pH Modulation Research Articles

Spatiotemporal Cell Control via High-Precision Electronic Regulation of Microenvironmental pH.

Accurate regulation of extracellular pH is crucial for controlling cell behaviors and functions. However, typical methods, which primarily rely on replacing cell culture media or using ionic diffusion, are slow, nondirectional, and lack spatiotemporal resolution. Here, we develop a microfabricated device that regulates microenvironmental pH within specific localized zones with high precision (uncertainty <0.1 pH units) and temporal resolution. The device uses a synchronization strategy that coordinates two processes: pulsatile modulation of pH through microelectrolysis and ultrasensitive graphene-electronic pH sensing, which operates in antiphase to the modulation. Using this device, we show real-time control of the dynamic behaviors of microscale clusters of bacteria (motility) and cardiomyocytes (calcium signaling and necrotic injury) in response to precisely regulated extracellular pH variations. Our device addresses the limitations of typical pH-altering techniques and holds significant potential to advance cell biology, physiology, tissue engineering, and regenerative medicine.

Systematic analysis of the glucose-PTS in Streptococcus sanguinis highlighted its importance in central metabolism and bacterial fitness.

Management of carbohydrate metabolism and environmental stress is key to the survival of oral commensal species such as S. sanguinis. Antagonism of oral pathobionts and modulation of the environmental pH and oxidative potential by commensals are crucial to the maintenance of microbial homeostasis and prevention of oral diseases including dental caries. It is therefore vital to understand how these species regulate sugar fermentation, production of acids and ammonia, and stress management in an environment known for a feast-and-famine cycle of carbohydrates and similar fluctuations in pH and oxygen tension. Here, we detail that genetic alterations of the glucose-PTS transporter in S. sanguinis can significantly affect the regulation of factors required for bacterial fitness and homeostatic ability independent of known catabolic regulators. It is then discussed how these changes may impact the survival of streptococcal species and affect caries onset.

Xylitol bioproduction by Candida tropicalis: effects of glucose/xylose ratio and pH on fermentation and gene expression.

Xylitol is a highly demanded polyol in the food, pharmaceutical, and chemical industries. However, its current production methods are considered energy-intensive, require the use of hazardous chemical catalysts, and depend on complex and costly equipment. The biotechnological route of xylitol production is proposed as a sustainable alternative, but it still requires process improvements, such as enhanced fermentation capabilities, to be economically competitive. This study examined Candida tropicalis yeast to improve xylose-to-xylitol conversion via glucose: xylose ratio and pH modulation. Key parameters evaluated included xylose consumption rate (rS), xylose-to-xylitol yield (YP/S), and xylitol volumetric productivity (QP). Conditions with 50g/L xylose at pH 3.5 exhibited superior xylitol production: 29.81g/L, QP of 0.52g/L/h, and YP/S of 0.54g/g at 48h. The statistical model demonstrated that the maximum YP/S and QP values have not yet been achieved. This could present an opportunity to be explored through yeast genetic engineering approaches. Additionally, the quantitative expression of the xylose transporter genes (XUT1 and STL2) and the xylose reductase gene (XYL1), previously identified in C. tropicalis, was evaluated under all tested conditions. Upregulation of the XUT1 was correlated with higher xylose concentrations, while STL2 was favored at lower xylose concentrations. The expression of XYL1 showed upregulation over time with higher xylose ratios. The high transcription levels and expression profile suggest that Xut1p-mediated xylose transport occurs through a proton symport mechanism. The results indicate that the pH factor indirectly influences XUT1 gene transcription, possibly as a compensatory response to the reduced transporter efficiency under high pH conditions. The present work underscores the influence of glucose ratios and pH in xylitol production, as well as the gene expression of xylose transporters and the key enzyme xylose reductase. Leveraging these insights can significantly enhance xylitol production from hemicellulosic hydrolysates through biotechnological pathways.

