This project introduces a new and revolutionary way to separate macromolecules. The principle is to use light to selectively retain some molecules over others depending on their differential interaction with optical fields. We call the method Photonic Crystal Defects Chromatography (PCDC), as it combines photonic crystals with artificial defects and a flow channel that constitutes a “column” of conventional liquid chromatography. The method will be useful both for biopolymers (like DNA and proteins) and synthetic polymers. It could potentially have profound implications for several biological and biomedical applications such as proteomics and cancer diagnostics, in which fast and high resolution separation of nucleic acids and proteins from a complex biological fluid is a key aspect.