Porous Tip Research Articles

Porous tip contact force-sensing catheters for pulmonary vein isolation: performance in a clinical routine setting.

In catheter ablation of atrial fibrillation (AF), contact force (CF)-sensing catheters with an irrigated tip are used to deliver radiofrequency (RF) energy to the tissue. The ThermoCool® Smarttouch™ Surroundflow catheter (STSF) integrates CF-sensing technology and a new porous tip for advanced external cooling. The aim was to evaluate the performance and safety of STSF in a clinical setting of pulmonary vein isolation (PVI) in comparison with standard contact force-sensing catheter (ST). We assigned consecutive patients (n = 80, prospectively, open-label, non-randomized) with symptomatic AF to either PVI with STSF (n = 60) or ST (n = 20). Total ablation time to achieve PVI was significantly shorter in STSF compared to that in ST (STSF, 1556 ± 435s vs. ST, 1922 ± 961s; p = 0.045). Ablation time to achieve loss of pace capture of left pulmonary veins was shorter using STSF (left veins, 155 ± 140s vs. 291 ± 188s; p = 0.01; right veins, 208 ± 196s vs. 369 ± 306s; p = 0.09). Furthermore, administered irrigation fluid was significantly reduced in STSF (241.4 ± 79.6ml vs. 540.3 ± 229.5ml; p < 0.01). CF was lower during ablation of left pulmonary veins. One steam pop occurred in STSF, which did not lead to pericardial effusion (vs. no steam pop in ST). The Kaplan-Meier estimate 12-month AF recurrence was 34.3% and 37.7% (p = 0.8). Integrating CF technology and the porous tip technology enables effective energy transfer to the tissue resulting in shorter ablation time and less irrigation fluid administration. In our cohort, PVI using the STSF was not associated with an increased complication rate or AF recurrence rate after 12-month follow-up when compared with the ST.

Sheathless CE-MS based metabolic profiling of kidney tissue section samples from a mouse model of Polycystic Kidney Disease

Capillary electrophoresis-mass spectrometry (CE-MS) using a sheathless porous tip interface emerged as an attractive tool in metabolomics thanks to its numerous advantages. One of the main advantages compared to the classical co-axial sheath liquid interface is the increased sensitivity, while maintaining the inherent properties of CE, such as a high separation efficiency and low sample consumption. Specially, the ability to perform nanoliter-based injections from only a few microliters of material in the sample vial makes sheathless CE-MS a well-suited and unique approach for highly sensitive metabolic profiling of limited sample amounts. Therefore, in this work, we demonstrate the utility of sheathless CE-MS for metabolic profiling of biomass-restricted samples, namely for 20 µm-thick tissue sections of kidney from a mouse model of polycystic kidney disease (PKD). The extraction method was designed in such a way to keep a minimum sample-volume in the injection vial, thereby still allowing multiple nanoliter injections for repeatability studies. The developed strategy enabled to differentiate between different stages of PKD and as well changes in a variety of different metabolites could be annotated over experimental groups. These metabolites include carnitine, glutamine, creatine, betaine and creatinine. Overall, this study shows the utility of sheathless CE-MS for biomass-limited metabolomics studies.

Utility of sheathless capillary electrophoresis-mass spectrometry for metabolic profiling of limited sample amounts

Metabolomics studies using a small amount of cells may save time and money, while in some cases (e.g., profiling pathogenic cells in an early-stage tissue), only a small number of cells are accessible for analysis. The analysis of small amounts of biological samples challenges the analytical toolbox used in present-day metabolomics studies, and a significant number of crucial biological questions cannot be properly addressed. To allow metabolic profiling of limited sample amounts, the potential of capillary electrophoresis-mass spectrometry (CE–MS) using a sheathless porous tip interface has been assessed using HepG2 cells in starting amounts of 500 and 10,000 cells as a model system in this work. It is shown that highly efficient and information-rich metabolic profiles for cationic metabolites at low-pH separation conditions could be obtained by sheathless CE–MS using an injection volume of only circa 42 nL, which equals the content/aliquot of circa 0.25 and 5 HepG2 cells, respectively. With as little as the content of 0.25 cell injected, more than 24 cationic metabolites could be identified. A further improvement of sample preparation and/or the injection part is required in order to effectively analyze the compounds of interest in very low sample amounts by sheathless CE–MS. However, the results obtained so far clearly indicate the strong potential of the proposed method for metabolic profiling of limited sample amounts.

