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Journal of the Royal Society, Interface Mar 2018The female sex organ of the liverwort () has a characteristic parasol-like form highly suitable for collecting water droplets containing sperm for fertilization....
The female sex organ of the liverwort () has a characteristic parasol-like form highly suitable for collecting water droplets containing sperm for fertilization. Motivated by this observation and using three-dimensional printing techniques, we develop a parasol-like rigid object that can grab, transport and release water droplets of a maximum size of about 1 cm. By combining experiments and scaling theory, we quantify the object's fundamental wetting and fluid dynamical properties. We construct a stability phase diagram and suggest that it is largely insensitive to properties of liquids such as surface tension and viscosity. A simple scaling argument is developed to explain the phase boundary. Our study provides basic design rules of a simple pipette-like device with bubble-free capture and drop of liquids, which can be used in laboratory settings and has applications within soft robotics. Through systematic experimental investigations, we suggest the optimal design criteria of the liverwort-inspired object to achieve maximal pipetting performance. We also provide, based on our scalable model experiments, a biological implication for the mechanistic advantage of this structure in liverwort reproduction.
Topics: Biological Transport, Active; Biomimetic Materials; Hepatophyta; Ovule; Wettability
PubMed: 29540542
DOI: 10.1098/rsif.2017.0868 -
Proceedings of the National Academy of... Jan 2017Studying how the membrane modulates ion channel and transporter activity is challenging because cells actively regulate membrane properties, whereas existing in vitro...
Studying how the membrane modulates ion channel and transporter activity is challenging because cells actively regulate membrane properties, whereas existing in vitro systems have limitations, such as residual solvent and unphysiologically high membrane tension. Cell-sized giant unilamellar vesicles (GUVs) would be ideal for in vitro electrophysiology, but efforts to measure the membrane current of intact GUVs have been unsuccessful. In this work, two challenges for obtaining the "whole-GUV" patch-clamp configuration were identified and resolved. First, unless the patch pipette and GUV pressures are precisely matched in the GUV-attached configuration, breaking the patch membrane also ruptures the GUV. Second, GUVs shrink irreversibly because the membrane/glass adhesion creating the high-resistance seal (>1 GΩ) continuously pulls membrane into the pipette. In contrast, for cell-derived giant plasma membrane vesicles (GPMVs), breaking the patch membrane allows the GPMV contents to passivate the pipette surface, thereby dynamically blocking membrane spreading in the whole-GMPV mode. To mimic this dynamic passivation mechanism, beta-casein was encapsulated into GUVs, yielding a stable, high-resistance, whole-GUV configuration for a range of membrane compositions. Specific membrane capacitance measurements confirmed that the membranes were truly solvent-free and that membrane tension could be controlled over a physiological range. Finally, the potential for ion transport studies was tested using the model ion channel, gramicidin, and voltage-clamp fluorometry measurements were performed with a voltage-dependent fluorophore/quencher pair. Whole-GUV patch-clamping allows ion transport and other voltage-dependent processes to be studied while controlling membrane composition, tension, and shape.
PubMed: 28003462
DOI: 10.1073/pnas.1609142114 -
Chemical Reviews Oct 2021Scanning ion conductance microscopy (SICM) has emerged as a versatile tool for studies of interfaces in biology and materials science with notable utility in biophysical... (Review)
Review
Scanning ion conductance microscopy (SICM) has emerged as a versatile tool for studies of interfaces in biology and materials science with notable utility in biophysical and electrochemical measurements. The heart of the SICM is a nanometer-scale electrolyte filled glass pipette that serves as a scanning probe. In the initial conception, manipulations of ion currents through the tip of the pipette and appropriate positioning hardware provided a route to recording micro- and nanoscopic mapping of the topography of surfaces. Subsequent advances in instrumentation, probe design, and methods significantly increased opportunities for SICM beyond recording topography. Hybridization of SICM with coincident characterization techniques such as optical microscopy and faradaic electrodes have brought SICM to the forefront as a tool for nanoscale chemical measurement for a wide range of applications. Modern approaches to SICM realize an important tool in analytical, bioanalytical, biophysical, and materials measurements, where significant opportunities remain for further exploration. In this review, we chronicle the development of SICM from the perspective of both the development of instrumentation and methods and the breadth of measurements performed.