TMIC-24. BICARBONATE RECEPTOR SLC4A4 SENSITIZES INFILTRATING GLIOBLASTOMA CELLS TO CHANGES IN EXTRACELLULAR PH

Abstract BACKGROUND Glioblastoma progression involves changes in extracellular pH (pHe) related to rapid cell turnover and growth. There exist differences in pH between contrast-enhancing solid tumor and non-enhancing infiltrating tumor. SLC4A4 is a two-way bicarbonate transporter used in cortical astrocytes to buffer intracellular pH. METHODS In patients undergoing surgery for newly diagnosed IDH wild-type glioblastoma, we obtained tissue from solid tumor and infiltrating tumor. Single-nucleus RNA sequencing (n=15), immunohistochemistry (n=20) were carried out to identify SLC4A4 in infiltrating tumor beyond the contrast enhancing edge. SLC4A4 knock-down models were used to evaluate functional biology of this bicarbonate receptor using our tumor – cortical organoid model of infiltrating glioma and gliomaspheres. pH measurements were recorded using pH sensitive microelectrodes to evaluate changes on pH buffering ability of tumor cells during acid titration assays. RESULTS Single-nucleus RNA sequencing (n=15) and spatial RNA sequencing (n=3) showed SLC4A4 to be the highest expressed transmembrane receptor on infiltrating glioblastoma cells but not solid tumor. IHC (n=20) confirmed higher protein expression in infiltrating tumor (p=0.0390). Infiltrating cells were specifically sensitive to decreasing pHe (p=0.0105). In the infiltrating glioma cortical-organoid model, the slc4a4- had increased proliferation (GFP+ cell quantitation; n=10, p=0.0410). There was also increased proliferation in wild-type cells treated with SLC4A4 inhibitor DIDS (n=10, p=0.0016). Immunostaining of these models showed that downmodulation of SLC4A4 was associated with increased Ki67 and decreased caspase staining. CONCLUSIONS SLC4A4 plays a role in pH buffering in glioblastoma. We hypothesize that loss of SLC4A4 in solid tumor allows for desensitization of these cells to an acidic extracellular environment and allows for increased tumor growth and density while infiltrating tumor remains sensitivity to changes in pHe. An understand of pH regulation may lead to therapeutic efficacy through pH modulation of tumor.

Vulnerability of kelp, Ecklonia radiata, to persistent nitrogen pollution and coastal darkening

Coastal darkening is expected to have pervasive impacts on benthic primary producers. However, the effects of nitrogen enrichment, an often-co-occurring stressor, on benthic primary producers and their functions is less clear. This study investigates the interactive effects of coastal darkening and nitrogenous eutrophication, including nitrogen source (NH4+ vs. NO3−), on the function of the kelp Ecklonia radiata. First, an in-situ experiment was used to assess the differential impacts of NH4+ and NO3− pulse enrichment on the photosynthetic performance and pH modulation capacity of E. radiata. Second, a laboratory experiment was used to assess the longer-term impacts of nitrogen enrichment under low-light conditions mimicking coastal darkening on service provisioning, including photosynthetic performance, pH modulation, nutrient uptake and growth. While pulse nitrogen enrichment had no impacts on the photosynthetic performance of E. radiata in-situ, persistent exposure to either NH4+ or NO3− acted as a stressor to sporophytes as indicated by elevated rates of dark respiration and lamina erosion and reduced photosynthetic efficiency and growth rates. Furthermore, low-light conditions elicited reduced photosynthetic capacity at saturating irradiance, which extended to a reduction in the extent of pH modulation, and significantly increased lamina erosion. While the two stressors appeared to act on distinct parameters, ultimately, both darkening and eutrophication directly reduced net primary production, especially when in combination. These results demonstrate the negative interactive effects of coastal darkening and eutrophication on E. radiata function, while suggesting a vulnerability of E. radiata to even moderate levels of persistent nitrogen enrichment. This vulnerability highlights the need to consider environmental conditions during kelp conservation and restoration, and when attempting to valorise kelp ecophysiology for nature-based solutions.

Na+-driven pH regulation by Na+/H+ antiporters promotes photosynthetic efficiency in cyanobacteria.

