Acidic Environment Research Articles

Investigation of impact of Calotropis procera extract for properties of mild steel in acidic mediums

Mild steel, widely used in gas and oil pipelines, is recognized for its remarkable capacity to absorb both internal and external energy, as well as its high tensile strength. Despite these attributes, the constant exposure to corrosive toxic substances within these pipelines poses a significant challenge. Over time, corrosion weakens the steel’s resilience to impact and increases the likelihood of failure or explosion due to the buildup of fluid pressure. To mitigate this issue, we explored an eco-friendly approach by introducing natural, non-toxic additives derived from the plant Calotropis procera (CP). The goal was to restore some of the steel's lost energy absorption capacity and enhance its resistance to corrosion and fracture.To test the effectiveness of Calotropis procera extract, we conducted weight-loss experiments using API 5L X70 steel in a solution containing 1 mol sulfuric acid and oil. We varied the concentration of CP plant extract in the solution, using 5%, 7%, 10%, and 13% to evaluate its corrosion inhibition properties. Surface examination was carried out using optical microscopy, which confirmed a corrosion inhibition rate of 50% in the CP + H₂SO₄ solution. To further investigate the mechanical performance, we performed Charpy impact tests in the same acidic environment with CP concentrations of 5%, 7%, and 10%. The results revealed that at a 10% concentration of plant extract, the steel exhibited an absorbed impact energy of 278 J, with a corresponding resilience value of 348.325 J/cm². These findings demonstrate the potential of Calotropis procera extract as an effective, sustainable solution for improving the durability of steel used in corrosive environments.

Targeted Screening of Lactiplantibacillus plantarum Strains Isolated from Tomatoes and Its Application in Tomato Fermented Juice

This study explores the functional attributes of Lactiplantibacillus plantarum (L. plantarum) strains isolated from fermented tomato juice, focusing on their physiological, biochemical, and probiotic characteristics. The identified 66 gram-positive strains included 36 L. plantarum ones, which exhibited robust growth in acidic environments (pH 2.0–5.0) and utilization of various carbohydrates. Notably, seven strains outperformed a commercial strain in extreme acidic conditions. Antioxidant activity varied, with strain A24 showing the highest hydroxyl radical scavenging ability, while strains with high surface hydrophobicity had lower DPPH scavenging activity, indicating no direct correlation between these properties. Strains also showed strain-specific differences in carbohydrate utilization and antibiotic resistance, with some resistant to gentamicin and ciprofloxacin. Survival rates under simulated gastrointestinal conditions were strain-specific, with some strains demonstrating high survival rates, indicating their potential as probiotics. Furthermore, 13 strains used as fermentation starters in tomato juice significantly enhanced antioxidant activity and reduced pH and total soluble solids, indicating efficient sugar utilization and lactic acid production. These findings suggest that L. plantarum strains are well-suited for functional food fermentation and probiotic applications, with strain-specific traits offering versatility for use in acidic food products and probiotic formulations.

Development and Validation of Stability Indicating RP-HPLC Method for the Estimation of Pirtobrutinib and Characterization of its Degradants by LC - MS

