Capillary Tip Research Articles

Evidence from the large VALIGA cohort validates the subclassification of focal segmental glomerulosclerosis in IgA nephropathy

Evidence from the Oxford IgA nephropathy (IgAN) cohort supports the clinical value of subclassifying focal segmental glomerulosclerosis lesions (S1). Using the larger Validation in IgA (VALIGA) study cohort, we investigated the association between podocytopathic changes and higher proteinuria, kidney outcome and response to immunosuppressive therapy. All biopsies were evaluated for glomeruli with segmental capillary occlusion by matrix ("not otherwise specified", NOS lesion), simple capsular adhesion without capillary occlusion (Adh), tip lesions, and podocyte hypertrophy (PH). S1 required a NOS lesion and/or Adh. A Chi-Squared Automatic Interaction Detection method was used to identify subgroups of FSGS lesions associated with distinctive proteinuria at biopsy. We assessed survival from a combined event (kidney failure or 50% decline in estimated glomerular filtration rate). Finally, we evaluated within each subgroup if immunosuppression was associated with a favorable outcome using propensity analysis. In 1147 patients, S1 was found in 70% of biopsies. Subclassification found NOS lesions in 44%, Adh in 59%, PH in 13%, and tip lesions in 3%, with much overlap. Four subgroups were identified with progressively higher proteinuria: from lowest, S1 without NOS, S1 with NOS but without Adh/PH, to highest, S1 with NOS and Adh but without PH, and S1 with NOS and PH. These four subgroups showed progressively worse kidney survival. Immunosuppression was associated with a better outcome only in the two highest proteinuria subgroups. Propensity analysis in these two groups, adjusted for clinical and pathological findings, found a significantly reduced time-dependent hazard of combined outcome with corticosteroids. Podocyte hypertrophy and glomeruli with simple adhesions appeared to reflect active lesions associated with a response to corticosteroids, while other S1 lesions defined chronicity. Thus, our findings support subclassifying S1 lesions in IgAN.

Interfacial Electromigration for Analysis of Biofluid Lipids in Small Volumes.

Lipids are important biomarkers within the field of disease diagnostics and can serve as indicators of disease progression and predictors of treatment effectiveness. Although lipids can provide important insight into how diseases initiate and progress, mass spectrometric methods for lipid characterization and profiling are limited due to lipid structural diversity, particularly the presence of various lipid isomers. Moreover, the difficulty of handling small-volume samples exacerbates the intricacies of biological analyses. In this work, we have developed a strategy that electromigrates a thin film of a small-volume biological sample directly to the air-liquid interface formed at the tip of a theta capillary. Importantly, we seamlessly integrated in situ biological lipid extraction with accelerated chemical derivatization, enabled by the air-liquid interface, and conducted isomeric structural characterization within a unified platform utilizing theta capillary nanoelectrospray ionization mass spectrometry, all tailored for small-volume sample analysis. We applied this unified platform to the analysis of lipids from small-volume human plasma and Alzheimer's disease mouse serum samples. Accelerated electro-epoxidation of unsaturated lipids at the interface allowed us to characterize lipid double-bond positional isomers. The unique application of electromigration of a thin film to the air-liquid interface in combination with accelerated interfacial reactions holds great potential in small-volume sample analysis for disease diagnosis and prevention.

Deep UV-LED induced nitrate-to-nitrite conversion for total dissolved nitrogen determination in water samples through persulfate digestion and capillary electrophoresis

