Rhodamine monitoring

Signals for methyl paraben were monitored with UV detection at 254 nm. The signal for rhodamine 110 chloride was monitored via fluorescence detection with an excitation filter of 482 nm (35 nm bandwidth) and emission filter of 535 nm (40 nm bandwidth). A gradient method (same as the one in Figure 6.16) was used. The compositions of mobile phases A and B were 5 95 H20 CH3CN with 0.1 HCOOH and CH3CN with 0.085% HCOOH, respectively, with a total flow rate of 300 fiL/ min (corresponding to 12.5 /rL/min for each column). 

Field experiments are generally performed by sampling and measurement in upstream and downstream stations of a sewer network. A volume of water in the sewer can be monitored by following the course of a tracer that is added in an upstream station. Substances like rhodamine, radiotracers and salts may typically be selected for that purpose. Sampling after the passage of such tracers is a convenient way to ensure that corresponding samples are taken and to avoid too much noise because of the variability in wastewater quality. 

Zenkl et al. [51] presented another approach to design saccharide-sensitive nanobeads. They prepared particles (0 380 nm) based on poly (/V- i sopropy I aery I am ide) cross-linked with phenylboronic acid moieties. In the presence of a saccharide (glucose or fructose) the particles reversibly swell due to the formation of negative charges. A FRET-indicator couple (fhiorescein/rhodamine) is used to monitor the... 

Fig. 3.9. Single-ion monitoring mass chromatogram (m/z 443, dwell time 500 ms) obtained in the positive-ion mode during the sequential step sampling (30 s sampling time) of four separate bands from developed spots (0.4 p each) of differing amounts of rhodamine 6G, namely, 0 (blank solvent), 1.4, 14 and 145 ng. Reprinted with permission from G. J. Van Berkel et al. [88],...

The mixing experiments were performed using a mercury lamp-induced fluorescence method [92], A microscope, a photomultiplier and a CCD camera were used for image monitoring. Sodium borate (10 mM) as buffer and Rhodamine B as sample were used. A gray-scale analysis was performed to obtain data on the concentration distribution. 

As a second imaging approach, confocal laser scanning microscopy was apphed to monitor the cross-sectional mixing of Rhodamine B solutions (99% ethanol) and pure 99% ethanol [58], Laser scanning over the entire cross-sectional area was performed and at various locations along the channel. 

Ferlini, C., Biselli, R., Nisini, R., and Fattorossi, A., 1995, Rhodamine 123 a useful probe for monitoring T cell activation, Cytometry 21 284-293. 

Function of mitochondria is also commonly monitored as an indicator of cellular toxicity. Mitochondrial uptake and retention of the fluorescent dye, rhodamine 123, can be visualized microscopically. Biochemical measurements of mitochondrial function include the ATP-ADP ratio and dehydrogenase activity with MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide), which yields a colored formazan product upon reduction. The dye, neutral red (3-amino-7-dimethyl-amino-2-methylphenazine hydrochloride), targets lysosomes, and its retention is inversely related to cytotoxicity. Commercially available versions of the MTT and neutral red assays have been adapted to microtiter plate formats to provide highly efficient screening assays. Examples of how cell-type-specific functions can be followed as indicators of cell toxicity are included in Table 8.1. 

Fig. 34 Example of mechanized mesoporous silica nanoparticles (MSNPs). SEM (a) and TEM (b) images show the structure and morphology of the MSNP platform [238]. (c) Structural formula of the a-cyclodextrin-based snap-top rotaxane that blocks the pores of an enzyme-cleavable mechanized MSNP. The stopper is connected to the stalk (dumbbell) by an ester or an amide bond [254]. (d) Release profile of rhodamine B from the snap-top MSNP. The addition of an esterase enzyme cleaves the ester bond, releasing the stopper, a-cyclodextrin, and cargo from the nanoparticles, which is monitored by the fluorescence intensity of rhodamine B. Controls employing an amide bond snap-top or deactivated enzyme do not release significant amounts of cargo...

At low rhodamine concentrations, the rate of diffusion into the hair shaft was sufficiently slow to monitor. A cross section of Caucasian hair exposed to rhodamine at 1 pg/mL is shown in Figure 16. As exposure time was increased, more rhodamine reached the interior of the hair. At 120 min, even though the surface was much brighter than the interior, substantial fluorescence was observed in the interior when compared with unexposed hair or to the 30-min exposure. At a rhodamine exposure of 10 pg/mL for 2 h the rhodamine had penetrated throughout the hair sample (Figure 16). 

The rotational reorientation times of the sample in several solvents at room temperature were measured by picosecond time-resolved fluorescence and absorption depolarization spectroscopy. Details of our experimental setups were described elsewhere. For the time-correlated single photon counting measurement of which the response time is a ut 40 ps, the sample solution was excited with a second harmonics of a femtosecond Ti sapphire laser (370 nm) and the fluorescence polarized parallel and perpendicular to the direction of the excitation pulse polarization as well as the magic angle one were monitored. The second harmonics of the rhodamine-640 dye laser (313 nm 10 ps FWHM) was used to raesisure the polarized transient absorption spectra. The synthesis of the sample is given elsewhere. All the solvents of spectro-grade were used without further purification. 

The effects of microinjected ADP-ribosylated actin are monitored by detection of morphological changes or by visualization of the microfilament system with rhodamine- or FITC-phalloidin (Kiefer ef a/., 1996). 

An important improvement of these assays is the use of fluorescent Pgp substrates with a much higher sensitivity than the anthracyclines. Many of these are dyes that had other applications to monitor cellular functions, such as viability, mitochondrial potential, or pH. We and others have compared extensively many of these dyes for their sensitivity and specificity to detect Pgp function in tumor cell lines (8,11), hematopoietic progenitor cells (12) and AMLs (13). We have chosen to use rhodamine 123 as dye and have validated its use by direct comparison with radiolabeled daunorubicin and vincristine accumulation in AMLs (14). 

Directly visualize the samples using a confocal microscope equipped with a 568 nm laser, suitable for monitoring Rhodamine-PE labelled liposomes (see Fig. 3). 

The emission intensity of FITC is monitored at 520 nm as the analytical signal. When FITC-labeled dextran is bound to Rh-ConA, the rhodamine label quenches the 520-nm emission, so that the intensity measured is at a minimum. In the presence of the analyte (glucose), which diffuses across the dialysis fiber at the tip of the optical fiber, FITC-dextran is displaced from Rh-ConA by glucose, and emission intensity at 520-nm increases. This sensor allows glucose quantitation at concentrations up to 5 mM, and has a relatively slow response due to equilibration of the macromolecular reactions. 

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