Microdroplet mixing for rapid reaction kinetics with Raman spectrometric detection

Resonance Raman Spectra of Native and Mesoheme-reconstituted Horseradish Peroxidase and Their Catalytic Intermediates

“…A 394 /A 280 ) Ն 3.5, was used for spectroscopic measurement immediately after preparation. The Compound I species are prepared by using compressed nitrogen to force the enzyme and buffered hydrogen peroxide solutions (Aldrich) (enzyme:H 2 O 2 ϭ 1:2.75), held in separate reservoirs, into a mixing chamber and subsequently through the microdroplet generator (30,31). A low temperature stirred cell (36) was employed for the measurement of Compound II species, while a conventional spinning cell was used for the resting state samples.…”

“…Later studies, using conventional flow methods (25) or short laser pulses (26,27), yielded spectra which were insignificantly different from that of HRP-II and were interpreted as being either that of HRP-I (25) or that of an HRP-II-like photoproduct (27). We (28) and others (29) attempted to overcome this photolability problem by using a novel microdroplet sampling device, first employed in our laboratory (28,30,31), which effectively reduces sample residence time in the beam (to less than 5 s). The results of these latter two studies were in essential agreement, giving a new spectrum at low laser powers which, at higher powers, reverted to the spectrum of a (presumably photoreduced) product which resembled that of authentic HRP-II.…”

Initial Collision Process of Two Miscible Droplets

“…A spatially and temporally reproducible generation of the liquid–liquid interface is essential to conduct investigations on the miscible interface. In that sense, liquid droplets facilitate the studies on the dynamics at the liquid–liquid interface, because small liquid droplets can be generated reproducibly by the use of a piezo droplet nozzle. , Simpson and co-workers have applied the collision of liquid droplets for the investigation of the rapid reaction kinetics triggered by mixing two solutions. − They merged two streams of droplets and observed the amount of the reactant and product species by Raman spectroscopy. They determined the rate constant of the complex-formation reaction of Fe 2+ and 1,10-phenanthroline by using this method .…”

Development of a microdroplet mixing technique for the study of rapid reactions by Raman spectroscopy

“…The needle is housed in a rectangular delrin block and provides the interface between the flow system and the capillary. In order to successfully collide droplets, three conditions must be satisfied: (1) the streams must be made to intersect; (2) the droplets of each stream must be equally spaced; and (3) they must be in phase. The first and third requirements are satisfied by mounting each generator assembly on a precision linear translator (l-µ resolution) as shown in Figure 2.…”