Photosynthetic organisms have developed mechanisms to regulate light reactions in response to varying light conditions. Photosynthetic electron transport leads to the formation of a ΔpH across the thylakoid membrane, which is crucial for regulating electron transport. However, other pH modulators remain to be identified, particularly in cyanobacteria. In this study, we evaluated the potential involvement of six Na+/H+ antiporters (NhaS1-NhaS6) in control of pH in the cyanobacterium Synechocystis sp. PCC 6803. Synechocystis showed a strong requirement for Na+ at high light intensities, with ΔnhaS1 and ΔnhaS2 strains unable to grow under high light conditions. We analyzed Na+ efflux-driven H+-uptake activities of NhaS1-NhaS6 in inverted membranes of Escherichia coli. Biological fractionation and immunoelectron microscopy revealed that NhaS1 localizes to both the plasma and thylakoid membranes while NhaS2 localizes to the plasma membrane. Measurement of photosynthesis activity indicated that NhaS2 promotes ATP production and electron transport from PQ to P700. Measurements of pH outside of the cells and in the cytoplasm suggested that both NhaS1 and NhaS2 are involved in plasma membrane-mediated light-dependent H+ uptake and cytoplasmic acidification. NhaS1 and NhaS2 were also found to prevent photoinhibition under high light treatment. These results indicate that H+ transport mediated by NhaS1 and NhaS2 plays a role in regulating intracellular pH and maintaining photosynthetic electron transport.

Sublingual Fast-Dissolving Thin Films of Loratadine: Characterization, In Vitro and Ex Vivo Evaluation.

Loratadine (LOR) is a second-generation antihistamine that exhibits a low and variable oral bioavailability (10-40%) and delayed onset owing to poor solubility and an extensive first-pass effect. Therefore, in light of the clinical need, the main goal of the present study was to develop sublingual fast-dissolving thin films of LOR-citric acid co-amorphous systems (LOR-CAs) with the aim of eliciting a faster onset and improving the bioavailability. We formulated sublingual fast-dissolving thin films of LOR by a film-casting technique using hydrophilic polymers like hydroxypropyl methylcellulose (HPMC E15), polyvinyl pyrrolidone K30 (PVP K30), and hydroxypropyl cellulose EL (HPC-EF) and citric acid as a pH modulator, while glycerin served as a plasticizer. The sublingual fast-dissolving thin films were characterized by FTIR, SEM, DSC, and XRD and evaluated for in vitro dissolution and ex vivo mucoadhesion. The best formulation (F1) developed using HPMC E15 as a polymer, glycerin as a plasticizer, and citric acid as a pH modulator was found to be the optimized formulation as it was smooth, clear, flexible, and displayed good mucoadhesion (11.27 ± 0.418 gm/cm2) and uniform thickness (0.25 ± 0.02 mm). The formulation F1 was found to display a significantly shorter DT (30.30 ± 0.6 s) and rapid release of LOR (92.10 ± 2.3% in 60 min) compared to other formulations (ANOVA, p < 0.001). The results indicated that the prepared sublingual films are likely to elicit a faster therapeutic effect, avoid first-pass metabolism, and improve the bioavailability.

Rapid intracellular acidification is a plant defense response countered by the brown planthopper

The brown planthopper (BPH) is the most destructive insect pest in rice. Through a stylet, BPH secretes a plethora of salivary proteins into rice phloem cells as a crucial step of infestation. However, how various salivary proteins function in rice cells to promote insect infestation is poorly understood. Among them, one of the salivary proteins is predicted to be a carbonic anhydrase (Nilaparvata lugens carbonic anhydrase [NlCA]). The survival rate of the NlCA-RNA interference (RNAi) BPH insects was extremely low on rice, indicating a vital role of this salivary protein in BPH infestation. We generated NlCA transgenic rice plants and found that NlCA expressed in rice plants could restore the ability of NlCA-RNAi BPH to survive on rice. Next, we produced rice plants expressing the ratiometric pH sensor pHusion and found that NlCA-RNAi BPH induced rapid intracellular acidification of rice cells during feeding. Further analysis revealed that both NlCA-RNAi BPH feeding and artificial lowering of intracellular pH activated plant defense responses and that NlCA-mediated intracellular pH stabilization is linked to diminished defense responses, including reduced callose deposition at the phloem sieve plates and suppressed defense gene expression. Given the importance of pH homeostasis across the kingdoms of life, discovery of NlCA-mediated intracellular pH modulation uncovered a new dimension in the interaction between plants and piercing/sucking insect pests. The crucial role of NlCA for BPH infestation of rice suggests that NlCA is a promising target for chemical or trans-kingdom RNAi-based inactivation for BPH control strategies in plants.

