Ion Pumps Research Articles

Review of methods for lithium extraction from geothermal brines

Lithium, a highly reactive and valuable metal, is essential for the clean energy transition, powering electronic devices, electric cars, and energy storage systems. With demand for lithium surging, environmentally responsible and economically viable extraction methods are crucial. Traditional sources include brines and mineral clays, but lithium-ion batteries have become a significant secondary source due to their high consumption of lithium. This review explores various extraction methods from geothermal brines, focusing on conventional techniques like solar evaporation, precipitation, and solvent extraction, highlighting their efficiency and limitations. Advanced electrochemical methods are also discussed, including the use of electrochemical ion pumping and electrodialysis, showcasing their potential for high-purity lithium recovery. Direct Lithium Extraction (DLE) technology, which offers over 90% recovery and reduces impurities by over 99%, is identified as a promising approach. The review underscores the need for large-scale field experiments and the development of new lithium sources to meet growing demand.

A seaweed-inspired separator for high performance Zn metal batteries: Boosting kinetics and confining side-reactions

Uncontrolled dendrite growth, sluggish reaction kinetics, and drastic side reactions on the anode-electrolyte interface are the main obstacles that restrict the application prospect of aqueous zinc-ion batteries. Traditional glass fiber (GF) separator with chemical inertness is almost ineffective in restricting these challenges. Herein, inspired by the ionic enrichment behavior of seaweed plants, a facile biomass species, anionic sodium alginate (SA), is purposely decorated on the commercial GF separator to tackle these issues towards Zn anode. Benefiting from the abundant zincophilic functional groups and superior mechanical strength properties, the as-obtained SA@GF separator could act as ion pump to boost the Zn2+ transference number (0.68), reduce the de-solvation energy barrier of hydrated Zn2+, and eliminate the undesired concentration polarization effect, which are verified by experimental tests, theoretical calculations, and finite element simulation, respectively. Based on these efficient modulation mechanisms, the SA@GF separator can synchronously achieve well-aligned Zn deposition and the suppression of parasitic side-reactions. Therefore, the Zn||Zn coin cell integrated with SA@GF separator could yield a prolonged calendar lifespan over 1230 h (1 mA cm−2 and 1 mAh cm−2), exhibiting favorable competitiveness with previously reported separator modification strategies. Impressively, the Zn-MnO2 full and pouch cell assembled with the SA@GF separator also delivered superior cycling stability and rate performance, further verifying its practical application effect. This work provides a new design philosophy to stabilize the Zn anode from the aspect of separator.

New insights into the cellular and molecular mechanisms of skeletal muscle fatigue: the Marion J. Siegman Award Lectureships.

Skeletal muscle fibers need to have mechanisms to decrease energy consumption during intense physical exercise to avoid devastatingly low ATP levels, with the formation of rigor cross bridges and defective ion pumping. These protective mechanisms inevitably lead to declining contractile function in response to intense exercise, characterizing fatigue. Through our work, we have gained insights into cellular and molecular mechanisms underlying the decline in contractile function during acute fatigue. Key mechanistic insights have been gained from studies performed on intact and skinned single muscle fibers and more recently from studies performed and single myosin molecules. Studies on intact single fibers revealed several mechanisms of impaired sarcoplasmic reticulum Ca2+ release and experiments on single myosin molecules provide direct evidence of how putative agents of fatigue impact myosin's ability to generate force and motion. We conclude that changes in metabolites due to an increased dependency on anaerobic metabolism (e.g., accumulation of inorganic phosphate ions and H+) act to directly and indirectly (via decreased Ca2+ activation) inhibit myosin's force and motion-generating capacity. These insights into the acute mechanisms of fatigue may help improve endurance training strategies and reveal potential targets for therapies to attenuate fatigue in chronic diseases.

The Membrane Dipole Potential and the Roles of Interfacial Water and Lipid Hydrocarbon Chains.

