NaCl Medium Research Articles

Hurdle Technology Approach to Control Listeria monocytogenes Using Rhamnolipid Biosurfactant.

This study evaluates the combination of mild heat with a natural surfactant for the inactivation of L. monocytogenes Scott A in low-water-activity (aw) model systems. Glycerol or NaCl was used to reduce the aw to 0.92, and different concentrations of rhamnolipid (RL) biosurfactant were added before heat treatment (60 °C, 5 min). Using glycerol, RL treatment (50-250 µg/mL) reduced bacterial population by less than 0.2 log and heat treatment up to 1.5 log, while the combination of both hurdles reached around 5.0 log reduction. In the NaCl medium, RL treatment displayed higher inactivation than in the glycerol medium at the same aw level and a larger synergistic lethal effect when combined with heat, achieving ≥ 6.0 log reduction at 10-250 µg/mL RL concentrations. The growth inhibition activity of RL was enhanced by the presence of the monovalent salts NaCl and KCl, reducing MIC values from >2500 µg/mL (without salt) to 39 µg/mL (with 7.5% salt). The enhanced antimicrobial activity of RL promoted by the presence of salts was shown to be pH-dependent and more effective under neutral conditions. Overall, results demonstrate that RL can be exploited to design novel strategies based on hurdle approaches aiming to control L. monocytogenes.

Temperature Effect on the Corrosion Behavior of Copper inhibited by3,4'-bi-1,2,4-Triazole in neutral salt-spray (NaCl 3%) Medium


 Abstract
 The temperature effect on the corrosion behavior of copper that was inhibited by 3,4'-bi-1,2,4-Triazole in NaCl 3% Medium was investigated using potentiodynamic polarization techniques. Inhibition effect was found to increase with decreasing the temperature. Polarization curves showed that 3,4'-bi-1,2,4-Triazole (bTA) act as mixed type inhibitors in 3% NaCl Medium. The obtained results showed that the 3,4'-bi-1,2,4-Triazole could serve as an effective inhibitor of the copper corrosion in 3% NaCl Medium at various temperature up to 55°C. 
 Keywords: copper, neutral salt-spray corrosion; electrochemical corrosion; corrosion behavior; corrosion resistance, 1,2,4-Triazole.

Formation of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) in the electrochemical oxidation of polluted waters with pharmaceuticals used against COVID-19

The COVID-19 pandemic has produced a huge impact on our lives, increasing the consumption of certain pharmaceuticals, and with this, contributing to the intensification of their presence in wastewater and in the environment. This situation demands the implementation of efficient remediation technologies, among them, electrochemical oxidation (ELOX) is one the most applied. This work studies the application of ELOX with the aim of eliminate pharmaceuticals used in the fight against COVID-19, assessing its degradation rate, as well as the risk of formation of toxic trace by-products, such as unintentional POPs like polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). To this end, model solutions containing 10 mg L-1 of dexamethasone (DEX), paracetamol (PAR), amoxicillin (AMX), and sertraline (STR) with two different electrolytes (NaCl and Na2SO4) have been evaluated. However, electrochemical systems that contain chloride ions in solution together with PCDD/Fs precursor molecules may lead to the formation of these highly toxic by-products. So, PCDD/Fs were quantified under conditions of complete degradation of the drugs. Furthermore, the presence of PCDD/Fs precursors such as chlorophenols was determined, as well as the role of Cl-, Cl• and SO4•− radicals in the formation of the by-products and PCDD/Fs. The maximum measured concentration of PCDD/Fs was around 2700 pg L-1 for the amoxicillin case in NaCl medium. The obtained results emphasise the importance of not underestimating the potential formation of these highly toxic trace by-products, in addition to the correct selection of oxidation processes and operation variables, in order to avoid final higher toxicity in the medium.

