Femtosecond phase control of spatial localization of the optical near-field in a metal nanoslit array.

We demonstrate spatial control of optical near-fields by femtosecond phase shaping in one-dimensional plasmonic structures. The near-field images display striking temporal-phase dependence, switching between double- and single-peak images within one lattice constant. The change of the near-field distribution is studied in the time and spectral domain. The spectral composition change observed by varying the time delay between two phase-locked femtosecond pulses explains the spatial control of the near-field images. Modal expansion calculations of linear light transmission using the surface impedance boundary condition are in excellent agreement with experiments.

Tumor regression in vivo by photothermal therapy based on gold-nanorod-loaded, functional nanocarriers.

We developed a very effective hyperthermia system for successful photothermal cancer therapy. Instead of applying individual gold nanorods (GNRs) that can absorb NIR light, GNRs were loaded into functional nanocarriers that could provide stable storage of GNRs and selective delivery to a target tumor site. The functional nanocarriers (chitosan-conjugated, Pluronic-based nanocarriers) were prepared by chemically cross-linking Pluronic F 68 with chitosan conjugation to form a flexible, soft, and excellent reservoir for biomacromolecules as well as tumor targeting. In vivo characteristics of the nanocarriers including a long circulation time, a good tumor accumulation, and low liver uptake were previously characterized by us. When GNRs were delivered by using these nanocarriers, much enhanced in vitro cellular uptake and a photothermal effect were observed for a cancer cell line. More importantly, an intravenous injection of this system followed by NIR laser irradiation to the tumor site resulted in a very efficient thermolysis in vivo. Thus, apparently complete tumor resorption was achieved without damage to the surrounding tissue, suggesting a promising candidate for clinical phototherapeutic applications.