BackgroundCapillary electrophoresis (CE) with capacitively coupled contactless conductivity detection (C4D) is widely used for water quality monitoring. However, there is currently no reported CE method for detecting total dissolved nitrogen (TDN), a crucial parameter for assessing water eutrophication. One challenge is the high sulfate concentration (100 mM) introduced during persulfate digestion, leading to overlap of nitrate (from TDN) and poor electrical stacking of nitrate in CE-C4D analysis. ResultsWe introduced an in-capillary UV-LED induced photoreaction to convert nitrate to nitrite, which can be baseline-separated from sulfate via the CE method, enabling accurate quantification of nitrate concentration derived from nitrite. A 2 nL post-persulfate digested sample solution within a fused silica capillary was exposed to UV-LED irradiation at the capillary tip. Subsequently, photoreduction-produced nitrite was electrophoretically separated from sulfate in an acidic buffer (pH = 3.7) within the same capillary, followed by contactless conductivity detection. The nitrate-to-nitrite conversion efficiency was influenced by irradiation wavelength, power, and duration, reaching a maximum efficiency of 77.4% when employing two 230 nm LEDs for 5 min. For more general applications, two 255 nm LEDs were used, providing a conversion efficiency of (66.4 ± 3.3)% (n = 11) for 5 min of irradiation. The proposed CE-C4D method exhibits a detection limit of 13 μM (0.18 mg N/L) and has been successfully employed for TDN determination in lake water samples. SignificanceThis innovative approach not only enhances the attractiveness of the CE-C4D method for the determination of water quality indicators but also highlights the potential for integrating deep-UV LEDs into environmental analysis.

Mathematical and numerical analyses of cellular, molecular and angiogenic parameters of a rat skin wound healing model.

The inflammatory phase is an important event in the skin wound healing process. The deposition of granulation tissue in the wound bed and the rebuilding of the vascular network occur as inflammation diminishes. An angiogenic component in the formation of granulation tissue is the secretion of vascular endothelial growth factor, which assists in the chemotaxis, proliferation, and replication of fibroblasts. In this paper, we develop a mathematical model of skin wound healing angiogenic factors based on inflammatory cells (macrophages and neutrophils) and mediators (interleukin 6 and interleukin 10). We highlight the importance of this process in vascular endothelial growth factor release and in the formation of new capillary tips. We used a mathematical model of partial differential equations based on the reaction-diffusion-advection equations. In order to calibrate the parameters, we considered an in vivo model composed by four treatments: hydroalcoholic extract and oil-resin of Copaifera langsdorffii at 10% concentration, collagenase, and Lanette cream. Using the laboratory data for the wound edge, our mathematical model estimated the values of vascular endothelial growth factor concentration, and tips density in the center of the wound with a maximum error of 2.9%, and predicted healing time required for each treatment. The region of viability for the parameters, in the proposed model, was found through numerical simulations from the Interleukin 6 and 10 dysregulation and we obtained that, among the parameters analyzed, the greatest influencer in the dynamics of the system is the one, which represents the production of Interleukin 10 during phagocytosis.

Auto-Lectin Dotcoding by Two Octopuses: Rapid Analysis of Fluorescence-Labeled Glycoproteins by an 8-channel Fully-Automatic Bead Array Scanner with a Rolling-Circle Detector.

Protein glycosylation is a crucial factor that must be evaluated in biological pharmaceuticals. The glycoform profile of a protein can vary depending on the conditions of the cultivation, purification process, and the selection of a host cell. Lectin microarrays are reliable bioanalytical methods used in the early phases of bioprocesses for the detection of glycosylation. The concept of a fully automated glycan detection with a bead array has been previously reported; however, no simple system has been constructed on fluorescence-based detection using a microarray. Here, we present a fully automated detection system equipped with a novel fluorescence detector for a 13-lectin bead array with a single tip. The lattice-like arrangement of a set of fibers proximate to the tip of the light emitting diode and photomultiplier tube detector minimized the noise caused by the reflection of incident light on the plastic capillary tip and bead. A unique rolling-circle fiber unit with quadruple lattices stacked in two layers realizes the 8-parallel automeasurement with a drastic reduction in scanning time and machine size. The 8-glycan profiles obtained automatically within 25 min were identical with those obtained with the conventional lectin microarray after overnight incubation. The signals obtained were represented as lectin dotcodes. Therefore, autolectin dotcoding assisted by the twin 8 legs named as "detection and irradiation octopuses" may be a rapid glyco-evaluation system during the production and development of biopharmaceuticals.