Background: Pirtobrutinib is a novel non-covalent BTK inhibitor used to treat adult patients with relapsed/refractory mantle cell lymphoma and B-cell leukemias. The mechanism of action involves binding and inhibition of Bruton's tyrosine kinase (BTK). Objective: The main goal of the current work was to create a selective liquid chromatographic method (RP-HPLC) that is easy to use, accurate and exact for quantifying Pirtobrutinib and its degradation products, thereby seeking insight into the drug’s degradation behaviour. Methods: Using an isocratic mode and a 50:50 mixture of acetonitrile and buffer solution (0.1% orthophosphoric acid) as the mobile phase, a High Performance Liquid Chromatographic System with a PDA detector and an X-Bridge Phenyl column (150 x 4.6mm, 3.5μm) at a flow rate of 1.0 ml/min was able to achieve good chromatographic separation. At 219 nm, the detection was carried out. A retention time of 2.271 minutes was discovered. To ascertain the drug's degrading properties and stability, forced degradation tests were carried out, leading to the development of the RPHPLC method. The chemical structures of the degradation products were clarified and their fragmentation mechanisms were suggested using LC-MS. Results: The suggested approach demonstrated a linearity within the 25-150% (2.5 to 15μg/mL) concentration range, with a correlation coefficient of 0.9999. The precision of the system (measured by % RSD=0.49) and the method (measured by % RSD=0.86) were all within the acceptable limits set by ICH guidelines, with % RSDs less than 1% and less than 2% for system precision and method precision, respectively. The LOD was 0.3μg/mL, and the LOQ was1μg/mL. Pirtobrutinib underwent rigorous tests for forced degradation under the specified conditions outlined in ICH Q1 (R2) guidelines. Pirtobrutinib was primarily broken down in acidic, alkaline, peroxide, and thermal conditions. It was found to remain stable under reduction, photolytic, and hydrolytic conditions. Through LC-MS analysis, the chemical structures of the resulting degradation by-products were identified, along with the proposed pathways of their fragmentation. Conclusion: The current study gives insight into Pirtobrutinib’s degradation behaviour. Pirtobrutinib was stable in reduction, photolytic, and hydrolytic conditions but degraded more readily in acidic, alkaline, peroxide, and thermal environments. The degradation products were characterized as 4-carbamoyl- 5-chloro-3(4-((5-fluoro-2-methoxybenzamido)methyl)phenyl)-4,5-dihydro-1H-pyrazol-5-aminium (acid impurity, DP1), N-(4-(4,5-diamino-1H-pyrazol-3-yl)benzyl)-5-fluoro-2-hydroxybenzamide (alkali impurity, DP2), 5-amino-3-(4-((s-fluro-2-methoxybenzamido)methyl))-4,5dihydro-1H-pyrazol-5-aminium (peroxide impurity, DP3) and N-(4-(4-acetyl-5-amino-4,5-dihydro-1H-pyrazol-3-yl)benzyl)-5-fluoro-2- methoxybenzamide compound with λ1-oxidane (1:1) (thermal impurity, DP4) and their fragmentation pathways were proposed. This study presents the first ever reported method for the quantification of Pirtobrutinib. It ensures precise quantitation of Pirtobrutinib, a new Bruton's Tyrosine Kinase inhibitor, and its degradation products. The method's enhanced sensitivity and regulatory compliance ensure its consistent use in the quantification of Pirtobrutinib.

Recent Advancements in Harnessing Lactic Acid Bacterial Metabolites for Fruits and Vegetables Preservation.

Postharvest losses in fruits and vegetables exert substantial economic and environmental repercussions. Chemical interventions are being widely utilized for the past six decades which may lead to significant health complications. Bioprotection of fruits and vegetables is the need of the hour in which use of lactic acid bacteria (LAB) with GRAS status predominantly stands out. Incorporation of LAB in postharvest fruits and vegetables suppresses the growth of spoilage organisms by synthesizing various antimicrobial compounds such as bacteriocins, organic acids, hydrogen peroxide (H2O2), exopolysaccharides (EPS), and BLIS. For example, Pediococcus acidilactici, Lactobacillus plantarum, and Limosilactobacillus fermentum convert natural sugars in fruits and vegetables to lactic acid and create an acidic environment that do not favour spoilage organisms. LAB can improve the bioavailability of vitamins and minerals and enrich the phenolic profile and bioactivity components. LAB has remarkable physiological characteristics like resistance towards bacteriophage, proteolytic activity, and polysaccharide production which adds to the safety of foods. They modify the sensory properties and preserve the nutritional quality of fruits and vegetables. They can also perform therapeutic role in the intestinal tract as they tolerate low pH, high salt concentration. Thus application of LAB, whether independently or in conjunction with stabilizing agents as edible coatings, is regarded as an exceptionally promising methodology for ensuring safer consumption of fruits and vegetables. This review addresses the most recent research findings that harness the antagonistic property of lactic acid bacterial metabolites, formulations and coatings containing their bioactive compounds for extended shelf life of fruits and vegetables.

