ABSTRACT In this study, we present the synthesis and sensing applications of Rh‐BPh , a new rhodamine‐based fluorescent sensor prepared through a simple and efficient synthetic method. The probe Rh‐BPh responded only to aluminum (Al 3+ ) in DMSO/water (v/v:1/1). As the water content increased, it became responsive to both Al 3+ and mercury (Hg 2+ ). Buffer studies across pH 5–8 showed a clear pH dependence: Hg 2 + was detected mainly under acidic buffers, whereas Al 3 + was selectively detected in basic buffers The detection limits are 366 nM for Hg 2+ and 554 nM for Al 3+ . Interestingly, the reversible interactions between the complexes and CN − (with Al 3+ ) or I − (with Hg 2+ ) ions show a reversible ring‐opening/ring‐closure process and enable the creation of a three‐input OR‐INHIBIT molecular logic gate. Additionally, the Rh‐BPh‐Al 3+ complex functions as a “turn‐off” fluorescent probe for cyanide ions in aqueous media, with a detection limit of 497 nM. Complementary colorimetric analyses performed in HEPES and Tris buffers, as well as on filter paper, indicate that the probe can also act as a practical color‐based detection system. Simultaneously, the Rh‐BPh‐Al 3+ complex offers a reversible and specific method for detecting cyanide ions.

Pb(II) contamination from landfill leachate poses a serious environmental and public health risk. This study demonstrates the valorisation of municipal solid waste (MSW) into an efficient Pb(II) adsorbent through MgO functionalisation of MSW-derived biochar using MgCl₂·6H₂O. Pristine biochar (P-BC) and MgO-modified biochar (MgO-BC) were synthesised from the organic fraction of MSW through pyrolysis at 450°C. SEM and FTIR analyses confirmed enhanced porosity and the introduction of Mg-O functional groups following modification. Batch adsorption experiments showed strong pH dependence, with maximum Pb(II) removal at pH 11 of 83.50% for P-BC and 99.82% for MgO-BC. Adsorption data were best described by the Freundlich isotherm and pseudo-second-order kinetic models, indicating multilayer chemisorption on heterogeneous surfaces. Langmuir maximum adsorption capacities were 24.82mg/g for P-BC and 36.63mg/g for MgO-BC. Intra-particle diffusion analysis revealed that boundary layer film diffusion dominated the adsorption process. Characterisations and comparative experiments confirm that MgO functionalisation significantly improves Pb(II) adsorption performance through the synergistic effects of ion exchange, electrostatic attraction, complexation, precipitation, and pore diffusion mechanisms. Overall, the results demonstrate the potential of MSW-derived biochar as a cost-effective, sustainable solution for landfill leachate treatment, supporting circularity and resource recovery in MSW management.

Diverging pH dependence and photocycle dynamics across members of the CryoRhodopsin clade.

Iron sulfide minerals are critical mediators of uranium (U) immobilization in anoxic environments, yet the electron transfer mechanisms across Fe- and S-containing phases remain incompletely understood. Here, we demonstrate that redox-driven structural transformations unlock a dual pathway for U(VI) reduction. Comparative experiments using pristine mackinawite (FeS), partially oxidized FeS (O-FeS), and sulfur-enriched FeS (S-FeS) revealed that FeS and O-FeS reduce U(VI) primarily through oxidation of structural S(-II), whereas sulfidation-induced structural alterations in S-FeS activate otherwise inert Fe(II) as a coreductant, as evidenced by Fe(III) formation. This dual electron-transfer pathway shows pH dependence. At pH 6.5, U(VI) reduction to U(V)/U(IV) is nearly complete in S-FeS, while the reduction extent decreases to 34% at pH 8.5, due to the formation of a passivated surface layer rich in Fe(III) and sulfur that inhibits further electron transfer. These findings demonstrate that oxidation- and sulfidation-driven variations in FeS stoichiometry and structure regulate uranium reduction and immobilization pathways, with important implications for predicting the fate of redox-sensitive metal contaminants in dynamic subsurface environments.

