Acidic Environment Research Articles

Mucormycosis and COVID-19: Unraveling the Interplay of Fungal Infection in a Global Health Crisis: An Overview.

The healthcare system has been greatly affected by the COVID-19 pandemic, result-ing in an increase in secondary and co-infections among patients. Factors like pulmonary dam-age and weakened immune systems make patients more susceptible to fungal infections. Mu-cormycosis, an opportunistic fungal infection, prospers in environments with limited oxygen, and elevated glucose levels due to conditions such as diabetes and steroid use, as well as in acidic environments from metabolic acidosis and diabetic ketoacidosis, where it demonstrates heightened germination ability. Recognizing these complications is critical to minimize harm to patients. The insights gained from this review can improve our understanding of how fungal infections develop in connection to COVID-19, leading to better predictive algorithms, tailored care plans, enhanced antifungal treatments, quicker diagnostics, and improved management strategies.

Crystalline o-Carborane Derivatives as a Fluorescence Turning-On Probe for Acid Environments

Crystalline <i>o</i>-Carborane Derivatives as a Fluorescence Turning-On Probe for Acid Environments

Synthesis and Optimization of Ethylenediamine-Based Zwitterion on Polymer Side Chain for Recognizing Narrow Tumorous pH Windows.

Polyzwitterions that show the alternation of net charge in response to external stimuli have attracted great attention as a new class of surface-polymers on nanomedicines. However, the correlation between their detailed molecular structures and expression of antifouling properties under physiological condition remain controversial. Herein, we synthesized a series of ethylenediamine-based polyzwitterions with carboxy groups/sulfonic groups and ethylene, propylene, and butylene spacers as potential surface-polymers for nanomedicines, allowing sensitive recognition of tumor acidic environments (pH = 6.5-5.5). Then, we evaluated their structure-based characteristics, including pH-dependent cellular uptakes and intracellular distributions. Additionally, the role of conformation stability, i.e., Gibbs free energy changes, was to induce an intramolecular electrostatic interaction in the zwitterionic moieties. These results highlight the practicality of fine-tuning the design of zwitterionic moieties on polymers for the future development of nanomedicines that can recognize the narrow pH window in tumor acidic environments.

Dual pH-responsive polypeptide nanoprobes for lysosomes enhanced bioimaging and tumor photothermal therapy under 1064 nm irradiation

Cancer cell precise fluorescence imaging and following tumor photothermal therapy have garnered ongoing interest. Lysosomes in cancer cells in a typical acidic environment can be used for smart bioimaging, and intelligent NIR-II fluorescence probes are attractive for tumor phototheranostics. Here, we successfully synthesized a pH-responsive NIR-II fluorescent dye FPZ and the introduction of N-methylpiperazine moiety at the ring position in the dye-endowed FPZ with fluorescence enhancement under acidic response. A pH-sensitive amphiphilic polypeptide was selected as the carrier to prepare FPZ-PN nanoparticles, which could be disassembled under acidic stimulation for efficient drug delivery and enrichment, and its fluorescence was significantly restored and enhanced (fluorescence enhancement of about 4.2 times) because of the blockage of the photoinduced electron transfer process, which allowed for efficient NIR-II fluorescence imaging, especially the lysosomes in cancer cells. In addition, the nanoparticles exhibited great photostability and a significant photothermal effect, with a photothermal conversion efficiency reaching as high as 69.96 % when subjected to a 1064 nm laser irradiation, which can effectively kill tumor cells. Thus, this work provides a new effective strategy for designing smart-responsive nanomedicine systems for precise localization and tumor elimination.

Toward understanding lipid reorganization in RNA lipid nanoparticles in acidic environments

The use of lipid nanoparticles (LNPs) for therapeutic RNA delivery has gained significant interest, particularly highlighted by recent milestones such as the approval of Onpattro and two mRNA-based SARS-CoV-2 vaccines. However, despite substantial advancements in this field, our understanding of the structure and internal organization of RNA-LNPs -and their relationship to efficacy, both in vitro and in vivo- remains limited. In this study, we present a coarse-grained molecular dynamics (MD) approach that allows for the simulations of full-size LNPs. By analyzing MD-derived structural characteristics in conjunction with cellular experiments, we investigate the effect of critical parameters, such as pH and composition, on LNP structure and potency. Additionally, we examine the mobility and chemical environment within LNPs at a molecular level. Our findings highlight the significant impact that LNP composition and internal molecular mobility can have on key stages of LNP-based intracellular RNA delivery.

