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Development of a novel sheathless CE-ESI-MS interface via a CO2 laser ablated opening
摘要： A new and easy to construct sheathless capillary electrophoresis electro spray ionization mass spectrometry (CE-ESI-MS) interface was developed that offers several advantages compared to traditional liquid junction interfaces. The fabrication of the device only requires a CO2 laser engraver that most groups working with microfluids have access to. It only takes a few seconds to create a CO2 laser ablated opening in the bare-fused silica capillaries and the opening can be placed as close as a few mm from the spray tip. The capillary is punctured through a silicone tube such that the opening is directly placed inside this tube, which also serves as a liquid reservoir for the make-up liquid. Electrical contact required for both CE separation and ESI is established via the liquid in this reservoir which is in contact with the electrode of an external high voltage power supply. The developed CE-ESI-MS interface is capable of analysing both small molecules and biomolecules such as peptides in physisorbed PEG polymer brush coated capillaries. Proof-of-principle of the interface was demonstrated by analysing a tryptic digest of BSA. Further, a range of drugs of abuse were also investigated. The examined small molecules (pethidine, nortriptyline, methadone, haloperidol and loperamide) have a quantification limit (LOQ) of 150 ng/mL and a detection limit (LOD) of 40 ng/mL (except for loperamide: LOD = 80 ng/mL). Finally, we used our novel CE-MS interface for the analysis of the Aβ40 peptide. This is a member of the beta-Amyloid peptide family, involved in the development of Alzheimer's disease. A LOQ of 9 μg/mL was obtained for Aβ40, corresponding to 23 fmoles in a sample volume of 11 nL.
关键词： Mass spectrometry,Aβ40,CO2 laser,Sheathless interface,Capillary electrophoresis
更新于2025-09-19 17:13:59
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Precise size separation of water-soluble red-to-near-infrared-luminescent silicon quantum dots by gel electrophoresis
摘要： A gel electrophoresis, which is a standard method for separation and analysis of macromolecules such as DNA, RNA and proteins, is applied for the first time to silicon (Si) quantum dots (QDs) for the size separation. In the Si QDs studied, boron (B) and phosphorus (P) are simultaneously doped. The codoping induces negative potential on the surface of a Si QD and makes it dispersible in water. Si QDs with different B and P concentrations and grown at different temperatures (950°C - 1200°C) are studied. It is shown that a native polyacrylamide gel electrophoresis can separate codoped Si QDs by size. The capability of gel electrophoresis to immobilize size-separated QDs in a solid matrix makes detailed analyses of size-purified Si QDs possible. For example, photoluminescence (PL) studies of dried gel of Si QDs grown at 1100°C demonstrate that a PL spectrum of a Si QDs solution with the PL maximum around 1.4 eV can be separated into more than 15 spectra with the PL maximum changing from 1.2 to 1.8 eV depending on the migration distance. It is found that the relation between the PL peak energy and the migration distance depends on the growth temperature of Si QDs as well as the B and P concentration. For all the samples with different impurity concentrations and grown at different temperatures, a clear trend is observed in the relation between the full width at half maximum (FWHM) and the peak energy of the PL spectra in a wide energy range. The FWHM increases with increasing the peak energy and it is nearly twice larger than those observed for undoped Si QDs. The large PL FWHM of codoped Si QDs suggests that excitons are further localized in codoped Si QDs due to the existence of charged impurities.
关键词： codoping,size separation,silicon quantum dots,photoluminescence,gel electrophoresis
更新于2025-09-19 17:13:59
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Transferrable thin film of ultrasonically exfoliated MoSe2 nanocrystals for efficient visible-light photodetector
摘要： Two-dimensional transition metal dichalcogenides (2D TMDC’s) materials are the impactful candidates in nanotechnology for diverse applications such as electrocatalyst, sensing and energy storage. Many efforts have been accomplished to solve the problem of green production with the scaling of TMDCs materials. Here we demonstrated the two-step method including electrophoresis deposition (EPD) and direct transfer of MoSe2 nanocrystals (NCs) thin film for fabricating visible-light photodetector. High-resolution transmission electron microscopy and atomic force microscopy show that the liquid exfoliated MoSe2 NCs exhibits good crystalline nature with multi-layered thickness. Raman spectra, UV-Visible spectra, and X-ray photoelectron spectroscopy confirm the presence of 2H-phase of MoSe2 NCs. EPD deposited thin film is detached by dipping into the water and transferred onto the etched ITO substrate. Ag/MoSe2 NCs/ITO photodetector is fabricated which demonstrated the excellent performance in the visible range and demonstrate remarkable values of responsivity, EQE (%) and specific detectivity of 566 mAW-1, 155 % and 3.69 × 1011 Jones. Considering our results, the fabrication technique along with the photoresponse application of TMDC NCs presented here is the innovative and efficient way for developing the large-area optoelectronic devices.