Applying antibacterial coatings onto food processing surfaces is essential for mitigating bacterial contamination, ensuring food safety, and maintaining hygienic standards in food production environments. This study explores environmentally friendly and food-safe antibacterial colloidal suspensions consisting of aggregated chitosan-pectin (CTS-Pec) coacervate complexes for applications in spray coatings and stimuli-responsive nanocarriers. Motivated by the lack of comprehensive studies on colloidal suspensions consisting of aggregated CTS-Pec coacervation complexes and the antibacterial properties of positively charged coacervate suspensions, this work serves as a complementary contribution to this area. Aqueous spontaneous ionic gelation was employed to synthesize CTS-Pec coacervate suspensions, systematically examining the effects of the biopolymer concentration, order of addition, mass ratio, and solution pH on coacervate formation. Analytical techniques were utilized to determine the physicochemical properties, while particle size and zeta potential analyses revealed that excess Pec led to negatively charged particles. The latter yielded larger particles versus particles prepared with excess CTS ratios, which yielded positively charged particles. Comprehensive MIC assays showed the antibacterial effectiveness of the positively charged nanoparticles, highlighting the role of surface charge and pH dependency. Notably, this study demonstrated that lower Pec concentrations could still produce positively charged particles, even at excess Pec-stoichiometric ratios, making them suitable for spray-on coatings. Additionally, the stimuli-responsive properties of the aggregated CTS-Pec coacervate systems were validated through pH-responsive absorption and pH- and temperature-dependent drug release behavior using methylene blue (MB) as a model system. These findings underscore the potential of aggregated CTS-Pec coacervate systems as sustainable, multifunctional materials for antibacterial applications and advanced drug delivery.

Preparation of double network hydrogel wound dressing based on starch/hyaluronic acid through host-guest interaction and Diels-Alder reaction.

Percutaneous metal absorption from airborne particulate matter: evaluating the role of skin barrier integrity.

The pH-mediated regulation of the glyoxal-dipeptide reaction pathway was systematically investigated via electrospray ionization mass spectrometry (ESI-MS) and nuclear magnetic resonance (13C-NMR) spectroscopy. The resulting mechanistic insights were then applied to optimize Camellia oleifera protein-based adhesive performance. Under alkaline conditions, glyoxal undergoes an intramolecular Cannizzaro reaction, where one aldehyde group is reduced to an alcohol hydroxyl group, and the other aldehyde group is oxidized to a carboxyl group, resulting in the salt form of glycolic acid (HOCH₂COO–). Glycolic acid enables extensive cross-linking via bifunctional, cooperative condensation with peptide amino and amide groups. A critical pH threshold of 11 was established for this process. In contrast, under acidic conditions, intramolecular cyclization of glyoxal to cyclic ether structures was observed. Simultaneously, the dipeptide’s aliphatic amino groups were protonated and inactivated, leaving only weakly nucleophilic amide groups available for reaction, which led to a significant reduction in overall efficiency. When applied to these adhesives, bond strength was shown to exhibit a distinct pH dependency. In the glyoxal-only system, a bond strength of 0.76 MPa was attained at pH 11, corresponding to a ~65% increase relative to acidic conditions. For the melamine-glyoxal modification, this value was further optimized to 0.95 MPa at pH 13, a result ascribed to the synergistic cross-linking effect of the triazine ring.

Virus-induced redox cycling in Fe(II)/peracetic acid systems: dual roles as reactant and catalytic promoter.

Leaching behavior and toxicity of solid waste from ore-based lithium extraction: Implications for safe storage and resource utilization.

Horse heart mini- and full length-myoglobin: pH effects on CO binding.

Circumneutral microbial Fenton catalysis: Harnessing iron-redox synergy for sustainable pharmaceutical degradation.

pH-dependent separation and identification of saponins from Beta vulgaris L. using high-speed countercurrent chromatography and high-resolution mass spectrometry.

Glyphosate is a commonly used herbicide. This compound is considered a probable human carcinogen; thus, an efficient and inexpensive method for promoting its facile decomposition into simpler and safer compounds is highly desirable. Ozone, a known disinfectant for aqueous solutions, is known to promote the degradation of glyphosate. The reaction between glyphosate and ozone under alkaline conditions was studied by a variety of spectroscopic techniques. We find that a glyphosate-ozone adduct is initially cleaved primarily into aminomethylphosphonic acid, AMPA, and glycine via an imine intermediate. Investigation of the pH dependence of the reaction, study of a quaternary amine derivative of this herbicide, and NMR analyses of 13C- and 15N-labeled glyphosate analogues support our proposed mechanism. Finally, AMPA and glycine undergo a mechanistically similar degradation as glyphosate and are converted to inorganic products.

