Transfer printing of metal nanoparticles with controllable dimensions, placement, and reproducible surface-enhanced Raman scattering effects.

This paper describes the fabrication of single, multiple strand, and three-dimensional patterning of metal nanoparticles by nanotransfer edge printing (nTEP), a method comprising nanoparticle self-assembly, nanotransfer printing (nTP), and edge lithography. In the process proposed here, 20 nm Au nanoparticles (AuNPs) are deterministically arranged in precise placement by manipulating a topographically patterned poly(dimethylsiloxane) (PDMS) stamp, and Ag nanoparticles are conjugated with AuNP patterns to construct surface-enhanced Raman scattering (SERS)-active substrate to detect trace amounts (10(-13) mol/L) of biological molecules such as thrombin with enhancement up to 10(10). The simple, convenient, and inexpensive procedure has extended nTP and nTEP from using evaporated thin metal film to using self-assembled nanoparticles, and may stretch to other organic and inorganic species to find broad applications in many areas.