RESUMEN
Microdroplets offer unique environments that accelerate chemical reactions; however, the mechanisms behind these processes remain debated. The localization and orientation of solute molecules near the droplet surface have been proposed as factors for this acceleration. Since significant reaction acceleration has been observed for electrospray- and sonic-spray-generated aerosol droplets, the analysis of microdroplets in air has become essential. Here, we utilized whispering gallery mode (WGM) resonances to investigate the localization and orientation of dissolved rhodamine B (RhB) in a levitated microdroplet (â¼3 µm in diameter) in air. Fluorescence enhancement upon resonance with the WGMs revealed the localization and orientation of RhB near the droplet surface. Numerical modeling using Mie theory quantified the RhB orientation at 68° to the surface normal, with a small fraction randomly oriented inside the droplet. Additionally, low RhB concentrations increased surface localization. These results support the significance of surface reactions in the acceleration of microdroplet reactions.
RESUMEN
Many ion channels and receptor proteins are potential targets for new drugs. However, standard methods for profiling these integral membrane proteins (IMPs) have not been fully established, especially when applied to rare and quantity-limited biological samples. We previously demonstrated that a mixture containing 1-butyl-3-methylimidazolium cyanate, an ionic liquid (IL), and NaOH (termed i-soln) is an excellent solubilizer for insoluble aggregates. In this study, we present a combined i-soln-assisted proteomic sample preparation platform (termed pTRUST), which is compatible with starting materials in the sub-microgram range, using our previously reported i-soln-based sample preparation strategy (iBOPs) and an in-StageTip technique. This novel and straightforward approach allows for the rapid solubilization and processing of a variety of IMPs from human samples to support highly sensitive mass spectrometry analysis. We also demonstrated that the performance of this technology surpasses that of conventional methods such as filter-aided sample preparation methods, FASP and i-FASP. The convenience and availability of pTRUST technology using the IL system have great potential for proteomic identification and characterization of novel drug targets and disease biology in research and clinical settings.