N, S-Codoped Carbon Quantum Dots with High Inhibition Efficiency: Implications for Corrosion Mitigation of Carbon Steel in Acidic Environments.

The environmental friendliness, economic feasibility, and high efficiency of carbon quantum dots (CQDs) render them as highly promising candidates for corrosion inhibitors. The present study proposed the fabrication of nitrogen- and sulfur-codoped CQDs via an one-step hydrothermal method using l-cysteine and 4-aminosalicylic acid as precursors. The structure, particle size, and surface ligands of the prepared CQDs were determined through spectroscopy and transmission electron microscopy characterization. Subsequently, the inhibition performance of the CQDs on carbon steel in a 0.5 M sulfuric acid solution was evaluated through weight loss measurement, electrochemical methods, and surface analysis. The CQDs exhibited remarkable inhibition efficiencies of 97.9% at 293 K and 98.9% at 313 K, with a concentration of 150 ppm. In addition, the obtained CQDs demonstrated a combined physisorption and chemisorption adsorption behavior, which complied with the Langmuir adsorption isotherm. These findings provide insight into the inhibition mechanism and highlight the potential of codoped CQDs for corrosion mitigation applications in acidic environments.

Chalcones as potential pepsin inhibitors: Synthesis, characterization, DFT and molecular docking studies

Pepsin, a unique protease activity at acidic environment in the stomach, can cause chronic inflammation in surrounding tissues after becoming hyperactive lead to enlarged tonsils, vocal fold polyps, laryngopharyngeal cancers, and other diseases. Therefore, design and development of new effective pepsin inhibitors becomes significant. In the present work, we synthesized, and characterized thiophene-based chalcones as anti-pepsin agents. The synthesized chalcones exhibited significantly better pepsin inhibition than commercially available drugs omeprazole and pantoprazole. The in-vitro screening revealed that the synthesized compounds exhibited pepsin inhibition in the range of 53.19–91.14 % at 3 × 10−8 M concentration showing promising results controlling elevated pepsin levels. Compound 3p was found the best inhibitor with an IC50 value 1.02 × 10−9 M. Molecular docking studies executed show the decrease in energy of interaction between pepsin and the synthesized compounds 3(a-t) varies from −69.104 to −83.124 kcal/mol and the highest decreased interaction energy with compound 3p. DFT analyses were conducted to gain a deeper understanding of the structural parameters. Energy minimization and quantum chemical parameters computed using Avagadro and ORCA software indicated ΔE values in the range 9.593–10.246 eV as per DFT calculations. The results obtained from the in vitro studies were supported with in silico studies.

INFLUENCE OF PHYSICOCHEMICAL FACTORS ON THE SARS-COV-2 STRAIN ISOLATED FROM A DOG

This article presented the results of a study on the impact of physicochemical factors on the biological activity of the SARS-CoV-2 coronavirus isolated from a dog in the Republic of Kazakhstan. The results indicated that storing the virus at a temperature of -70°C led to a decrease in viral activity, similar to the effect observed when stored at room temperature. Storage at +40°C resulted in complete inactivation of the virus. The study on the effect of various concentrations of ionic and non-ionic detergents revealed that exposure to the ionic detergent DOC at concentrations of 0.1% and 0.5% caused a decrease in viral activity, while no change was observed at a concentration of 0.01%. The detergent SDS, at concentrations of 0.01%, 0.1%, and 0.5%, reduced the biological activity of the virus from the initial titer (5.25 lg TCID50/cm³) to 4.00 lg TCID50/cm³. Similarly, the use of non-ionic detergents, Triton X-100 and Tween-20, led to a reduction in viral activity from the initial titer to 4.50 lg TCID50/cm³. The effect of pH in acidic, neutral, and alkaline environments on the biological activity of the virus was also studied. A decrease in viral activity was observed at acidic and alkaline pH levels, whereas a neutral pH environment had no impact on viral activity.