Characteristics of Root Cells during In Vitro Rhizogenesis under Action of NaCl in Two Tomato Genotypes Differing in Salt Tolerance

Understanding the mechanisms of plant salt tolerance as a complex trait is an integral part of many studies, the results of which have been used in the breeding process. The aim of this study was to compare the root response of two tomato (Solanum lycopersicum L.) genotypes (breeding line YaLF and cultivar Recordsmen) differing in salt tolerance. Rhizogenesis was induced in tomato shoots in vitro with different concentrations of NaCl in the culture medium. A number of morphobiological and cytological parameters were evaluated at the organ, tissue, and cellular levels for possible use in a comprehensive assessment of genotypes for salt tolerance. The influence of NaCl caused disruption of the cell cycle and redistribution of cells in the phases of the cell cycle. An increase in the degree of vacuolization was shown in cv Recordsmen at 75 and 150 mM NaCl and in the YaLF line at 150 mM NaCl. Under salt action, an increase/decrease in the length of cells such as columella cells (both genotypes) and epidermal cells (in cv Recordsmen at 75 and 150 mM NaCl) was shown. Differences between genotypes were demonstrated by changes in the area of the central cylinder and primary root cortex cells, as well as by changes of the Snucleolus/Snucleus ratio in these cells. Transmission electron microscopy (TEM) showed the modification of the chromatin structure in the root cells of these genotypes. Various cytoskeletal disorders were revealed in interphase cells of the tomato root of cv Recordsmen and the YaLF line by immunofluorescent staining under saline conditions. These morphometric and cytological parameters can be used for a comparative evaluation of genotypes differing in salt tolerance in a comprehensive assessment of varieties.

Corrosion Protection Evaluation of Copper Coated with a Block Copolymer and Block Coploymer/Carbon Black Nanoparticles in 3 wt% NaCl Solution

AbstractThis paper presents a successful preparation of SEBS (a copolymer polystyrene‐block‐poly (ethylene‐ran‐butylene)‐block‐polystyrene) and SEBS‐CB (SEBS‐Carbon Black nanoparticles) coatings on a copper surface following a well‐defined immersion protocol. Such coatings′ protection capacity was tested in a 3 wt% NaCl medium using potentiodynamic polarization, cyclic voltammetry (CV), and electrochemical impedance techniques (EIS). The electrochemical measurements indicate that SEBS and SEBS‐CB are cathodic‐type inhibitors mainly hindering the diffusion of oxygen molecules toward the copper substrate. It also indicates the decrease in chloride ion attack on the coated copper layer. Not only that, but it also affirms the decrease in ‘s transport to the bulk solution, resulting in our sample being further protected at more positive potential. Cu‐SEBS‐CB electrodes showed a slight improvement in corrosion protection compared to Cu‐SEBS electrodes. π‐π stacking was associated with improving the performance of these coatings. The keys functions of incorporating CB are improving the electrode conductivity and having a denser and more compact coating than that without CB. The order of inhibition efficiency obtained by potentiodynamic polarization is in good agreement with the results achieved by electrochemical impedance spectroscopy. Also, the inhibition efficiency of Cu‐SEBS and Cu‐SEBS‐CB increases with increasing the ratio of SEBS. Adsorption of SEBS and SEBS‐CB on copper surface follows the Langmuir isotherm.

Corrosion behavior of fiber laser welded Ti-6Al-4V alloy rods with different pH and temperature in 0.9 wt% NaCl medium

The corrosion resistance of laser welded samples was carried out in a shaken incubator in body-simulated liquid environments and kept at pH3-5 and 25-50˚C conditions for 24 hours. It was determined that acicular α' martensite structures were formed in the fusion regions and these structures increased the hardness of the alloy by 20% compared to the base metal. The welded samples had the highest tensile strength of 144 MPa. Weight changes after the corrosion test were calculated and the highest weight loss was found to be 0.0025 g for the sample with an initial weight of 4.1394 g. TiO2 oxides and {1 0 0} and {1 1 1} chamber-shaped salt crystals were formed larger and more intensely in the fusion zones than the base metal. Dental metallic implant welding with fiber laser will have higher corrosion resistance in oral use with different temperature and pH environments compared to screw joints.

