Physiological pH Research Articles

Physiological and Technological Properties of Probiotic Lacticaseibacillus rhamnosus GG Encapsulated with Alginate-Chitosan Mixture and Its Incorporation in Whole Milk.

This study developed and evaluated chitosan-sodium alginate capsules containing the probiotic Lacticaseibacillus rhamnosus GG using extrusion and emulsification techniques. The encapsulated L. rhamnosus GG cells were also evaluated for technological and probiotic-related physiological functionalities, as well as when incorporated in UHT and powdered milk. Extrusion (86.01 ± 1.26%) and emulsification (74.43 ± 1.41%) encapsulation techniques showed high encapsulation efficiency and high survival rates of L. rhamnosus GG during 28days of refrigeration and room temperature storage, especially emulsification capsules (> 81%). The encapsulated L. rhamnosus GG cells showed high survival rates during exposure to simulated gastrointestinal conditions (72.65 ± 1.09-114.15 ± 0.44%). L. rhamnosus GG encapsulated by extrusion and emulsification performed satisfactorily in probiotic-related physiological (pH and bile salts tolerance) and technological properties (positive proteolytic activity, diacetyl and exopolysaccharides production, high NaCl tolerance (> 91%), besides having high heat tolerance (> 76%)). L. rhamnosus GG in extrusion and emulsification capsules had high survival rates (> 89%) and did not significantly affect physicochemical parameters in Ultra-High Temperature (UHT) and powdered milk during storage. The results demonstrate that L. rhamnosus GG can be successfully encapsulated with alginate-chitosan as a protective material through extrusion and emulsification techniques. UHT and powdered milk could serve as appropriate delivery systems to increase the intake of this encapsulated probiotic by consumers.

Gill ionocyte remodeling mediates blood pH regulation in rockfish (Sebastes diploproa) exposed to environmentally relevant hypercapnia.

Marine fishes excrete excess H+ using basolateral Na+-K+-ATPase (NKA) and apical Na+/H+ exchanger 3 (NHE3) in gill ionocytes. However, the mechanisms that regulate H+ excretion during exposure to environmentally relevant hypercapnia (ERH) remain poorly understood. Here, we explored transcriptomic, proteomic, and cellular responses in gills of juvenile splitnose rockfish (Sebastes diploproa) exposed to 3 days of ERH conditions (pH ∼7.5, ∼1,600 μatm Pco2). Blood pH was fully regulated at ∼7.75 despite a lack of significant changes in gill 1) mRNAs coding for proteins involved in blood acid-base regulation, 2) total NKA and NHE3 protein abundance, and 3) ionocyte density. However, ERH-exposed rockfish demonstrated increased NKA and NHE3 abundance on the ionocyte plasma membrane coupled with wider apical membranes and greater extension of apical microvilli. The observed gill ionocyte remodeling is consistent with enhanced H+ excretion that maintains blood pH homeostasis during exposure to ERH and does not necessitate changes at the expression or translation levels. These mechanisms of phenotypic plasticity may allow fishes to regulate blood pH during environmentally relevant acid-base challenges and thus have important implications for both understanding how organisms respond to climate change and for selecting appropriate metrics to evaluate its impact on marine ecosystems.NEW & NOTEWORTHY Splitnose rockfish exposed to environmentally relevant hypercapnia utilize existing proteins (rather than generate additional machinery) to maintain homeostasis.

α-Synuclein oligomers form by secondary nucleation

Oligomeric species arising during the aggregation of α-synuclein are implicated as a major source of toxicity in Parkinson’s disease, and thus a major potential drug target. However, both their mechanism of formation and role in aggregation are largely unresolved. Here we show that, at physiological pH and in the absence of lipid membranes, α-synuclein aggregates form by secondary nucleation, rather than simple primary nucleation, and that this process is enhanced by agitation. Moreover, using a combination of single molecule and bulk level techniques, we identify secondary nucleation on the surfaces of existing fibrils, rather than formation directly from monomers, as the dominant source of oligomers. Our results highlight secondary nucleation as not only the key source of oligomers, but also the main mechanism of aggregate formation, and show that these processes take place under conditions which recapitulate the neutral pH and ionic strength of the cytosol.

