This paper reports successful synthesis of multifunctional nanoclusters of upconversion nanoparticle (UCNP) and gold nanorod (AuNR) through a PEGylation process. UCNPs emit visible luminescence under near-infrared excitation, producing high-contrast images with no background fluorescence. When coupled with AuNRs, the resulting UCNP-AuNR multifunctional nanoclusters is capable of simultaneous detection and treatment of bladder cancer. These UCNP-AuNR nanoclusters are further functionalized with antibodies to epidermal growth factor receptor (EGFR) to target bladder cancer cells known to overexpress EGFRs. This paper demonstrates, for the first time, efficient targeting of bladder cancer cells with UCNP-AuNR nanoclusters. In addition to high-contrast imaging and consequently high sensitivity detection of bladder cancer cells, highly selective optoporation-assisted chemotherapy was accomplished using a dosage of chemotherapy agent significantly lower than any previous reports, within a clinically relevant incubation window. These results are highly relevant to the eventual human application in which the nanoclusters and chemotherapy drugs will be directly instilled in bladder via urinary catheter.

Surface reactions between heated aluminum nanoparticles (Al NPs) and thin α-MoO 3 sheets are investigated. Localized photothermal heating on Al NP clusters is provided by a Raman spectrometer laser, while enhanced heating rates and imaging resolution are enabled by the use of a plasmonic grating substrate. Prominent linear reaction zones extending from Al NPs in the 〈001〉 crystal direction are observed on the surface of the host MoO 3 sheets after heating. Raman spectroscopy and x-ray diffraction indicate that α-Al 2 O 3 is generated within these extended reacted regions, while AFM and SEM indicate that the topology of the reaction regions are indistinguishable from the MoO 3 host. We hypothesize that these Al 2 O 3 zones are formed by surface diffusion and subsequent sub-surface adsorption of heated Al adatoms along the lowenergy 〈001〉 MoO 3 direction. Understanding and controlling these reaction mechanisms could lead to enhanced combustion of Al/MoO 3 nanothermite systems.

High nonlinearity optical devices are of interest for compact, low power devices. Whispering gallery mode (WGM) microresonators offer strong nonlinear optical responses due to high quality factors and the small mode volume. To achieve high nonlinearity with these WGM devices, both a material with a high nonlinear index as well as a high quality factor is required. Indium tin oxide (ITO) is an excellent nonlinear material due to an exceptionally high nonlinear refractive index found at the epsilon-near-zero wavelength. However, ITO’s enormous absorption at this point prohibits having a resonator with a high quality factor. Here, we present a novel ITO nanoparticle-coated silica microsphere with significantly enhanced nonlinearity while maintaining high quality factors. Nonlinear refractive index and quality factor of the ITO nanoparticle-coated silica microsphere are obtained by fitting the measured transmission spectra with a theoretical model that includes thermal and Kerr effects. By controlling the number of particles on a silica surface, we achieve 39–187 times higher nonlinear indices compared with a pure silica microsphere and quality factors between 106 and 107. The study establishes a new avenue toward novel nonlinear optical devices based on ITO nanoparticles, which can be readily incorporated in a variety of geometries.

A plasmonic nanostructure with lanthanide-doped upconversion nanoparticles for an improved ratiometric sensing platform.

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