Wear and corrosion behavior of selected up-quenched and step-quenched CuZnSn shape memory alloys

The effect of thermal treatment on the wear and corrosion behavior of three categories of Cu-Zn-Sn-Fe SMAs designated A, B, and C is studied. Wear properties were investigated using a tribometer whilst corrosion in 0.3 M H2SO4and 3.5%NaCl media was studied using the potentiodynamic polarization method. The microstructure of the alloys mainly consists of FCC Cu-rich phase and Cu5Zn8phase. The up-quenched A alloys show the highest hardness and lowest wear rate values of 72.1 HRB and 0.143 mm3/N/m respectively. Average COF was higher for the samples subjected to direct-quenching (0.35–0.12) than the up-quenched (0.16–0.12) and step-quenched (0.2–0.08) samples. Wear occurred by mixed mode mechanisms of abrasion and adhesion evident by grooves and wear particles on the surface. In 0.3 M H2SO4medium, step-quenched alloys had corrosion rates in the range of 0.1022 to 1.1705 mm/yr, which is lower than the range of 0.1466 to 0.2855 mm/yr, and 0.1730 to 0.6027 mm/yr obtained for direct quenched and up-quenched samples respectively. In 3.5% NaCl solution, step-quenched alloys had the lowest corrosion rates 0.0251 mm/yr relative to samples subjected to up-quenching and direct quenching treatment. Generally, step-quenching treatment effectively improved the corrosion resistance of alloys in both media.

Influence of salt concentration on microbial growth in Kashkaval cheese

The aim of the present study was to evaluate the influence of NaCl concentration on the microflora in Kashkaval cheese produced from cow’s milk. Three cheese samples were obtained - with low (0.7%), medium (1.5%), and standard (3.1%) content of NaCl. Microbiological analyses were performed on the 1st, 15th, 30th, and 45th d of cheese ripening. It was established that the NaCl content has a significant (p < 0.05) influence on the growth and activity of the microflora in studied samples. It has been observed that the total Lactic acid bacteria (LAB) increased up to 30 d during ripening, after which their concentration decreased. A higher LABs count of samples with 0.7% NaCl and 1.5% NaCl in comparison with those containing 3.1% NaCl was found. At the same time, the variations in the salt content do not have a significant (p > 0.05) impact on the growth of Psychrotrophic bacteria, while in samples with a low salt content, the growth of Yeast and Molds was more intense. The data obtained in the present study showed that the concentration of NaCl is important for the regulation of activity of microbiological processes during the ripening of the Kashkaval cheese samples.

Investigation of seawater electrolyte on hydrogen evolution reaction from the perspective of kinetics and energy consumption using an Ni-based electrocatalyst supported on carbon nanotubes.

In this study, a Ni-based composite incorporating Ni4N and La2O3 supported on carbon nanotubes (Ni-La-Ni4N/CNT) was synthesized as an efficiency electrocatalyst towards the hydrogen evolution reaction in different electrolytes with the kinetics and energy consumption investigated in detail. The Ni-La-Ni4N/CNT exhibits overpotentials of 124 mV and 200 mV at the current density of 10 mA cm-2 in 1.0 M KOH and alkaline seawater, respectively. As quantitative comparison, the exchange current density (j°) based on Volmer-Heyrovsky-Tafel mechanism was calculated from various polarization curves, which indicated that the addition of NaCl in alkaline medium or using seawater alone reduced the reactivity of the catalyst. The activity of Ni-La-Ni4N/CNT in alkaline seawater was equal to 91% of that in 1.0 M KOH. Furthermore, dynamic polarization resistance and corresponding current were obtained by the analysis of the equivalent circuit model with the extended Kalman filter algorithm. The analysis of the resistance power at 1 mW also shows that the current between the conditions in KOH and in seawater is 2.76 times. Adding alkaline substances to seawater can narrow it to 1.19 times. These strategies provide novel approaches for inspecting the activity changes of materials in different electrochemical environments.