Topics: Electrodes; Electrolytes; Ions; Microscopy
PubMed: 33295182
DOI: 10.1021/acs.chemrev.0c00962 -
Nature Biomedical Engineering Sep 2019
Topics: Algorithms; Animals; Brain; Electrophysiology; Glass; Mice; Microelectrodes; Patch-Clamp Techniques; Rats
PubMed: 31501567
DOI: 10.1038/s41551-019-0452-x -
The Review of Scientific Instruments Nov 2016The handheld micropipette is the most ubiquitous instrument for precision handling of microliter-milliliter liquid volumes, which is an essential capability in biology...
The handheld micropipette is the most ubiquitous instrument for precision handling of microliter-milliliter liquid volumes, which is an essential capability in biology and chemistry laboratories. The range of one pipette is typically adjustable up to 10-fold its minimum volume, requiring the use and maintenance of multiple pipettes for liquid handling across larger ranges. Here we propose a design for a single handheld pipette adjustable from 0.1 μl to 1000 μl (i.e., 10-fold) which spans the range of an entire suite of current commercial pipettes. This is accomplished by placing an elastic diaphragm between the existing pipette body and tip, thereby de-amplifying its native volume range while maintaining its simple manual operating procedure. For proof-of-concept, we adapted a commercial pipette (100-1000 μl nominal range) with a selection of rubber sheets to function as the diaphragms and confirmed the accuracy and precision of drawn volumes are within international ISO-8655 standards across the entire 10-fold volume range. The presence of the diaphragms introduces a nonlinear mechanical behavior and a time-dependency due to heat transfer, however, by model and experiment, these are redressed so as to maintain the pipette's accuracy and precision.
PubMed: 27910408
DOI: 10.1063/1.4966989 -
Molecular Biology of the Cell Jun 2024
Topics: Humans; Art; Science
PubMed: 38805384
DOI: 10.1091/mbc.E24-04-0149 -
Biosensors & Bioelectronics Dec 2022In-field screening of pathogenic bacteria is important for preventing food poisoning. Here, a portable pipette-adapted biosensor using magnetic grid separation and...
In-field screening of pathogenic bacteria is important for preventing food poisoning. Here, a portable pipette-adapted biosensor using magnetic grid separation and nanocatalyst signal amplification was elaboratively developed for rapid detection of Salmonella typhimurium. A common pipette was innovatively adapted with multiple functions to complete the whole bacterial detection procedure, including mixing, separation, catalysis, washing, detection, analysis and display. The target bacteria were effectively captured by the immune magnetic nanobeads and labeled with immune gold@platinum nanocatalysts through pipette-blowing mixing to form the nanobeads-bacteria-nanocatalyst complexes, which were separated against the magnetic grid separation tip under the magnetic field. The pressure change resulting from oxygen production due to mimicking catalysis of hydrogen peroxide by these nanocatalysts on the complexes was quantified through measuring the moving duration of the conductive liquid in the pipette for bacteria determination. Under optimal conditions, this biosensor could detect target bacteria in 90 min with low detection limit of 180 CFU/mL. This pipette-adapted biosensor is affordable, sensitive, specific, user-friendly, rapid and robust, equipment-free and deliverable to end-users (ASSURED), and has the potential for in-field testing of foodborne pathogens to ensure food safety, especially in resource-constrained areas.
Topics: Biosensing Techniques; Food Microbiology; Platinum; Food Contamination; Hydrogen Peroxide; Salmonella typhimurium; Gold; Oxygen; Limit of Detection
PubMed: 36208529
DOI: 10.1016/j.bios.2022.114765 -
Reproductive Biomedicine Online Sep 2023Can an automated sperm injection robot perform Automated Intracytoplasmic Sperm Injection (ICSIA) for use in human IVF? (Clinical Trial)
Clinical Trial
RESEARCH QUESTION
Can an automated sperm injection robot perform Automated Intracytoplasmic Sperm Injection (ICSIA) for use in human IVF?
