ABSTRACT
Micro free-flow electrophoresis (µFFE) is a continuous separation technique in which analytes are streamed through a perpendicularly applied electric field in a planar separation channel. Analyte streams are deflected laterally based on their electrophoretic mobilities as they flow through the separation channel. A number of µFFE separation modes have been demonstrated, including free zone (FZ), micellar electrokinetic chromatography (MEKC), isoelectric focusing (IEF) and isotachophoresis (ITP). Approximately 60 articles have been published since the first µFFE device was fabricated in 1994. We anticipate that recent advances in device design, detection, and fabrication, will allow µFFE to be applied to a much wider range of applications. Applications particularly well suited for µFFE analysis include continuous, real time monitoring and microscale purifications.
Subject(s)
Electrophoresis , Microfluidic Analytical Techniques , Cell Line , Equipment Design , Humans , Lab-On-A-Chip Devices , Proteins/analysis , Proteins/chemistry , Proteins/isolation & purificationABSTRACT
Two-dimensional (2D) separations are able to generate significantly higher peak capacities than their one-dimensional counterparts. Unfortunately, current hyphenated 2D separations are limited by the speed of the second dimension separation and the consequent loss of peak capacity due to under sampling of peaks as they elute from the first dimension separation. Continuous micro free flow electrophoresis (µFFE) separations eliminate under sampling as a limitation when incorporated as the second dimension of a 2D separation. In the current manuscript we describe the first coupling of capillary electrophoresis (CE) with µFFE to perform 2D CE × µFFE separations. The CE separation capillary was directly inserted into the µFFE separation channel using an edge on interface. Analyte peaks streamed directly into the µFFE separation channel as they migrated off the CE capillary. No complicated injection, valving, or voltage changes were necessary to couple the two separation modes. 2D CE × µFFE generated an ideal peak capacity of 2â¯592 in a 9 min separation of fluorescently labeled peptides (7.6 min separation window, 342 peaks/min). Data points were recorded every 250-500 ms (>8 data points/peak), effectively eliminating under sampling as a source of band broadening. CE × µFFE generated an ideal peak capacity of 1885 in a 2.7 min separation of fluorescently labeled small molecule bioamines (1.8 min separation window, 1053 peaks/min). Peaks in the 2D CE × µFFE separation of peptides covered 30% of the available separation space, resulting in a corrected peak capacity of 778 (102 peaks/min). The fractional coverage of the 2D CE × µFFE separation of small molecule bioamines was 20%, resulting in a corrected peak capacity of 377 (209 peaks/min).
Subject(s)
Amines/analysis , Electrophoresis, Capillary/methods , Peptides/analysis , Amines/isolation & purification , Animals , Cattle , Peptides/isolation & purification , Serum Albumin, Bovine/chemistry , Serum Albumin, Bovine/metabolismABSTRACT
Guest induced shape change of the cucurbit[8]uril cavity is likely rate limiting in the supramolecular photocatalytic cycle for CB8 mediated photodimerization of 6-methylcoumarin.
Subject(s)
Bridged-Ring Compounds/chemistry , Coumarins/chemistry , Imidazoles/chemistry , Catalysis , Crystallography, X-Ray , Dimerization , Kinetics , Molecular Conformation , Photochemical Processes , Spectrometry, FluorescenceABSTRACT
Magnetic resonance imaging of hyperpolarized nuclei provides high image contrast with little or no background signal. To date, in vivo applications of prehyperpolarized materials have been limited by relatively short nuclear spin relaxation times. Here, we investigate silicon nanoparticles as a new type of hyperpolarized magnetic resonance imaging agent. Nuclear spin relaxation times for a variety of Si nanoparticles are found to be remarkably long, ranging from many minutes to hours at room temperature, allowing hyperpolarized nanoparticles to be transported, administered, and imaged on practical time scales. Additionally, we demonstrate that Si nanoparticles can be surface functionalized using techniques common to other biologically targeted nanoparticle systems. These results suggest that Si nanoparticles can be used as a targetable, hyperpolarized magnetic resonance imaging agent with a large range of potential applications.
Subject(s)
Contrast Media/chemistry , Image Enhancement/methods , Magnetic Resonance Imaging/methods , Nanostructures/chemistry , Silicon/chemistry , Titanium/chemistry , Crystallization/methods , Macromolecular Substances/chemistry , Magnetic Resonance Imaging/instrumentation , Materials Testing , Molecular Conformation , Nanomedicine/methods , Nanostructures/ultrastructure , Particle Size , Surface PropertiesABSTRACT
Coumarin derivatives with non-polar substituents at the 6 or 7 position undergoes photodimerization in the presence of CB[8] in water to give the syn dimer as the major product. It is postulated that these neutral coumarins form dynamic complexes in the presence of CB[8] and the product selectivity is reflective of the type of complex, available volume in the CB[8] cavity and relative rate of photodimerization inside and outside the CB[8] cavity.
