Amplification of interference color by using liquid crystal for protein detection

Micrometer-sized, periodic protein lines printed on a solid surface cause interference color which is invisible to the naked eye. However, the interference color can be amplified by using a thin layer of liquid crystal (LC) covered on the surface to form a phase diffraction grating. Strong interference color can thus be observed under ambient light. By using the LC-amplified interference color, we demonstrate naked-eye detection of a model protein-immunoglobulin G (IgG). Limit of detection can reach 20 mu g/ml of IgG without using any instrumentation. This detection method is potentially useful for the development of low-cost and portable biosensors. (C) 2013 AIP Publishing LLC.