Degradation Products Research Articles

Gamma Radiolysis of n‐Dodecane: Physicochemical Properties and Metal Retention Behavior

AbstractThe gamma radiolytic degradation behavior of n‐dodecane (n‐DD) was investigated under conditions both with and without the presence of nitric acid. The physicochemical property alterations due to radiolysis were quantified and compared against an unirradiated system. Compositional changes in n‐DD post radiolysis was measured, and the degraded n‐DD was characterized using Fourier‐transform infrared (FT‐IR) spectroscopy, gas chromatography (GC), and gas chromatography–mass spectrometry (GC–MS) analysis. The presence of nitric acid was observed to accelerate the radiolytic degradation of n‐DD. The extent of diluent degradation caused by gamma irradiation was assessed through the retention behavior of uranium [U(VI)], plutonium [Pu(IV)], and zirconium [Zr(IV)] in 1.1 M tri‐n‐butyl phosphate (TBP) in irradiated diluent. Furthermore, the effectiveness of hydrazine carbonate (HC) as a solvent wash reagent for the removal of diluent degradation products was evaluated.

Evaluation of Benzene Presence and Formation in Benzoyl Peroxide Drug Products

The potent carcinogen, benzene, is a known degradation product of benzoyl peroxide (BPO) and was recently reported to form when BPO drug products, used for acne and rosacea treatment, are incubated at body temperature and elevated temperatures expected during storage and transportation. This study provides evidence for a wide range of benzene concentrations (0.16 ppm to 35.30 ppm) detected by GC-MS in 111 over-the-counter BPO drug products tested and maintained at room temperature. A prescription encapsulated BPO drug product was stability tested at cold (2°C) and elevated temperature (50°C), resulting in no apparent benzene formation at 2°C, and high levels of benzene formation at 50°C, suggesting that encapsulation technology may not stabilize BPO drug products but cold storage may greatly reduce benzene formation. Face model experiments where BPO drug product was applied to PolyMethyl MethAcrylate (PMMA) photoprotection test skin plates and benzene was detected in surrounding air by SIFT-MS, showed detectable benzene through evaporation and substantial benzene formation when exposed to UV light at levels below peak sunlight. Results suggest that potential benzene exposure from formation during BPO drug product use poses significant risks independent of the starting benzene concentration.

Cerium-regulated Mg3FeO4@biochar activated persulfate to enhance degradation of aqueous tetracycline: The dominant role of cerium

The role of cerium (Ce) in Ce-regulated Mg3FeO4@biochar (CMF@BC) and the mechanism by which CMF@BC activates persulfate (PS) remain unclear. In this work, a novel CMF@BC was synthesized through the simple impregnation–pyrolysis process and utilized as a PS activator for the removal of aqueous tetracycline (TC). Under the optimal degradation conditions, the removal efficiency and mineralization rate of TC reached 92.7 % and 84.2 % within 60 min, respectively, the corresponding rate constant was 0.0487 min−1. The CMF@BC catalyst exhibited extremely high stability and excellent reusability after five cycles. The characterization results identified Fe2+ and oxygen vacancies as major catalytic sites. The Ce dopant inhibited the aggregation of metal ions of Mg3FeO4 during the high-temperature pyrolysis process and the Ce3+/Ce4+ redox cycle promoted Fe2+ regeneration, thus improving the catalyst performance. The degradation process was dominated by non-free radical (1O2) pathways. The possible TC-removal pathway was inferred from liquid chromatography–mass spectrometry results and density functional theory calculations. The toxicity of the degradation products was also evaluated. The CMF@BC catalyst displayed excellent catalytic performance and recyclability, wide pH adaptability, and a low ion-leaching rate, confirming its broad application prospects as a PS activator in antibiotic wastewater treatment.