Comparison of two low flow interfaces for measurement of mobilities and stability constants by affinity capillary electrophoresis–mass spectrometry

Affinity capillary electrophoresis (ACE) is typically used for the determination of stability constant, Kst, of weak to moderately strong complexes. Sensitive detection such as mass spectrometry (MS) is required for extension of ACE methodology for estimation of Kst of stronger complexes. Consequently, an efficient interface for hyphenation of CE with MS detection is necessary. For evaluation of interfaces for electrospray ionization mass spectrometric (ESI/MS) detection in ACE conditions, potassium-crown ether complexation was used as model system. The effective mobilities of the crown ether ligands and the Kst of their potassium complexes were measured/determined by ACE-ESI/MS using two lab-made interfaces: (i) a sheathless porous tip CE-ESI/MS interface and (ii) a nano-sheath liquid flow CE-ESI/MS interface, and, in turn, compared with those obtained by ACE with UV spectrophotometric detection. Apparent stability constant of potassium-crown ether complexes in 60/40 (v/v) methanol/water mixed solvent, pH* 5.5, was about 1300 L/mol for dibenzo-18-crown-6, 1600 L/mol for benzo-18-crown-6 and 5200 L/mol for 18-crown-6 ligands, respectively. It was observed that electrophoretic mobilities from CE-MS experiments differ from reference values determined by UV detection by ∼7% depending on the CE-MS interface used. Good agreement of CE-MS and CE-UV data was achieved for nano-sheath liquid flow interface, in which the spray potential and the CE separation potential can be effectively decoupled. As for sheathless porous tip interface, a correction procedure involving a mobility marker has been proposed. It provides typically only ca. 1% difference of effective mobilities and Kst values obtained from CE-MS data as compared to those received by the reference ACE-UV method.

The best of two worlds? Pulmonary vein isolation using a novel radiofrequency ablation catheter incorporating contact force sensing technology and 56-hole porous tip irrigation.

This study aimed to evaluate feasibility and safety as well as 1-year clinical outcome of pulmonary vein isolation (PVI) using a unique radiofrequency ablation catheter ("Thermocool SmartTouch SurroundFlow"; STSF) incorporating both, contact force (CF) sensing technology and enhanced tip irrigation with 56 holes, in one device. A total of 110 patients suffering from drug-refractory atrial fibrillation underwent wide area circumferential PVI using either the STSF ablation catheter (75 consecutive patients, study group) or a CF catheter with conventional tip irrigation ("Thermocool SmartTouch", 35 consecutive patients, control group). For each ablation lesion, a target CF of ≥ 10-39g and a force time integral (FTI) of > 400 gs was targeted. Acute PVI was achieved in all patients with target CF obtained in > 85% of ablation points when using either device. Mean procedure time (131.3 ± 33.7min in the study group vs. 133.0 ± 42.0min in the control group; p = 0.99), mean fluoroscopy time (14.0 ± 6 vs. 13.5 ± 6.6min; p = 0.56) and total ablation time were not significantly different (1751.0 ± 394.0 vs. 1604.6 ± 287.8s; p = 0.2). However, there was a marked reduction in total irrigation fluid delivery by 51.7% (265.52 ± 64.4 vs. 539.6 ± 118.2ml; p < 0.01). The Kaplan-Meier estimate 12-month arrhythmia-free survival after the index procedure following a 3-month blanking period was 79.9% (95% CI 70.4%, 90.4%) for the study group and 66.7% for the control group (95% CI 50.2%, 88.5%). This finding did not reach statistical significance (p = 0.18). Major complications occurred in 2/75 patients (2.7%; one pericardial tamponade and one transient ischemic attack) in the study group and no patient in the control group (p = 18). PVI using the STSF catheter is safe and effective and results in beneficial 1-year clinical outcome. The improved tip irrigation leads to a significant reduction in procedural fluid burden.

Toward Confirmatory On-Site Real-Time Detection of Emerging Drugs Using Portable Ultrafast Capillary Electrophoresis Mass Spectrometry.

