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

Geißler, David; Belder, Detlev

doi:10.1002/elps.201500192

Cited by 10 publications

(9 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The spectrum of analytes accessible by fluorescence detection could be further extended if deep-UV light is used for excitation. In this case, UV-transparent fused silica chips , would need to be used instead of soda-lime glass, which absorb deep-UV light below 300 nm …”

Section: Resultsmentioning

confidence: 99%

On-Line Coupling of Chip-Electrochromatography and Ion Mobility Spectrometry

et al. 2020

Self Cite

View full text Add to dashboard Cite

We report the first hyphenation of chip-electrochromatography (ChEC) with ion mobility spectrometry (IMS). This approach combines the separation power of two electrokinetically driven separation techniques, the first in liquid phase and the second in gas phase, with a label-free detection of the analytes. For achieving this, a microfluidic glass chip incorporating a monolithic separation column, a nanofluidic liquid junction for providing post-column electrical contact, and a monolithically integrated electrospray emitter was developed. This device was successfully coupled to a custom-built high-resolution drift tube IMS with shifted potentials. After proof-of-concept studies in which a mixture of five model compounds was analyzed in less than 80 s, this first ChEC−IMS system was applied to a more complex sample, the analysis of herbicides spiked in the wine matrix. The use of ChEC before IMS detection not only facilitated the peak allocation and increased the peak capacity but also enabled analyte quantification. As both, ChEC and IMS work at ambient conditions and are driven by high voltages, no bulky pumping systems are needed, neither for the hydrodynamic pumping of the mobile phase as in high-performance liquid chromatography nor for generating a vacuum system as in mass spectrometry. Accordingly, the approach has great potential as a portable analytical system for field analysis of complex mixtures.

show abstract

Section: Resultsmentioning

confidence: 99%

On-Line Coupling of Chip-Electrochromatography and Ion Mobility Spectrometry

et al. 2020

Self Cite

View full text Add to dashboard Cite

show abstract

“…This is not only true for excitation at 266 nm in a one-photon approach but also for the detection of light at higher wavelengths for the two-photon equivalent at 532 nm. Previous studies on label-free detection utilizing PDMS chip materials revealed that full-body PDMS devices are not suitable for this purpose [ 32 ].…”

Section: Resultsmentioning

confidence: 99%

“…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

Self Cite

View full text Add to dashboard Cite

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

show abstract

“…3 shows the optical transparency of different building materials such as fused silica, borosilicate glass, cyclic olefin copolymer (COC), cyclic olefin polymer (COP), PMMA and PDMS for microfluidic devices. 130 White et al developed a low-cost thermoplastic microfluidic chip using PMMA for SERS measurements. 125 Polymeric materials often suffer from poor chemical stability and exhibit Raman signals.…”

Section: Materials and Fabricationmentioning

confidence: 99%