Capillary self-aspirating electrospray ionization (CSESI) for convenient and versatile mass spectrometry analysis

Electrospray ionization (ESI) is one of the most widely used ionization techniques, and its simplification can benefit many interested users. In this study, sample introduction by capillary action was studied and used to develop a simple ESI source called capillary self-aspirating electrospray ionization (CSESI). A conventional CSESI source requires only a common capillary of appropriate diameter in addition to the support of high voltage (HV). No pumps and sample loading is needed because the solution can spontaneously climb across the capillary by capillary action. With the proper modification of the glass capillary, the operation of CSESI can be further simplified and efficient. Specifically, cold plasma processing of the capillary creates a more hydrophilic surface that can facilitate sample introduction. Moreover, sputtering a thin platinum layer on the capillary tip makes the application of HV more convenient, and it also eliminates the influence of air bubbles in the capillary to ensure a sustained and stable electrospray. Overall, CSESI exhibits multiple desirable features such as simple structure, self-aspiration ability, low sample consumption, and inherent physical filtration capability. Apart from the routine ESI-MS analysis, it has also been applied in real-time monitoring of the oxidative dimerization of 8-methyl-1,2,3,4-tetrahydroquinoline, as well as direct analysis of muddy soil solutions without pretreatment.

Canal Drying Protocols to Use with Calcium Silicate–based Sealer: Effect on Bond Strength and Adhesive Interface

IntroductionThe aim of this study was to evaluate the influence on bond strength and interface quality of different canal drying protocols in roots filled with Bio-C Sealer (BCS; Angelus, Londrina, Paraná, Brazil). MethodsNinety-six roots of upper canines were prepared with an R50 file (Reciproc; VDW GmbH, Munich, Germany) and irrigated with 2.5% sodium hypochlorite and 17% EDTA under ultrasonic agitation. Roots were divided according to the drying protocol as follows: dry, the White Mac tip (Ultradent, Indaiatuba, SP, Brazil) for 5 seconds followed by aspiration with a capillary tip for 5 seconds and paper points; slightly moist, the White Mac tip followed by capillary aspiration without paper points; wet, the White Mac tip followed by a single paper point. The roots were filled with BCS or AH Plus (AHP; Dentsply Maillefer, Ballaigues, Switzerland) (n = 16) and sectioned for the push-out test after 3 months. Failure modes were assessed, and the interface morphology was analyzed under scanning electron microscopy. After 6 months, the other half of the roots were evaluated. Data were analyzed by analysis of variance/Tukey test at 5%. The chi-square test was used in the failure analysis and the Kruskal-Wallis/Dwass-Steel-Critchlow-Fligner for interface analysis. ResultsThe AHP-filled roots had the highest bond strength when the canal was dried (P < .05). No difference was found for periods (P > .05). For BCS, the highest bond strength was found in the slightly moist canals (P < .05). A predominance of adhesive failures was observed. The dried canals filled with AHP had the highest percentage of good adaptation, whereas BCS had no difference. ConclusionsThe best drying protocol for AHP is using the White Mac tip followed by capillary tip aspiration and paper points until complete dryness, and for BCS, it is using the White Mac tip followed by capillary aspiration without paper points.

Granulomatous Mediastinitis: A Rare Cause of Pulmonary Hypertension.

A rare case of a patient with chronic obstructive pulmonary disease who developed secondary anthracofibrosis to biomass exposure, fibrosing mediastinitis due to anthracotic enlarged lymph nodes in the mediastinum, and pulmonary hypertension because of compres- sion of the lymph nodes on the pulmonary arteries is presented. This is a case report of a 71-year-old female patient who has been followed up with chronic obstructive pulmonary disease for 10 years, has no history of smoking, and has been exposed to biomass for many years. The patient, who had been hospitalized in various centers for the last 3 years due to progressive shortness of breath and dry cough, applied to us with dry cough and dyspnea complaints. On echocardiography, systolic pulmonary arterial pressure was found to be 59 mmHg. For the etiology of pulmonary hypertension, dual-energy thoracic computed tomography was performed with the suspicion of chronic thromboembolic pulmonary hypertension. No filling defect compatible with thromboembolism was detected. In right heart catheterization, mean pulmonary artery pressure was 27 mmHg, pulmonary capillary tip pressure was 7 mmHg, and pulmonary vascular resistance was 3.71 woods units. Endobronchial ultrasound was applied to the patient with the preliminary diagnoses of lymphoma, anthracosis, fibrosing mediastinitis, and infection. Widespread anthracosis was observed in all lobes and segments macroscopically. The lymph node in the subcarinal area was interpreted as anthracotic lymph node. Anthracosis is defined as black pigmentation involving the mucosal, and submucosal layers of the tracheobronchial tree and the lung parenchyma. If anthracosis is associated with luminal obliteration and/or mucosal proliferation causing obstruction, it is considered anthracofibrosis. In this case, we saw that secondary anthracofibrosis, fibrosing mediastinitis due to anthracotic enlarged lymph nodes in the mediastinum, and pulmonary hypertension may develop because of compression of the lymph nodes on the pulmonary arteries, and we wanted to draw attention to it was a rare case.