Currently, law enforcement agencies rely upon presumptive tests such as color tests (or spot tests) for on-site, real-time identification of forensic evidence, such as controlled substances. These tests are simple and easy to use and require no instrumentation. However, they are unreliable and have a large false positive rate. On the other hand, confirmatory tests are done in analytical laboratories using sophisticated instrumentation by expert analysts, and have lower false positive rates. However, they are bulky and impractical for on-site real-time analysis. To provide more accurate identification of forensic evidence on-site, in real-time, it is important to develop portable confirmatory instrumentation using information-rich technologies. Moreover, because the analysis of controlled substances could be complicated by the existence of various isomers (including optical isomers) it is desirable that the portable instruments have the capability to separate structural and optical isomers of the controlled substances, because scheduling is some timesdependent upon which isomer is present. To this end, we have developed a portable ultrafast capillary electrophoresis (UFCE) system for the separation of controlled substances and their structural and optical isomers. The UFCE instrument has an integrated porous tip for facile interfacing with electrospray ionization mass spectrometry. The technique has been successfully applied to the analysis of mixtures of several controlled substances such as amphetamines, cathinones, nor-mephedrone, and pregabalin and their optical isomers in about a minute.

Sheathless Capillary Electrophoresis-Mass Spectrometry for theProfiling of Charged Metabolites in Biological Samples.

Capillary electrophoresis (CE) is well suited for the profiling of highly polar and charged metabolites as compounds are separated on the basis of their charge-to-size ratio. The protocol presented here is based on using a recently developed sheathless interfacing design, i.e., a porous tip interface, for coupling CE to electrospray ionization mass spectrometry (MS). It is demonstrated that sheathless CE-MS employing a bare fused-silica capillary at low-pH separation conditions can be used for the profiling of both cationic and anionic metabolites by only switching the MS detection and electrophoretic separation voltage polarity. The proposed sheathless CE-MS protocol allows efficient and sensitive profiles to be obtainedfor a broad array of charged metabolites, including amino acids, organic acids, nucleotides, and sugar phosphates, in various biological samples, such as urine and extracts of the glioblastoma cell line.

Sheathless Capillary Electrophoresis-Mass Spectrometry for Metabolic Profiling of Biological Samples.

In metabolomics, a wide range of analytical techniques is used for the global profiling of (endogenous) metabolites in complex samples. In this paper, a protocol is presented for the analysis of anionic and cationic metabolites in biological samples by capillary electrophoresis–mass spectrometry (CE-MS). CE is well-suited for the analysis of highly polar and charged metabolites as compounds are separated on the basis of their charge-to-size ratio. A recently developed sheathless interfacing design, i.e., a porous tip interface, is used for coupling CE to electrospray ionization (ESI) MS. This interfacing approach allows the effective use of the intrinsically low-flow property of CE in combination with MS, resulting in nanomolar detection limits for a broad range of polar metabolite classes. The protocol presented here is based on employing a bare fused-silica capillary with a porous tip emitter at low-pH separation conditions for the analysis of a broad array of metabolite classes in biological samples. It is demonstrated that the same sheathless CE-MS method can be used for the profiling of cationic metabolites, including amino acids, nucleosides and small peptides, or anionic metabolites, including sugar phosphates, nucleotides and organic acids, by only switching the MS detection and separation voltage polarity. Highly information-rich metabolic profiles in various biological samples, such as urine, cerebrospinal fluid and extracts of the glioblastoma cell line, can be obtained by this protocol in less than 1 hr of CE-MS analysis.

Sheathless Capillary Electrophoresis&amp;#8211;Mass Spectrometry for Metabolic Profiling of Biological Samples

In metabolomics, a wide range of analytical techniques is used for the global profiling of (endogenous) metabolites in complex samples. In this paper, a protocol is presented for the analysis of anionic and cationic metabolites in biological samples by capillary electrophoresis–mass spectrometry (CE-MS). CE is well-suited for the analysis of highly polar and charged metabolites as compounds are separated on the basis of their charge-to-size ratio. A recently developed sheathless interfacing design, i.e., a porous tip interface, is used for coupling CE to electrospray ionization (ESI) MS. This interfacing approach allows the effective use of the intrinsically low-flow property of CE in combination with MS, resulting in nanomolar detection limits for a broad range of polar metabolite classes. The protocol presented here is based on employing a bare fused-silica capillary with a porous tip emitter at low-pH separation conditions for the analysis of a broad array of metabolite classes in biological samples. It is demonstrated that the same sheathless CE-MS method can be used for the profiling of cationic metabolites, including amino acids, nucleosides and small peptides, or anionic metabolites, including sugar phosphates, nucleotides and organic acids, by only switching the MS detection and separation voltage polarity. Highly information-rich metabolic profiles in various biological samples, such as urine, cerebrospinal fluid and extracts of the glioblastoma cell line, can be obtained by this protocol in less than 1 hr of CE-MS analysis.