Understanding membrane charge transport processes, including the actions of ion channels, pumps, carriers, and membrane-active peptides, requires a description of the electrostatics of the lipid bilayer. We have simulated a library of different lipid chemistries to reveal the impact of the headgroup, glycerol backbone, and hydrocarbon chains on the membrane dipole potential. We found a strong dependence of the potential on lipid packing, but this was not caused by the packing of lipid polar components, due to cancellation of their electric fields by electrolyte. In contrast, lipid tail contributions were determined by area per lipid, arising from two countering effects. Increased area per lipid leads to chain tilting that increases methylene dipole projections to strengthen the electric field within the bilayer, while at the same time decreasing the electric field from terminal methyl groups. Moreover, electric fields from some nonterminal groups and the terminal methyl group can extend beyond the bilayer center and be canceled by the opposing leaflet. This interleaflet field annulment explains the experimental reduction in dipole potential for unsaturated and branched lipid bilayers, by as much as ∼200 mV, as well as experiments that substitute chain carbons with sulfur. Replacing ester with ether groups (eliminating two carbonyl groups) causes a significant reduction in potential, also by ∼200 mV, in agreement with experiment. We show that the effect can be largely attributed to the loss of aligned water molecules in the glycerol backbone region, lowering the potential inside the bilayer core. When only one of the two carbonyls is removed (using a hybrid ester-ether lipid or a single-chain lipid), most of this reduction in potential was lost, with the single carbonyl group able to maintain full hydration in the interfacial region. While headgroup chemistry can have a major effect (by as much as ±100 mV relative to phosphatidylcholine), anionic headgroups either decrease or increase the dipole potential, with the variation involving perturbation in hydrogen-bonded water molecules and changes in packing of lipid tails. Overall, these results suggest that membrane electrostatics are dominated by aligned water molecules at the polar-hydrocarbon interface and, surprisingly, by the charge distribution of the nonpolar lipid tails, and not the packing of headgroup and glycerol carbonyl dipoles.

Charging and Discharging Modeling of Inertial Sensors Based on Ultraviolet Charge Management

Inertial sensors act as inertial references in space gravitational wave detection missions, necessitating that their internal test mass (TM) maintains minimal residual acceleration noise. High-energy particles and cosmic rays in space, along with ion pumps in ground-based torsion pendulum experiments, can cause charge accumulation on the TM surface, leading to increased residual acceleration noise. Consequently, a charge management system was introduced to control the TM’s charge. The complex light path propagation within the electrode housing (EH) makes the TM’s charging and discharging process difficult to theoretically calculate and fully simulate. To address this issue, we propose a simulation method for charging and discharging inertial sensors within ultraviolet (UV) charge management systems. This method innovatively considers the impact of photoelectron emission angle and the TM’s position offset from symmetry on performance. The method also simulates charging and discharging rates over time under conditions of symmetry and preliminarily examines factors affecting the TM’s equilibrium potential. Simulation results indicate that this method effectively models the charge management system’s operation, providing a valuable reference for system design.

Construction of SuperKEKB vacuum control system and its eight years operation experience

SuperKEKB has two main rings (MRs), namely low- and high-energy rings, with circumferences of 3 km; beam transport (BT) lines; and a positron damping ring (PDR). We upgraded the MRs and BT line vacuum control systems and designed a new PDR vacuum control system for upgrading KEKB to SuperKEKB.Here, we describe the basic configuration of the vacuum control system, which includes the interlock logic (gate valve open/closed control, non-evaporable getter pump activation, and beam abortion). We subsequently present the collimator driving system and the cooling water control system for the beam pipe of the final focusing superconducting quadrupole magnet as examples of special SuperKEKB vacuum control systems. Examples of problems in the SuperKEKB vacuum control system, including the discharge at the high-voltage connector of the ion pump, stoppage of the cooling water pump for the vacuum system, and failure of the collimator position measurement device are described.

Visualizing Single V-ATPase Rotation Using Janus Nanoparticles.

