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A 16-fold metal-enhanced fluorescence (MEF) from well organized and closely packed long-chain nitrobenzoxadiazole (NBD-C16 and NBD-C18) probes on silver island films (SIFs) deposited with the use of the Langmuir-Blodgett technique is reported. The results reveal that the increase in MEF efficiency is justified based on the cooperative effects of the modulations in electronic density of the surface plasmon absorption band of SIFs and defined probe orientation that might lead to preferential excitation.

Laser scanning confocal fluorescence microscopy (LSCM) is now an important method for tissue and cell imaging when the samples are located on the surfaces of glass slides. In the past decade, there has been extensive development of nano-optical structures that display unique effects on incident and transmitted light, which will be used with novel configurations for medical and consumer products. For these applications, it is necessary to characterize the light distribution within short distances from the structures for efficient detection and elimination of bulky optical components. These devices will minimize or possibly eliminate the need for free-space light propagation outside of the device itself. We describe the use of the scanning function of a LSCM to obtain 3D images of the light intensities below the surface of nano-optical structures. More specifically, we image the spatial distributions inside the substrate of fluorescence emission coupled to waveguide modes after it leaks through thin metal films or dielectric-coated metal films. The observed spatial distribution were in general agreement with far-field calculations, but the scanning images also revealed light intensities at angles not observed with classical back focal plane imaging. Knowledge of the sub-surface optical intensities will be crucial in the combination of nano-optical structures with rapidly evolving imaging detectors. [ABSTRACT FROM AUTHOR]

We have tested the feasibility of tear glucose sensing using a daily, disposable contact lens embedded with boronic acid-containing fluorophores as a potential alternative to current invasive glucose-monitoring techniques. Our findings show that our approach may, indeed, be suitable for the continuous monitoring of tear glucose levels in the range 50-500 [micro]M, which track blood glucose levels that are ~5-10-fold higher. We compare the response of the boronic acid probes in the contact lens to solution-based measurements and can conclude that both the pH and polarity within the contact lens need to be considered with respect to choosing/designing and optimizing glucosesensing probes for contact lenses.

The ensemble and single-molecule fluorescence spectral properties of CdTe nanocrystals spin coated in polyvinyl alcohol (PVA) matrix on glass and silver island films (SIFs) are described, where CdTe are prepared using a modified Weller method. The single-molecule study has provided information about the heterogeneity in the fluorescence enhancement and lifetimes of the CdTe nanocrystals on both glass and SIF surfaces and also on the metal-fluorophore interactions to understand the Metal-Enhanced Fluorescence (MEF).