Poly(2-Deoxy-2-Methacrylamido-D-Glucose)-Based Complex Conjugates of Colistin, Deferoxamine and Vitamin B12: Synthesis and Biological Evaluation.

Growing resistance to traditional antibiotics poses a global threat to public health. In this regard, modification of known antibiotics, but with limited applications due to side effects, is one of the extremely promising approaches at present. In this study, we proposed the synthesis of novel complex polymeric conjugates of the peptide antibiotic colistin (CT). A biocompatible and water-soluble synthetic glycopolymer, namely, poly(2-deoxy-2-methacrylamido-D-glucose) (PMAG), was used as a polymer carrier. In addition to monoconjugates containing CT linked to PMAG by hydrolyzable and stable bonds, a set of complex conjugates also containing the siderophore deferoxamine (DFOA) and vitamin B12 was developed. The structures of the conjugates were confirmed by 1H NMR and FTIR-spectroscopy, while the compositions of conjugates were determined by UV-Vis spectrophotometry and HPLC analysis. The buffer media with pH 7.4, corresponding to blood or ileum pH, and 5.2, corresponding to the intestinal pH after ingestion or pH in the focus of inflammation, were used to study the release of CT. The resulting conjugates were examined for cytotoxicity and antimicrobial activity. All conjugates showed less cytotoxicity than free colistin. A Caco-2 cell permeability assay was carried out for complex conjugates to simulate the drug absorption in the intestine. In contrast to free CT, which showed very low permeability through the Caco-2 monolayer, the complex polymeric conjugates of vitamin B12 and CT provided significant transport. The antimicrobial activity of the conjugates depended on the conjugate composition. It was found that conjugates containing CT linked to the polymer by a hydrolyzable bond were found to be more active than conjugates with a non-hydrolyzable bond between CT and PMAG. Conjugates containing DFOA complexed with Fe3+ were characterized by enhanced antimicrobial activity against Pseudomonas aeruginosa compared to other conjugates.

A metal–organic framework composite loaded with coumarin guests as a turn-on luminescent sensor for detection of cysteine in aqueous solution

In this work, a composite material (ACE@UiO-66-NH2) has been synthesized conveniently by loading a cysteine-responsive molecular probe Acrylic acid 3-acetyl-2-oxo-2H-chromen-7-yl ester (ACE) on a UiO-type zirconium-based metal–organic framework (UiO-66-NH2). Furthermore, the resulting ACE@UiO-66-NH2 demonstrated to be a fluorescent turn-on probe for selective recognition of Cys from other amino acids in aqueous HEPES buffer systems. Additionally, the proposed recognition mechanism has been confirmed by 1H NMR and TLC. The study provided a promising approach to rationally design MOF-based fluorescent sensor for Cys in aqueous system.

Voltammetric Assessment of Paracetamol on a CuONPs – MWCNTs Modified Glassy Carbon Electrode

In this work, an electrochemical sensor using differential pulse voltammetric method for the assessment of antipyretic and analgesic drug, paracetamol was developed. The CuO nanoparticles were synthesized and characterized. A glassy carbon electrode (GCE) fabricated with the suspension of CuO nanoparticles (CuONPs) and multi-walled carbon nanotubes (MWCNTs) were used. The fabricated electrode was characterized using Potassium ferricyanide as a redox probe, which showed increase in the electro active area in the modified electrode. The modified electrode showed improved anodic peak current enhancement in phosphate buffer solution. The consequence of pH of supporting electrolyte and amount of nanoparticles suspension were investigated at a physiological pH of 7.4. Using differential pulse voltammetry, the fabricated electrode showed linear dynamic range from 9 to 160 nM of paracetamol concentration. From the calibration plot, the computed detection limit was 5.06nM and quantification limit was16.88 nM. The developed method was checked for its reproducibility and assay during a day and intraday as well and the results were good with permitted range of errors. The developed process was fruitfully applied to detect paracetamol in pharmaceutical formulations.