Understanding the function of rotary molecular motors, such as the rotary ATPases, relies on our ability to visualize the single-molecule rotation. Traditional imaging methods often involve tagging those motors with nanoparticles (NPs) and inferring their rotation from translational motion of NPs. Here, we report an approach using "two-faced" Janus NPs to directly image the rotation of single V-ATPase from Enterococcus hirae, an ATP-driven rotary ion pump. By employing a 500-nm silica/gold Janus NP, we exploit its asymmetric optical contrast - silica core with a gold cap on one hemisphere - to achieve precise imaging of the unidirectional counter-clockwise rotation of single V-ATPase motors immobilized on surfaces. Despite the added viscous load from the relatively large Janus NP probe, our approach provides accurate torque measurements of single V-ATPase. This study underscores the advantages of Janus NPs over conventional probes, establishing them as powerful tools for single-molecule analysis of rotary molecular motors.

Role of Piezo1 in Terminal Density Reversal of Red Blood Cells.

Density reversal of senescent red blood cells has been known for a long time, yet the identity of the candidate ion transporter(s) causing the senescent cells to swell is still elusive. While performing fractionation of RBCs from healthy individuals in Percoll density gradient and characterization of the separated fractions, we identified a subpopulation of cells in low-density fraction (1.02% ± 0.47) showing signs of senescence such as loss of membrane surface area associated with a reduction in band 3 protein abundance, and Phosphatidylserine (PS) exposure to the outer membrane. In addition, we found that these cells are overloaded with Na+ and Ca2+. Using a combination of blockers and activators of ion pumps and channels, we revealed reduced activity of Plasma membrane Ca2+ ATPase and an increase in Ca2+ and Na+ leaks through ion channels in senescent-like cells. Our data revealed that Ca2+ overload in these cells is a result of reduced PMCA activity and facilitated Ca2+ uptake via a hyperactive Piezo1 channel. However, we could not exclude the contribution of other Ca2+-permeable ion channels in this scenario. In addition, we found, as a universal mechanism, that an increase in intracellular Ca2+ reduced the initially high selectivity of Piezo1 channel for Ca2+ and allowed higher Na+ uptake, Na+ accumulation, and swelling.

Light-Driven Ionic and Molecular Transport through Atomically Thin Single Nanopores in MoS2/WS2 Heterobilayers.

Nanofluidic ionic and molecular transport through atomically thin nanopore membranes attracts broad research interest from both scientific and industrial communities for environmental, healthcare, and energy-related technologies. To mimic the biological ion pumping functions, recently, light-induced and quantum effect-facilitated charge separation in heterogeneous 2D-material assemblies is proposed as the fourth type of driving force to achieve active and noninvasive transport of ionic species through synthetic membrane materials. However, to date, engineering versatile van der Waals heterostructures into 2D nanopore membranes remains largely unexplored. Herein, we fabricate single nanopores in heterobilayer transition metal dichalcogenide membranes with helium ion beam irradiation and demonstrate the light-driven ionic transport and molecular translocation phenomena through the atomically thin nanopores. Experimental and simulation results further elucidate the driving mechanism as the photoinduced near-pore electric potential difference due to type II band alignment of the semiconducting WS2 and MoS2 monolayers. The strength of the photoinduced localized electric field near the pore region can be approximately 1.5 times stronger than that of its counterpart under the conventional voltage-driven mode. Consequently, the light-driven mode offers better spatial resolution for single-molecule detection. Light-driven ionic and molecular transport through nanopores in van der Waals heterojunction membranes anticipates transformative working principles for next-generation biomolecular sequencing and gives rise to fascinating opportunities for light-to-chemical energy harvesting nanosystems.

The pumping performance, mechanism and challenges of low voltage and non-magnetic ion pump based on pyroelectric principle

In this paper, a low voltage non-magnetic ion pump based on pyroelectric materials is proposed, mainly applied in non-magnetic and high vacuum systems such as cold atom inertial sensors. By utilizing the discharge characteristics of pyroelectric materials in vacuum, the discharge current and high-voltage electric field required for the operation of ion pump can be obtained, eliminating the need to apply high voltage to the cathode like traditional ion pumps based on Penning source. The effectiveness of the pyroelectric ion pump is verified by activating it simultaneously with the molecular pump and only activating the ion pump in a 1000 cm3 stainless steel vacuum chamber. The working mechanism of the pyroelectric ion pump is proposed and experimentally verified.