Failure signal of high orientation Poly(L-lactic acid) monofilament for self-expanding stent during lifetime: Disappeared amorphous connections

The premature failure of bioresorbable self-expanding stents for peripheral arterial disease could lead to form thrombosis and threaten patients′ lives. Predicting the time and cause of mechanical and structural failure is crucial to prevent premature failure of implanted stents. Herein, we report a situ accelerated hydrolysis to investigate the degradation properties of self-expanding stents braided by high-performance Poly(L-lactic acid) (PLLA) monofilaments in an accelerated term over a formal long one. Degradation, microstructure, and mechanical properties were comprehensively evaluated to identify key factors of the failure during lifetime. The results show that the upper temperature limit for accelerated hydrolysis is 50 °C. The mechanical properties undergo multiple stages of functional holding, decreasing, and eventual failure. It is attributed to uneven degradation and distribution of crystalline and amorphous regions. Specifically, the disappearance of amorphous chains between fibrils at 6 months leads to mechanical failure. Further disappearance of amorphous chains within fibrils at 18 months results in structural disintegration. Additionally, the degradation behavior of the stents and potential effects of degradation products on vascular tissues are validated for predictive accuracy. These insights provide valuable experimental references for optimizing design and clinical application of PLLA-based self-expanding stents.

Advances in the application of ion chromatography-mass spectrometry in the fields of life and health

Ion chromatography is a technique commonly used to separate strongly polar and ionizable substances; it can be used to separate, identify, and quantify ionizable compounds in complex samples when coupled with mass spectrometry, and is currently being used in the application of food analysis, drug analysis, metabolomics and clinical poisoning analysis. Herein, we review the development of ion chromatography-mass spectrometry (IC-MS), its progress over the past 20 years, and future trends in the abovementioned areas. The IC-MS research progress and applications for the determination of inorganic anions, organic acids, polar pesticides, biogenic amines, and sugars in the food field are discussed. Drug analysis applications are discussed mainly in relation to the analysis of drug impurities, identifying drug degradation products, and determination of plasma concentration, while the separation and analysis of strongly polar metabolites, such as organic acids, sugar phosphates, and nucleotides in biological matrices are discussed in relation to metabolomics. Advances in the analysis of strongly polar or ionizable toxic compounds, such as alkyl methylphosphonic acid, methylphosphonic acid, glyphosate, 3-nitropropionic acid, and indandione rodenticides, are mainly discussed in clinical poisoning analysis field. This paper is expected to become a useful reference for the further expansion and application of IC-MS in the life and health fields.

Degradation kinetics, influencing factors, and mechanisms of polycyclic aromatic hydrocarbons in a Fe3O4-nZVI Fenton-like system

To improve the catalytic performance of nano zero-valent iron (nZVI) in a Fenton-like system, Fe3O4 supported nZVI (Fe3O4-nZVI) was produced by the liquid-phase reduction method and co-precipitation method, then characterized by SEM, EDS, XRD, XPS, and VSM. Fe3O4-nZVI was used as the catalyst in a Fenton-like system to degrade polycyclic aromatic hydrocarbons (PAHs) such as naphthalene (Nap), phenanthrene (Phe), and pyrene (Pyr) in simulated wastewater. The results showed that under the optimization conditions, which were 25℃, 0.6g/L of Fe3O4-nZVI dosage, 3 of the pH in the reaction system, and 10-15mmol/L of the concentration of H2O2, the sequence of degradation efficiency in this system was Phe (99.76%)>Pyr (99.71%)>Nap (98.01%). The reused experiments on Fe3O4-nZVI showed that the degradation efficiency for PAHs remained above 87% after 4 reuses of Fe3O4-nZVI. These results indicated that nanoscale magnetic composites of Fe3O4-nZVI had excellent reactivity, stability, and reuse performance. The fitting parameters of kinetics showed that the degradation of PAHs in the Fenton-like system with the Fe3O4-nZVI catalyst fitted well with the Behnajady-Modirshahla-Ghanbery kinetic model. The radial quenching experiment proved that ·OH was the dominant free radical for the degradation of PAHs in the Fe3O4-nZVI Fenton-like system. Based on the degradation products of PAHs and the related literature, the possible degradation paths of the three PAHs in the Fe3O4-nZVI Fenton-like system were inferred. The above results could provide a reference and basis for the treatment of wastewater containing PAHs by Fe3O4-nZVI Fenton-like technology.