关键词： MoSe2 nanocrystals,Liquid-phase exfoliation,Electrophoresis,Visible-light photodetector
更新于2025-09-19 17:13:59
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Capillary Electrophoresis with Laser Induced Fluorescence Detection for Study of the Association of HSP60 Gene Polymorphism with Gouty Arthritis
摘要： Background: Gout arthritis is a common inflammatory arthritis and it poses a major threat to human health. Objective: A method of capillary electrophoresis with laser-induced fluorescence detection (CE-LIF) for the detection of HSP60 gene polymorphism has been developed and applied to the exploration of correlation between gouty arthritis and HSP60 gene polymorphism. Methods: The genomic deoxyribonucleic acid from 59 patients with gouty arthritis and 64 control subjects was extracted and the conservative fragment of HSP60 was amplified. The products were digested with restriction endonuclease NlaIII and then separated and detected by the proposed method. Results: In the case group, there were 7 cases of TT genotype, 29 cases of CC genotype, and 23 cases of CT genotype. In the control group, there were 4 cases of TT genotype, 6 cases of CC genotype, and 54 cases of CT genotype. The detection results of the samples were statistically analyzed by binary logistic regression and Spearman correlation analysis. After adjusting gender, age, and other compounding factors, the TT genotype and CT genotype of the HSP60 gene were found to affect gouty arthritis. Conclusions: When used for gene polymorphism research, the proposed CE-LIF method has the advantages of high efficiency, rapidity, sensitivity, and low sample consumption. A moderate correlation between gouty arthritis and HSP60 genotype distribution was discovered for the first time. Highlights: A new method using CE-LIF for the detection of HSP60 gene polymorphism of 59 patients with gouty arthritis and 64 control subjects in China. The correlation between gouty arthritis and HSP60 gene polymorphism was explored for the first time.
关键词： Gouty arthritis,Capillary electrophoresis,HSP60 gene polymorphism,Laser-induced fluorescence
更新于2025-09-12 10:27:22
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Capillary electrophoresis/visible‐LED induced fluorescence of tryptophan: What's new?
摘要： Tryptophane (Trp) labelled by 3-(4-carboxybenzoyl)-2-quinolinecarboxaldehyde (CBQCA) is very dif?cult to identify using CE and ?uorescence detection (480 nm). Why in this article some mass spectrometry experiments show that Trp is really labelled by CBQCA as Leucine (Leu)? If the maximum of UV absorption ((cid:2)max) is the same between Leu-CBQCA and Trp-CBQCA, the molar extinction coef?cient is around 2 fold higher for Trp-CBQCA. The ?uorescence of the Leu-CBQCA derivative is 50 times more important than for Trp-CBQCA. The addition of 7.5 mM of (cid:3)-cyclodextrin ((cid:3)-CD) was found to be a good mean to improve 2.1 fold the sensitivity of the Trp-CBQCA ?uorescence. Using a buffer containing SDS and (cid:3)-CD in CE, a LOD of 0.7 μM of L-Trp can be reached and the ratio of the intensities between Leu, Isoleucine, Valine, Trp is 100, 21, 15, 1. Negative ESI/MS and MS/MS of the labeled amino acids show that a loss of the carboxylate function takes place. In the presence of two enantiomers of Trp-CBQCA, we have shown that this decarboxylation is not due to the derivatization process in the solution but rather occurs in the source of the mass spectrometer.