Application and Development of Cell Membrane Functionalized Biomimetic Nanoparticles in the Treatment of Acute Ischemic Stroke.

Ischemic stroke is a serious neurological disease involving multiple complex physiological processes, including vascular obstruction, brain tissue ischemia, impaired energy metabolism, cell death, impaired ion pump function, and inflammatory response. In recent years, there has been significant interest in cell membrane-functionalized biomimetic nanoparticles as a novel therapeutic approach. This review comprehensively explores the mechanisms and importance of using these nanoparticles to treat acute ischemic stroke with a special emphasis on their potential for actively targeting therapies through cell membranes. We provide an overview of the pathophysiology of ischemic stroke and present advances in the study of biomimetic nanoparticles, emphasizing their potential for drug delivery and precision-targeted therapy. This paper focuses on bio-nanoparticles encapsulated in bionic cell membranes to target ischemic stroke treatment. It highlights the mechanism of action and research progress regarding different types of cell membrane-functionalized bi-onic nanoparticles such as erythrocytes, neutrophils, platelets, exosomes, macrophages, and neural stem cells in treating ischemic stroke while emphasizing their potential to improve brain tissue's ischemic state and attenuate neurological damage and dysfunction. Through an in-depth exploration of the potential benefits provided by cell membrane-functionalized biomimetic nanoparticles to improve brain tissue's ischemic state while reducing neurological injury and dysfunction, this study also provides comprehensive research on neural stem cells' potential along with that of cell membrane-functionalized biomimetic nanoparticles to ameliorate neurological injury and dysfunction. However, it is undeniable that there are still some challenges and limitations in terms of biocompatibility, safety, and practical applications for clinical translation.

Hydrogen-Bonding and Hydrophobic Interaction Networks as Structural Determinants of Microbial Rhodopsin Function.

Microbial pump rhodopsins are highly versatile light-driven membrane proteins that couple protein conformational dynamics with ion translocation across the cell membranes. Understanding how microbial pump rhodopsins use specific amino acid residues at key functional sites to control ion selectivity and ion pumping direction is of general interest for membrane transporters, and could guide site-directed mutagenesis for optogenetics applications. To enable direct comparisons between proteins with different sequences we implement, for the first time, a unique numbering scheme for the microbial pump rhodopsin residues, NS-mrho. We use NS-mrho to show that distinct microbial pump rhodopsins typically have hydrogen-bond networks that are less conserved than anticipated from the amino acid residue conservation, whereas their hydrophobic interaction networks are largely conserved. To illustrate the role of the hydrogen-bond networks as structural elements that determine the functionality of microbial pump rhodopsins, we performed experiments, atomic-level simulations, and hydrogen bond network analyses on GR, the outward proton pump from Gloeobacter violaceus, and KR2, the outward sodium pump from Krokinobacter eikastus. The experiments indicate that multiple mutations that recover KR2 amino acid residues in GR not only fail to convert it into a sodium pump, but completely inactivate GR by abolishing photoisomerization of the retinal chromophore. This observation could be attributed to the drastically altered hydrogen-bond interaction network identified with simulations and network analyses. Taken together, our findings suggest that functional specificity could be encoded in the collective hydrogen-bond network of microbial pump rhodopsins.

Wood Ion Pumps Enabled by Light-Responsive MoS2-Decorated Nanocellulosic Channels.