Acoustic Atomization-Induced Pumping Based on a Vibrating Sharp-Tip Capillary.

Pumping is an essential component in many microfluidic applications. Developing simple, small-footprint, and flexible pumping methods is of great importance to achieve truly lab-on-a-chip systems. Here, we report a novel acoustic pump based on the atomization effect induced by a vibrating sharp-tip capillary. As the liquid is atomized by the vibrating capillary, negative pressure is generated to drive the movement of fluid without the need to fabricate special microstructures or use special channel materials. We studied the influence of the frequency, input power, internal diameter (ID) of the capillary tip, and liquid viscosity on the pumping flow rate. By adjusting the ID of the capillary from 30 µm to 80 µm and the power input from 1 Vpp to 5 Vpp, a flow rate range of 3 to 520 µL/min can be achieved. We also demonstrated the simultaneous operation of two pumps to generate parallel flow with a tunable flow rate ratio. Finally, the capability of performing complex pumping sequences was demonstrated by performing a bead-based ELISA in a 3D-printed microdevice.

High-Resolution, Multiplex Antibody Patterning using Micropillar-Focused Droplet Printing, and Microcontact Printing.

Antibody arrays have great implications in many biomedical settings. However, commonly used patterning methods have difficulties in generating antibody arrays with both high resolution and multiplexity, limiting their applications. Here, a convenient and versatile technique for the patterning of multiple antibodies with resolution down to 20µm is reported using micropillar-focused droplet printing and microcontact printing. Droplets of antibody solutions are first printed and stably confined on the micropillars of a stamp, and then the antibodies absorbed on the micropillars are contact-printed to the target substrate, generating antibody patterns faithfully replicating the micropillar array. The effect of different parameters on the patterning results is investigated, including hydrophobicity of the stamps, override time of the droplet printing, incubation time, and the diameters of the capillary tips and micropillars. To demonstrate the utility of the method, multiplex arrays of anti-EpCAM and anti-CD68 antibodies is generated to capture breast cancer cells and macrophages, respectively, on the same substrate, and successful capturing of individual cell types and enrichment among the cells are achieved. It is envision that this method would serve as a versatile and useful protein patterning tool for biomedical applications.

High-Throughput Nanoliter Sampling and Direct Analysis of Biological Fluids Using Droplet Imbibition Mass Spectrometry.

A high-throughput droplet imbibition mass spectrometry (MS) experiment is reported for the first time that allows direct analysis of ultra-small volumes of complex mixtures. In this experiment, an array of optimized tips of glass capillaries containing the analyte solution is sampled by rapidly moving charged microdroplets, which picks up (i.e., imbibes) the analyte and transfers it to a proximal mass spectrometer. The advantages associated with this droplet imbibition experiment include (1) ultra-small sample consumption (1.3 nL/min), which reduces the matrix effect in complex mixture analysis, and (2) high surface activity, which eliminates ion suppression effects caused by competition for the space charge on the droplet surface. Collectively, the enhanced surface effect and small flow rates dramatically increase the sensitivity of the droplet imbibition MS approach. This was experimentally shown by constructing calibration curves for cocaine analysis in human raw urine and whole blood, achieving 2 and 7 pg/mL limits of detection, respectively. The high-throughput feature was demonstrated by analyzing five structurally different compounds in 20 s intervals. With the measured flow rate of 1.3 nL/min on a 5 μm glass tip size, the results described in the current study showcase droplet imbibition MS to be a powerful and high-throughput alternative for conventional nano-electrospray ionization (flow rate <100 nL/min), which is the most efficient method for transferring small sample volumes to mass spectrometers.