Photo-responsive Pickering emulsions triggered by in-situ pH modulation using a photoacid generator

HypothesisPickering emulsions that respond to changes in pH by the addition of acid or alkali have been extensively studied, but the development of photo-responsive Pickering emulsions has been more challenging. This study attempts to demonstrate a novel approach to achieve photo-responsiveness in Pickering emulsions by incorporating a photoacid generator (PAG) into the oil phase. Upon UV irradiation, the PAG is expected to release protons (H+), which can then regulate the pH of the emulsion system and control its stability. ExperimentsAmphiphilic colloidal particles obtained by modifying silica particles with poly (2-(dimethylamino)ethyl methacrylate) (SiO2-PDMAEMA) are used to stabilize the Pickering emulsions. The protonation and deprotonation of the SiO2-PDMAEMA particles at different pH values allow for the tuning of emulsion stability. By introducing the PAG into the stable Pickering emulsion system and applying UV irradiation to trigger the in-situ release of H+, the pH of the emulsion is systematically decreased, and the corresponding changes in emulsion stability are investigated. FindingsThe results show that UV irradiation alone cannot induce emulsion instability. However, when PAG is added to the oil phase, the Pickering emulsions exhibit a significant decrease in pH under UV irradiation, ultimately leading to emulsion destabilization and phase separation. At a UV intensity of 20 mW/cm2 for 2 min, the H+ release from the PAG significantly lower the emulsion’s pH, causing the SiO2-PDMAEMA particles to detach from the oil–water interface and resulting in emulsion instability. Higher concentrations of SiO2-PDMAEMA particles in the emulsion require more PAG to induce instability, as confirm by confocal laser scanning microscopy (CLSM) image. This study presents a versatile approach to develop photo-responsive Pickering emulsions which can have potential applications in areas such as drug delivery, cosmetics, and responsive materials.

A novel merocyanine photoacid for visible light-controlled pH modulation

Merocyanine-based photoacids generate high proton concentrations under visible light irradiation. In the past decade, it has been established that these photoacids offer significant advantages over photoacid generators (PAGs) and hydroxyaryl photoacids, enabling better spatiotemporal control of proton transfer reactions in bulk media. In this study, we modified the core structure of the first generation of meroyanine photoacids. We developed a novel photoacid with color tuning capabilities and high solubility in polar organic solvents. Specifically, by incorporating a cationic benzoindolium moiety as an acceptor, we have altered the photoacid’s light absorption properties. Unlike the first generation of indolium-based merocyanine photoacids, this photoacid can now be activated with green light (λmax = 525 nm) as well as blue (λmax = 450 nm) and ultraviolet (λmax = 365 nm) lights. Furthermore, the novel photoacid exhibits high photo stability, photo-acidity (Π = 3.28 ± 0.08) and moderate reverse reaction rate (k = 1.08 × 10−3 ± 0.00017 s−1) in solution. We envision that with improved color tuning capabilities, this class of photoacids will be a more versatile tool for controlling proton-induced reactions in different systems, including biological reactions.

Computational screening of single-atom transition metals on boron-rich boron nitride nanosheets for efficient hydrogen evolution catalysis in all pH range.