Ultrafast capillary electrophoresis/mass spectrometry of controlled substances with optical isomer separation in about a minute

Analysis of forensic evidence by information-rich technologies such as mass spectrometry (MS) is one of the fastest growing areas in forensic analysis. To provide more accurate identification of forensic evidence, in the past few years there has been a growing interest in moving this technology to the field for on-site, real-time analysis. To this end, several portable mass spectrometers have been introduced; however, the analysis of controlled substances could be complicated by the existence of various isomers including optical isomers in which sentencing may depend on the identification of the isomer. To date very few portable separation devices are capable of separating and identifying the optical isomers. In this study, the application of the portable ultrafast capillary electrophoresis (UFCE) to the separation of controlled substances is presented and the results are compared with the results obtained from a bench-top CE system. Both a nominal mass ion trap mass spectrometer and an accurate mass orbitrap mass spectrometer were interfaced with CE using a porous tip capillary. A mixture of several controlled substances can be separated and detected using UFCE/MS in about a minute using field strengths of ≥1000V/cm. Furthermore, separation and detection of underivatized optical isomers of amphetamine, cathinone, nor-mephedrone, and pregabalin using UFCE/MS can be achieved with an analysis time of less than two minutes. Resolutions of 1.3, 3.7 and 3.8 were achieved for pregabalin, cathinone and nor-mephedrone, respectively, under UFCE/MS conditions. Amphetamine, cathinone, nor-mephedrone and pregabalin were separated and detected in about a minute, demonstrating the utility of the portable CE instrument for the analysis of controlled substances and their optical isomers. Copyright © 2016 John Wiley & Sons, Ltd.

Improvement of Mitochondria Extract from Saccharomyces cerevisiae Characterization in Shotgun Proteomics Using Sheathless Capillary Electrophoresis Coupled to Tandem Mass Spectrometry.

In this work, we describe the characterization of a quantity-limited sample (100 ng) of yeast mitochondria by shotgun bottom-up proteomics. Sample characterization was carried out by sheathless capillary electrophoresis, equipped with a high sensitivity porous tip and coupled to tandem mass spectrometry (CESI-MS-MS) and concomitantly with a state-of-art nano flow liquid chromatography coupled to a similar mass spectrometry (MS) system (nanoLC-MS-MS). With single injections, both nanoLC-MS-MS and CESI-MS-MS 60 min-long separation experiments allowed us to identify 271 proteins (976 unique peptides) and 300 proteins (1,765 unique peptides) respectively, demonstrating a significant specificity and complementarity in identification depending on the physicochemical separation employed. Such complementary, maximizing the number of analytes detected, presents a powerful tool to deepen a biological sample's proteomic characterization. A comprehensive study of the specificity provided by each separating technique was also performed using the different properties of the identified peptides: molecular weight, mass-to-charge ratio (m/z), isoelectric point (pI), sequence coverage or MS-MS spectral quality enabled to determine the contribution of each separation. For example, CESI-MS-MS enables to identify larger peptides and eases the detection of those having extreme pI without impairing spectral quality. The addition of peptides, and therefore proteins identified by both techniques allowed us to increase significantly the sequence coverages and then the confidence of characterization. In this study, we also demonstrated that the two yeast enolase isoenzymes were both characterized in the CESI-MS-MS data set. The observation of discriminant proteotypic peptides is facilitated when a high number of precursors with high-quality MS-MS spectra are generated.

Sheathless capillary electrophoresis-mass spectrometry for anionic metabolic profiling.

