- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Scaling behavior in on-chip field-amplified sample stacking
摘要： Field amplified sample stacking (FASS) uses differential electrophoretic velocity of analyte ions in the high-conductivity background electrolyte zone and low-conductivity sample zone for increasing the analyte concentration. The stacking rate of analyte ions in FASS is limited by molecular diffusion and convective dispersion due to non-uniform electroosmotic flow (EOF). We present a theoretical scaling analysis of stacking dynamics in FASS and its validation with a large set of on-chip sample stacking experiments and numerical simulations. Through scaling analysis, we have identified two stacking regimes that are relevant for on-chip FASS, depending upon whether the broadening of the stacked peak is dominated by axial diffusion or convective dispersion. We show that these two regimes are characterized by distinct length and time scales, based on which we obtain simplified non-dimensional relations for the temporal growth of peak concentration and width in FASS. We first verify the theoretical scaling behavior in diffusion and convection dominated regimes using numerical simulations. Thereafter, we show that the experimental data of temporal growth of peak concentration and width at varying electric fields, conductivity gradients, and EOF exhibit the theoretically predicted scaling behavior. The scaling behavior described in this work provides insights into the effect of varying experimental parameters, such as electric field, conductivity gradient, electroosmotic mobility, and electrophoretic mobility of the analyte on the dynamics of on-chip FASS.
关键词： dispersion,scaling analysis,on-chip electrophoresis,field-amplified sample stacking
更新于2025-09-23 15:23:52
-
Direct detection of cysteine peptidases for MALDI-TOF MS analysis using fluorogenic substrates
摘要： A method is described for the direct detection of unstable cysteine peptidase activity in polyacrylamide gels after native electrophoresis using new selective fluorogenic peptide substrates, pyroglutamyl-phenylalanyl-alanyl-4-amino-7-methylcoumaride and pyroglutamyl-phenylalanyl-alanyl-4-amino-7-trifluoromethyl-coumaride (Glp-Phe-Ala-AFC). The detection limit of the model enzyme papain was 17 pmol (0.29 μg) for Glp-Phe-Ala-AMC and 43 pmol (0.74 μg) for Glp-Phe-Ala-AFC, with increased sensitivity and selectivity compared to the traditional method of protein determination with Coomassie G-250 staining or detection of activity using chromogenic substrates. Using this method, we easily identified the target digestive peptidases of Tenebrio molitor larvae by matrix assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) analysis. The method offers simplicity, high sensitivity, and selectivity compared to traditional methods for improved identification of unstable cysteine peptidases in multi-component biological samples.
关键词： Postelectrophoretic activity,Cysteine peptidases,Fluorogenic substrates,Tenebrio molitor,Native electrophoresis
更新于2025-09-23 15:23:52
-
Growth behavior and thermally stable electrical properties of TiNbO5 nanosheet thin films grown using the electrophoretic method
摘要： TiNbO5 (TNO) thin films were deposited by electrophoresis at room temperature by using TNO nanosheets. These TNO films exhibited a large (001) interplanar distance (1.18 nm) owing to the presence of TBA+ between the TNO layers. The TBA+, which were used to synthesize the TNO nanosheets, were removed from the TNO film after annealing at 600 °C. Two types of structures were developed in the film annealed at 600 °C: type-1 and type-2, which revealed (001) interplanar distances of 0.52 and 0.71 nm, respectively. The TNO film annealed at 600 °C showed a dielectric constant of 48.5, low dielectric loss (0.02), and small leakage current density of 4.16 × 10^-7 A/cm^2 at 0.6 MV/cm. The dielectric properties were stable with respect to the film thickness and the applied electric field; the dielectric and insulation properties were maintained up to 300 °C. Therefore, TNO films are good candidates for high-temperature capacitors.