Light-driven active ion transport discovered in nanomaterials (e.g., graphene, metal-organic framework, and MXene) implicates crucial applications in membrane-based technology and energy conversion systems. However, it remains a challenge to achieve bulk assembly. Herein, we employ the scalable wood as a framework for in situ growth of MoS2 nanosheets to facilitate light-responsive ion transport. Owing to the aligned and negatively charged wood nanochannels, the MoS2-decorated wood exhibits an excellent nanofluidic conductivity of 8.3 × 10-5 S cm-1 in 1 × 10-6 M KCl. Asymmetric light illumination creates the separation of electrons and holes in MoS2 nanosheets, enabling ions to move uphill against a wide range of concentration gradients. As a result, the MoS2-decorated wood can pump ions uphill against a 20-fold concentration gradient at a light intensity of 300 mW cm-2. When the illumination is applied to the opposite side, the osmotic current along the 20-fold concentration gradient can be enhanced to 75.1 nA, and the corresponding osmotic energy conversion power density increases to more than 12.6 times that of the nonilluminated state. Based on the light-responsive behaviors, we are extending the use of MoS2-decorated wood as the ionic elements for nanofluidic circuits, such as ion switches, ion diodes, and ion transistors. This work provides a facile and scalable strategy for fabricating light-controlled nanofluidic devices from biomass materials.

Hesperetin-7-O-rhamnoglucoside ameliorates dichlorvos-facilitated cardiotoxicity in rats by counteracting ionoregulatory, ion pumps, redox, and lipid homeostasis disruptions

The contamination of edible agricultural goods with pesticides, including dichlorvos (DVDP), poses a substantial public health risk, promoting severe morbidity and mortality, especially in developing countries. It has been shown that hesperidin (hesperetin-7-O-rhamnoglucoside or Hes-7-RGlc) preserves cytomembrane, redox, and lipid homeostasis; unfortunately, its function on dichlorvos-incited heart damage has not been investigated. This work explored the ameliorative influence of Hes-7-RGlc on DVDP-activated cardiotoxicity. For this end, forty-two rats were randomly appropriated into seven groups (6 rats/group): Control, DVDP alone (8 mg.kg⁻¹day⁻¹), DVDP supplied with either Hes-7-RGlc (50 and 100 mg.kg⁻¹day⁻¹) or the reference medication atropine (0.2 mg.kg⁻¹day⁻¹), and Hes-7-RGlc alone (50 and 10 mg.kg⁻¹day⁻¹) were the seven groups investigated. DVDP was administered orally for seven days, followed by fourteen days of Hes-7-RGlc therapy. Then the rats were euthanized, and their blood and hearts were removed. Hes-7-RGlc chemotherapy substantially (p<0.05) restored DVDP-elicited dynamics in plasma and cardiac/myocardium creatine kinase isoenzyme (CK-MB), major lipids (cholesterol, triacylglycerol, and phospholipids), electrolytes (Na⁺, K⁺, Ca²⁺, Mg²⁺, Cl⁻), and total protein. Hes-7-RGlc remedy decidedly (p<0.05) abolished DDVP-stimulated amplification in the cardiac concentration of H₂O₂, NO and malondialdehyde; annulled DVDP-educed decreases in heart GSH levels, activities of GST, SOD, catalase, and glutathione peroxidase, ion transporters (Na⁺/K⁺-ATPase and Ca²⁺/Mg²⁺-ATPase), ALT, AST, ALP, and LDH-1. Collectively, Hes-7-RGlc can be advocated as a natural supplementary candidate and blocker of DVDP-provoked heart deficits via its capacity to reverse disruptions of electrolytes, ion pumps, redox status, and lipid homeostasis.

HepG2 cells undergo regulatory volume decrease by mechanically induced efflux of water and solutes.

This study challenges the conventional belief that animal cell membranes lack a significant hydrostatic gradient, particularly under anisotonic conditions, as demonstrated in the human hepatoma cell line HepG2. The Boyle van't Hoff (BvH) relation describes volumetric equilibration to anisotonic conditions for many cells. However, the BvH relation is simple and does not include many cellular components such as the cytoskeleton and actin cortex, mechanosensitive channels, and ion pumps. Here we present alternative models that account for mechanical resistance to volumetric expansion, solute leakage, and active ion pumping. We found the BvH relation works well to describe hypertonic volume equilibration but not hypotonic volume equilibration. After anisotonic exposure and return isotonic conditions cell volumes were smaller than their initial isotonic volume, indicating solutes had leaked out of the cell during swelling. Finally, we observed HepG2 cells undergo regulatory volume decrease at both 20°C and 4°C, indicating regulatory volume decrease to be a relatively passive phenomenon and not driven by ion pumps. We determined the turgor-leak model, which accounts for mechanical resistance and solute leakage, best fits the observations found in the suite of experiments performed, while other models were rejected.

