OPTICAL AMPLIFICATION OF LIGAND-RECEPTOR BINDING USING LIQUID-CRYSTALS

Liquid crystals (LCs) were used to amplify and transduce receptor-medi ated binding of proteins at surfaces into optical outputs, Spontaneous ly organized surfaces were designed so that protein molecules, upon bi nding to ligands hosted on these surfaces, triggered changes in the or ientations of 1- to 20-micrometer-thick films of supported LCs, thus c orresponding to a reorientation of similar to 10(5) to 10(6) mesogens per protein. Binding-induced changes in the intensity of light transmi tted through the LC were easily seen with the naked eye and could be f urther amplified by using surfaces designed so that protein-ligand rec ognition causes twisted nematic LCs to untwist. This approach to the d etection of ligand-receptor binding does not require labeling of the a nalyte, does not require the use of electroanalytical apparatus, provi des a spatial resolution of micrometers, and is sufficiently simple th at it may find use in biochemical assays and imaging of spatially reso lved chemical libraries.