关键词： Electrophoresis,Robust dielectric,Inorganic nanosheets,TiNbO5 film,High temperature capacitor
更新于2025-09-23 15:22:29
-
Determination of formaldehyde in single cell by capillary electrophoresis with LIF detection
摘要： As a small molecule gas, formaldehyde (FA) is the simplest carbonyl active material and plays an important role in the carbon cycle of metabolism. However, due to the volatile nature of the gas, it is difficult to accurately quantify its content, which limits the study of the mechanism of action in life activities. Thus, an efficient approach to quantitative detection of FA in cells especially in single cell is urgent needed. Nevertheless, no method for quantifying FA in single cell has been reported to date. In this work, a fluorescent probe N-propyl-4-hydrazino-naphthalimide (NPHNA), which has highly desirable attributes and has been applied to living biological samples, was chosen as labeling reagent to detect endogenous FA at single cell level. After optimization of separation conditions, fast baseline separation of the FA derivative N-propyl-4-hydrazone-naphthalimide product (NPHNA-FA) and NPHNA was achieved in about 5 min by capillary electrophoresis with laser-induced fluorescence detection. The detection limit for FA was 5 amol (signal-to-noise ratio of 3). The developed method was validated by the measurements of intracellular levels of FA in single cell.
关键词： Capillary electrophoresis,Endogenous formaldehyde levels,Single cell
更新于2025-09-23 15:22:29
-
Rapid Detection of Proteins on One-Dimensional Polyacrylamide Gel Electrophoresis Using an Inexpensive Fluorescent Optical Brightener
摘要： A commercial fabric fluorescent optical brightener Ranipal? (F-OB), has been successfully employed to stain proteins on native and SDS-1D-PAGE. The F-OB was purified by using a biphasic solvent system of dichloromethane and water. The Rf value (0.63) of purified and crude F-OB were comparable on TLC. The mass spectrometry of purified F-OB indicated base peak at 414 (m/z). Absorption and emission maxima of F-OB were found to be 350 nm and 430 nm, respectively. The F-OB could stain the proteins both pre- and post-electrophoretic run, on native gel. Post-electrophoretic staining was rapid and required 20 min to visualize the stained proteins. On the other hand, in SDS gels, an additional 20 min was required for the extraction of SDS before staining the proteins with F-OB. SDS was found to interfere with binding of F-OB to proteins. Varying concentrations of molecular weight markers were loaded and their fluorescent intensity was plotted against the concentration of the proteins. The r2 values ranged from 0.965 to 0.997 indicating excellent linearity. The detection for carbonic anhydrase was in the range of 8.0-800 ng. Unlike most of the dyes used for protein staining, staining with F-OB could be carried out in tank buffer (2 mg/100 mL) and was also reversible. The F-OB, perhaps would be the most cost-effective fluorescent dye to stain the proteins (US $ 0.04/25.0 g). The F-OB was found to be simple, safe, sensitive, less time consuming and economical fluorescent dye as an alternative, for staining proteins on polyacrylamide gels.
关键词： Fluorescent optical brightener,1D-Electrophoresis,CCD-based digital image based analysis system,Protein staining
更新于2025-09-23 15:21:21
-
Application of Capillary Zone Electrophoresis Coupled with a Diode Array Detector (CZE-DAD) for Simultaneous Analysis of Ibuprofen and Phenylephrine
摘要： Background: A validated method based on capillary zone electrophoresis coupled with a diode array detector (CZE-DAD) was investigated for analyzing binary mixture of ibuprofen (IBU) and phenylephrine (PHE) in their bulk and combined dosage form. Objective: This binary mixture is a challenging one as IBU is acidic and PHE is alkaline, which may affect their simultaneous analysis using CZE. The literature lacks any CZE report for IBU and PHE simultaneous analysis. Methods: Fused silica capillary (85 cm × 75 μm id) was used, and the electrolyte was a 50 mM borate buffer adjusted to pH 11 with 0.5 M NaOH. Results: The concentration ranges were 5–200 and 5–100 μg/mL for IBU and PHE, respectively, using CZE. High efficiency was achieved (N > 92990). Reasonable migration time (tm) was attained (tm< 8.5 min). Conclusions: Although the results obtained by the proposed CZE method and reported HPLC method were statistically comparable, the proposed method showed lower linearity ranges, higher efficiency, and a more reasonable run time. Highlights: CZE-DAD was used for the analysis of IBU and PHE in bulk and tablets, as no report was found for their determination using CZE. Binary mixture is challenging due to differences in chemical and physical properties. A detailed discussion of electrophoretic parameters optimization is included. Confirmation of peak purity was attained using DAD.