Gold Nanotriangle-Assembled Nanoporous Structures for Electric Field-Assisted Surface-Enhanced Raman Scattering Detection of Adenosine Triphosphate.

A reliable, rapid, cost-effective, and simple method for the detection of biomolecules would greatly promote the research of analytical detection of single molecules. A nanopore-based analytical technique is promising for detecting biomolecules. Conventional electrochemical nanopores cannot distinguish biomolecules precisely because of their fast translocation speed and limited electrochemical information. Therefore, it is highly desirable to develop electrochemical surface-enhanced Raman scattering (SERS) nanopores to obtain multidimensional information. Herein, we designed and fabricated gold nanotriangle (AuNT)-assembled porous structures at the tip of a glass capillary using dithiol adenosine triphosphate (ATP) aptamers as cross-linking molecules. The AuNTs exhibited an edge length of 57.3 ± 6.2 nm and thickness of about 15 nm. The gold nanoporous structure (GPS) showed a strong ion rectification even at a high concentration of electrolyte (2 M) and a high SERS activity. Based on these designed structures, SERS and electrochemistry techniques were combined to control the rapid movement of ATP to the vicinity of the GPS by an applied potential of +1 V, where ATP was concentrated by ATP aptamers and the molecular signals were amplified by SERS. As a result, the GPS successfully detected ATP at a concentration as low as 10-7 M.

Pocket-Size Wireless Nanoelectrospray Ionization Mass Spectrometry for Metabolic Analysis of Salty Biofluids and Single Cells.

Analysis of volume-limited biological samples such as single cells and biofluids not only benefits clinical purposes but also promotes fundamental research in life sciences. Detection of these samples, however, imposes strict requirements on measurement performance because of the minimal volume and concentrated salts of the samples. Herein, we developed a self-cleaning nanoelectrospray ionization device powered by a pocket-size "MasSpec Pointer" (MSP-nanoESI) for metabolic analysis of salty biological samples with limited volume. The self-cleaning effect induced by Maxwell-Wagner electric stress helps with keeping the borosilicate glass capillary tip free from clogging and thus increasing salt tolerance. This device possesses a high sample economy (about 0.1 μL per test) due to its pulsed high voltage supply, sampling method (dipping the nanoESI tip into analyte solution), and contact-free electrospray ionization (ESI) (the electrode does not touch the analyte solution during ESI). High repeatable results could be acquired by the device with a relative standard deviation (RSD) of 1.02% for voltage output and 12.94% for MS signals of caffeine standard. Single MCF-7 cells were metabolically analyzed directly from phosphate buffered saline, and two types of untreated cerebrospinal fluid from hydrocephalus patients were distinguished with 84% accuracy. MSP-nanoESI gets rid of the bulky apparatus and could be held in hand or put into one's pocket for transportation, and it could operate for more than 4 h without recharge. We believe this device will boost scientific research and clinical usage of volume-limited biological samples with high-concentration salts in a low-cost, convenient, and rapid manner.

Influence of root canal moisture conditions on the bond strength of endodontic sealers to dentin

Objective: To investigate the influence of intraradicular moisture conditions on the bond strength of 3 different endodontic cements in the coronal, middle, and apical thirds of the root canal. Materials and Methods: 90 single-rooted teeth were instrumented with a reciprocal R#50 file and randomly divided into 3 experimental groups: Dry group: dry canals with absorbent paper tips; Moist group: suction syringe and capillary tip coupled to a vacuum pump; Wet group: aspiration with endodontic suction. The groups were divided according to the endodontic sealer used: AH plus (Denstply), Hiflow (Brasseler) and Bio-c Sealer (Angelus). Obturation was performed using Tagger's hybrid technique with a single cone. The teeth were subjected to the "push-out" test to evaluate the bond strength of the cements. Results: Data were analyzed using the Kolgomorov-Smirnoff normal distribution test and the Mann Whitney U test to compare means within and between groups. The standard error established was 5% at a significance level of 95%. AH plus showed better results regardless of canal moisture conditions. Hiflow showed better bond strength in the dry group compared to the moist group (p=0.023) in the cervical area. Bio-C Sealer showed no statistically significant differences (p &gt; 0.05). Conclusion: Moisture conditions affected the bond strength values of endodontic cements. The prevalence of failure moduli was mixed in all root thirds, regardless of the cement used.