The performance of CE coupled on‐line to MS via a sheathless porous tip sprayer was evaluated for anionic metabolic profiling. A representative metabolite mixture and biological samples were used for the evaluation of various analytical parameters, such as peak efficiency (plate numbers), migration time and peak area repeatability, and LODs. The BGE, i.e. 10% acetic acid (pH 2.2), previously used for cationic metabolic profiling was now assessed for anionic metabolic profiling by using MS detection in negative ion mode. For test compounds, RSDs for migration times and peak areas were below 2 and 11%, respectively, and plate numbers ranged from 60 000 to 40 0000 demonstrating a high separation efficiency. Critical metabolites with low or no retention on reversed‐phase LC could be efficiently separated and selectively analyzed by the sheathless CE‐MS method. An injection volume of only circa 20 nL resulted in LODs between 10 and 200 nM (corresponding to an amount of 0.4–4 fmol), which was an at least tenfold improvement as compared to LODs obtained by conventional CE‐MS approaches for these analytes. The methodology was applied to anionic metabolic profiling of glioblastoma cell line extracts. Overall, a sheathless CE‐MS method has been developed for highly efficient and sensitive anionic metabolic profiling studies, which can also be used for cationic metabolic profiling studies by only switching the MS detection and separation voltage polarity.

The Incidence of Audible Steam Pops Is Increased and Unpredictable With the ThermoCool® Surround Flow Catheter During Left Atrial Catheter Ablation: A Prospective Observational Study.

Open irrigated radiofrequency (RF) ablation catheters with a porous tip (56 holes, TC-SF) permit delivering RF energy in a temperature-controlled mode without temperature rise. This prospective observational study investigated the association of different catheter parameters on the occurrence of audible steam pops during left atrial (LA) ablation. A total of 226 patients underwent TC-SF catheter ablation for atrial fibrillation. RF power delivery, impedance and catheter tip temperature were continually recorded throughout the ablation. Pulmonary vein isolation was performed with a maximum of 27 W and LA electrogram-guided or linear ablation with a maximum of 30 W. A total of 59 audible steam pops occurred, 2 of them resulting in pericardial tamponade. In the initial 89 patients, with an irrigation flow rate of 10 mL/min, 18 steam pops with one tamponade occurred in 12 (14%) patients. Subsequently, the irrigation flow rate was increased to 20 mL/min in the following 137 patients, resulting in the occurrence of 41 steam pops including one case of tamponade in a total of 30 (22%) patients. The maximal power was significantly higher in RF applications associated with a pop than those that did not. In only 12 (20%) steam pops, a significant impedance change occurred immediately before pop occurrence (4 [7%] impedance rise >10 ohm, 8 [13%] impedance drop >15 ohm). The TC-SF catheter does not provide sufficient feedback from the ablated tissue to prevent steam popping.

Micro-patterning of porous alumina layers with aligned nanopores

Arrays of nanoporous microfeatures of alumina are demonstrated via isotropic chemical etching of commercially available nanoporous alumina substrates. Etch rates are established for four morphologies of aligned nanopores having pore sizes in the range 20–220 nm and porosities from 30–60%. Parametrically varying etch conditions yields a process for creating microfeatures over large areas which is used to create a 384 porous tip array at a pitch of 70 µm with the 200 nm porosity.

Compatibility of highly sulfated cyclodextrin with electrospray ionization at low nanoliter/minute flow rates and its application to capillary electrophoresis/electrospray ionization mass spectrometric analysis of cathinone derivatives and their optical isomers.

Sodium salts of cyclodextrins are commonly used in capillary electrophoresis/mass spectrometry (CE/MS) analysis of illicit drugs and their optical isomers. To avoid the suppression effect of cyclodextrins under electrospray ionization (ESI), the partial filling technique (PFT) is commonly utilized, which has a limited resolution. Low-flow nano-ESI has been shown to reduce the suppression effect of the salts. To test the compatibility of low-flow ESI with a background electrolyte (BGE) containing sodium salts of cyclodextrin, sheathless narrow capillary CE/MS with flow rates of low nanoliters/minute (nL/min) was applied to the separation and detection of cathinones and their positional and optical isomers for the first time. Low-flow sheathless CE/MS using a 20-µm-i.d. capillary in conjunction with a porous tip interface was used for the separation of cathinone derivatives and their optical isomers. Highly sulfated γ-cyclodextrin (HS-γ-CD) in conjunction with (+)-18-crown-6-tetracarboxylic acid ((+)-18-C-6-TCA) was used as the BGE and an ion trap mass spectrometer operating in full scan mode was utilized. Utilizing low flow rate (~10 nL/min) sheathless CE/MS, the use of the sodium salt of HS-γ-CD as the BGE was compared with the same solution using PFT. The relative and absolute sensitivity of detection of cathinones were about the same, indicating that under low-flow sheathless CE/MS there was no significant suppression due to the existence of HS-γ-CD in the electrospray process. However, enhanced resolution of cathinone derivatives and their positional and optical isomers was observed when the solution of HS-γ-CD was used as the BGE. The enhanced resolution was because of the presence of the HS-γ-CD in the entire capillary during the analysis. The addition of 15 mM (+)-18-C-6-TCA to the BGE containing HS-γ-CD further enhanced the resolution resulting in separation of all cathinones and their positional and optical isomers. A novel CE/MS technique has been introduced that combines low-flow sheathless CE/MS, with HS-γ-CD and 15 mM (+)-18-C-6-TCA as the BGE for separation of cathinone derivatives as well as their positional and optical isomers.