Enhancing the resilience of cement mortar: Investigating Nano-SiO2 size and hybrid fiber effects on sulfuric acid resistance

This article explores fortifying cement mortars against severe sulfuric acid (SLA) attacks by studying the impact of nano-SiO2 (NS), macro-steel (ST), and micro-polypropylene (PP) fibers. The aim is to assess their effects on workability, physical attributes, mechanical properties, and durability against SLA attacks when incorporated into mortar blends. Replacing 1 % of cement weight with NS, having average particle diameters of 15 nm (nm) (NS15) and 55 nm (NS55), and utilizing macro-ST and micro-PP fibers at volumes of 0.5 % and 1 % in singular and hybrid forms resulted in significant changes in mortar characteristics. While these additives increased fresh mortar viscosity and negatively affected workability, they substantially boosted mortar strength and durability against SLA attacks. The most substantial improvements were observed using smaller NS particle sizes and employing hybrid ST/PP fibers. The formation of calcium-silicate-hydrate (C-S-H) bonds by NS within the network emerged as a pivotal factor. NS's high pozzolanic activity and void-filling capacity significantly enhanced the mortars' strength and durability against SLA attacks. Furthermore, instead of their singular application, the combined use of ST and PP fibers proved more effective in restraining micro and macro cracks within the mortar matrix. The bridging effect of hybrid ST/PP fibers delayed crack propagation throughout the network, highlighting their superior efficiency against SLA attacks.Overall, these findings hold promise for designing cement-based composites resilient to harsh, acidic environments. Using smaller NS particles and hybrid fiber combinations presents potential pathways to prolong service life in challenging conditions.

The role of probiotics in maintaining vaginal ecosystem

A disturbed vaginal ecosystem is characterized by reduced or non-existing lactobacillary flora and damaged vaginal epithelium. It may not always be apparent whether alterations of the vaginal epithelium or pathogenic microorganisms are the primary cause of a disturbed vaginal ecosystem. Estriol plays a key role in developing and maintaining a healthy vaginal epithelium, stimulating cell growth and differentiation, increases epithelial thickness, and also promotes glycogen synthesis, which is required to maintain an acidic environment. Estriol deficiency results in the vulvovaginal atrophy and the development of atrophic vaginitis. In turn, Lactobacillus acidophilus maintains a healthy microbiome, protecting against infections and creating an acidic environment unfavourable for the growth of pathogens. In recent years, an increasing interest has been developed in probiotics with the belief that probiotics could be able to restore the vaginal microbiota health. A review of scientific articles on the use of an ultra-low-dose vaginal estriol 0.03 mg in combination with Lactobacillus acidophilus to normalize the vaginal microbiota and treat vaginal infections has been conducted. An analysis of published clinical studies and meta-analyses on the use of probiotics in vaginal infections showed the mechanisms of action of probiotics, their biological role and clinical effects. The integration of probiotics into the treatment and prevention of bacterial vaginosis is growing more urgent. The results of numerous studies and meta-analyses confirmed their high efficacy and safety. The supplementation of standard antibiotic therapy with probiotics improves cure rates, restores normal vaginal microflora and reduces the risk of relapse. Therefore, further studies on the use of probiotics to develop more effective and personalized treatment strategies providing long-term results are needed. The publication of new evidence will make it possible to introduce best practices into clinical practice and ensure a healthier future for patients worldwide.

A Mucous Permeable Local Delivery Strategy Based on Manganese-Enhanced Bacterial Cuproptosis-like Death for Bacterial Pneumonia Treatment.

