Adhesion Enhancements and Surface-Enhanced Raman Scattering Activity of Ag and Ag@SiO Nanoparticle Decorated Ragweed Pollen Microparticle Sensor.

A simple solution processed layer-by-layer approach was used to immobilize metal nanoparticles (NPs) on the surface of ragweed pollen exine to obtain multifunctional particles with significant surface-enhanced Raman scattering (SERS), two-photon excited fluorescence, and enhanced adhesion properties. The rugged pollen exine was functionalized with an amine terminated silane and then treated with Ag or Ag@SiO NPs that were electrostatically attached to the exterior of the pollen by incubation in an NP solution of the appropriate pH. Nanoparticle agglomeration on the pollen gives rise to broadband near infrared (NIR) (785-1064 nm) plasmonic activity, and strong SERS signals from benzenedithiol deposited on NP-pollen composite particles were observed.

Three-dimensional organic microlasers with low lasing thresholds fabricated by multiphoton and UV lithography.

Cuboid-shaped organic microcavities containing a pyrromethene laser dye and supported upon a photonic crystal have been investigated as an approach to reducing the lasing threshold of the cavities. Multiphoton lithography facilitated fabrication of the cuboid cavities directly on the substrate or on the decoupling structure, while similar structures were fabricated on the substrate by UV lithography for comparison. Significant reduction of the lasing threshold by a factor of ~30 has been observed for cavities supported by the photonic crystal relative to those fabricated on the substrate.