Ruminal CO2 Holdup Monitoring, Acidosis Might Be Caused by CO2 Poisoning

The ruminal buffering system is composed of bicarbonate (HCO3-) and dissolved CO2 (dCO2). While low pH indicates high dCO2 formation, the pH scale is a ratio between acids and bases in a solution, i.e. HCO3- and dCO2, and fail to provide individual component concentrations. For instance, modern feeding practices can reduce CO2 gas fugacity from the ruminal fluid or "CO2 holdup". Under those conditions, not only dCO2 can reach critical concentrations, but the buffering system might favour HCO3- formation resulting in normal ruminal pH values, the quotient, regardless of the harmful dCO2 accumulation. Consequently, subacute ruminal acidosis (SARA), traditionally associated with low or variable pH, might be triggered by CO2 holdup. This observational study aimed to continuously monitor ruminal dCO2 and characterised CO2 holdup within the ruminal fluid targeting the specific infrared signal of dCO2 with an attenuated total reflectance infrared (ATR-IR) spectrometer. Three lactating dairy cattle were longitudinally exposed to diets designed to elevate both ruminal dCO2 and SARA risk. Indwelling pH sensors and ruminal fluid samples served as references for dCO2 analysis, while a categorical analysis detected CO2 holdup from the output of the ATR-IR sensor. Milk yield, milk components, and feed intake supported the known positive role for high dCO2 in rumen function. However, SARA was associated with ruminal CO2 holdup, suggesting that prolonged exposure to critical dCO2 concentrations during extended postprandial periods might trigger SARA. Continuous dCO2 monitoring with the proposed methodology and analysis may offer a valuable tool for optimising rumen function and prevent SARA risk.

Determination of hexachlorophene residue in fruits and vegetables by ultra-high performance liquid chromatography-tandem mass spectrometry.

A modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) -LC-MS/MS method was developed for the determination of hexachlorophene in fruits and vegetables. Samples were extracted by acetonitrile and then salted with an acetate buffer system. Extractants neutral alumina (Al-N), strong cation exchange silica gel bonded adsorbent (SCX) and graphitized carbon black (GCB) were used for sample purification. The method demonstrates excellent accuracy and reproducibility. Under optimized conditions, the correlation coefficients of hexachlorophene were higher than 0.995 in the range of 0.5-20 ng/mL. The limit of quantification (LOQ) was 2.0 μg/kg. The average recoveries, assessed at three spiked levels (2.0, 4.0, and 20.0μg/kg) across various matrices including cabbage, celery, tomato, eggplant, potato, radish, cowpea, chives, apple, peach, grape, citrus, bitter melon, banana and hami melon ranged from 72.0 to 100.5% with relative standard deviations from 3.2 to 9.8% (n = 6).

Simultaneous prognostic score validation in patients with out-of-hospital cardiac arrest by a post-hoc analysis based on national multicenter registry

Using a nationwide multicenter prospective registry in Japan’s data, we calculated prognostic and predictive scores, including the Out-of-Hospital Cardiac Arrest (OHCA); Cardiac Arrest Hospital Prognosis (CAHP); Nonshockable rhythm, Unwitnessed arrest, Long no-flow or Long low-flow period, blood PH < 7.2, Lactate > 7.0 mmol/L, End-stage chronic kidney disease on dialysis, Age ≥ 85 years, Still resuscitation, and Extracardiac cause (NULL-PLEASE); revised post-Cardiac Arrest Syndrome for Therapeutic hypothermia (rCAST); and MIRACLE2 scores, for adult patients with cardiac arrest. The MIRACLE2 score was validated with the modified MIRACLE2 score, which excludes information of pupillary reflexes. Each score was calculated only for the cases with no missing data for the variables used. These scores’ accuracies were compared using neurological outcomes 30 days after out-of-hospital cardiac arrest (OOHCA). Patients with a cerebral performance category scale of 1 or 2 were designated as having favorable neurological outcomes. Each score’s discrimination ability was evaluated by the receiver operating characteristic curve’s area under the curve (AUC). To assess in detail in areas of high specificity and high sensitivity, which are areas of interest to clinicians, partial AUCs were also used. The analysis included 11,924 hospitalized adult patients. The AUCs of the OHCA, MIRACLE2, CAHP, rCAST, and NULL-PLEASE scores for favorable neurological outcomes were 0.713, 0.727, 0.785, 0.761, and 0.831, respectively. The CAHP and NULL-PLEASE scores were significantly more accurate than the rest. Accuracies did not differ significantly between the CAHP and NULL-PLEASE scores. The NULL-PLEASE score was significantly better at discriminating favorable neurological prognoses at 30 days in patients with OOHCA compared to other scoring systems.

