Plasmonic Sensing via Photoluminescence of Individual Gold Nanorod

Label-free plasmonic sensors based on localized surface plasmon resonances of nanostructured noble metal materials usually transduce optical refractive index changes occurring in the vicinity of the nanostructures by optical scattering or by extinction. We demonstrate in experiments that the photoluminescence of plasmonic nanoparticles can also be employed to detect biological molecule binding events efficiently. Photoluminescence probably due to plasmon emission of a single gold nanorod presents a similar resonance peak and resembles the response to a refractive index change observed by scattering. The well-known biotin–streptavidin binding assay was detected successfully using the photoluminescence of an individual isolated nanorod. The localized surface plasmon resonances’ responses by scattering <i>in situ</i> with the same nanorod and control experiments were also performed to verify the sensing process. The results evidence that a nanoscale plasmonic sensor can also be archived effectively through the photoluminescence of a single plasmonic nanostructure. Furthermore, key parameters to optimize the photoluminescence based label-free plasmonic sensing are discussed in detail. The photoluminescence provides an alternative way for label-free plasmonic sensing. And it is believed that further exploration of this concept could lead to a whole new class of efficient plasmonic sensors with diverse and novel functionalities.