increase the safety of extended space flight. The design and assembly of these devices has been pioneered at the Michigan Nanotechnology Institute for Medicine and Biological Sciences. M-NIMBS is a multidisciplinary team of chemists, physicists, engineers, pharmacists, (bio)informatics specialists, and biologists collaborating on nanoscience in biology and medicine.

Colleagues from the College of Engineering Center of Ultrafast Optical Sciences developed and tested a flow cytometer–laser system.

miniaturized flow cytometer inside the capillaries in an astronaut's ear — Nanoparticles circulating the blood stream specifically bind to lymphocytes and leukocytes to generate unique fluorescent signals when the lymphocytes become apoptotic due to exposure to radiation. These signals are detected with a miniaturized flow cytometer from the capillaries inside the astronaut's ear. - Graphic created by Paul D. Trombley -

By using dendrimer-dye-folic acid conjugates, we are able to differentiate cell samples. We also proved that our two-photon flow cytometry system is capable of detecting both a single nanosphere in a fluid stream and submicron viruses. We conducted in vivo flow cytometry measurements using immuno-camouflaged KB cells stained with two dendrimer-dye-folic acid biosensors. We are further investigating the underlying science and exploring the possibility of finding parameters associated with cell apoptosis. We plan to assemble the dendrimer-dye-folic acid conjugate with an apoptosis sensor for in vivo monitoring of early events associated with cell apoptosis. See the Flow Cytometry page for greater detail on this technology.

This work has been supported by the U.S. National Aeronautics and Space Administration.