The manufacturing and characterization of pentamidine-loaded poly(lactic-co-glycolic acid) nanoparticles produced by microfluidic method

In recent years, special attention has been paid to the study of manufacturing processes that can precisely control the physicochemical properties of nanoparticles (NPs) and reduce batch-to-batch variability. Microfluidics has recently emerged as an advanced production method that can manage NP properties by monitoring the diffusion/emulsification mechanism. Pentamidine free base (PTM-B), a diamidine compound positively charged at physiological pH, has already been used as a model drug for incorporation into poly(lactic-co-glycolic acid) (PLGA) via an ion-pairing strategy using a conventional bulk production method. The same formulation was chosen to study the scaling-up process and preparation using the microfluidic technique. The formulation of PLGA NP loaded with PTM-B by the microfluidic technique was optimized by adding 1 % Lutrol F68 as a surfactant agent to stabilize the nanosuspension during the solvent diffusion in the microchannel of the chip, and then, washed away in the final suspension. A thorough investigation of process parameters (i.e., total flow rate, flow rate ratio) was conducted to obtain a monodisperse suspension characterized by a mean diameter of less than 150 nm. In addition, in vitro studies on mammalian cancer cell lines demonstrated the potential antitumor activity of PTM-B-loaded NPs prepared by the microfluidic technique.

Visible Light-Driven CO2 Capture and Release Using Photoactive Pyranine in Water in Continuous Flow.

The urgent need to address climate change and its environmental consequences demands innovative carbon capture technologies, given the relationship between rising global temperatures and increased atmospheric CO2 levels. Here, we present a reversible photochemical carbon capture and release strategy and system utilizing photoactive pyranine in an aqueous bicarbonate buffer system. Control experiments suggested that the photoacid effect occurs at the surface which contributes to CO2 release, complemented by the photothermal effect at the surface and in the bulk. A continuous flow setup employing a tube-in-tube configuration with a hollow fiber membrane demonstrates the efficiency and reliability of the visible light-driven carbon capture system, with the release of CO2 captured from a 15% CO2 feed in the dark, at a rate of 0.48 mmol CO2 per hour to a nitrogen sweep stream under light irradiation at 200 W/m2, a level comparable to solar intensity of visible light (150 W/m2 of blue light -250 W/m2 of blue and green light). The robustness and scalability of the system has been demonstrated, with long-term operation over 7 days yielding 60 mmol (1.34 L CO2 at STP) of cumulated CO2 separation. Additionally, we explored the potential for direct air capture, yielding 3 μmol of CO2 separation over 2 h of operation from a bicarbonate buffer solution saturated with ambient air (420 ppm). This work introduces the prospect of photoswing of carbon capture systems, which can avoid external energy input beyond solar irradiation, offering promising avenues for addressing the challenges associated with climate change.

PREPARATION OF DEEP EUTECTIC SOLVENTS FOR MAKING AN OIL-DISPLACING COMPOSITION BASED ON TETRAHYDROXY ALCOHOL, CARBAMIDE, QUATERNARY AMMONIUM SALT, AND A SURFACTANTS

The binary systems of deep eutectic solvents (DESs) have been synthesised and investigated: tetraxydroxy alcohol - a salt of a quaternary ammonium base (DES1), tetrahydroxy alcohol - carbamide (DES2), a salt of a quaternary ammonium base - carbamide (DES3), and the ternary system tetrahydroxy alcohol - a salt of a quaternary ammonium base - carbamide (DES4). Eutectic compositions of binary systems DES1, DES2 and DES3 are characterised by significantly lower pour/melting points than those of the initial components. The lowest pour point among the binary mixtures is that of eutectic composition DES3. The ternary system is characterised by an even lower melting point (-14 °C), which is associated with the formation of intermolecular donor-acceptor hydrogen bonds within the system. An aqueous solution of DES4 with the concentration of 26 wt% was prepared, and its pH value was determined depending on temperature during preparation. At room temperature, pH of three-component DES is 6.6-7.1, but after thermostating for 6 h at 150 °C pH increases to 9.2 due to carbamide hydrolysis. It is assumed that further on, using DES4 as the basis for an alkaline oil-displacing composition directly in the reservoir, under the influence of the temperature of injected heat carrier, CO2 is formed, along with the ammonia buffer system with the maximal buffer capacity within the pH range 9-10. Resulting carbon dioxide, dissolving predominantly in oil, will cause a decrease in its viscosity, on the one hand, while the formed alkaline medium, being most favourable for surfactant performance due to a decrease in interfacial tension, liquefaction of high-viscosity layers or films at the oil-water-rock boundaries, on the other hand, will ensure efficient use of this system for oil displacement. In addition, the oil-displacing composition based on DES4 will be low-solidifying, which opens the possibility of its transportation and use in the northern regions and the Arctic zone.