Novi nalazi o koroziji feritnih varova od nerđajućeg čelika - pregled

This study covers the review of the degradation of ferritic stainless-steel weldments between 2015 and 2022. The industrial and automotive sectors make extensive use of ferritic stainless steel (FSS) due to its superior oxidation and corrosion resistance, low price, high thermal conductivity, and low thermal expansion. However, it has been reported that ferritic stainless steel is harder to weld than austenitic stainless steel and that doing so would probably result in a weaker welded joint owing to the coarsening of grains high welding temperatures. According to past research, the amount of heat applied during the welding procedure affected how soon the FSS (409 M) weldment degraded after being exposed to NaCl (3.5%) medium. The coarsening of the grains was considered to be the cause of this. When the shielding gas' CO2 content increased, the intergranular corrosion of the FSS weld metal was found to increase. Welds made with the ER430LNb filler metal had significantly lower intergranular corrosion of FSS (AISI 441) than those made with the ER430Ti filler metal. It was discovered that boiling Cu-CuSO4 - 50% H2SO4 solution increased the corrosion rate for the FSS (AISI 430) weldment more than boiling 40% HNO3 Solution. Weldments made of FSS (AISI 430) were found to be negatively affected by the CuCuSO4 - 50% H2SO4 environment in terms of intergranular corrosion attack.

Effect of Multi-Walled Carbon Nanotubes (MWCNTs) in Reducing the Corrosion Rate in Cr-MWCNTs Composite Coatings

Carbon steel was coated with Cr-multi-walled carbon nanotube (MWCNTs) coatings via electrodeposition. In this article, the impact of a combination of MWCNTs into the chromium coating on the morphology of the coating surface and corrosion characteristics was inspected. The MWCNTs seem to be evenly distributed across the chromium layer, according to scanning electron microscopy (SEM). Electrochemical measurements were used to conduct corrosion tests on samples of MWCNTs– chromium composite coated and pure chromium coated samples in aqueous NaCl (3.5 wt.%). The outcomes demonstrated a considerable increase in the resistance of corrosion due to the inclusion of MWCNTs during the chromium deposition procedure. In addition, the mechanism of anti-corrosion of the composite coating is also presented. Using an electrolyte bath containing various concentrations of dispersed MWCNTs (0.5, 1, and 1.5 g/L), crack-free and compact coating of Cr-MWCNT composite were electrodeposited on the substrates of the mild steel. The potentiodynamic polarization technique was used to examine the coatings corrosion performance subjected to a 3.5 weight percent of NaCl medium. When compared to chromium coating, the Cr-MWCNT composite coating showed the lowest corrosion rate (1.045x108 mpy) compared to chromium coating (4.891x108 mpy).

Electrochemical corrosion behaviors of Ti3SiC2/Cu composites in a 3.5% NaCl solution

AbstractThe electrochemical corrosion behaviors of Ti3SiC2/Cu composite and polycrystalline Ti3SiC2 in a 3.5% NaCl medium were investigated by dynamic potential polarization, potentiostat polarization, and electrochemical impedance spectroscopy. The polycrystalline Ti3SiC2 was tested on the identical condition as a control. The characterizations of XRD, X‐ray photoelectron spectroscopy, scanning electron microscope, and energy‐dispersive spectrometer were used to study the relevant passivation behavior and corrosive mechanism. The self‐corrosion current density of Ti3SiC2/Cu (6.46 × 10−6 A/cm2) was slightly higher than that of Ti3SiC2 (1.64 × 10−7 A/cm2). Under open circuit potential, the corrosion resistance of Ti3SiC2/Cu was better than that of Ti3SiC2. Ti3SiC2/Cu exhibited a typical passivation feature with a narrow passivation interval and a breakdown phenomenon. The better corrosion resistance of Ti3SiC2 was due to the more stable Si layer of the former. In comparison, for Ti3SiC2/Cu composites, Cu reacted with the reactive Si layers in Ti3SiC2 to form Cu–Si compounds and TiC, destroying the weak interaction between Si layers and Ti–C layers. In the other hand, the as‐formed Cu–Si compounds and TiC dissolved during the corrosion of Ti3SiC2/Cu in the 3.5% NaCl medium, causing to the destruction of the passivation film on its surface.

