A new type of "good cholesterol," made in the lab, could one day deliver drugs to where they are needed in the body to treat disease or be used in medical imaging, according to scientists. Their report on the high-density lipoprotein（脂蛋白） (HDL) mimic, which is easy to make in large amounts, appears in the journal ACS Nano. Zahi A. Fayad, Robert Langer, YongTae (Tony) Kim, Francois Fay, Willem Mulder and colleagues explain that HDL is a natural nanoparticle that carries cholesterol throughout the body. Because it acts like a scavenger（清道夫）, collecting cholesterol and taking it to the liver for breakdown, HDL has emerged from being simply a marker for cardiovascular disease -- the number one killer of men and women in America -- to being a therapeutic agent. Clinical trials are testing its potential to combat atherosclerosis（动脉粥样硬化）, the build-up of plaques in blood vessels that can lead to heart attacks or strokes. Scientists are also exploring new ways to use it for drug delivery. But HDL is complex and comes in many varieties. It takes several labor-intensive steps to get a uniform collection of these particles with current methods, which aren't easily scaled up for clinical applications. That's why Fayad and Langer's groups devised a new and improved method for making HDL-like particles.

The scientists showed that microfluidics -- the same technology that enabled the invention of inkjet printers -- allowed them to make material called µHDL that looks and acts like HDL in a single, rapid step. Not only does this material offer a possible, easy new way to treat cardiovascular disease, but the researchers also attached drug compounds, as well as dyes and nanocrystals used in medical imaging (such as those used for MRIs and CT scans), to the particles.