关键词： Capillary zone electrophoresis,phenylephrine,diode array detector,simultaneous analysis,ibuprofen
更新于2025-09-23 15:21:01
-
A novel intracellular signal amplification strategy for the quantification of ATP in single cells by microchip electrophoresis with laser induced fluorescence detection
摘要： An intracellular signal amplification strategy was developed for quantification of ATP in single cells by microchip electrophoresis with laser induced fluorescence detection. By using the method proposed, intracellular ATP levels in single Hela, HepG2 and HL-7702 cell were found in the range of 30～150, 30~140, and 19～120 fmol/cell, respectively.
关键词： laser induced fluorescence,ATP,microchip electrophoresis,single-cell analysis,signal amplification
更新于2025-09-23 15:21:01
-
Au nanoparticle preconcentration coupled with CE-electrochemiluminescence detection for sensitive analysis of fluoroquinolones in European eel ( <i>Anguilla anguilla</i> )
摘要： In this work, a novel method based on gold nanoparticle preconcentration coupled with CE for electrochemiluminescent detection of ciprofloxacin, enrofloxacin, ofloxacin, and norfloxacin in European eels was developed. The addition of gold nanoparticles induced the rapid enrichment of fluoroquinolones, which was simpler than the conventional enrichment approaches such as solid phase extraction and solid-phase microextraction. More than 100 times enrichment was observed after gold nanoparticle aggregation-based preconcentration. The CE-electrochemiluminescent parameters that affected the separation and detection were optimized. Under the optimized conditions, the linear ranges for the four fluoroquinolones were 0.090—8.0 μmol/L with the detection limits between 0.020 to 0.050 μmol/L. The proposed approach showed the advantages of high sensitivity, high selectivity, wide linear range, and low detection limit. It was used to analyze fluoroquinolones in European eel, and the results showed that the developed method can satisfy the detection requirements for fluoroquinolones determination in aquatic products set by China and European Union.
关键词： Capillary electrophoresis,fluoroquinolones,preconcentration,European eel,gold nanoparticle
更新于2025-09-23 15:21:01
-
[Methods in Molecular Biology] Microfluidic Electrophoresis Volume 1906 (Methods and Protocols) || Paper-Based Electrophoresis Microchip as a Powerful Tool for Bioanalytical Applications
摘要： This chapter describes the development of paper-based microchip electrophoresis (pME) devices for the separation of clinically relevant compounds. pME were fabricated by laser cut and thermal lamination process using polyester pouches. In addition, hand-drawn pencil electrodes were integrated to the device to perform capacitively coupled contactless conductivity detection (C4D). Finished device costs less than US$ 0.10 and did not require either sophisticated instrumentation or clean room facilities. Furthermore, pME is lightweight, easy to handle, ?exible, and robust. pME-C4D device revealed an excellent capacity to separate BSA and creatinine in less than 150 s with baseline resolution. The device proposed in this chapter has proven to be a good alternative as a platform for the diagnosis of diseases from renal disorders such as diabetes mellitus and heart disease.
关键词： Biomolecules,Paper electrophoresis,Kidney failure,Pencil electrodes,Bovine serum albumin,Creatinine,Clinical diagnosis,Contactless conductivity detection
更新于2025-09-23 15:21:01
-
Large-Scale Purification of Photon-Upconversion Nanoparticles by Gel Electrophoresis for Analog and Digital Bioassays
摘要： The performance of photon-upconversion nanoparticles (UCNPs) as background-free luminescent labels in bioanalytical applications strongly depends on the preparation of well-defined and water-dispersible nanoconjugates. We have exploited the separation power of agarose gel electrophoresis to purify milligram amounts of homogeneous UCNPs covered with carboxylated silica, biotin or streptavidin with recovery rates of 30 to 50%. Clusters containing discrete numbers of UCNPs were isolated from the gel and reanalyzed by agarose gel electrophoresis, single nanoparticle upconversion microscopy and additional complementary methods. The purified nanoconjugates improved conventional (analog) bioaffinity assays and provided highly monodisperse conjugates for assays that rely on counting individual UCNPs (digital assays).
关键词： streptavidin,bioconjugate,Agarose gel electrophoresis,purification,digital bioassay,biotin
更新于2025-09-23 15:19:57