Evaluation of encapsulated Bacillus subtilis bio-mortars for use under acidic conditions

This research aimed to examine the effects of an acidic environment on the mechanical properties and durability of bio-mortar (BM) encapsulated with Bacillus subtilis bacteria, in comparison to normal mortar (NM). The results at 28 days indicated that both 3% and 6% HCl significantly increased the compressive strength of the BM by 25% and 50%, respectively, compared with that of the NM. However, when 11% HCl was introduced, the compressive strength of the BM decreased to 50% lower than that of the NM. Furthermore, the water absorption rate of the BM was 33% lower than that of the NM. The mass loss for both 3% and 6% HCl was comparable, whereas at 11% HCl, BM experienced a mass loss that was 68% greater than that of NM. These findings suggest that with 3% and 6% HCl, the microbially induced calcium carbonate precipitation (MICP) process effectively generated CaCO3, which filled the pores and enhanced the structural integrity of the BM, leading to improved compressive strength and durability. Conversely, at 11% HCl, the MICP benefits in BM were diminished due to adverse environmental conditions that negatively affected the bacterial cells, highlighting the limitations of the HCl concentration for optimizing MICP efficiency in mortar.

Impact of Acidic and Alkaline Environments on the Surface Morphology of Biodentine and White Mineral Trioxide Aggregate - An In-vitro Study.

The physical and chemical properties of calcium silicate cement might be affected due to exposure to acidic or alkaline conditions during clinical use. The present study aimed to evaluate the effect of acidic and alkaline environments on the surface morphology of biodentine (BD) and white mineral trioxide aggregate (wMTA). Disc-shaped specimens of BD (n = 30) and wMTA (n = 30) were prepared in a metal mould and wrapped in pieces of gauze. They were divided into three sub-groups according to the storage media: group A, soaked in sterile distilled water at a pH of 7.0; group B, exposed to butyric acid buffered at pH 4.0; and group C, exposed to calcium hydroxide solution buffered at pH 12.0. The specimens were incubated for 7 days at 37°C, followed by examination under scanning electron microscopy at 1000x and 5000x magnification to characterise the microstructural morphology. Definite changes were seen in the microstructure of BD and wMTA on exposure to acidic and alkaline pH. The microstructure of wMTA tends to exhibit reduced cohesion when exposed to an acidic environment, especially when compared to an alkaline pH. Acidic pH exerts a milder influence on the morphological structure of BD when contrasted with its effects on wMTA. Biodentine may emerge as a more prudent choice than wMTA for utilisation in inflamed periapical regions.

Carbon-Capped PtNi Catalysts for the Oxygen Reduction Reaction in Acidic Environment: A Durability Study

Carbon-Capped PtNi Catalysts for the Oxygen Reduction Reaction in Acidic Environment: A Durability Study

PH-Responsive Micelles Containing Quinine Functionalities Enhance Intracellular Gene Delivery and Expression.

Quinine is a promising building block for creating polymer carriers for intracellular nucleic acid delivery. This is due to its ability to bind to genetic material through intercalation and electrostatic interactions and the balance of hydrophobicity and hydrophilicity dependent on the pH/charge state. Yet, studies utilizing cinchona alkaloid natural products in gene delivery are limited. Herein, we present the incorporation of a quinine functionalized monomer (Q) into block polymer architectures to form self-assembled micelles for highly efficient gene delivery. Q was incorporated into the core and/or the shell of the micelles to introduce the unique advantages of quinine to the system. We found that incorporation of Q into the core of the micelle resulted in acid-induced disassembly of the micelle and a boost in transfection efficiency by promoting endosomal escape. This effect was especially evident in the cancerous cell line, A549, which has a more acidic intracellular environment. Incorporation of Q into the shell of the micelles resulted in intercalative binding to the genetic payload as well as larger micelle-DNA complexes (micelleplexes) from the hydrophobicity of Q in the shell. These factors enable the micelleplexes to be more resistant to serum and have more persistent protein expression post-transfection. Overall, this study is the first to demonstrate the benefits of including quinine functionalities into self-assembled micelles for highly efficient gene delivery and presents a platform for inclusion of other natural products with similar properties into micellar systems.