Effects of Plasma Therapy on Laboratory Factors and Clinical Improvement of COVID-19 Patients

Objectives: Over 50 million confirmed cases and 1.5 million fatalities worldwide have been linked to the COVID-19 pandemic. Researchers have used convalescent plasma (CP) from recovered patients, which includes neutralizing antibodies, to develop therapeutics for virus neutralization and prevention. This study assessed the effectiveness of CP using several clinical and laboratory variables. Methods: The intervention group received two doses of CP on the day of hospitalization, while the control group received standard care. Clinical and analytical data were documented and evaluated before plasma therapy and on the third and fifth days after therapy. The results were measured in the patient’s blood using the ELISA method. Results: The present study showed that the ICU hospitalization times for the control and CP groups were similar, with a slightly lower mortality rate in the CP group (6.2% vs. 8.2%, p &gt; 0.05). There was no significant association between COVID-19 and clinical factors such as blood pressure, heart rate (HR), respiration rate (RR), and temperature. The blood serum urea, serum LDH, ALT, PTT, PLT, and IL-6 were significantly higher in the CP group than in the control group (p &lt;0.05). Our results indicated that there was no difference in blood pH, PO2 , HCO3 , ESR, WBC counts, serum troponin, Na, AST, CRP, D-dimer, and PT between patients in the CP and control groups. Conclusion: Overall, in certain instances, CP therapy may help individuals with COVID-19 recover. In general, additional research is required to determine the efficacy of plasma treatment in COVID-19 patient care.

Experimental and computational perspectives on the interaction of nerve agent VX metabolite ethyl methylphosphonic acid with human serum albumin

This study employed electrochemical methods to investigate the interaction between ethyl methylphosphonic acid (EMPA), the primary hydrolysis product of the nerve agent VX, and human serum albumin (HSA). Utilizing cyclic voltammetry (CV) and differential pulse voltammetry (DPV) on the surface of a glassy carbon electrode (GCE). The interaction was analyzed based on changes in the electrochemical behavior of the K3Fe(CN)6/K4Fe(CN)6 redox species under physiological pH conditions. Electrochemical parameters of the redox probe in the presence of HSA, EMPA, and the EMPA-HSA complex were measured. The alteration of the redox couple responses indicates the formation of an electro-inactive complex between the protein and EMPA. The binding parameters of the EMPA-HSA interaction, including the binding constant and complex stoichiometry, were determined, revealing the formation of EMPA-HSA complex with a binding constant of 1.03 × 104M−1 and a binding number of 0.624, suggesting a 1:1 stoichiometry. Molecular modeling was also conducted to further investigate the binding mode of EMPA with HSA, where the binding energy of EMPA to HSA was calculated as −4.78 kcal/mol with hydrogen bonding and hydrophobic contacts being the main interactions behind the complex formation. This research offers valuable insights into the albumin-EMPA interaction, with implications for toxicology, pharmacokinetics, and environmental impact.

Human Serum Albumin Protein Corona in Prussian Blue Nanoparticles.

