How Gold Nanoparticles Have Stayed in the Light: The 3M’s Principle

tion of noble metal systems that can manipulate light at the nanoscaleOhas attracted significant atten-tion recently because of a combination of several factors, which we have designated as the 3M’s principle: make, measure, model. Advances in nanoparticle synthesis and fabrication, innovations in new analyti-cal tools and measurements, and clever theoretical modeling have kept surface plasmons in the spotlight. The contents of this issue of ACS Nano are no different; three papers perfectly illustrate the 3M’s prin-ciple. Make: Wang and co-workers exhibit control over gold nanorod diameter and length to demonstrate how large rods could scatter light more strongly than small rods with the same length/diameter ratio (Figure 1A).1 Measure: Hafner and co-workers show that localized surface plasmon resonance sensors could be used to monitor antibodyantigen binding in real time and that the binding rates were consistent with literature values (Figure 2).2 Model: Nord-lander and co-workers propose strategies to design substrates for surface-enhanced Raman scattering (SERS) and surface-enhanced infrared absorption (SEIRA) based on “hot spots ” between gold nanoshells.3 All three papers exploit gold nanostruc-tures that support localized surface plas-mons (LSPs), collective oscillations of con-duction electrons that form when light is incident on noble metal structures. In par-ticular, Mayer et al. and Le et al. highlight a key important characteristic of LSPs: they can amplify relatively weak processes. In this Perspective, we focus on (1) how plas-monic nanoparticles can enhance or enable the detection of molecular processes; (2) how the characteristics of nanostructures can be tuned to achieve maximum en-hancement; and (3) how the prospects of LSPs can shine when the “right ” application is found