Ajuga orientalis L. Extract as a Green Corrosion Inhibitor of Aluminum in an Acidic Solution: An Experimental and DFT Study

The inhibitory effect of A. orientalis L. extract (AO) on aluminum corrosion in a 1.0 M HCl solution was investigated utilizing weight loss, electrochemical polarization, electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). The results show that AO is a potent inhibitor in an acidic environment, and that the inhibition potency increases with concentration. Temperature investigations showed that, in an acidic medium, the efficiency decreased, increased, and then decreased as the temperature rose. Adsorption isotherms from Freundlich, Temkin, El Awady, and Redlich–Peterson (R-P) approximated the inhibitor’s adsorption properties. For the inhibitory behavior, a physical and chemical adsorption mechanism is proposed. The adsorption process’s thermodynamic parameters (Ea, ΔH*, and ΔS*) were determined and explained. The inhibitor, AO, was identified as a mixed-type (anodic and cathodic) inhibitor based on polarization studies. According to the SEM findings, the inhibitor partially covers the metal surface, providing it with a respectable level of protection. The weight loss, electrochemical polarization, EIS, scanning electron microscopy (SEM), and quantum chemical calculations show a strong agreement, indicating that the AO extract is a highly effective inhibitor of aluminum in an acidic solution.

An ultrastable luminescent covalent organic polymer for selective Pd2+ detection in strong acid

AbstractThe low natural abundance of palladium (10 ppb) in the Earth's crust highlights its considerable potential as a valuable resource, especially given that spent nuclear fuel contains approximately 1–2 kg of Pd per ton. However, the detection and separation of Pd2+ from high‐level liquid waste (HLLW) present significant challenges due to high acidity (2–5 M HNO3) and intense radiation conditions inherent in spent fuel reprocessing. We present a cyano‐olefin‐linked covalent organic polymer (COP‐TnPp) that exhibits remarkable stability in strong acidic environments and resilience to radiation. Thanks to its olefin linkage, which facilitates π‐electron conjugation, COP‐TnPp exhibits strong luminescence, whose intensity remains stable across a range of 1–5 M nitric acid solutions. Pd2+ ions can effectively quench the fluorescence of COP‐TnPp in 1 and 5 M HNO3 solutions with detection limits of 0.37 and 0.63 μM, respectively. Additionally, COP‐TnPp demonstrates exceptional selectivity for Pd2+ ions, even amidst 22 other interfering ions in a simulated HLLW solution (5 M HNO3), with the detection limit remaining at 0.697 μM. This work not only marks an advancement in the development of materials for detecting Pd2+ in extreme acidic conditions but also offers new insights into the detection of other radionuclides under similarly challenging environments.

Comparison of the Reactivity for the Solvent Extraction of Gold(iii) from Concentrated HCl Solutions Among D2EHPA, PC 88A, and Cyanex 272

ABSTRACT In this study, the chemical reactivity of three organophosphorus acidic extractants (D2EHPA, PC 88A, and Cyanex 272) was compared for the extraction of the anionic gold(III) complex, AuCl4 −, from the concentrated hydrochloric acid solutions. The extraction behavior was examined by varying the hydrochloric acid concentration from 1 to 9 M. Among the three extractants, only Cyanex 272 showed significant efficiency in extracting Au(III) with the extraction percentage was proportional to hydrochloric acid concentration. In contrast, the extraction of Au(III) by D2EHPA and PC 88A was not significant. FT-IR spectra analysis indicated that the P=O bond in Cyanex 272 weakened after extraction, suggesting its involvement in the process. Based on the structural differences between the extractants and the observed dependence of gold(III) extraction on the hydrochloric acid concentration, a nucleophilic addition reaction was proposed as the extraction mechanism. Specifically, the phosphoryl oxygen of protonated Cyanex 272 likely forms a coordinate bond with the gold ion in AuCl4 −, facilitating its extraction. This mechanism was supported by both extraction and spectroscopic data, making Cyanex 272 a promising candidate for the selective extraction of Au(III) from highly acidic solutions. The findings offer insights into the extraction of metal ions using organophosphorus extractants in highly acidic environments.