Low-cost and high-efficiency catalysts are of crucial importance for the electrocatalytic hydrogen evolution reaction (HER). Two-dimensional (2D) boron nitride (B-N) compounds formed by the combination of boron and nitrogen atoms of group III and V elements are promising candidates for electrocatalytic HER due to their significant electronic properties. Hence, an electrocatalyst is computer-aided designed with isolated single atoms of 3d, 4d, and 5d transition metals supported on 2D B-N (B2N, B5N3, and B7N5) monolayers to fabricate single-atom catalysts (SACs) with an excellent HER performance. Moreover, pH modulations are considered to improve the HER activity theoretically based on first-principles calculation. Our results indicate that B-N compounds surface doping with transition metal atoms can effectively enhance the HER catalytic performance over a wide range of pH. Among all SACs studied, Co-, Ti-, V-, Nb-, Ru-, Tc-, Zr-, and Os-embedded B2N, Sc-, Cr-, Mn-, Ti-, and Y-embedded B5N3, and Sc- and Mn-embedded B7N5 have excellent catalytic activity under acidic conditions, while Mo-, Ir-, Re-, Ta-, and W-embedded B2N and Ti- and Fe-embedded B7N5 show high catalytic activity under alkaline conditions. Interestingly, Hf@B2N and V@B5N3 systems exhibit promising catalytic activity under acidic, neutral, and alkaline conditions. Our work offers cost-effective candidates with a wide pH range HER performance for exploring ideal electrocatalysts.

Patterns and causes of soil heavy metals and carbon stock in green spaces along an urbanization gradient

The surge in urbanization has correspondingly given rise to exacerbated carbon footprint and burgeoning heavy metal (HM) contamination, constituting a critical impediment to the realization of environmentally sustainable urban development pathways. Therefore, it is highly essential to investigate the impacts of urbanization process on soil carbon, heavy metals (HMs), as well as their interrelationships. Employing remote sensing and land use data within a 45 km radius in Chongqing, this study selected 31 sites to assess the variation in urban green spaces (UGSs) carbon sequestration capabilities and associated HM pollution risks across differing urbanization levels. Results showed that urbanization dynamics and land use history play a more decisive role than current anthropogenic management in shaping the distribution of soil carbon and HMs within urban environments. The average soil organic carbon (SOC) distribution of UGSs is 8.47 mg ha−1 (1.50–24.20 mg ha−1), concurrent with moderate HM pollution showing Ni: 32.03–33.50 mg kg−1, Pb: 27.93–29.65 mg kg−1, Cu: 26.97–41.20 mg kg−1, while Cd exhibits the most severe pollution range of 0.23–0.30 mg kg−1. The rate of urbanization significantly influences SOC stocks, exhibiting an increase when the urbanization rate is below 70.79 % and a decrease upon surpassing this threshold. The concentration of HMs is predominantly determined by the historical usage of the land, with a marked escalation correlating with the duration of land utilization history. These relationships were quantitatively modeled through the application of fitted linear functions. The structural equation model demonstrated that UGSs operating without anthropogenic disturbance tend towards degradation, indicating that temporary homeostasis might be sustained via the addition of N and P nutrients and pH modulation. In conclusion, we formulate an Urban Green Spaces Development Hypothesis that aims to shed light on the multifaceted challenges encountered by cities amidst varying degrees of urbanization and, concurrently, to probe potential ameliorative strategies.

Could oxygen gradient ektacytometry help to detect sickle cell trait carriers at risk for kidney disorders or exercise-related complications?

The study of Ellsworth etal. (Br J Haematol, 2024) demonstrated the usefulness of oxygen gradient ektacytometry technique to better identify the physiological parameters that could increase the risk of sickling of red blood cells (RBCs) from sickle cell trait (SCT) carriers. Oxygen gradient ektacytometry combined with pH and osmolality modulations could help in identifying SCT carriers at risk for kidney disorders or exercise-related complications. Other factors than the percentages of haemoglobin S are probably involved in the propensity of RBCs from SCT carriers to sickle during deoxygenation. Commentary on: Ellsworth etal. Hypertonicity and/or acidosis induce marked rheological changes under hypoxic conditions in sickle trait red blood cells. Br J Haematol 2024; 205:1565-1569.

A REVIEW STUDY ON ROLE OF CONTRACEPTIVES AND THEIR VARIOUS TYPES.