A competitive photoelectrochemical assay for estradiol based on in situ generated CdS-enhanced TiO2

A novel and simple photoelectrochemical (PEC) bioassay protocol for estradiol was proposed based on in situ generated CdS-enhanced TiO2 film via competitive strategy. The CdS was generated in situ by immediately dropping S2− onto the Cd2+-functionalized titanium phosphate nanoparticles (TiP@Cd2+). The TiO2 photoactive sensing film with countless active sites was obtained by calcination and further explored for estradiol (E2) capture. The TiP@Cd2+ was used as labels and immobilized through affinity-specific binding with E2 on the surface of the electrode. Greatly enhanced sensitivity was achieved by using porous TiP nanoparticles as carriers to load a large amount of Cd2+ and further for more CdS production through the S2− deposition. What's more, the photocurrent of CdS generated on the electrode surface could be significantly amplified by the coupling of CdS and TiO2, which could enhance the excitation and photo-to-electric conversion efficiency. Through the application of a competitive binding assay, the proposed biosensor showed high sensitivity with a detection limit down to 2pg/mL. This simple and fast PEC E2-sensing approach offers great promise to extend its application for the assay of small molecules of biomedical, food and environmental interest. Additionally, the strategy of employing in situ generated narrow-band gap semiconductors paves a new way for PEC sensing.

Acute safety of an open-irrigated ablation catheter with 56-hole porous tip for radiofrequency ablation of paroxysmal atrial fibrillation: analysis from 2 observational registry studies.

Acute Safety from 2 AF Ablation RegistriesIntroductionThis report presents safety data on the use of a new open-irrigation radiofrequency ablation (RFA) catheter with a 56-hole porous tip in 742 patients enrolled in 2 US prospective, multicenter observational registry studies representing real-world use of the catheter.MethodsThis analysis is comprised of patients who underwent RFA of drug-refractory recurrent symptomatic paroxysmal atrial fibrillation (AF). Acute adverse events (AEs) were collected and categorized by seriousness, timing, and relatedness, with 7 days of follow-up data in one study and at least 120 days of data from a 1-year follow-up in the other. Acute serious adverse events (SAEs) that were identified as potentially related to the device and/or procedure were adjudicated by an independent safety committee.ResultsA total of 30 patients (4.0%) in the combined studies experienced an acute SAE related to the device and/or procedure, which was similar in the subset of patients age 65 and over (4.2%). These SAEs included 1.2% cardiac tamponade/perforation, 0.7% pericarditis, 0.5% pulmonary events, and 0.8% vascular access complications. No myocardial infarction, stroke, transient ischemic attack, or atrioesophageal fistulas within 7 days postprocedure were reported. In the study with extended follow-up, 1 pulmonary vein stenosis and 1 esophageal injury were seen beyond 7 days postprocedure (0.2% each). There were no device or procedure related deaths.ConclusionResults from 2 large observational studies demonstrated that a new porous tip RFA catheter was safe for the treatment of drug refractory, recurrent, symptomatic paroxysmal AF, including treatment of older patients (≥65 years).

