We reported sonication-mediated film assembly of gold nanoparticles at a water/hexane interface used as a surface-enhanced Raman scattering(SERS) substrate.Gold colloids/hexane biphasic system was emulsified by sonication,and then the emulsions were left undisturbed to allow natural breaking emulsions.In the end,gold nanoparticle films were formed at the interface.The interfacial nanoparticle films can be easily transferred onto a Cu grid and Si wafer for transmission electron microscopy(TEM) and SERS characterizations,respectively.TEM image shows that the as-formed gold nanoparticle films are of a monolayer structure without notable aggregates.SERS measurements indicate that when the gold nanoparticle films were used as SERS substrates to detect 4-MPY,the detection limit can be reached to 1×10-8 mol/L.