RE(III) 3-Furoate Complexes: Synthesis, Structure, and Corrosion Inhibiting Properties.

In this study, two types of Rare Earth (RE) 3-furoate complexes were synthesized by metathesis reactions between RE chlorides or nitrates and preformed sodium 3-furoate. Two different structural motifs were identified as Type 1RE and Type 2RE. The Type 1RE monometallic complexes form 2D polymeric networks with the composition [RE(3fur)3(H2O)2]n (1RE = 1La, 1Ce, 1Pr, 1Nd, 1Gd, 1Dy, 1Ho, 1Y; 3furH = 3-furoic acid) while Type 2RE bimetallic complexes form 3D polymeric systems [NaRE(3fur)4]n (2RE = 2Ho, 2Y, 2Er, 2Yb, 2Lu). The stoichiometric mole ratio used (RE: Na(3fur) = 1:3 or 1:4) in the metathesis reaction determines whether 1RE or 2RE (RE = Ho or Y) is formed, but 2RE (RE = Er, Yb, Lu) were obtained regardless of the ratio. The corrosion inhibition behaviour of the compounds has been examined using immersion studies and electrochemical measurements on AS1020 mild steel surfaces by a 0.01 M NaCl medium. Immersion test results revealed that [Y(3fur)3(H2O)2]n has the highest corrosion inhibition capability with 90% resistance after 168 h of immersion. Potentiodynamic polarisation (PP) measurements also indicate the dominant behaviour of the 1Y compound, and the PP curves show that these rare earth carboxylate compounds act predominantly as anodic inhibitors.

Poppy-leaf extract-derived biomolecules adsorption on the rGO-nanoplatforms and application as smart self-healing material for epoxy coating

Nowadays, low-dimensional materials have been utilized as potential materials for designing smart composite coatings. Not only the coating's barrier function but also its self-healing ability can be improved via the inclusion of nano-particles. Herein, the graphene oxide (GO) nanosheets are firstly functionalized by Poppy-leaf extract (MGO) and then modified with Zn (II) ions. Thereupon, the Zn@MGOs are incorporated into the epoxy coating (EC).First, Zn@MGOs were synthesized and then characterized by Raman, XRD, and FT-IR techniques. Second, the anti-corrosion impacts of Zn@MGOs in 3.5% NaCl media and after inclusion into the epoxy coating (EC) were investigated. The reason for applying the solution phase studies was to investigate the anti-corrosion behavior of the designed nano-hybrid in a neutral salty solution. In the coating phase, electrochemical studies were done on the scratched and intact coatings to investigate the self-healing behavior and barrier properties of the designed nano-composites. Also, other experiments including salt spray and cathodic delamination tests were carried out to further study the protection function of the designed composites. Outcomes from the EIS and polarization tests proved that the Zn@MGO could enhance the metal resistance against corrosion via a mixed-type inhibition mechanism in the solution phase. Besides, the EIS studies in the coating phase clarified that the epoxy film self-healing action and barrier function were simultaneously improved in the presence of the Zn@MGO.