Bi2MoO6/MgIn2S4 S-scheme heterojunction with rich oxygen vacancies for effective organic pollutants degradation: Degradation pathways, biological toxicity assessment, and mechanism research

Designing and constructing novel photocatalysts for organic pollutant degradation is of critical significance for water environment treatment. Constructing a Bi2MoO6/MgIn2S4 (BMO/MIS) S-scheme heterojunction with oxygen vacancies, which efficiently removed RhB within visible light irradiation. Oxygen vacancies regulated the band structure of Bi2MoO6 (BMO) and enhanced the adsorption of RhB on the catalyst's surface. The S-scheme heterojunctions contributed to the separation and transfer of photo-generated charge, retained the optimal redox ability of Bi2MoO6-Vo (BMO-Vo) and MgIn2S4 (MIS) at the same time. X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) further confirmed the S-scheme charge transfer mechanism and the presence of oxygen vacancies. Within 30 min of visible light irradiation, RhB was completely degraded by BMO/MIS-8%, while the degradation efficiency of RhB by BMO-Vo and MIS were only 39.93 % and 80.87 %, respectively. The kinetics constant is 0.1035 min−1 of BMO/MIS-8%, which was 20.29 and 1.95 times that of BMO-Vo and MIS, respectively. At the same time, BMO/MIS-8% achieved removal efficiency of 24.28 %, 56.53 %, 59.15 % and 100 % for MO, TC,H-TC and MB, respectively. Compared to the previously synthesized Bi-ZFO/BMO-Vo photocatalyst, BMO/MIS-8% demonstrated superior degradation efficiency, exhibiting a degradation kinetic constant that was 2.12 times greater than that of Bi-ZFO/BMO-Vo under visible light irradiation. To improve the practical application of BMO/MIS, the effects of pH, co-existing ions and types of pollutants on degradation efficiency were evaluated. In addition, the biological toxicity assessment showed a significant decrease in the toxicity of RhB degradation products. This work provides a feasible avenue for constructing Bi2MoO6-based heterojunctions to treat dye wastewater.

Polycystic Ovary Syndrome Accompanied by Hyperandrogenemia or Metabolic Syndrome Triggers Glomerular Podocyte Injury.

Objective: To determine whether the urinary excretion of podocyte degradation products varies according to PCOS phenotype and metabolic syndrome (MetS). Methods: The concentrations of podocalyxin (PDX) and nephrin, chronic markers of podocyte damage, and neutrophil gelatinase-associated lipocalin (NGAL), a marker of acute glomerular damage, were analyzed in the morning urine samples of 50 PCOS patients and 50 healthy controls matched by age and BMI. Albuminuria was assessed by calculating the urine albumin-creatinine ratio (uACR). Results: The PDX, nephrin and NGAL concentrations of PCOS participants were significantly higher than those of the control group. While PDX, nephrin and NGAL levels of classic phenotypes were similar, they were higher than ovulatory and non-hyperandrogenic phenotypes. Significant increases in urinary levels of each podocyte protein were detected in PCOS patients with MetS compared to patients without MetS. A positive significant correlation between podocyte proteins and BMI, systolic blood pressure, testosterone, glucose, HOMA-IR and uACR. After adjusting for age and BMI, podocyte proteins were an independent risk factor for microalbuminuria. The incidence of microalbuminuria in PCOS increased 6-fold compared to controls. The frequency of microalbuminuria was higher in classical phenotypes than in ovulatory phenotype. The frequency of microalbuminuria in PCOS patients with MetS was 6.5 times higher than in PCOS patients without MetS. Conclusions: In PCOS accompanied by hyperandrogenemia or metabolic syndrome, leakage of acute and chronic podocyte breakdown products into the urine becomes more pronounced.

Strong enhancement on diclofenac degradation in Cu(II)/H2O2 system by adding ascorbic acid: Efficiency, mechanism and influencing factors

