by Jim Caryl
Tomorrow I have a day workshop in nanomedicine. Working in bionanosciences, which is my current gig, I’d like to think I’ll get more out of it than just a free lunch, but we’ll have to see. Nanomedicine is the application of nanoscience to medicine; you’re probably wondering what on Earth nanoscience is? If you know, could you let me know before my boss finds out?
I jest. Actually, a good example of nanomedicine is described in an upcoming publication from Children’s Hospital Boston, where some enterprising chaps (Yung et al.) have developed a blood cleansing device for use in treating sepsis. Sepsis is a lethal systemic bacterial infection that spreads by the blood and rapidly overcomes the body’s defence system. Typical antibiotic therapies are not sufficient as they do not fully eliminate the infection, and the toxin load on the body, both as a result of live bacteria and dying bacteria, can cause systematic organ failure.
The researcher’s approach is to introduce what are called magnetic nanoparticles, spheres that are a few millionths of a millimetre in diameter, into the blood. These nanoparticles have two important properties, besides being extremely small: they can be attracted by a magnet; and the surfaces of each particle can be covered with an antibody (an immune system protein that binds to foreign molecules) that specifically binds a particular bug. In the case of this work, they used antibodies that bind the fungus Candida albicans, which can cause sepsis in people whose immune systems are not functioning.
When introduced into infected blood, the nanoparticles start to accumulate on each of the fungal cells; the next task it to remove the nanoparticles themselves, which is how the researcher’s have improved upon previous concepts.
They created a microfluidic filter, basically densely packed fluid channels that are themselves minutely thin in diameter, through which blood is pumped. Running along side the blood channels are collection channels; these are the channels into which the fungus-loaded nanoparticles move. The boundary between the blood channels and the collection fluid is essentially porous, but blood loss into the collection channel is reduced by having the fluid in the collection channel under high pressure, thus it takes an additional force, such as a magnetic field, to draw particles from the blood.
In their blood samples, the device was able to remove 80% of the pathogen load in a single pass, and at a flow rate that is clinically viable, i.e. in practise, it would remove and return the blood to a patient before it’s missed.
The system needs to be scaled up and successful phase 1, 2 and 3 clinical trials performed, but it looks promising.
Yung, C., Fiering, J., Mueller, A., & Ingber, D. (2009). Micromagnetic–microfluidic blood cleansing device Lab on a Chip DOI: 10.1039/b816986a