Ultrafast capillary electrophoresis/mass spectrometry with adjustable porous tip for a rapid analysis of protein digest in about a minute

This paper introduces a novel ultrafast capillary electrophoresis (UFCE) mass spectrometry (MS) method comprised of a short (< 20 cm) and narrow (≤ 5 µm) capillary, with an integrated porous segment at the terminus of the capillary, for sheathless interfacing of CE to MS. The sheathless nature of the interface minimizes dead volume which is particularly important for ultrafast CE because of the small diameters of the capillaries. The separation voltage across the capillary was set to produce an electric field of ≥1000 V/cm to provide an analysis time of approximately 1 min. For the analysis of peptides and protein digests, a background electrolyte containing 0.1% cationic polymer (polybrene or Poly-E) in 0.1% acetic acid in water was used to prevent analyte-wall interaction. Uniquely, the porous tip of the capillary is adjustable. This allows the porous tip to be pulled inside the sheath liquid for sample stacking during injection, or sample focusing in isoelectric focusing (IEF), or, alternatively, pushed outside of the sheath liquid for electrospray ionization (ESI). The adjustable interface preserves electrical conductivity during electrokinetic injection with reverse electro-osmotic flow. Therefore, pre-concentration of analytes at the capillary inlet is achieved without the need to disassemble the interface, improving the throughput. As a proof of concept, the application of UFCE-MS was demonstrated by the analysis of a peptide mixture and a protein digest in ~1 min.

Enhanced Efficiency of a Novel Porous Tip Irrigated RF Ablation Catheter for Pulmonary Vein Isolation

Irrigated tip radiofrequency (RF) catheter ablation is the most frequently used technology for pulmonary vein isolation (PVI). The purpose of this study was to compare the efficiency and the safety of 2 different open irrigated tip RF ablation catheters. A total of 160 patients with symptomatic AF (29% persistent, 68% male, 61 ± 10 years) were randomized to circumferential PVI using 2 different irrigated tip catheters: (1) the novel Thermocool SF(®) with a porous tip (56 holes) or (2) the Thermocool(®) catheter with 6 irrigation holes at the distal tip in both power- and temperature-controlled modes. PVI procedural time and RF duration were significantly shorter with SF(®) versus Thermocool(®) catheter: 104.5 versus 114 minutes (P = 0.023) and 35.4 minutes versus 39.9 minutes (P < 0.001), respectively. Similarly, the total fluoroscopy time and dose were shorter with SF(®) versus. Thermocool(®) catheter: 21 minutes versus 24 minutes (P = 0.02) and 1014.5 μGy*m(2) versus 1377 μGy*m(2) (P < 0.0001), respectively. Irrigation volume was lower with SF(®): 600 mL versus 1100 mL, (P < 0.0001) and the rates of complications were not significantly different (0.6% vs 0.49%, P = 0.66). At 20.5 ± 7.5 months follow-up, there were no significant differences with regard to arrhythmia freedom between SF(®) (59.2%) and TC® groups (59.3%), (P = 0.61). Using the novel irrigated tip SF catheter, PVI is achieved within a shorter ablation and procedural durations. The underlying mechanisms and potential differences in RF lesion size remain to be elucidated.

Low-Flow Sheathless Capillary Electrophoresis–Mass Spectrometry for Sensitive Glycoform Profiling of Intact Pharmaceutical Proteins

Capillary electrophoresis coupled to time-of-flight mass spectrometry (CE-TOF-MS) via a porous tip sheathless electrospray ionization (ESI) interface was studied for the characterization of pharmaceutical glycoproteins. To achieve optimal glycoform separation, background electrolytes of low pH were used in conjunction with a capillary with a neutral coating exhibiting near-zero electroosmotic flow. Crucial interfacing parameters, like ESI voltage and ESI tip-to-end plate distance, were optimized for very low flow rates (∼5 nL/min) in order to attain maximum sensitivity and stable performance. Under optimal conditions, the sheathless CE-MS interface provided significantly increased ionization efficiencies for intact proteins and decreased ionization suppression leading to detection limits in the picomolar-range. Analysis of a sample of recombinant human interferon-β allowed the assignment of at least 18 glycoforms, plus a variety of deamidation, succinimide, and oxidation products, representing a considerable improvement over sheath-liquid CE-MS. The sheathless CE-MS system also proved highly suitable for the glycoprofiling of recombinant human erythropoietin, revealing 74 glycoforms in a 60-min run. In addition, oxidation and acetylation products were detected, overall resulting in assignment of more than 250 different isoforms. Semiquantitative glycoprofiles could be derived for both pharmaceutical proteins, with estimated glycoform concentrations analyzed ranging from 0.35 to 950 nM. These profiles may be very useful for quality control of biopharmaceuticals and their biosimilars.