Preparation of pH-Responsive Kas@ZnO Quantum Dots for Synergistic Control of Rice Blast and Enhanced Disease Resistance in Rice.

The construction of controlled-release formulations improves the sustained-release performance and utilization efficiency of pesticides, which are important aspects in plant protection and environmental chemistry. The current study employs kasugamycin (Kas), which is widely used to control Magnaporthe oryzae, conjugated with carboxyl-functionalized ZnO quantum dots via amide linkages to yield a pH-responsive pesticide delivery system (Kas@ZnO). Physicochemical characterizations indicated the successful preparation of the Kas@ZnO nanoparticles. In vitro drug release assessments indicated that Kas@ZnO exhibited a loading capacity of 21.05% and could effect the controlled release of Kas in an acidic environment, which is beneficial given the unique acidic microenvironment of M. oryzae. Bioactivity assays demonstrated that Kas@ZnO could simultaneously inhibit mycelial growth and spore germination. Additionally, bioactivity tests showed that the control efficacy of Kas@ZnO against rice blast reached 67.43% after 14 days of in vivo spray inoculation, which was higher than that obtained with Kas (55.50%), suggesting improved beneficial effects of Kas@ZnO application over a prolonged duration. Moreover, Kas@ZnO enhanced the activity of defense-related enzymes in rice and upregulated the expression of defense-related genes, such as OsPR2, OsPR3, OsPR5, OsWRKY45, OsLYP6, and OsNAC4. Ultimately, the biosafety assessments revealed that Kas@ZnO did not exert any harmful effects on rice and demonstrated slight toxicity toward zebrafish. These findings indicate that Kas@ZnO can function as a pH-sensitive pesticide delivery system, allowing for targeted release of the pesticide within plant tissues. This technology demonstrates significant potential for eco-friendly plant disease management.

Comammox Nitrospira was the dominant ammonia oxidizer in an acidic biofilm reactor at pH 5.5 and pH 5.

Nitrification is a vital process in the biological removal of inorganic nitrogen compounds. In order to ensure the stability and effectiveness of this process, buffer solutions should be added to the system to maintain neutral to slightly alkaline conditions. With a focus on the newly discovered comammox Nitrospira, this research investigates the transition of the nitrifying community within a biofilm reactor under different acidic levels (initiated at pH 6 and gradually decreased to pH 5). During the 305-day continuous operation experiment, it was observed that responsible ammonia oxidizers transitioned from ammonia-oxidizing bacteria (AOB) during the initial stages (setup stage and early stage of pH 6) to comammox Nitrospira under pH 5.5 and pH 5. Further analysis using next-generation sequencing targeting both the 16S rRNA region and amoA region revealed a shift in the dominant cluster of both Nitrospirae and comammox Nitrospira under varying pH conditions. Our study identified a distinct cluster of comammox Nitrospira that is phylogenetically closed to sequences found in acidic environments, but exhibits dissimilarity from known comammox Nitrospira isolates and the majority of environmental sequences. This cluster was found to be prevalent in the acidic biofilm reactor studied and thrived particularly well at pH 5. These findings underscore the potential significance of this distinct, uncultivated group of comammox Nitrospira in performing ammonia oxidation under acidic conditions. KEY POINTS: • Ammonia was effectively removed under pH 5.5 and 5 in the biofilm reactor • The dominant ammonia oxidizer was comammox Nitrospira when pH was 5.5 and 5 • A potential acidophilic cluster of comammox Nitrospira was identified in this acidic biofilm reactor.

PH-Responsive MOF Nanoparticles Equipped with Hydrophilic "Armor" Assist Fungicides in Controlling Peanut Southern Blight.