Study of Surfactant‐Induced Deformations at the Interface of Emulsion Droplets by Digital Image Analysis of Droplet Projections

AbstractEmulsion droplets do not always have smooth surfaces. Under certain conditions, the formation of surface‐active species at oil–water interfaces leads to interfacial instabilities that cause a spontaneous increase in the droplet surface area, which results in fascinating droplet morphologies. The specific system presented in this study consists of stearic acid encapsulated in an oil droplet and the quaternary ammonium surfactant cetyltrimethylammonium bromide in the aqueous phase. This system is studied by examining the deformation of single emulsion droplets hanging on a capillary tip. By using digital image analysis, the relative perimeters and fractal dimensions from the droplet outlines are calculated and the influences of several process parameters on their temporal development are studied. It is demonstrated that the surfactant concentration, pH value, salt addition, alcohol addition, and viscosity have a considerable impact on the droplet morphology and possible causes for this behavior are discussed. Through this study, important insights are gained into the deformation mechanism and kinetics that can potentially guide the future preparation of particles with special surface morphologies.

(Invited) Electrochemical Detection of Pseudomonas Aeruginosa Quorum Sensing Molecules at Micro Liquid|Liquid Interface Via Facilitated Proton Transfer Mechanism

The micro interface between two electrolyte solutions (micro-ITIES) has been exploited as a miniaturized electrochemical platform for detection of Pseudomonas aeruginosa. Electrochemical detection methods for point-of-care-devices in healthcare environments are ideal owing to their small equipment footprint and relative ease of use, while simultaneously, disposable electrode materials are easily fabricated. Meanwhile, P. aeruginosa is a pathogenic bacteria that poses a serious health risk to patients with compromised immune systems. Herein, a proof-of-concept electrochemical method is demonstrated that employs a micro-ITIES between water and oil (w/o) held at the tip of a glass capillary which targets two quorum sensing (QS) molecules produced throughout the bacteria’s life-cycle: 4‐hydroxy‐2‐heptylquinoline (HHQ) and 2‐heptyl‐3,4‐dihydroxyquinoline (PQS, Pseudomonas quinolone signal). QS molecules are used to signal colony growth in a pseudo-multicellular fashion; however, HHQ and PQS are also known virulence factors and are unique to this form of pathogenic bacteria. HHQ and PQS show excellent solubility in chlorinated organic solvent with limited partitioning to the aqueous phase. Moreover, as observed electrochemically, they facilitate proton transfer across the w/o interface which can be monitored/quantified and is exploited here as a means for early bacterial detection. This work demonstrates that the micro-ITIES can serve as a viable platform for P. aeruginosa identification and quantification. Density functional theory calculations were also performed to determine the proton affinities and gas-phase basicities of HHQ/PQS, as well as elucidate the likely site of stepwise protonation within each molecule. Figure 1

Controllable Fabrication of Small-Size Holding Pipets for the Nondestructive Manipulation of Suspended Living Single Cells.

The capture and manipulation of single cells are an important premise and basis for intracellular delivery, which provides abundant molecular and omics information for biomedical development. However, for intracellular delivery of cargos into/from small-size suspended living single cells, the capture methods are limited by the lack of small-size holding pipets, poor cell activity, and the low spatial accuracy of intracellular delivery. To solve these problems, a method for the controllable fabrication of small-size holding pipets was proposed. A simple, homemade microforge instrument including an imaging device was built to cut and melt the glass capillary tip by controlling the heat production of a nichrome wire. The controllable fabrication of small-size holding pipets was realized by observing the fabrication process in real time. Combined with an electroosmotic drive system and a micromanipulation system with high spatial resolution, the holding pipet achieved the active capture, movement, and sampling of suspended living single cells. Moreover, solid-phase microextraction was performed on captured single pheochromocytoma cells, and the extracted dopamine was successfully detected using an electrochemical method. The homemade microforge instrument overcame the limitations of traditional microforges, resulting in holding pipets that were sufficiently small for small-size suspended single living cells (5-30 μm). This proactive capture method overcame the shortcomings of existing methods to achieve the multiangle, high-precision manipulation of single cells, thereby allowing the intracellular delivery of small-size single cells in suspension with high spatiotemporal resolution.