Complement 1q binding protein (C1qBP) and cyclophilin D (CypD) are mitochondrial matrix proteins; C1qBP has been implicated in many cellular processes, including the regulation of oxidative phosphorylation, and CypD is widely associated with the regulation of mitochondrial permeability transition pore (mPTP) opening. In this study, C1qBP and CypD were shown, in vitro, to form a stable protein–protein complex. CypD–C1qBP interaction was disrupted by cyclosporin A and compromised by mutations of the CypD active site residues R55 and R82. AlphaFold protein modelling revealed that the large negatively charged surface of C1qBP binds to the positive surface of CypD. This electrostatically driven interaction was confirmed by the pH dependence of the protein–protein interaction, with lower affinities observed at higher pH values. C1qBP was shown to undergo conformational changes when bound to Ca2+ in vitro, conferring multiple Ca2+ interaction sites in a multi-phase process, thereby indicating that C1qBP may act as a Ca2+ sequester. In contrast, CypD binding to C1qBP diminished the Ca2+-induced conformational changes in C1qBP, lowering its Ca2+-binding capacity. Our findings suggest that C1qBP functions as a mitochondrial Ca2+ chelator, with its efficiency reduced by CypD, this most likely due to CypD and Ca2+ both competing for the same negative surface of C1qBP. The parallels between the features of CypD–C1qBP interaction and the regulation of Ca2+-dependent mPTP opening by CypD highlight a possible functional role of CypD which has so far been elusive.

Per- and polyfluoroalkyl substances (PFAS) are known to bind to specific proteins, leading to their accumulation in specific organs/tissues, ultimately resulting in adverse health effects. Salts strongly impact PFAS and protein behaviors in the environment and biota, but the impact of salt on PFAS/protein interaction has not been assessed. In this study, we investigated the impact of salt on anionic PFAS (including PFBA, PFHxA, PFHpA, PFOA, PFNA, PFDA, PFBS, PFHxS, PFOS, and GenX) and bovine serum albumin (BSA) interactions. PFAS/BSA binding affinity was found to depend on PFAS chain length and headgroup, salt composition, ionic strength, and solution pH. PFAS/BSA interactions weakened with increasing ionic strength and decreasing cation valency. The molecular structure of PFAS did not affect how the ionic strength influenced binding affinities. However, the binding affinity exhibits pH dependence, with salt effects becoming more pronounced as the pH decreased. Thermodynamic analysis indicated a hydrophobic-dominant interaction between PFAS and BSA. Additionally, we developed a model to predict binding affinity under varying salt conditions, suggesting that different PFAS associate with wastewater to differing extents, strongly influenced by salt content. This model can be used to predict PFAS environmental fate and toxicity.

This work investigated the electrical, dielectric, and magnetic properties of ferrofluids containing Fe3O4 nanoparticles and their composites with chitosan (30–100 cP and 100–300 cP), relevant to magnetic hyperthermia. The nanoparticles were synthesized by coprecipitation and characterized using impedance spectroscopy, X-ray diffraction, scanning microscopy with X-ray microanalysis, Mössbauer spectroscopy, and calorimetry. The study showed that the chitosan coating altered the textural properties of Fe3O4, reducing the specific surface area from 76.3 m2/g to 68.9–72.5 m2/g. The zeta potential and particle size showed strong pH dependence. Impedance measurements showed that the conductivity of ferrofluids was frequency- and temperature-dependent, with both metallic and dielectric conductivity observed. The complex dielectric permittivity exhibited Maxwell–Wagner–Sillars interface polarization. Calorimetry revealed that specific absorption rate (SAR) ranged from 11.4 to 23.4 W/g, depending on the chitosan concentration and type, while the chitosan coating reduced SAR by 12–40%. These results confirm that the electrical and dielectric parameters of ferrofluids significantly influence their thermal capabilities, which is important for optimizing magnetic hyperthermia therapy when energy dissipation is considered in bio-heat models.

