Capillary electrophoresis techniques in biomedical analysis

© 2015 by Taylor & Francis Group, LLC. Capillary electrophoresis (CE) is a microscale analytical separation technique that has matured rapidly over the past 20 years since the groundbreaking publications of Jorgenson and Lukacs.1,2 Biomedical applications of CE are a leading factor driving the development of what has now evolved into a broad family of related separation techniques. Certainly the most prominent biomedical application of CE is the sequencing of the human genome.3 e accelerated achievement of this goal depended on CE separations.3-5 From 1981 through the writing of this text, more than 14,000 papers were published that included CE and related techniques. A survey of this literature over the past 12 months indicates that more than 70% of these reports include bioanalytical applications of CE

Dispersion Characteristics in Disk-on-Pillar Array Nanostructures for Surface-Enhanced Raman Spectroscopy

In this paper, we analyze periodic disk-on-pillar nanoarrays as a platform for surface-enhanced Raman spectroscopy measurements. The nanostructure is a two-dimensional grating of silicon pillars covered by thin layers of silica and silver. The system supports both localized surface plasmons and surface plasmon polaritons. We investigate the dispersion characteristics of the nanoarray and present the relevant field distribution for each plasmon mode. The interaction between localized and propagating modes can be tuned to synergistically enhance the electric field, which results in larger surface-enhanced Raman signals. We find that utilizing this effect can generate Raman enhancements that are approximately 1000 times larger than that of an isolated pillar under the same excitation conditions

Local Field Enhancement of Pillar Nanosurfaces for SERS

Optical spectra and atomic force microscopy (AFM) images of individually selected spheres and mechanically assembled silica-coated gold nanosphere pairs were recorded. The shell served as a means of rigid control of the minimum spacing between the metal cores. The spectra of the assembled spheres were simulated using classical electrodynamics. The observed spectra resulted in superior characterization of the particle assembly geometry, relative to the AFM data. Experimental investigations regarding less-rigid polyvinylpyrrolidone (PVP) sphere coatings were also performed and some comparisons were made

Efficient disc on pillar substrates for surface enhanced Raman spectroscopy

In this work, geometrical optimizations of Ag disc on pillar (DOP) hybrid plasmonic nanostructures were conducted and allowed us to achieve reproducible average enhancement factors of 1 x 10(9) and greate

Airborne chemistry coupled to Raman spectroscopy

In this paper, the use of airborne chemistry (acoustically levitated drops) in combination with Raman spectroscopy is explored. We report herein the first Raman studies of crystallization processes in levitated drops and the first demonstration of surface-enhanced Raman scattering (SERS) detection in this medium. Crystallization studies on the model compounds benzamide and indomethacin resulted in the formation of two crystal modifications for each compound, suggesting that this methodology may be useful for investigation of polymorphs. SERS detection resulted in a signal enhancement of 27 000 for benzoic acid and 11 000 for rhodamine 6-G. The preliminary results presented here clearly indicate that several important applications of the combination between Raman spectroscopy and acoustic drop levitation can be expected in the future