Bacterial pneumonia is one of the most challenging global infectious diseases with high morbidity and mortality. Considering the antibiotic abuse and resistance of bacterial biofilms, a variety of metal-based materials have been developed. However, due to the high oxygen environment of the lungs, some aerobic infection bacteria have high tolerance to oxygen and ROS, and most of the metal-based materials based on ROS may not achieve good therapeutic effects. Inspired by the sensitivity of cuproptosis to aerobic respiratory cells, we designed a copper composite antibacterial nanoparticle and found that it can effectively induce cuproptosis-like death in the aerobic bacteria of the lungs. To address the challenge of in vivo application of cuproptosis, manganese dioxide was first incorporated to deplete protective glutathione, which can interact with copper and thus hinder the interaction of copper with proteins and assist in antibacterial action through immune enhancement. Cuproptosis-like death also requires a large number of copper ions. To meet this demand, we deliver positively hydrophilic modified composite nanoparticles that effectively penetrate the lung mucus layer directly to the lungs through local administration, and the copper ions are further released rapidly by the acidic environment at the infected site, which can further destroy bacterial biofilms in synergy with manganese. This drug-delivery system can effectively treat pneumonia caused by aerobic bacteria and avoid systemic toxicity that can be caused by large doses of copper.

NiIr Nanowire Assembles as an Efficient Electrocatalyst Towards Oxygen Evolution Reaction in Both Acid and Alkaline Media.

Oxygen evolution reaction (OER) is the rate-limiting step in water electrolysis due to its sluggish kinetic, and it is challenging to develop an OER catalyst that could work efficiently in both acid and alkaline environment. Herein, NiIr nanowire assembles (NAs) with unique nanoflower morphology were prepared by a facile hydrothermal method. As a result, the NiIr NAs exhibited superior OER activity in both acid and alkaline media. Specifically, in 0.1 M HClO4, NiIr NAs presented a superior electrocatalytic performance with a low overpotential of merely 242 mV at 10 mA cm-2 and a Tafel slope of only 58.1 mV dec-1, surpassing that of commercial IrO2 and pure Ir NAs. And it achieved a significantly higher mass activity of 148.40 A/g at -1.5 V versus RHE. In 1.0 M KOH, NiIr NAs has an overpotential of 291 mV at 10 mA cm-2 and a Tafel slope of 42.1 mV dec-1. Such remarkable activity makes the NiIr NAs among the best of recently reported representative Ir-based OER electrocatalysts. Density functional theory (DFT) calculations confirmed alloying effect promotes surface bonding of NiIr with oxygen-containing reactants, resulting in excellent catalytic properties.

PH‐Tunable 3D Interconnected Network of Multiwalled Carbon Nanotubes /Polyacrylic Acid Hydrogel with Excellent Electromagnetic Radiation Shielding Capability

AbstractThe fabrication of durable and high anticorrosion hydrogel composite materials composed of multi‐walled carbon nanotubes (MCNTs) and crosslinked polyacrylic acid (PAA) for EMI shielding application is reported. The MCNTs contribute to the generation of 3D porous structures and enhance the mechanical properties of composite hydrogel. The 3D porous structure and high electrical conductivity inherited from ultrahigh electrically conductive MCNTs enable excellent EMI shielding properties with a total shielding efficiency EMI SE (SET) value of 32.8 dB (>99.9%) at only 3 wt% filler content of MCNTs. The MCNTs/PAA hydrogels also display superior EMI shielding performance under a strong acidic environment with SET > 99.99% while the 3D porous structure remained intact. The combination of electron–ion system in pH solution enriches the charge transfer and accumulation, enabling dipole orientation and polarization that are favorable for enhancing EMI attenuation. Moreover, the porous structure of MCNTs/PAA also contributes to partial trapping and dissipation of EM radiation energy via multiple scattering phenomena. This work thus paves the way toward applications of 3D hierarchical network materials for EMI shielding applications in both land and aqueous environments.

Metabolic Acidity/H2O2Dual-Cascade-Activatable Molecular Imaging Platform toward Metastatic Breast Tumor Malignancy.