DESIGN
The ICSIA robot automated the sperm injection procedure, including injection pipette advancement, zona pellucida and oolemma penetration with piezo pulses, and pipette removal after sperm release. The robot was first tested in mouse, hamster and rabbit oocytes, and subsequently using discarded human oocytes injected with microbeads. A small clinical pilot trial was conducted with donor oocytes to study the feasibility of the robot in a clinical setting. The ICSIA robot was controlled by engineers with no micromanipulation experience. Results were compared with those obtained with manual ICSI conducted by experienced embryologists.
RESULTS
The ICSIA robot demonstrated similar results to the manual procedure in the different animal models tested as well as in the pre-clinical validations conducted in discarded human oocytes. In the clinical validation, 13 out of 14 oocytes injected with ICSIA fertilized correctly versus 16 out of 18 in the manual control; eight developed into good-quality blastocysts versus 12 in the manual control; and four were diagnosed as chromosomally normal versus 10 euploid in the manual control. Three euploid blastocysts from the ICSIA robot group have been transferred into two recipients, which resulted in two singleton pregnancies and two babies born.
CONCLUSIONS
The ICSIA robot showed high proficiency in injecting animal and human oocytes when operated by inexperienced personnel. The preliminary results obtained in this first clinical pilot trial are within key performance indicators.
Topics: Female; Humans; Male; Pregnancy; Fertilization; Fertilization in Vitro; Oocytes; Semen; Sperm Injections, Intracytoplasmic; Spermatozoa
PubMed: 37400320
DOI: 10.1016/j.rbmo.2023.05.009 -
Analytical Chemistry Feb 2022This paper describes OsciDrop, a versatile chip-free droplet generator used to produce size-tunable droplets on demand. Droplet generation is fundamental to miniaturized...
This paper describes OsciDrop, a versatile chip-free droplet generator used to produce size-tunable droplets on demand. Droplet generation is fundamental to miniaturized analysis. We designed OsciDrop to segment the fluid flowing out of the orifice of a disposable pipette tip into droplets by oscillating its distal end underneath an immiscible continuous phase. We described the theoretical model and investigated the effect of flow rate, oscillating amplitude, frequency, and waveform on droplet generation. Our study revealed a previously underexplored Weber number-dominated regime that leverages inertial force instead of viscous force to generate droplets. The same pipette tip allowed robust and deterministic generation of monodisperse droplets with programmable sizes ranging from 200 pL to 2 μL by asymmetrical oscillation. We validated this platform with two droplet-based nucleic acid amplification tests: a digital loop-mediated isothermal amplification assay for absolute quantification of African swine fever virus and a multi-volume digital polymerase chain reaction assay for the high dynamic range measurement of human genomic DNA. The OsciDrop method opens a facile avenue to miniaturization, integration, and automation, exhibiting full accessibility for digital molecular diagnostics.
Topics: African Swine Fever Virus; Animals; Biological Assay; DNA; Pathology, Molecular; Polymerase Chain Reaction; Swine
PubMed: 35060717
DOI: 10.1021/acs.analchem.1c04852 -
Annual Review of Analytical Chemistry... Jul 2021The reduction in ion current as a fine pipette approaches a cell surface allows the cell surface topography to be imaged, with nanoscale resolution, without contact with...
The reduction in ion current as a fine pipette approaches a cell surface allows the cell surface topography to be imaged, with nanoscale resolution, without contact with the delicate cell surface. A variety of different methods have been developed and refined to scan the topography of the dynamic cell surface at high resolution and speed. Measurement of cell topography can be complemented by performing local probing or mapping of the cell surface using the same pipette. This can be done by performing single-channel recording, applying force, delivering agonists, using pipettes fabricated to contain an electrochemical probe, or combining with fluorescence imaging. These methods in combination have great potential to image and map the surface of live cells at the nanoscale.
Topics: Cell Membrane
PubMed: 34314223
DOI: 10.1146/annurev-anchem-091420-120101