ABSTRACT Water contamination by organic pollutants such as synthetic dyes and pharmaceutical residues is a major environmental concern. In this study, a cerium – manganese oxide (CeMnO3) perovskite photocatalyst was synthesized via a simple citrate-based sol – gel method and thoroughly characterized via XRD, FTIR, FESEM, BET, XPS, and UV – Vis DRS analyses. The catalyst demonstrated strong photocatalytic performance under visible light, achieving a degradation efficiency of 81.8% methyl orange within 120 minutes, including a 30-minute dark adsorption phase at pH 9. The high efficiency is attributed to its narrow bandgap (2.40 eV), which facilitates efficient visible light absorption and enhanced charge separation. Operational parameters such as pH, catalyst dosage, and initial pollutant concentration were systematically investigated. For mixed organic pollutants, the degradation efficiencies were 81% for methylene blue, 75.9% for Brilliant Green, 71.9% for phenol red, and 63.9% for chloramphenicol. The addition of H2O2 and Na2SO4, which act as radical promoters and electron hole scavengers, increased the photocatalytic activity. Kinetic studies demonstrated a strong pH dependence on the rate constant, half-life, and degradation efficiency. The predictive equation for methyl orange was R(%) = (0.0546 pH + 0.204) × 100 (R2 = 0.9955), highlighting the role of alkaline conditions in enhancing pollutant removal.

Meat adulteration poses significant challenges to public health and consumer trust, necessitating the development of effective detection methods. Isothermal nucleic acid amplification (NAA) techniques, such as loop-mediated isothermal amplification (LAMP) and polymerase spiral reaction (PSR), have emerged as rapid and cost-effective alternatives to conventional polymerase chain reaction (PCR). These techniques simplify infrastructure requirements and can enable naked-eye detection (NED) through visible color changes with specific dyes. This study highlights the potential and suitability of various dyes for the NED of IA-based meat adulteration detection. Intercalating dyes, such as SYBR Green I, bind to the amplified DNA and emit fluorescence. pH-sensitive dyes, including phenol red, neutral red, and xylenol orange, change color with pH shifts during amplification. Triphenylmethane dyes, such as crystal violet and malachite green, directly interact with DNA, showing no pH dependence. Intercalating dyes, such as SYBR Green I, achieve superior sensitivity, often reaching 10fg of target DNA. Conversely, other dyes like Hydroxynaphthol blue and other pH-sensitive and pH-independent dyes provide slightly lesser sensitivity, typically ranging from 100fg to 1 pg. Dye-based NED combined with IA offers advantages such as rapid results, high sensitivity and specificity, suitability for field testing, and potential integration into lab-on-chip systems. However, further research is required to optimize dye formulations, develop multiplex assays, enhance sample preparation for complex food matrices, and investigate novel isothermal methods and primer designs. Accurate standardization and validation of these techniques are crucial for their widespread adoption to ensure food safety and consumer trust in the meat industry.

L-A9 is one of the important short peptides having biomedical applications in relation to its affinity towards HER2 receptors. The peptide has been synthesised using manual solid phase synthesis protocol and the redox property has been investigated using the voltammetric techniques. The oxidation peak of the peptide has shown strong pH dependency, revealed the 1 e and 2 proton transfer process. Electroanalytical method is developed with limit of detection of 1.17 × 10−7 M. The modulation of the redox property has been monitored to investigate the binding of the peptide with dsDNA, with binding constant of 1.8 × 10⁵ M− 1. Spectroscopic measurements of the peptide revealed the pH dependent electronic transition and the binding constant with dsDNA of 1.4 × 104 M− 1. The needle like assembly of L-A9 peptide has been indicated from the SEM measurements with coil kind of morphology of dsDNA has been observed when the L-A9 peptide and dsDNA interacted with each other. The electrochemical and spectroscopic investigations indicated that the acidic functional groups of L-A9 interacts with the major groove of dsDNA through the modifications of 3 hydrogen bonds between the strands, whereas the basic functional groups of L-A9 binds externally with dsDNA by formation of bonds with O atoms of the phosphodiester groups, which has been supported from the molecular docking investigations.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-025-30000-w.