Contraception is the process used to stop unwanted pregnancy and control birth rate. Contraceptives reduces the chances of pregnancy after sexual intercourse. Contraceptives prevent pregnancies by interfering with the procedure of fertilization. Contraceptives reduces the chances of abortion by preventing unintended pregnancies on their partners, in which 842 million (44%) are modern using modern methods of Contraceptives are accessible in huge varieties and types . Numerous contraceptives are available, 790 million (42%) are traditional method users according the statistical data of 2019. The most common contraceptive techniques that are use of contraceptives are increasing day by day, 922 million of women of reproductive age used worldwide are female sterilization and male condoms, female sterilization are used in 219 million users (24%), male condoms are used in 189 million users (21%) according the data of 2019. The use of traditional methods and IUDs has reduced worldwide since 1994. According to WHO, The only form of birth control is a condom,that can prevent both unintended pregnancies and sexually transmitted diseases. The need of family planning is increased globally up to 77% from 2015 to 2020.. Over the past 20 years, the number of women using family planning methods has grown, rising from 900 million in 2020 to 2000 million. Use of modern contraceptive methods is also increased from 663 million to 851 million with the prevalence rate of 47.7% to 49.0%. Numerous contraceptive methods exist, including hormonal methods like CHC vaginal ring, CHC transdermal patch, and combination hormonal contraceptives. Progestin-only techniques include hormonal male contraceptives, progestin-only pills, DMPA injections, implants, and progestin-only IUDs. The other approach is non-hormonal and consists of vaginal pH modulators, barrier techniques like condoms, and copper IUDs. Traditional methods, such as the LAM method, the fertile cycle method, and the withdrawal approach, comprise the third type of contraception. Herbal contraceptives, which use a variety of herbs and plant preparations, are the fourth technique of birth control.

Effect of Integrated Extraction Techniques on the Technofunctional and Bioactive Properties of Brosimum alicastrum Swartz Proteins.

This study addresses the need for effective protein extraction and characterization to unlock the potential of underutilized plant resources like Brosimum alicastrum Swartz nuts, aiming to enhance their value as functional ingredients in food applications. Extraction methods, including pH modulation, ultrasound-assisted extraction, and enzymatic hydrolysis, are employed to enhance technofunctional and bioactive properties. The protein extracts are evaluated for solubility, emulsifying capacity, foaming properties, and water/oil-holding capacities to assess their technofunctional potential. Additionally, the bioactive properties, such as antioxidant and anti-inflammatory activities, are analyzed to explore potential health benefits. The results demonstrate that integrated extraction techniques significantly improve the yield and quality of Brosimum alicastrum Swartz nut proteins. Enzymatic hydrolysis, in particular, produces hydrolysates with superior bioactive properties. These findings highlight the potential of Brosimum alicastrum Swartz proteins as valuable ingredients for the food and pharmaceutical industries, promoting the utilization of underexploited plant resources for sustainable and health-promoting applications.

Autophagic cell death induced by pH modulation for enhanced iron-based chemodynamic therapy

Iron-based chemodynamic therapy (CDT) exhibits commendable biocompatibility and selectivity, but its efficacy is constrained by the intracellular pH of tumors. To overcome this obstacle, we constructed a silica delivery platform loaded with autophagy-inducing reagents (rapamycin, RAPA) and iron-based Fenton reagents (Fe3O4). This platform was utilized to explore a novel strategy that leverages autophagy to decrease tumor acidity, consequently boosting the effectiveness of CDT. Both in vitro and in vivo experiments revealed that RAPA prompted the generation of acidic organelles (e.g., autophagic vacuoles and autophagosomes), effectively changing the intracellular pH in the tumor microenvironment. Furthermore, RAPA-induced tumor acidification significantly amplified the efficacy of Fe3O4-based Fenton reactions, consequently increasing the effectiveness of Fe3O4-based CDT. This innovative approach, which leverages the interplay between autophagy induction and iron-based CDT, shows promise in overcoming the limitations posed by tumor pH, thus offering a more efficient approach to tumor treatments.

Improving standardization and accuracy of in vivo omega plot exchange parameter determination using rotating-frame model-based fitting of quasi-steady-state Z-spectra.