Fluorescence imaging in the second near-infrared window (NIR-II) is crucial for accurate tumor diagnosis, offering superior resolution and penetration capabilities. Current NIR-II probes are limited by either being "always on" or responding to one stimulus, leading to low signal-to-noise ratios and potential false positives. We introduced a dual-lock-controlled probe, HN-PBA, activated by both H2O2 and tumor acidic environment. This dual response ensures bright fluorescence at tumor sites, leading to higher tumor-to-normal tissue ratios (T/NT) compared to conventional "always on" probes and probes activated only by H2O2. This strategy allows precise tumor identification and removal of primary and metastatic tumors, achieving superior T/NT ratios (24.3/6.4 for orthotopic and lung metastasis, respectively). Our probe also effectively detected lung metastatic foci as small as ≤ 0.7 mm and showed the capability for accurate lesion localization in clinical breast cancer specimens. This dual-stimuli-responsive strategy could aid future diagnostic probe design.

Immuno‐Isolation Strategy with Tacrolimus‐Loaded Nanofilm Promotes Stable Stem Cell‐Based Cartilage Regeneration

AbstractBone marrow stem cells (BMSCs)‐engineered cartilage (BEC) shows promise for clinically repairing cartilage defects. However, when implanted in immunocompetent large animals, BEC becomes susceptible to ossification due to inflammatory infiltration. To address this, a nanofilm isolation approach is developed to enhance BEC's chondrogenic stability. Tacrolimus (FK506), known for its immunosuppressive effect, is integrated into adipic dihydrazide (ADH)‐modified hyaluronic acid (HA), creating an acid‐responsive macromolecular prodrug called FK506@HA‐ADH. This prodrug is then blended with poly(lactic‐co‐glycolic acid) (PLGA) to form electrospun FK506@HA/PLGA nanofilm. Goat‐derived BMSCs are induced in vitro to form BEC, which is enclosed within the FK506@HA/PLGA nanofilm and subcutaneously implanted in autologous goats. The nanofilm acted as a physical barrier, preventing immunocyte infiltration. Additionally, in response to the acidic environment triggered by inflammation and the gradual degradation of PLGA, the FK506@HA‐ADH prodrug is cleaved, releasing FK506 as needed. The released FK506 effectively countered inflammatory cytokines and promoted cartilaginous maturity. These combined mechanisms significantly inhibited BEC hypertrophy and improved its chondrogenic stability within an immunocompetent goat model. This nanofilm‐based isolation strategy established an immunosuppressive niche, successfully preventing endochondral ossification and promoting stable cartilage formation in BEC. These advancements are crucial for translating stem cell‐based therapies into clinical use for cartilage repair.

Polyoxometalates‐Mediated Selectivity in Pt Single‐Atoms on Ceria for Environmental Catalysis

AbstractOptimizing the reactivity and selectivity of single‐atom catalysts (SACs) remains a crucial yet challenging issue in heterogeneous catalysis. This study demonstrates selective catalysis facilitated by a polyoxometalates‐mediated electronic interaction (PMEI) in a Pt single‐atom catalyst supported on CeO2 modified with Keggin‐type phosphotungstate acid (HPW), labeled as Pt1/CeO2‐HPW. The PMEI effect originates from the unique arrangement of isolated Pt atoms and HPW clusters on the CeO2 support. Electrons are transferred from the ceria support to the electrophilic tungsten in HPW clusters, and subsequently, Pt atoms donate electrons to the now electron‐deficient ceria. This phenomenon enhances the positive charge of Pt atoms, moderating O2 activation and limiting lattice oxygen mobility compared to the conventional Pt1/CeO2 catalyst. The resulting electronic structure of Pt combined with the strong and local acidic environment of HPW on Pt1/CeO2‐HPW leads to improved efficiency and N2 selectivity in the degradation of NH3 and NO, as well as increased CO2 yield when inputting volatile organic compounds. This study sheds the light on the design of SACs with balanced reactivity and selectivity for environmental catalysis.

Exploring the potent corrosion inhibition properties of phenolic Schiff bases on mild steel in acidic environments, part A: coupling experimental and theoretical investigations.