Paralog switching facilitates diadromy: ontogenetic, microevolutionary and macroevolutionary evidence.

Identifying how the demands of migration are met at the level of gene expression is critical for understanding migratory physiology and can potentially reveal how migratory forms evolve from nonmigratory forms and vice versa. Among fishes, migration between freshwater and seawater (diadromy) requires considerable osmoregulatory adjustments, powered by the ion pump Na+, K+-ATPase (NKA) in the gills. Paralogs of the catalytic α-subunit of the pump (NKA α1a and α1b) are reciprocally upregulated in fresh- and seawater, a response known as paralog-switching, in gills of some diadromous species. We tested ontogenetic changes in NKA α-subunit paralog expression patterns, comparing pre-migrant and migrant alewife (Alosa pseudoharengus) sampled in their natal freshwater environment and after 24h in seawater. In comparison to pre-migrants, juvenile out-migrants exhibited stronger paralog switching via greater downregulation of NKA α1a in seawater. We also tested microevolutionary changes in the response, exposing juvenile diadromous and landlocked alewife to freshwater (0 ppt) and seawater (30 ppt) for 2, 5, and 15days. Diadromous and landlocked alewife exhibited salinity-dependent paralog switching, but levels of NKA α1b transcription were higher and the decrease in NKA α1a was greater after seawater exposure in diadromous alewife. Finally, we placed alewife α-subunit NKA paralogs in a macroevolutionary context. Molecular phylogenies show alewife paralogs originated independently of paralogs in salmonids and other teleosts. This study demonstrated that NKA paralog switching is tied to halohabitat profile and that duplications of the NKA gene provided the substrate for multiple, independent molecular solutions that support a diadromous life history.

Ionic Pumping Effect at the Tailored Mesoporous Carbon Interface for an Extra-Stable Lithium Ion Battery at Low Temperatures.

Ion transportation at the interface significantly influences the electrochemical performance of the lithium ion battery, especially at high rates and low temperatures. Here, we develop a controlled self-assembly strategy for constructing a mesoporous carbon nanolayer with a uniform pore size and varied thicknesses on the two-dimensional monolayer MXene substrate. On the basis of the excellent electron conductivity of MXene, the mesoporous carbon layer is found with a voltage-driven ion accumulation effect, acting as an "ionic pump". The thicker mesoporous layer (∼2.28 nm) has the ability to accommodate a substantial quantity of ions, demonstrating enhanced ionic conductivity, remarkable cycling stability (192.8 mAh/g after 9400 cycles at 5.0 A/g), and outstanding rate capability at ambient and sub-zero temperatures (∼601 mAh/g at 0 °C and 0.05 A/g). This work provides valuable insights and guidance for the further development of high-performance electrode materials at high rates or low temperatures.

In situ Ion Pumping Anodization to Confine Single‐Atom Fe onto TiO2 Nanotubes for Enhanced Noble‐Metal‐Free Photocatalytic Hydrogen Generation

AbstractAchieving a high dispersity of deposited transition metal is crucial in the anodization preparation of noble‐metal‐free composites for photocatalytic hydrogen generation. Herein, for the first time, an in situ ion pumping anodization method is proposed to confine single‐atom Fe within the spatially ordered structure of anodized TiO2 nanotubes (TNT), assisted by ferric sodium salt of ethylenediaminetetraacetic acid (EDTA) as an “ion pump” to deliver Fe3+ toward anodes. Both experimental and theoretical calculations confirm that highly dispersed single‐atom Fe can interact with single‐electron‐trapped oxygen vacancies (SETOV), effectively reducing the oxygen vacancy concentration in TiO2 nanotubes. This reduction promotes efficient charge carrier separation through the Fe(III)/Fe(II) pathway and enhances hydrogen desorption, ultimately boosting the photocatalytic hydrogen evolution performance.