3D printed devices and infrastructure for liquid sample delivery at the European XFEL.

The Sample Environment and Characterization (SEC) group of the European X-ray Free-Electron Laser (EuXFEL) develops sample delivery systems for the various scientific instruments, including systems for the injection of liquid samples that enable serial femtosecond X-ray crystallography (SFX) and single-particle imaging (SPI) experiments, among others. For rapid prototyping of various device types and materials, sub-micrometre precision 3D printers are used to address the specific experimental conditions of SFX and SPI by providing a large number of devices with reliable performance. This work presents the current pool of 3D printed liquid sample delivery devices, based on the two-photon polymerization (2PP) technique. These devices encompass gas dynamic virtual nozzles (GDVNs), mixing-GDVNs, high-viscosity extruders (HVEs) and electrospray conical capillary tips (CCTs) with highly reproducible geometric features that are suitable for time-resolved SFX and SPI experiments at XFEL facilities. Liquid sample injection setups and infrastructure on the Single Particles, Clusters, and Biomolecules and Serial Femtosecond Crystallography (SPB/SFX) instrument are described, this being the instrument which is designated for biological structure determination at the EuXFEL.

NanoCEasy: An Easy, Flexible, and Robust Nanoflow Sheath Liquid Capillary Electrophoresis-Mass Spectrometry Interface Based on 3D Printed Parts.

Capillary electrophoresis-mass spectrometry (CE-MS) is a powerful tool in various fields including proteomics, metabolomics, and biopharmaceutical and environmental analysis. Nanoflow sheath liquid (SL) CE-MS interfaces provide sensitive ionization, required in these fields, but are still limited to a few research laboratories as handling is difficult and expertise is necessary. Here, we introduce nanoCEasy, a novel nanoflow SL interface based on 3D printed parts, including our previously reported two capillary approach. The customized plug-and-play design enables the introduction of capillaries and an emitter without any fittings in less than a minute. The transparency of the polymer enables visual inspection of the liquid flow inside the interface. Robust operation was systematically demonstrated regarding the electrospray voltage, the distance between the emitter and MS orifice, the distance between the separation capillary and emitter tip, and different individual emitters of the same type. For the first time, we evaluated the influence of high electroosmotic flow (EOF) separation conditions on a nanoflow SL interface. A high flow from the separation capillary can be outbalanced by increasing the electrospray voltage, leading to an overall increased electrospray flow, which enables stable operation under high-EOF conditions. Overall, the nanoCEasy interface allows easy, sensitive, and robust coupling of CE-MS. We aspire the use of this sensitive, easy-to-use interface in large-scale studies and by nonexperts.

Experimental and Computational Analysis of Mixing Inside Droplets for Microfluidic Fabrication of Gold Nanoparticles

Emulsions formed by mixing reactant streams inside microdroplets are efficient microscale reactors for the synthesis of nano/microparticles/crystals due to small quantities of reagents confined within each droplet and the separation of droplet contents from the reactor walls. In this work, the synthesis of size-tunable gold nanoparticles (AuNPs) within emulsion droplets generated in a three-phase glass capillary microfluidic device was investigated experimentally and numerically using computational fluid dynamics (CFD). AuNPs were produced by micromixing two aqueous streams, 1.15 mM HAuCl4 containing the 1% poly(vinylpyrrolidone) capping agent and 20 mM ascorbic acid solutions, inside monodispersed droplets created by three-dimensional (3D) counter-current flow focusing in a medium-chain triglyceride. The mean particle size of AuNPs was tunable in the range between 26 and 56 nm and depended on the degree of premixing of the reactant streams shortly before droplet generation, and the mixing efficiency within droplets, which was controlled by hydrodynamic conditions within the microfluidic device. The CFD results were compared and validated against experimental observations and revealed the presence of a recirculation zone near the outer wall of the injection capillary tip. The mixing efficiency was higher at smaller droplet size causing a reduction in the particle size of the AuNPs.