In this study, we conduct a comparative investigation into the corrosion inhibition properties of two Schiff base compounds, namely 4,4'-((1E,1'E)-(ethane-1,2 diylbis(azaneylylidene))bis(methaneylylidene))diphenol (PSB5) and (1E,1'E)-N,N'-(ethane-1,2 diyl)bis(1-(4-nitrophenyl)methanimine) (PSB6), on mild steel in an acidic environment. The inhibitory efficiency and adsorption behavior of the inhibitors were assessed through electrochemical and gravimetric analyses. The inhibitors' deposition was further verified by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The findings of electrochemical tests demonstrate that these chemical compounds are potent inhibitors, with 96.5% inhibition provided by PSB5 at 10-3M. Therefore, PSB5 and PSB6 inhibitors are likely of mixed-form, as evidenced by changes in their Ecorr values of 59.8 mV and 33.0 mV, respectively when compared to the blank solution. Furthermore, the adsorption of these inhibitors onto the MS surface, as determined by the Langmuir adsorption isotherm, yielded free energy values of - 38.40 kJ mol-1 for PSB5 and - 35.20 kJ mol-1 for PSB6. These findings highlight a robust and spontaneous adsorption process for both inhibitors. Surface analysis using SEM-EDS revealed the preservation of the mild steel surface morphology and the adsorption of inhibitors. Theoretical investigations utilizing density functional theory (DFT) and molecular dynamics (MD) simulations supported and complemented the experimental findings. This research enhances the understanding of the corrosion protection potential of Schiff base compounds and their potential applications in various industries.

Phosphatization in the São Pedro and São Paulo Archipelago (SPSPA), Equatorial Atlantic, Brazil: Insights from guano leaching and chemical weathering

This research explores the phosphatization process in the São Pedro and São Paulo Archipelago (SPSPA), located in the Equatorial Atlantic, by analyzing the geochemical interactions between guano coatings and the underlying rocks. The study also examines the geochemical characteristics of the substrates, assessing the behavior of major, minor, trace, and rare earth elements, and determines the degree of weathering degradation of guano crusts, speleothems, peridotites and carbonate sedimentary rocks affected by environmental factors as rain, wind and halmyrolysis. The distribution of chemical elements in water-soluble, adsorbed, acid-extractable/exchangeable, readily acid and reducible, acid oxidizable, and residual phases were investigated. The principal findings of this method show that elevated Na levels are leached in water-soluble fractions, thereby highlighting the occurrence of rapid and active geochemical cycling, which is influenced by seawater. In contrast, in more acidic environments (pH close 4.8 to 2.0), considerable amounts of macroelements like P, Fe, Mg, Al, and Mn are found in association with remaining phases, indicating a slower and more incremental geochemical cycle of mature guano in the input and output systems of these nutrients in the archipelago. The mineralogy, as indicated by the presence of mafic minerals such as olivine, augite, and Cr-spinel, as well as phosphates including fluorapatite, collinsite, and spheniscidite, also supports this finding. The findings underscore the complex interplay between biological activities and geochemical processes, which influence the elemental dynamics in the phosphate-rich rocks of the SPSPA at depth. This study not only enhances our understanding of phosphatization processes but also offers important insights into the sustainable management of marine resources in environmentally sensitive areas. The research underscores the necessity of considering biological and environmental variables when examining geochemical cycles, particularly in regions exhibiting distinctive geological and biological interactions that challenge the prevailing models, such as those identified in the ASPSP.

Current Advancements in the Behavior Analysis of EPDM Elastomers in Peripheral Applications of the Cathodic Side of PEMFC Systems

This review examines the latest developments in the study of how Ethylene Propylene Diene Monomer (EPDM) elastomers behave in peripheral applications of Proton Exchange Membrane Fuel Cells (PEMFCs), specifically on the cathodic side. The review highlights the crucial role of EPDM in maintaining the integrity and efficiency of PEMFCs in challenging conditions characterized by varying temperatures, humidity, and acidic environments. The study examines the impact of various additives and vulcanization procedures on EPDM's mechanical and chemical properties, demonstrating enhancements in tensile strength, thermal stability, and chemical resistance. The study also investigates the compounding methods and selection of fillers, such as silica and carbon black, to optimize the performance of EPDM. Additionally, the effects of prolonged operational circumstances on EPDM's mechanical integrity and aging resistance in PEMFCs are being examined. This research emphasizes EPDM's suitability for long-term use in fuel cell systems. This review aims to guide the design of more durable and efficient PEMFC systems by optimizing the use of EPDM elastomers.

