Isopropyl alcohol 70% / Hydrogen peroxide 0.125% liquid

The O-demethylation of lignin aromatics is a rate-limiting step in their bioconversion to higher-value compounds. A recently discovered cytochrome P450, SyoA, demethylates the S-lignin aromatic syringol. In this work, we solve high-resolution X-ray crystal structures of substrate-free and substrate-bound SyoA and evaluate demethylation of para-substituted S-lignin aromatics via monooxygenase and peroxide shunt pathways. We find that SyoA demethylates S-lignin aromatics exclusively using the peroxide shunt pathway. The atomic-resolution structures reveal the position of non-canonical residues in the I-helix (Gln252, Glu253). Mutagenesis of this amide-acid pair in SyoA shows they are critical for catalytic activity. This work expands the enzymatic toolkit for improving the capacity to funnel lignin derived aromatics towards higher value compounds and defines the chemistry within the active site of the enzyme that enables peroxygenase activity. These insights provide a framework for engineering peroxygenase activity in other heme enzymes to generate easier to use biocatalysts.

Abstract licence: CC BY-NC-ND

Additive manufacturing (AM), particularly fused deposition modeling (FDM) 3D printing, has emerged as a versatile and accessible technology for prototyping and functional part production across a wide range of industrial applications. One of the critical performance-limiting factors in AM is the chemical resistance of thermoplastic materials, which directly influences their structural integrity, durability, and suitability in chemically aggressive environments. This study systematically investigates the chemical resistance of eight different widely utilized FDM filaments—acrylonitrile butadiene styrene (ABS), acrylonitrile styrene acrylate (ASA), polyamide (PA, Nylon), polycarbonate (PC), polyethylene terephthalate glycol (PETG), polylactic acid (PLA), polypropylene (PP), and polyvinyl butyral (PVB)—by examining their tensile strength and impact resistance after immersion in representative chemical agents: distilled water, ethanol (99.5%), isopropyl alcohol (75% and 99%), acetic acid (8%), hydrochloric acid (37%), hydrogen peroxide (30%), and acetone (99.5%). Quantitative mechanical testing was conducted in accordance with ASTM D638 and ASTM D256 standards, and statistical variability was accounted for using triplicate measurements with standard deviation analysis. The results reveal that PP exhibits the highest chemical resilience, retaining over 97% of its mechanical properties even after 7 days of immersion in aggressive solvents like acetone. PETG and ASA also demonstrated quite successful stability (>90% retention) in mildly corrosive environments such as alcohols and weak acids. In contrast, PLA, due to its low crystallinity and polar ester backbone, and PVB, due to its high amorphous content, showed substantial degradation: tensile strength losses exceeding 70% and impact resistance dropping below 20% in acetone. Moderate resistance was observed in ABS and PC, which maintained structural properties in neutral or weakly reactive conditions but suffered mechanical deterioration (>50% loss) in solvent-rich media. A strong correlation (r > 0.95) between tensile and impact strength reduction was found for most materials, indicating that chemical attack affects both static and dynamic mechanical performance uniformly. The findings of this study provide a robust framework for selecting appropriate 3D printing materials in applications exposed to solvents, acids, or oxidizing agents. PP is recommended for harsh chemical environments; PETG and ASA are suitable for moderate exposure scenarios, whereas PLA and PVB should be limited to low-risk, esthetic, or disposable applications.

Abstract licence: CC BY

Catalytic degradation of Acid Orange 7 (AO7) by hydrogen peroxide in an aqueous solution has been investigated using cobalt(II) complex of 5, 10, 15, 20 Tetrakis [4-(hydroxy)phenyl] porphyrin [Co(II) TPHPP] covalently supported chitosan/Graphene Oxide nanocomposite [Co(II) TPHPP]-Cs/GO, as highly efficient and recoverable heterogeneous catalyst. The structures and properties of [Co(II) TPHPP]-Cs/GO nanocomposite were characterized by techniques such as UV-Vis, FT-IR, SEM, EDX, TEM, and XRD. The oxidation reaction was followed by recording the UV-Vis spectra of the reaction mixture with time at λmax = 485 nm. [Co(II) TPHPP]-Cs/GO nanocomposite demonstrated high catalytic activity and could decompose 94% of AO7 within 60 min. The factors that may influence the oxidation of Acid Orange 7, such as the effect of reaction temperature, pH, concentration of catalyst, Acid Orange 7, and hydrogen peroxide, have been studied. The results of total organic carbon analysis (TOC) showed 50% of dye mineralization under mild reaction conditions of AO7 (1.42 × 10-4M) with H2O2 (8 × 10-2M) in the presence of [Co(II) TPHPP]-Cs/GO nanocomposite (15 × 10-3 g/ml) and pH = 9 at 40 °C. The reuse and stability of the nanocomposite were examined and remarkably, even after six cycles of reuse, there was no significant degradation or deactivation of the recycled catalyst. Residual organic compounds in the reaction mixture were identified by using GC-MS analyses. The radical scavenging measurements and photoluminescence probing technology of disodium salt of terephthalic acid indicated the formation of the hydroxyl radical as the reactive oxygen species in the [Co(II) TPHPP]-Cs/GO nanocomposite/H2O2 system. A mechanism for the oxidation reaction has been discussed.

Abstract licence: CC BY

The overuse of antibiotics has led to the development of antimicrobial resistance. As a result, topical antiseptics may become more important in clinical practice. Unlike antibiotics, antiseptics are less likely to induce resistance due to their unspecific mode of action and high local concentrations. However, there are challenges associated with using antiseptics, such as tolerability, inactivation by organic matter, and potential side effects. This review focuses on the challenges of using antiseptics, with a detailed discussion on the antimicrobial properties and possible resistances of octenidine dihydrochloride, povidone-iodine, hydrogen peroxide, chlorhexidine, and isopropyl alcohol antiseptics. The review also explores and discusses their antimicrobial efficacy, resistance, wound-healing properties, skin tolerability, and side effects. Orv Hetil. 2024; 165(41): 1621–1627.

Abstract licence: CC BY