Plastic Designer Molecules May Boost Immune System

Plastic molecules made to mimic the body’s natural disease-fighters and injected into living animals behaved like antibodies, latching onto foreign molecules and launching an attack against them in the bloodstream.

The breakthrough is a step toward the medical use of these custom-fabricated particles for targeted attacks on viruses and other harmful antigens, researchers said in a statement. Antigens are objects foreign to an organism's bloodstream, such as viruses, a wide range of bacteria, and allergens such as house dust and plant pollen.   Otherwise known as antibodies, the class of proteins responsible for recognizing antigens disables them through diverse shapes that bind with their surfaces like a key in a lock. Deprived of its surface reactivity, the harmful molecule is effectively neutralized. Scientists used a mold of sorts to produce artificial antibodies from plastic. The chosen antigen was melittin, the primary toxin in bee venom. When mixed with melittin and triggered by a chemical reaction in the lab, nano-sized synthetic particles hardened around the melittin and grew into long chains. After bleeding out the toxin, scientists were left with tiny particles shaped like the surface of the bee-venom antigen.   Mice injected with lethal amounts of melittin recovered in significantly higher rates when immediately injected with the fabricated nanoparticle strands, the scientists said. The result is the first to demonstrate that plastic antibodies work in the bloodstream, they said. "This opens the door to serious consideration for these nanoparticles in all applications where antibodies are used," said study scientist Kenneth Shea at the University of California, Irvine.