关键词： Tryptophan,Capillary electrophoresis,Fluorescence,Biomolecule,3-(4-carboxybenzoyl)-2-quinolinecarboxaldehyde
更新于2025-09-11 14:15:04
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Detection and Separation of Inorganic Cations in Natural, Potable, and Wastewater Samples Using Capillary Zone Electrophoresis with Indirect UV Detection
摘要： Capillary zone electrophoresis (CZE) is a sensitive and rapid technique for determining traces of inorganic cations in water samples. CZE with indirect UV-diode array detection (CZE-DAD) was utilized to identify several inorganic cations in natural, potable, and wastewater samples. A pH 4.35 background electrolyte system was employed and consisted of 15 mM imidazole, 8 mM malonic acid, 2 mM 18-crown-6 ether as complexing agents, 10% v/v methanol as an organic modifier with indirect absorbance reference at 214 nm. The CZE method involved electromigration injection at 5 kV for 5 s, a separation voltage of 20 kV at 25°C, and a detection wavelength of 280 nm. Six main cations (ammonium, potassium K+, calcium Ca2+, sodium Na+, magnesium Mg2+, and lead Pb2+) were tested, and all but lead, were detected in the water samples at concentrations between 0.03 and 755 ppm with a detection limit ranging between 0.023 and 0.084 ppm. The successful evaluation of the proposed methodology allowed us to reliably detect and separate six metal ions in different water samples without any pretreatment. All water samples were collected from Northern New York towns and the Raquette River water system, the third longest river in New York State and the largest watershed of the central and western Adirondacks.
关键词： Indirect UV Detection,Adirondack Watershed,Capillary Zone Electrophoresis,Inorganic Cations,Northern New York Raquette River
更新于2025-09-10 09:29:36
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[Methods in Molecular Biology] Microfluidic Electrophoresis Volume 1906 (Methods and Protocols) || Integrated Microfluidic System for Rapid DNA Fingerprint Analysis: A Miniaturized Integrated DNA Analysis System (MiDAS)—Swab Sample-In to DNA Profile-Out
摘要： A fully automated rapid DNA analysis system requires integrating several operational elements performing multiple steps onto one single micro?uidic platform. The functions to include on the micro?uidic platform consist of substrate lysis, lysate DNA extraction, single or multiplexed PCR ampli?cation, amplicon separation, and product readout. Here we describe a fully automated integrated system for forensic short tandem repeat (STR) analysis of reference samples, achieving buccal swab-in and DNA pro?le-out.
关键词： Integration,STR analysis,DNA extraction,Micro?uidics,Multiplexed PCR,Capillary electrophoresis
更新于2025-09-10 09:29:36
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Hydroxypropyl Methacrylate Interaction and Chitosan Coating for Enhanced UV Detection Sensitivity of Colloidal Nanoparticles in Capillary Electrophoresis Analysis
摘要： The binding interactions between silica (SiO2), titania (TiO2) or polymeric nanoparticles with hydroxypropyl methacrylate (HPMA) were investigated for enhancing the ultraviolet (UV) detection sensitivity of these nanoparticles in capillary electrophoresis (CE) analysis. HPMA interacted with colloidal SiO2 nanoparticles, producing a larger CE-UV peak at a slightly shorter migration time. An increase in particle size with HPMA binding was validated using dynamic light scattering. The interaction was selective as HPMA did not interact with TiO2 nanoparticles in aqueous suspension. Chitosan coating of SiO2 or TiO2 nanoparticles produced significantly larger hydrodynamic diameters to further enhance the sensitivity of their UV detection. The analytical technique, which involves coating SiO2 nanoparticles with chitosan first and binding with HPMA next, is novel. It has allowed us to achieve a significant enhancement of 50 folds in detection sensitivity.
关键词： Titania,Colloid,Nanoparticles,Capillary electrophoresis,Chitosan,Hydroxypropyl methacrylate,Silica,Polymer,Dynamic light scattering
更新于2025-09-09 09:28:46
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[IEEE 2018 IEEE 2nd International Conference on Dielectrics (ICD) - Budapest (2018.7.1-2018.7.5)] 2018 IEEE 2nd International Conference on Dielectrics (ICD) - An original in-situ way to build field grading materials (FGM) with permittivity gradient using electrophoresis
摘要： This paper reports on an original method developed at LAPLACE to structure field grading materials (FGM) by local handling of high permittivity ceramic (SrTiO3) particles in an epoxy resin using electrophoresis (i.e. DC voltage application). This new way of structuring composites allows building FGM with a high permittivity region (region with high particle concentration) while the rest of the composite remains with low particle concentration). The resin curing enables to ‘freeze’ the particles with this spatial arrangement. Process details and dielectric characterization of each region of the FGM composites are reported. Finally, a clear demonstration of the FGM performances, used as a field grading encapsulation material for high voltage power electronics modules, is shown supported both by field repartition simulation and experimental breakdown voltage improvements of encapsulated direct bonded copper (DBC) substrates.
关键词： SrTiO3,Encapsulation,Epoxy,Permittivity,Composites,Power modules,Field grading,FGM,Power electronics,Functionally graded materials,Electrophoresis
更新于2025-09-04 15:30:14