A functional MXene/cellulose nanofibers separator for high-performance dendrite-free zinc anode under harsh conditions

Aqueous zinc-ion batteries (AZIBs) show great potential for mass energy storage because of their intrinsic plentifulness and security. Nevertheless, the development of zinc dendrites is still a major challenge for the practical industrialisation of AZIB, especially under the demanding conditions of elevated current density and high temperatures. To combat this situation, we developed an ultrathin separator composed of cellulose nanofibers and MXene (noted as CM-15 separator) with a thickness of only 27 μm. The strong zincophilic characteristics and outstanding electrical/thermal conductivity of MXene make them suitable for use as an ion pump to expedite the transmission of Zn2+ through the electrolyte, which significantly increases the zinc ion transfer number and results in the deposition of homogeneous Zn nuclei and dendritic-free Zn. As a result, the symmetric battery equipped with a CM-15 separator enabled excellent dendrite free plating/stripping behavior, high coulomb efficiency (97.7 %) and cumulative plated capacity of 4.8 Ah/cm2 at 80 mA/cm2 at room temperature and as well as sustained operation for at least 300 h under 60 °C. More impressively, the Zn-MnO2/CNT battery equipped with a CM-15 separator achieved 72.6 % capacity retention after 10,000 cycles at 2 A/g under room temperature and 92.1 % capacity retention after 200 cycles at 1 A/g under 60 °C. Our research confirms the potential of functional separators to promote the application of AZIBs, especially under demanding conditions.

P-113 Comparison of mitochondrial function between expanded and hatching human blastocysts

Abstract Study question Is there a difference in mitochondrial function between expanded and hatching fresh and vitrified blastocysts? Summary answer Freezing and thawing may lead to mitochondrial dysfunction. What is known already Mitochondria, as crucial cellular organelles, play role in energy production through the electron transport chain, cell motility and organelle movement. They also have a significant impact on embryonic development. Furthermore, during the process of embryonic hatching, the energy generated by these organelles can affect ion pump activity, blastocyst expansion, and collapse. Therefore, factors that stress embryonic mitochondria may contribute to embryogenesis and hatching. Cooling and warming, as stress factors, maybe result in organelle damage, protein denaturation, membrane disruption, and DNA fragmentation. Additionally, they can cause changes in mitochondrial function, leading to decreased ATP levels and increased ROS levels. Study design, size, duration In this study, vitrified and fresh human 8-cell embryos were collected from April 18, 2021, to July 19, 2023. The embryos were cultured until the blastocyst stage, and then four samples were assessed in four groups. These groups included vitrified expanded blastocysts, vitrified hatching blastocysts, fresh expanded blastocysts, and fresh hatching blastocysts. Participants/materials, setting, methods Vitrified embryos were sourced from the embryo bank of the Royan Institute, while fresh embryos were obtained from good-quality 3PN embryos or excess embryos from couples who did not wish to freeze them. A stock solution containing lipophilic cationic JC-1 dye in dimethyl sulfoxide was prepared. Blastocysts were then exposed to a concentration of 1 μg/ml of JC-1 diluted in HamsF10-HSA. After washing with HF-HSA, imaging was performed using a 2-photon confocal microscope. Main results and the role of chance Our results showed that mitochondrial membrane potential in expanded blastocysts of both fresh and vitrified eight-cell embryos was significantly higher than in hatching blastocysts of fresh and vitrified embryos (P &amp;lt; 0.05). However, there was no significant difference in mitochondrial function between the vitrified and fresh groups, neither in expanded nor hatching blastocysts. Limitations, reasons for caution Due to the human origin of the samples, the minimum necessary replicates were considered for each experimental group. Wider implications of the findings In this study, it appears that plump zona breakers can be detected in hatching blastocysts using confocal microscopy. Previous studies, such as the one conducted by Sathananthan, identified these cells using a TEM microscope. Trial registration number -