Prussian Blue nanoparticles (PBnps) are now popular in nanomedicine thanks to the FDA approval of PB. Despite the numerous papers suggesting or describing the in vivo use of PBnps, no studies have been carried out on the formation of a protein corona on the PBnp surface and its stabilizing role. In this paper, we studied qualitatively and quantitatively the corona formed by the most abundant protein of blood, human serum albumin (HSA). Cubic PBnps (41 nm side), prepared in citric acid solution at PB concentration 5 × 10-4 M, readily form a protein corona by redissolving ultracentrifuged PBnp pellets in HSA solutions, with CHSA ranging from 0.025 to 7.0 mg/mL. The basic decomposition of PBnp@HSA was studied in phosphate buffer at the physiological pH value of 7.4. Increased stability with respect to uncoated PBnps was observed at all concentrations, but a minimum CHSA value of 3.0 mg/mL was determined to obtain stability identical to that observed at serum-like HSA concentrations (35-50 mg/mL). Using a modified Lowry protocol, the quantity of firmly bound HSA in the protein corona (hard corona) was determined for all the CHSA used in the PBnp@HSA synthesis, finding increasing quantities with increasing CHSA. In particular, an HSA/PBnp number in the 1500-2300 range was found for CHSA 3.0-7.0 mg/mL, largely exceeding the 180 HSA/PBnp value calculated for an HSA monolayer on a PBnp. Finally, the stabilization brought by the HSA corona allowed us to carry out pH-spectrophotometric titrations on PBnp@HSA in the 3.5-9-0 pH range, revealing a pKa value of 6.68 for the water molecules bound to the Fe3+ centers on the PBnp surface, whose deprotonation is responsible for the blue-shift of the PBnp band from 706 nm (acidic solution) to 685 nm (basic solution).

Electrochemical Studies of Gold in Mops Buffer System

Recent work in this laboratory has investigated interactions of L-cysteine with metal ions.1 For this purpose the MOPS [(3-N-morpholino)propanesulfonic acid] aqueous buffer system has been employed in order to minimize interactions between the metal ions and buffer anions.2 Gold electrodes are expected to be useful in the investigation of L-cysteine and related substances,3 so it is useful to ascertain the background behavior of gold in the aqueous MOPS buffer system. It is the purpose of the present work to determine the voltammetric features in this situation for use in amino acid/metal ion studies.As shown in the accompanying figure, an initial positive-going sweep has a very small oxidation process at +0.45 V vs Ag/AgCl, presumably for the initial oxidation of the gold surface in pH 7.4 MOPS buffer. As this sweep continues, a much larger cathodic process corresponding to bulk gold oxidation is observed. On the return negative-going sweep, there is only a reduction process corresponding to the initial surface oxidation process. It is interesting to note that this reduction process is not observed upon reversing the sweep at only +0.50 V. On the second scan, the initial oxidation process has increased, possibly due to surface roughening in the first scan. Another investigation has involved addition of EDTA to the MOPS solution, resulting in an increase of the second (or bulk) gold oxidation process. This increase is apparently due to the ability of the EDTA to complex the gold cations formed in the oxidation process. This overall behavior is somewhat different compared to that found in other buffer systems such as phosphate,3 and contrasts to such behavior are planned for presentation in this talk. T. Cheek and D. Peña, J. Electrochem. Soc., 167, 155522 (2020).M. H. Ferreira, I. S. S. Pinto, E. V. Soares, and H. M. V. M Soares, RSC Advances, 5(39), 30989 (2015). G.T. Cheek and M.A. Worosz, ECS Trans., 72(27), 1 (2016). doi:10.1149/07227.0001ecst Figure 1

Enhanced Glucose Sensing Performance through Controlled Pulsed Laser Deposition of Au Clusters on Anodized Glassy Carbon Electrodes