Genomic insights into key mechanisms for carbon, nitrogen, and phosphate assimilation by the acidophilic, halotolerant genus Acidihalobacter members.

In-depth comparative genomic analysis was conducted to predict carbon, nitrogen, and phosphate assimilation pathways in the halotolerant, acidophilic genus Acidihalobacter. The study primarily aimed to understand how the metabolic capabilities of each species can determine their roles and effects on the microbial ecology of their unique saline and acidic environments, as well as in their potential application to saline water bioleaching systems. All four genomes encoded the genes for the complete tricarboxylic acid cycle, including 2-oxoglutarate dehydrogenase, a key enzyme absent in obligate chemolithotrophic acidophiles. Genes for a unique carboxysome shell protein, csoS1D, typically found in halotolerant bacteria but not in acidophiles, were identified. All genomes contained lactate and malate utilization genes, but only Ac. ferrooxydans DSM 14175T contained genes for the metabolism of propionate. Genes for phosphate assimilation were present, though organized differently across species. Only Ac. prosperus DSM 5130T and Ac. aeolianus DSM 14174T genomes contained nitrogen fixation genes, while Ac. ferrooxydans DSM 14175T and Ac. yilgarnensis DSM 105917T possessed genes for urease transporters and respiratory nitrate reductases, respectively. The findings suggest that all species can fix carbon dioxide but can also potentially utilize exogenous carbon sources and that the non-nitrogen-fixing species rely on alternative nitrogen assimilation mechanisms.

Hierarchical Structures of Amino Acid Derived Polyhydroxyurethanes: Promising Candidates as Drug Carriers and Cell Adhesive Scaffolds.

In this study, we examined the self-assembly of a series of biodegradable and biocompatible amino acid-based polyhydroxyurethanes (PHUs), investigating the structural influence of these polymers on their self-assembly and the resulting morphological features. The presence of hydrophilic and hydrophobic segments, along with carbonyl urethane, ester, and hydroxyl groups in the PHU backbone, facilitates intermolecular hydrogen bonding, enabling the formation of self-assemblies with hierarchical nanodimensional morphologies. We determined the critical aggregation concentration (CAC) and found that it largely depends on the PHU's structure. In-depth morphological studies demonstrated that the evolution of morphology proceeds in four steps: (1) the initial formation of micelles, which act as seeds at very low concentrations, (2) the elongation of these micelles into nanorod or nanopalette shapes below the CAC range, (3) the epitaxial growth of nanofibers at the CAC, and (4) the complete formation of fibrous mats above the CAC. Additionally, these hierarchical structures were utilized for the encapsulation and release of the drug doxorubicin (DOX). We observed that 75% of the encapsulated DOX was readily released in a mildly acidic environment, similar to the physiological conditions of cancer cells. Cellular uptake studies confirmed the effective uptake of the drug-loaded nanoassemblies into the cytoplasm of cells. Our studies also confirmed that these self-assembled structures can serve as effective cell adhesive scaffolds for tissue engineering applications.