Although Ω-plot-driven quantification of in vivo amide exchange properties has been demonstrated, differences in scan parameters may complicate the fidelity of determination. This work systematically evaluated the use of quasi-steady-state (QUASS) Z-spectra reconstruction to standardize in vivo amide exchange quantification across acquisition conditions and further determined it in vivo. Simulation and in vivo rodent brain chemical exchange saturation transfer (CEST)data at 4.7 T were fit with and without QUASS reconstruction using both multi-Lorentzian and model-based fitting approaches. pH modulation was accomplished both in simulation and in vivo by inducing global ischemia via cardiac arrest. Amide parameters were determined via Ω-plots and compared across methods. Simulation showed that Ω-plots using multi-Lorentzian fitting could underestimate the exchange rate, with error increasing as conditions diverged from the steady state. In comparison, model-based fitting using QUASS estimated the same exchange rate within 2%. These results aligned with in vivo findings where multi-Lorentzian fitting of native Z-spectra resulted in an exchange rate of 64 ± 13 s-1 (38 ± 16 s-1 after cardiac arrest), whereas model-based fitting of QUASS Z-spectra yielded an exchange rate of 126 ± 25 s-1 (49 ± 13 s-1). The model-based fitting of QUASS CEST Z-spectra enables consistent and accurate quantification of exchange parameters through Ω-plot construction by reducing error due to signal overlap and nonequilibrium CEST effects.

PH modulation on properties of mycelium protein isolates

pH modulation on properties of mycelium protein isolates

Applying pH Modulation to Improve the Thermal Stability of Melamine-Formaldehyde Microcapsules Containing Butyl Stearate as a Phase-Change Material.

This paper presents a two-stage microencapsulation process that uses pH modulation to enhance the thermal stability of microcapsules that consist of a melamine-formaldehyde (MF) shell and a butyl stearate core. In the first stage, the pH value was modulated between 6.0 and 8.0. Rising the pH value to 8.0 slowed the polycondensation rate, allowing the MF resin with a lower degree of polymerization to migrate to the capsule surface and form a smooth shell. Lowering the pH value to 6.0 accelerated polycondensation. In the second stage, a relatively fast, continuous reduction in the pH value to 5.0 led to further MF polycondensation, hardening the shell. Post-curing at 100 °C prevented shell damage caused by the liquid-gas phase transition of the core material during the process. The microcapsules produced by increasing the pH value to 8.0 twice demonstrated improved thermal stability, with only a minimal overall weight loss of 5% at 300 °C. Significant weight loss was observed between 350 and 400 °C, temperatures at which the methylene bridges in the MF shell undergo thermal degradation. The results from differential scanning calorimetry, electron microscopy, and thermogravimetry analyses confirmed a successful optimization of the microencapsulation, showing that these microcapsules are promising for thermal energy storage and other applications that require high thermal stability.

Effects of a pH-Regulating Emollient Cream in Mild Atopic Dermatitis Patients with Moderate Localized Lesions

Introduction: Increased skin pH values in patients with atopic dermatitis (AD) contribute to poor antimicrobial and permeability barrier functions of the skin. In practice, the majority of topical preparations available for dry skin conditions do not provide sufficient pH and buffering capacity for maintaining optimum skin surface conditions. To address this issue, we tested a novel zinc lactobionate preparation to determine whether the regular application would lower skin surface pH, and in doing so improve the condition of lesional skin. Methods: The assessment for local severity of AD was done with the Scoring Atopic Dermatitis Index (SCORAD) and skin dryness was assessed by capacitance measurement. Results: The results showed that the test product lowered skin pH and improved AD skin lesions from moderate to mild during 2 weeks of application. In the treated area a lowered pH of about 0.85 units was found. Together with the lowering of pH, the local SCORAD significantly improved from 8.3 on average down to 4.0, while in the untreated area, only a slight improvement (from 8.2 to 6.4) was found. Conclusion: Synergistic effects of the test product’s pH lowering and emollient properties might explain the observed improvements in clinical signs of AD and further research against a comparator would allow the specific contribution of pH modulation to these improvements to be unambiguously isolated.