Diabetes, a global health problem, necessitates precise blood glucose measurement for effective management. Despite their prevalence, enzymatic glucose sensors suffer from sensitivity to temperature and pH and limited lifetime of the enzyme, thus requiring replacement every two weeks (Teymourian et al., 2020). In contrast, non-enzymatic sensors offer enhanced durability, superior sensitivity, and ease of miniaturization, making them promising for the so-called "fourth generation" glucose sensors (Aun et al., 2021). Noble metals like Pt (Kim et al., 2012), Au (Shen et al., 2022), Pd (Elkholy et al., 2019), and Ir (Dong et al., 2018) have emerged as prospective candidates for glucose sensing due to their ability to oxidize glucose at a physiological pH of 7.4. Among these, Au has gained attention due to its remarkable electroactivity for glucose electro-oxidation (Vassilyev et al., 1985), despite its weak chemisorptive properties arising from filled d-orbitals (Hammer & Nørskov, 1995). Various methods have been employed to fabricate nanostructured gold electrodes, encompassing direct electrostatic assembly, covalent linking, polymer entrapment or co-mixing, sol-gel processes, electrochemical etching, and electrodeposition (Dahan et al., 2023). Nevertheless, many of these fabrication approaches entail the use of hazardous chemicals or involve cumbersome procedures, de facto limiting their practical application. As a result, scalable solutions to catalyst fabrication and deposition are needed to seamlessly integrate with the cleanroom process flows to build non-enzymatic glucose sensors.In this study, 7x7mm glassy carbon electrodes (GCs) served as working electrodes in a three-electrode system, with a reversible hydrogen electrode employed as a reference and a Pt mesh as a counter electrode. The GCs underwent meticulous polishing using alumina slurry of varying sizes (1μm, 0.3 μm, and 0.01 μm). Subsequently, they were anodized in 1M KOH at 1.8V for 2 hours in ambient air conditions. The electroactive area of the GCs was determined by measuring the capacitance with EIS before and after anodization, and by later dividing by the specific capacitance (13 μF/cm2). A remarkable tenfold increase in surface area was observed after anodization. With a custom-built cluster deposition apparatus (Figure 1a), four monolayers of gold clusters were deposited on three bare GCs (BareGC) and three anodized ones (AnGC). Field Emission Scanning Electron Microscopy (FE-SEM) images captured the morphology of BareGC and AnGC, both with and without clusters (Figure 1b). Atomic force microscopy was also utilized to complement the morphology study of the electrodes' surface. Grazing Incidence X-ray Diffraction (XRD) at 0.5 degrees revealed a peak corresponding to the Au(111) plane in Au+BareGC (Figure 1c). Rutherford backscattering was employed to quantify the gold loading on the samples. To facilitate the generation of active Au-OH species on the nanoclusters, the electrodes underwent cycling between 0.43V and 1.53V in 0.1M PBS, devoid of chlorides. Subsequently, the sensing performance towards glucose was evaluated via chronoamperometric methods, maintaining the potential at 0.884V under stirring conditions (250 rpm). Gradual increases in glucose concentration were applied in steps of 0.25 mM and later in 1 mM increments up to 7 mM (Figure 1d).Both Au+BareGC and Au+AnGC electrodes exhibited an extremely linear response (R²=0.99) within the 0.25 mM to 7 mM linear range. After calibration, the electrodes underwent cycling in 0.5 M H2SO4 between 0.015V and 1.715V (vs RHE). The gold oxide reduction peak was integrated (Figure 1e), allowing estimation of the electroactive surface area (ESA) using the formula ESA=(Integrated charge)/(scan rate*0.386 mC/cm-2). A comparative analysis with similar nanostructured Au samples (Table 1) revealed that Au+AnGC displayed a four times higher sensitivity and substantially lower detection limits.The impact of chlorides was explored by repeating the chronoamperometric calibration in a PBS+0.1M KCl buffer. Chloride adsorption led to complete catalyst deactivation and eventually to gold loss from both samples. Notably, Au+BareGC displayed higher sensitivity to Cl etching, experiencing a 50% reduction in gold ESA compared to a 30% drop in Au+AnGC.This work has proved that the deposited nanoclusters possess an extremely high density of active sites towards glucose electro-oxidation. In addition, the deposition on highly porous electrodes decreases the poisoning effect of chlorides. These findings show significant promise as a scalable fabrication strategy to glucose sensor development.References in Table 1:[1] https://www.sciencedirect.com/science/article/pii/S001346861400766X#bib0060[2] https://pubs.acs.org/doi/10.1021/jp810235v[3] https://www.sciencedirect.com/science/article/pii/S0925400515007133?via%3Dihub[4] https://www.sciencedirect.com/science/article/pii/S0039914012008971[5] https://pubs.acs.org/doi/10.1021/ac035143t Figure 1

Comparing the Corrosion Behavior and Microstructure of a WE43 Mg Alloy in Simulated Body Fluids Under Different CO2 Conditions

