Label-Free Fluorescence Detection of Aromatic Compounds in Chip Electrophoresis Applying Two-Photon Excitation and Time-Correlated Single-Photon Counting

Beyreiss, Reinhild; Geißler, David; Ohla, Stefan; Nagl, Stefan; Posch, Tjorben Nils; Belder, Detlev

doi:10.1021/ac4010937

Cited by 15 publications

(11 citation statements)

References 72 publications

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“…For example, a typical 266-nm deep-UV source translates to excitation at 532 nm in the visible range. This is perfectly compatible with common chip materials [31][32][33][34] and optical elements, which also leads to less photostress in living cells [35][36][37].…”

Section: Introductionmentioning

confidence: 99%

Two-photon fluorescence lifetime for label-free microfluidic droplet sorting

et al. 2021

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Microfluidic droplet sorting systems facilitate automated selective micromanipulation of compartmentalized micro- and nano-entities in a fluidic stream. Current state-of-the-art droplet sorting systems mainly rely on fluorescence detection in the visible range with the drawback that pre-labeling steps are required. This limits the application range significantly, and there is a high demand for alternative, label-free methods. Therefore, we introduce time-resolved two-photon excitation (TPE) fluorescence detection with excitation at 532 nm as a detection technique in droplet microfluidics. This enables label-free in-droplet detection of small aromatic compounds that only absorb in a deep-UV spectral region. Applying time-correlated single-photon counting, compounds with similar emission spectra can be distinguished due to their fluorescence lifetimes. This information is then used to trigger downstream dielectrophoretic droplet sorting. In this proof-of-concept study, we developed a polydimethylsiloxane-fused silica (FS) hybrid chip that simultaneously provides a very high optical transparency in the deep-UV range and suitable surface properties for droplet microfluidics. The herein developed system incorporating a 532-nm picosecond laser, time-correlated single-photon counting (TCSPC), and a chip-integrated dielectrophoretic pulsed actuator was exemplarily applied to sort droplets containing serotonin or propranolol. Furthermore, yeast cells were screened using the presented platform to show its applicability to study cells based on their protein autofluorescence via TPE fluorescence lifetime at 532 nm. Graphical abstract

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Section: Introductionmentioning

confidence: 99%

Two-photon fluorescence lifetime for label-free microfluidic droplet sorting

et al. 2021

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“…A major challenge in chip‐based separations is however still the detection of minute sample amounts in such miniaturized channels. In this context, fluorescence detection is the most popular approach because of its high sensitivity and simplicity . However, as native fluorescent compounds are rather rare, an additional labeling step of the sample with a suitable fluorophore before analysis is often necessary, which is laborious and may alter the chemical properties of the sample.…”

Section: Introductionmentioning

confidence: 99%

Chip‐based electrochromatography coupled to ESI‐MS detection

et al. 2016

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In this study, we present the coupling of chip-based electrochromatography to MS using a glass chip with a monolithically integrated nanoelectrospray emitter. As separation column, an acrylate-based porous polymer monolith is implemented into the glass chip by photopolymerization. For the establishment and development of this method, we used a test mixture detectable with both fluorescence and ESI-MS. After successful evaluation of the approach with the test solutes, it was applied exemplarily for drug analysis such as high-speed separations of benzodiazepines in pharmaceuticals.

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“…These characteristics enable laser‐induced fluorescence detection in the deep UV with low autofluorescence in materials, which are otherwise intransparent. In earlier work, we applied TPE in glass microfluidic chips . At that time, the intended extension to polymer chips was hampered by laser damage of the plastic chips.…”

Section: Introductionmentioning

confidence: 99%

Two‐photon excitation in chip electrophoresis enabling label‐free fluorescence detection in non‐UV transparent full‐body polymer chips

Geißler

Belder

2015

Electrophoresis

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One of the most commonly employed detection methods in microfluidic research is fluorescence detection, due to its ease of integration and excellent sensitivity. Many analytes though do not show luminescence when excited in the visible light spectrum, require suitable dyes. Deep-ultraviolet (UV) excitation (<300 nm) allows label-free detection of a broader range of analytes but also mandates the use of expensive fused silica glass, which is transparent to UV light. Herein, we report the first application of label-free deep UV fluorescence detection in non-UV transparent full-body polymer microfluidic devices. This was achieved by means of two-photon excitation in the visible range (λex = 532 nm). Issues associated with the low optical transmittance of plastics in the UV range were successfully circumvented in this way. The technique was investigated by application to microchip electrophoresis of small aromatic compounds. Various polymers, such as poly(methyl methacrylate), cyclic olefin polymer, and copolymer as well as poly(dimethylsiloxane) were investigated and compared with respect to achievable LOD and ruggedness against photodamage. To demonstrate the applicability of the technique, the method was also applied to the determination of serotonin and tryptamine in fruit samples.

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Label-Free Fluorescence Detection of Aromatic Compounds in Chip Electrophoresis Applying Two-Photon Excitation and Time-Correlated Single-Photon Counting

Cited by 15 publications

References 72 publications

Two-photon fluorescence lifetime for label-free microfluidic droplet sorting

Two-photon fluorescence lifetime for label-free microfluidic droplet sorting

Chip‐based electrochromatography coupled to ESI‐MS detection

Two‐photon excitation in chip electrophoresis enabling label‐free fluorescence detection in non‐UV transparent full‐body polymer chips

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