Gold nanoisland arrays prepared by sputtering and bio-functionalization of their surfaces

Gold nanoisland arrays (Au NIA) were prepared by sputtering without masking and lithography and were investigated by local surface plasmonic resonance (LSPR) effect. Self-assembly of 11 mercaptoundecanoic acid (11-MUA) monolayers were used for bio-functionalization of Au surfaces because MUA improves an attachment of biontolecides (proteins, antibodies) to the surface of Au. Coverage of 11-MUA induced the blue or the red shift of LSPR wavelength depending on the Au NIA size (nominal thickness t). In accordance with the universal size-scaling model, smaller NIA structures with nominal thicknesses of 5 nm showed little blue shifts Delta lambda = - 11 nm (Au NIA) and Delta lambda = - 13 nm (Au/Ti NIA). In the case of the thicker Au NIA (thickness of 16 nm) the refractive index-based sensing was dominant and the red shift of LSPR wavelength was observed Delta lambda = + 24 nm.