Injectable nanocomposite hydrogel with cascade drug release for treatment of uveal melanoma

Uveal melanoma (UM) is the most common malignant intraocular tumor with the trait of distant metastases. Currently, the standard clinical therapy results in suboptimal outcomes due to ineffective inhibition of tumor metastasis. Thus, developing novel therapeutic modalities for UM remains a critical priority. Herein, we have developed an injectable nanocomposite hydrogel (HA-DOX/LAP gel) through integrating hyaluronic acid-based drug-loaded nanoparticles into an alginate-dopamine gel, delivering the chemotherapeutic drugs, lapatinib and doxorubicin for combinational treatment of UM. HA-DOX/LAP gel is fabricated in situ by a simple injection of the mixed precursor solution into tumor sites and maintains in vivo for more than 21 days. The entrapped drug-loaded nanoparticles can gradually release from HA-DOX/LAP gel, enhancing tumor targeting and penetration, and synchronously releasing lapatinib and doxorubicin into the acidic intracellular environment to synergistically destroy UM cells. In vivo anti-tumor studies conducted in MuM-2B tumor models demonstrated that HA-DOX/LAP gel significantly impedes tumor growth, diminishes postoperative recurrence, and prolongs overall survivals of UM tumor-bearing mice through only single injection. Remarkably, the escaped drug-loaded nanoparticles effectively reduce the risk of tumor metastases. Our findings provide new insights for the development of multifunctional nanocomposite-incorporating combination therapy against UM by targeting tumor recurrence and metastases.

Cationic and ionizable amphiphiles based on di-hexadecyl ester of <I>L</I>-glutamic acid for liposomal transport of RNA

Various RNAs are among the most promising and actively developed therapeutic agents for the treatment of tumors, infectious diseases and a number of other pathologies associated with the dysfunction of specific genes. Some nanocarriers are used for the effective delivery of RNAs to target cells, including liposomes based on cationic and/or ionizable amphiphiles. Cationic amphiphiles contain a protonated amino group and exist as salts in an aqueous environment. Ionizable amphiphiles are a new generation of cationic lipids that exhibit reduced toxicity and immunogenicity and undergo ionization only in the acidic environment of the cell. In this work we developed a scheme for the preparation and carried out the synthesis of new cationic and ionizable amphiphiles based on natural amino acids (L-glutamic acid, glycine, beta-alanine, and gamma-aminobutyric acid). Cationic and ionizable liposomes were formed based on the obtained compounds, mixed with natural lipids (phosphatidylcholine and cholesterol), and their physicochemical characteristics (particle size, zeta potential, and storage stability) were determined. Average diameter of particles stable for 5–7 days did not exceed 100 nm. Zeta potential of cationic and ionizable liposomes was about 30 and 1 mV, respectively. The liposomal particles were used to form complexes with RNA molecules. Such RNA complexes were characterized by atomic force microscopy and their applicability for nucleic acid transport was determined.

Durability and Compressive Strength of Composite Polyolefin Fiber-Reinforced Recycled Aggregate Concrete: An Experimental Study

This study investigates of using recycled concrete aggregates along with the reinforcement of polyolefin fibers to augment both the compressive strength and durability of concrete, in alignment with the principles of sustainable development. This study experimentally investigated the compressive strengths and durability of composite polyolefin fiber-reinforced recycled aggregate concrete (PFRRAC) exposed to chloride and acidic environments. For this purpose, 150 cubic samples of 100 × 100 × 100 concrete with various combinations of recycled aggregates and polyolefin fibers were made and subjected to axial compressive loading. The results show that the addition of fibers significantly enhances the compressive strength of concrete, with an increase of up to 34.36% at 5% fiber content. However, increasing the proportion of recycled aggregates reduces the compressive strength, with reductions ranging from 21.12% to 43.85% as the recycled aggregate content rises to 70%. Moreover, the combination of fibers and recycled aggregates demonstrates potential for improving the sustainability and durability of concrete under challenging environmental conditions, particularly in chloride and acidic environments. In acidic environments, the inclusion of fibers significantly enhances the resistance to strength reduction. Furthermore, the study uncovers that a higher concentration of recycled aggregates exacerbates the reduction in strength in chloride-rich settings, emphasizing the imperative nature of meticulous mix design and material selection. The findings for the integration of even minor quantities of polyolefin fibers to amplify the performance and sustainability of concrete mixtures, especially when utilizing recycled aggregates, thus promoting eco-friendly construction practices.