Corrosion behavior of graphene coated Ti-6Al-4 V alloy by anodic plasma coating method

In this study, graphene layers were deposited onto Ti-6Al-4 V plates by Thermionic Vacuum Arc (TVA) deposition technology to improve the corrosion resistance of biomedical material. For this purpose, the distance from the sample (4 and 7 cm) and duration of coating (5 and 15 mins) parameters were tested. The corrosion performance of the sample was carried out using electrochemical tests in 0.9 wt% NaCl medium. Furthermore, the applied coatings were characterized by using FESEM, AFM, EDS, and FTIR devices. The microstructural findings revealed that the graphene coating was found dispersed in the grain and grain boundaries and was applied successfully to the surface of Ti-6Al-4 V for all applied TVA parameters. In general, the corrosion potential of the coated sample was more anodic when compared to the uncoated sample. The passivation area of the sample TP21 was more prominent, and the corrosion current was lower than in other samples. Furthermore, the polarization resistance was higher, and the corrosion rate was 8 times lower compared to the uncoated sample. Graphene coatings are promising anticorrosion coating materials for Ti-6Al-4 V.

Corrosion Inhibition of Rumex vesicarius Mediated Chitosan-AgNPs Composite for C1018 CS in CO2-Saturated 3.5% NaCl Medium under Static and Hydrodynamic Conditions

Rumex vesicarius (RVE) mediated chitosan–AgNPs composite was produced in situ by using an aqueous extract of Rumex vesicarius leaves as the reducing agent to reduce Ag+ to Ag0. The synthesized composite was evaluated as a sweet (CO2) corrosion inhibitor (CI) for C1018 carbon steel (CS) in 3.5 wt% NaCl solution under static and hydrodynamic conditions. The corrosion inhibitive performance was evaluated using electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR), and potentiodynamic polarization (PDP) techniques, as well as scanning electron microscopy (SEM)/energy dispersive X-ray spectroscopy (EDAX), and atomic force microscopy (AFM) on corroded C1018 CS without and with additives. The effect of concentration, immersion time, temperature, and rotation speed on the CI performance of the composite was also investigated. The corrosion inhibitive effect increased with increasing composite dosage, with the highest inhibition efficiency (IE) acquired at the maximum composite dosage of 0.3%. Beyond this concentration, the IE decline with increasing concentration. Furthermore, IE was found to increase with immersion time and decline with a temperature rise from 25 to 40 °C, with the optimum temperature of 60 °C found to accelerate corrosion without and with RVE-mediated Chi–AgNPs composite. Under high shear stress, the Chi–AgNPs composite exhibits moderate corrosion inhibition under hydrodynamic conditions. The surface analysis results validate the formation of a protective covering due to composite adsorption on the CS surface. The RVE-mediated chitosan–AgNPs composite could be recommended as a CI for C1018 CS in sweet (CO2) corrosion environments at ambient temperature.

English

The variation of some growth, agronomical and biochemical parameters of Vigna unguiculata (L. Walp) under salinity stress were investigated in the greenhouse and farm conditions. Plants were subjected to 0, 50, 100 and 200 mM NaCl. The increases of NaCl in the culture medium significantly (P< 0.001) decreased the growth parameters (number of leaves, noose diameter, leaf area and stem height), dry biomass (roots, shoots and total), chlorophyll contents and micronutrients (Zn, Fe and Mn) from 100 mM NaCl. Macronutrients (K, Ca and Mg) and K/Na ratio significantly (P < 0.001) decreased in plant partitioning with increasing salinity. The metabolites (proline, total soluble carbohydrates, soluble proteins, total free amino acids, total phenolic and flavonoids contents) significantly (P < 0.001) increased from 50 mM NaCl in variety Ekomcalle compared to Mouala GG and could be considered as biochemical indicators of early selection and osmotic adjustment ability for salt tolerant plants. At 50 mM NaCl, a relative tolerance of variety Ekomcalle compared to Mouala GG for all agronomic parameters (the flowering time, number of flowers per plant, number of pods/plant, number of seeds/pod, pod yield, seed yield and harvest index) was observed suggesting that Ekomcalle could increase cowpeas production on salty soils. Key words: Vigna unguiculata, salinity, growth, metabolites, mineral uptake, agronomic parameters.