With the low density and high specific strength, magnesium (Mg) alloys are lightweight alloys with various applications. In addition, combined with biocompatibility, similar mechanical properties to human bones, and unique biodegradability, Mg alloys are promising biodegradable implant materials for orthopedic surgeries. However, the degradation rates of Mg alloys are too fast in physiological environments, which limits the clinical applications of Mg implants. Therefore, understanding the corrosion behavior in physiological environments is crucial for developing biodegradable Mg alloys.During Mg alloy degradation, hydroxide (OH-) ions are generated, and the pH near the alloy surface increases. Since carbonate-bicarbonate (CO3 2--HCO3 -) is a vital pH buffer system in the human body, the corrosion behavior of Mg alloys would be affected by the CO2 concentrations of the test environments. In this study, we performed electrochemical and corrosion tests of a solution heat-treated WE43 (Mg-4 wt%Y-3 wt%Nd) alloy in Hanks’ balanced salt solutions (HBSS) at 37°C. By performing the tests in air and in an incubator maintained at 5% CO2, the effect of carbonate-bicarbonate pH buffering on the corrosion behavior and corrosion microstructure of the WE43 Mg alloy was investigated.When testing the WE43 Mg alloy in air, a general corrosion morphology was observed during the 24-hour immersion. In contrast, WE43 Mg alloy tested in the incubator shows a more active surface potential and localized corrosion initiates on the alloy surface in the early stages of immersion. Electrochemical impedance spectroscopy (EIS) analysis shows that WE43 Mg alloy tested in air has better corrosion resistance than in the incubator. Furthermore, the corrosion resistance of the alloy tested in air increases with immersion time but decreases when tested in the incubator. Potentiodynamic polarization curves after 24-hour immersion confirm that the corrosion current density (i corr) of the WE43 Mg alloy tested in the incubator is higher than that when tested in air. The difference in corrosion behavior is owing to the carbonate-bicarbonate pH buffering effect and will be discussed based on corrosion microstructure characterizations. Figure 1

(Invited) Electrochemical Marine Carbon Dioxide Removal (mCDR)

Ebb Carbon is developing an electrochemical system to safely remove carbon dioxide from the atmosphere and store it in the ocean as dissolved inorganic carbon. The core process uses bipolar electrodialysis (BPED) to process incoming seawater into aqueous acid and alkaline seawater. The acid is kept on land and used for beneficial purposes that result in its neutralization. The alkaline seawater is returned to the ocean, shifting the carbonate buffer system toward carbonate, resulting in the removal of CO2 from the air into oceanic bicarbonate as air-sea equilibration is restored.For the mCDR system to be impactful on a global level, it must reach gigaton scale while being energy efficient and cost effective.The BPED stack dominates the energy demand of the system and is a prime design task for Ebb Carbon. The stack and system are undergoing development and testing in Ebb Carbon’s labs as well as at the labs of institutional partners. Combining all of these system elements requires a multitude of scientific and engineering disciplines to work together. In this talk, I will discuss the potential for improving the energy and Faradaic efficiencies of these systems, including the opportunity for collaboration with the electrochemical research community.

3D Hybrid branched carbon/ZnO core-shell nanostructure as biosensor for sensitive and selective detection of glucose

Reliable glucose monitoring at physiological pH and clinical practical range is critical for appropriate diabetes management which remains one of a major health concern. Herein, we describe the construction of flexible and 3D hybrid electrode for glucose sensing by successful immobilization of the GOx on branched carbon/ZnO core–shell nanostructures electrode. The microstructure, morphology and device properties of glucose sensor was systemically characterized by using HRTEM, SEM, FT-IR, and electrochemical analysis. The branched carbon/ZnO core–shell nanostructure sensor showed reliable stability, selectivity and remarkable sensitivity (i.e., 32.48 (±0.04) µA mM−1 cm−2) for glucose in clinical range at physiological pH conditions. The mediator less direct electron communication between the electrode surface and the redox center (FADH & FAD) was also analyzed comprehensively, which concludes an efficient direct electron communication (DET). This enhanced DET can be attributed to the larger surface area provided by the branched carbon/ZnO core–shell nanostructure and also favorable orientation of GOx which allows close proximity of the redox center and the electrode surface. It is believed that such kind of sensors could provide an ideal platform for continuous glucose monitoring (CGM) device fabrication which could perform glucose sensing in real-time and in-vivo analysis.