The development of novel, safe, and efficient pest and disease control technologies for agricultural crops remains a pivotal area of research. In this study, by combining ZIF-8 and ZIF-90, a water-stable, pH-responsive bilayer MOF nanoparticle (NP) named Z8@Z90 was created, and tebuconazole (TEB) was added to form T@Z8@Z90, used for controlling peanut southern blight. The loading efficiency of TEB within the T@Z8@Z90 reached 26.15%, enabling rapid release in acidic environments triggered by oxalic acid (OA) secreted by Sclerotium rolfsii. In vitro experiments showed that T@Z8@Z90 can regulate the oxalic acid secretion of S. rolfsii and destroy its cell membrane structure. Additional experiments revealed that T@Z8@Z90 reduced sclerotial formation, decreased the total protein content of sclerotia, and influenced their sensitivity to pesticides, thereby mitigating the risk of reinfection by S. rolfsii. Notably, T@Z8@Z90 exhibited efficient translocation within peanut seedlings, being absorbed through the roots and transported to the leaves. At a concentration of 200 mg/L, T@Z8@Z90 exhibited high safety profiles for peanut seedling growth compared to the TEB suspension. Moreover, T@Z8@Z90 is safer for earthworms than TEB SC. Overall, this study offers valuable insights for the management of soil-borne diseases in agriculture and contributes to the advancement of sustainable agricultural practices.

Copper-promoted growth of hierarchical Cu–Co–Ni alloys on copper nanodendrites for enhanced hydrogen evolution in a wide pH range

Efficient and sustainable electrocatalysts for the hydrogen evolution reaction (HER) using earth-abundant elements are crucial for eco-friendly hydrogen production, particularly under neutral and acidic conditions. In metallic alloys, careful selection of alloying elements and control over the composition, morphology, electronic structure, and structural defects are expected to tune electrocatalytic activities. In this work, we introduce a two-step electrodeposition approach to create a 3D porous trimetallic alloy, Cu@Cu–Ni–Co, exhibiting excellent catalytic activity and stability for HER in neutral and acidic environments. The process begins with the electrodeposition of 3D copper dendrites, which was found to be crucial for the catalyst's mechanical stability, followed by the deposition of the trimetallic alloy, where copper's inclusion promotes the controlled growth of the alloy's 3D structure. The Cu@Cu–Ni–Co catalyst outperforms Cu@Ni, Cu@Co, Cu@Ni–Co, and GC@Cu–Ni–Co electrocatalysts in neutral and acidic conditions, highlighting the importance of the developed electrodeposition approach. In 1.0 M phosphate-buffer solution (PBS), Cu@Cu–Ni–Co achieves a current density of 10 mA cm−2 at an overpotential of 275 mV with a Tafel slope of 134 mV dec−1, maintaining remarkable stability in both acidic and neutral conditions at high current densities (48–165 mA cm−2) for up to 50 h without any decline in activity.

Effect of pre-exposure to chloride environment on the tensile deformation of SS 304HCu at 973 K

304HCu austenitic stainless steel (SS 304HCu) with 3 % copper content is utilized as the tubing material for advanced ultra-supercritical boilers, which operate at temperatures around 973 K and a pressure of 31 MPa. The current investigation aimed to examine the influence of prior exposure to an acidic chloride environment on the tensile characteristics of SS 304HCu at 973 K with the nominal strain rate of 1× 10−3 s−1 in solution annealed as well as thermally aged (973 K/10000 h) conditions. In the prior exposure condition, both the solution annealed and aged specimens were subjected to a pre-determined potential of −0.14 V (Ag/AgCl) for 48 h in 5 M NaCl + 0.15 M Na2SO4 + 2 ml HCl solutions. Thermally aged SS 304HCu showed lower strength in both true UTS and true yield strength compared to the solution annealed specimen tested at 973 K. Exposure to an acidic environment resulted in a considerable reduction in tensile strength and uniform plastic strain. For all the conditions, saturation-stress-based relationship was employed to describe the flow behaviour of the alloy. The relationship adequately fits the true stress-true strain data of SS 304HCu. A systematic variation in strain hardening parameters with respect to different test conditions is noticed. In the case of the aged alloy, the observed microstructure revealed the presence of M23C6 at grain boundaries and copper precipitates in the grain interior. The increased chromium depletion and the higher degree of sensitization led to the formation of localized pits in pre-exposed aged specimen conditions. Consequently, the synergistic influence of precipitation and pitting corrosion significantly affected the tensile deformation behaviour of SS 304HCu alloy in the aged and pre-exposed condition compared to the solution annealed condition.