Periodic arrays of pseudotetrahedal-shaped gold nanoparticles were fabricated using nanosphere lithography (NSL) and examined for localized surface plasmon resonance (LSPR). The dependence of the LSPR on particle size of the periodic gold nanostructures was explored for potential application as a new biosensor. With increasing size and height of the Au nanoparticles, the absorption peak of the LSPR shifts to the longer wavelength and becomes relatively sharper. With thinner metal deposition or finer Au nanostructure, the absorption signal varies more sensitively for the changes in the Au particle size. The binding affinity study for biotin-streptavidine system on the Au nanopat-terns resulted in blue-shifted absorption signal, opening up the possibility of the nanostructured Au pattern as a new LSPR biosensor.