Influence of Different Aqueous Media on the Corrosion Behavior of B4C-Modified Lightweight Al-Mg-Si Matrix Composites

In this study, we have investigated the electrochemical corrosion behavior of boron carbide (B4C) ceramic-reinforced Al-Mg-Si matrix composites in various aqueous environments (NaOH, NaCl, HCl, and H2SO4). The samples were produced by the powder metallurgy (P/M) route and the corrosion investigations were conducted by potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) methods. The morphology of the as-prepared and corroded samples was examined by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) studies. The investigations revealed that the corrosion resistance of Al-Mg-Si composites is highest in NaCl medium due to a less negative corrosion potential, higher charge transfer (Rct) resistance, and lower double-layer capacitance (Cdl) as compared to other media. The SEM morphology suggests that B4C ceramics enhance corrosion resistance by forming a protective barrier layer of OH- and Cl- deposits in the composite and unreinforced alloy, respectively.

Effect of water jet cavitation peening on electrochemical corrosion behavior of nickel-based alloy 600 in NaCl solution

Surface roughness, residual stress, grain boundary microstructure of the surface layer, the electrochemical corrosion behavior and the surface chemical state after the electrochemical test in alloy 600 in 3.5 wt% NaCl medium was investigated. After the WJP treatment, the surface roughness was increased and residual compressive stress was introduced. A low angle grain boundary layer and a lamellae-shaped layer were formed on the surface. A passivation film with higher Cr content was formed on the WJP treated surface after the electrochemical test. After the WJP treatment, the electrochemical corrosion potential changed from −151 ± 4.6 mV to −133 ± 3.1 mV, the corrosion current density changed from 0.298 ± 0.003 μA/cm2 to 0.052 ± 0.001 μA/cm2, the pitting potential increased from 258 ± 13 mV to 350 ± 8 mV, and the film resistance increased from 4283 ± 158 Ω/cm2 to 124,850 ± 187 Ω/cm2. The superior corrosion resistance was attributed to the change in stress state and microstructure of the surface layer.

QCM sensor provides insight into the role of pivotal ions in cellular regulatory volume decrease.

All vertebrate cells generally self-regulate for sustaining homeostasis and cell functions. As a major regulatory mechanism, regulatory volume decrease (RVD) occurs in hypotonicity-induced cell swelling, and then shrinking by the efflux of intracellular osmolytes and water, in which the ions K+, Cl-, and Ca2+ play a key role in the RVD process. We observed that these pivotal ions could result in novel RVD behaviors under repeatedly hypotonic stimulation. However, there is a lack of valid means for assessing the effect of pivotal ions on RVD. In this work, we proposed an effective measurement process based on a quartz crystal microbalance (QCM) combined with cell function of RVD for revealing acute variations in cell volume regulation induced by the pivotal ions. A QCM sensor was implemented by adhering MCF-7 cells to a poly-l-lysine-modified gold chip and cyclic stimulation with hypotonic NaCl medium, in which a frequency shift (Δf) showed the superior feasibility of the technique in exhibiting RVD behaviors. With the increase in the number of cycles, the RVD values decreased progressively under three stimulation cycles with hypotonic NaCl alone. Compared with the first cycle, the RVD level in the second and third cycles declined by 60.7±1.7% and 82.1±1.6% (n=3), respectively; conversely, it recovered in NaCl-KCl solution, but was significantly enhanced by 52.2±0.8% in NaCl-CaCl2 solution. Moreover, the inhibition of chloride channels to block Cl- efflux also decreased the RVD level by 56.2±3.0%. The results indicate that these ions (K+, Cl-, Ca2+) are all able to affect the function of RVD, among which intracellular Cl- depletion reduced RVD during measurement, but which recovered with K+ supplement, and Ca2+ enhanced RVD due to activation of ion channels. Therefore, this work provides a comprehensive assessment of cellular behavior and offers an innovative method for gaining insight into cellular functions and mechanisms. A novel strategy was conducted by integrating a quartz crystal microbalance (QCM) with the function of cell volume regulation for analyzing the role of the pivotal ions ( K+, Cl-, Ca2+) in NaCl media on the behaviors of regulatory cell volume decrease (RVD).