Detection of nonfluorescent molecules using differential interference contrast thermal lens microscope for extended nanochannel chromatography

Abstract

An ultrasensitive absorbance detector, the differential interference contrast thermal lens microscope (DIC-TLM), was employed for a chromatography system using silica nanochannel. Recently, separation of ultrasmall volume sample has been strongly required for single-cell biological and chemical analysis. Previously, we have developed a chromatography system using nanochannels of ~100 nm scale (extended nanochannels) fabricated on a silica substrate. The extended nanochromatography realized highly efficient separation of samples <1 fL without packing materials. However, its detection method was limited to fluorescence method due to the small volume, and a new detector based on absorbance has been required. On the contrary, we have also developed DIC-TLM, a photothermal spectrometer based on absorption and thermal relaxation of sample for determination of concentration of nonfluorescent molecules in extended nanochannel. In this paper, we combined the extended nanochromatography and the DIC-TLM for separation and detection of nonfluorescent dyes. Particularly, basic performances of the DIC-TLM including quantitative performance and sensitivity were deliberated for injected samples of ~fL volume.

EBM in primary care: a qualitative multicenter study in Spain

“…It was verified by the interviewers and field notes were added. Analysis was done following the model of sociological discourse analysis [25,26]. Using this model, the reading, organization and interpretation of data does not come from a fragmentation of texts but from a more global view, keeping in mind the context in which data were generated.…”

Progress in Thermal Lens Spectrometry and Its Applications in Microscale Analytical Devices

“…Counting of individual gold nanoparticles (5 nm) was demonstrated by this system. Later, the same authors applied this instrument for determination of the concentration of nonfluorescent species in an extended nanochannel where a LOD of 2.4 mM of Sunset Yellow dye, corresponding to 390 molecules in the detection volume of 0.25 fL, was achieved in a 21 mm wide  500 nm deep nanochannel (Shimizu et al, 2010), and in extended nanochromatography where the LOD was $10 mM, corresponding to $1000 molecules in the detection volume of 0.25 fL (Shimizu et al, 2011).…”

“…As reviewed before (Dudkoa et al, 2012;Ghaleb and Georges, 2004;Kitamori et al, 2004;Tokeshi et al, 2003), different TLM instruments have found many applications in chemical, biochemical/biomedical, and environmental fields for analysis of different compounds, such as metal ions, antigens, amino acids, catecholamines, cytochrome c, pharmaceuticals, and pesticides. In recent years, some new variations of TLM have been developed for specific applications, such as circular dichroism TLM in the UV region (UV-CD-TLM) for chiral analysis on a microchip , polarization modulation TLM (PM-TLM) for imaging the orientation of nonspherical nanoparticles (Zhang et al, 2011), and differential interference contrast TLM (DIC-TLM) in a microchannel or extended nanochannel for background-free detection of nanoparticles (Shimizu et al, 2009(Shimizu et al, , 2010(Shimizu et al, , 2011. With the development of a more accurate TL theoretical model , the signal-generation mechanism in micro space was better understood , incorporation of an incoherent light source (ILS) into the TLM as the excitation source was demonstrated as feasible , rapid detection of environmental samples was realized (Liu and Franko, 2014b), and molecular diffusion in a two-phase system in the microchannel was investigated as well.…”

Micro and Extended-Nano Fluidics and Optics for Chemical and Bioanalytical Technology

“…Previously, a conventional TLM with a UV excitation laser was successfully used as a detector of chromatography [96]. In addition, the detection performance of DIC-TLM was verified as a detector of the extended-nano chromatography [97]. Combining the UV excitation, DIC-TLM and extended-nano chromatography, an integrated sys- …”