ac500793e_si_001.pdf (577.21 kB)
Rapid Prototyping of Electrochromatography Chips for Improved Two-Photon Excited Fluorescence Detection
journal contribution
posted on 2014-04-15, 00:00 authored by Claudia Hackl, Reinhild Beyreiss, David Geissler, Stefan Jezierski, Detlev BelderIn
the present study, we introduce two-photon excitation at 532
nm for label-free fluorescence detection in chip electrochromatography.
Two-photon excitation at 532 nm offers a promising alternative to
one-photon excitation at 266 nm, as it enables the use of economic
chip materials instead of fused silica. In order to demonstrate these
benefits, one-photon and two-photon induced fluorescence detection
are compared in different chip layouts and materials with respect
to the achievable sensitivity in the detection of polycyclic aromatic
hydrocarbons (PAHs). Customized chromatography chips with cover or
bottom slides of different material and thickness are produced by
means of a rapid prototyping method based on liquid-phase lithography.
The design of thin bottom chips (180 μm) enables the use of
high-performance immersion objectives with low
working distances, which allows one to exploit the full potential
of two-photon excitation for a sensitive detection. The developed
method is applied for label-free analysis of PAHs separated on a polymer
monolith inside polymer glass sandwich chips made from fused silica
or soda-lime glass. The obtained limits of detection range from 40
nM to 1.95 μM, with similar sensitivities in fused silica thin
bottom chips for one-photon and two-photon excitation. In deep-UV
non- or less-transparent devices two-photon excitation is mandatory
for label-free detection of aromatics with high sensitivity.