According to American heart association cholesterol is just one of the many substances created and used by our bodies to keep us healthy. There are two types of cholesterol: “good” and “bad”. When too much LDL (bad), (high-density lipoprotein) cholesterol circulates in the blood, it can slowly build up in the inner walls of the arteries that feed the heart and brain. Together with other substances, it can form plaque, a thick, hard deposit that can narrow the arteries and make them less flexible. If a clot forms and blocks a narrowed artery, heart attack or stroke can result. Low levels of HDL (less than 40 mg/dL) also increase the risk of heart disease and medical experts think that HDL tends to carry cholesterol away from the arteries and back to the liver, where it is passed from the body. Northwestern University scientists have developed a synthetic HDL, and built a cholesterol sponge which can help fight chronically high cholesterol levels and the deadly heart disease that often results. The researchers have successfully designed synthetic HDL and showed that the nanoparticle version is capable of irreversibly binding cholesterol. The synthetic HDL, based on gold nanoparticles, is similar in size to natural HDL and mimics HDL's general surface composition and is expected to be an useful therapeutics of the future. Synthetic HDL has a gold nanoparticle as the core and is then layered on a lipid that attaches to the gold surface and then with another lipid and finally a protein, called APOA1 which is the main protein component of naturally occurring HDL which is a having about 18 nanometers in diameter and similar to natural HDL.