Utilization of trace Cu(II) (at μM level) inherently existing in wastewater to activate hydrogen peroxide (H2O2) has exhibited significant potential to remove aqueous organic contaminants. Nevertheless, the Cu(II)/H2O2 system was only efficient under alkaline conditions. Herein, ascorbic acid (H2A), an environmentally benign and natural reductant, was introduced to broaden pH range of Cu(Ⅱ)/H2O2 process by expediting the Cu(II)/Cu(I) cycle. The H2A/Cu(Ⅱ)/H2O2 system performed well in degrading diclofenac across a wide pH range from 4.0 to 9.0, and its kinetic rate constant of diclofenac elimination was 247 times greater than its counterpart without H2A at the optimal pH of 6.0, outperforming the performance of most previously reported reductant-enhanced Cu(Ⅱ)/H2O2 system. Electron paramagnetic resonance analysis, periodate colorimetric method, and in situ Raman spectroscopy tests indicated that hydroxyl radical (HO), rather than Cu(III), was the dominant reactive species of diclofenac degradation. Thirteen degradation products of diclofenac were identified by LC-Q-TOF-MS, and five different elimination pathways were proposed. Furthermore, the presence of SO42− exerted an insignificant influence on diclofenac degradation, while the addition of Cl−, HCO3− and humic acid slightly suppressed the abatement of diclofenac. H2A/Cu(Ⅱ)/H2O2 system was still highly efficient in degrading diclofenac in actual water matrix (i.e., reservoir water and lake water). Overall, this study provided an eco-friendly approach to enhance the oxidation capacity of the Cu(II)/H2O2 system over a wide pH range, which might be a potential technology for degrading refractory organic pollutants in water treatment.

Ecologically friendly remediation of groundwater sulfamethoxazole contamination: Biologically synergistic degradation by thermally modified activated carbon-activated peracetic acid in porous media

This study examines the efficacy and environmental impact of peracetic acid (PAA) activated by thermally modified activated carbon (AC600) for degrading antibiotics in actual groundwater. Laboratory-scale experiments evaluated the system's effects on contaminant degradation, ecological balance, and substance cycling in the hyporheic zone. Our findings demonstrated the effectiveness of the AC600/PAA system in removing sulfamethoxazole (SMX) from groundwater porous media. Additionally, the AC600/PAA system synergistically interacted with the in-situ microbiota of the hyporheic zone, producing more fragmented degradation products without increasing mixed toxicity. Bacterial abundance increased post-reaction, with notable alterations in the bacterial community and enhanced bacterial metabolism. Key genera such as Lysobacter thrived in the treated environment, playing critical roles in microbiota modification and SMX degradation. The pH remained stable before and after the reaction, while dissolved organic carbon content increased. Overall, our results highlight the promising potential of PAA activation by carbonaceous materials as a low-impact, ecologically friendly technology for in-situ remediation of organic pollutants in groundwater, characterized by high compatibility and biosynthesis.

Liquid chromatography-tandem mass spectrometry analysis of nitrogen mustard degradation products after derivatization with benzoylimidazole

Nitrogen mustards are highly toxic compounds and strictly controlled by the Chemical Weapons Convention. When those agents are used, exposure must be confirmed by analyzing biological samples from victims to allow prompt medication and reduction of secondary damage. In this study, a derivatization-liquid chromatography (LC)-tandem mass spectrometry (MS/MS) method to analyze nitrogen mustard degradation products (ethanolamines; EAs) in human urine was developed. Benzoylimidazole (BzI) was used as a derivatization reagent, and two highly hydrophilic EAs (methyldiethanolamine and ethyldiethanolamine) were analyzed by using a reversed-phase column with sufficient retention. For urine samples, after solid-phase extraction with cation exchange cartridge and derivatization, EAs were analyzed at low limits of detection (5 ng/mL). The calibration curves had a wide linear range (50–1000 ng/mL), and the quantitation results were sufficient for screening. Compared with our previous derivatization-LC-MS/MS method using pentafluorobenzoyl chloride as a derivatization reagent and hydrophilic interaction liquid chromatography (HILIC)-MS/MS method, not only the limits of detection but also the operability and throughput were improved. The performance of the newly developed derivatization reagent was also evaluated using density functional theory (DFT) calculations.

Green-synthesized BiFeO3 nanoparticles for efficient photocatalytic degradation of organic dyes, antibiotic and catalytic reduction of 4-nitrophenol

Green-synthesized nanoparticles have recently emerged as promising catalysts for the removal of toxic dyes from water bodies. In this article, Bismuth ferrite (BiFeO3) nanoparticles were synthesized by a simple and low-cost method using Couroupita guianensis plant leaf extract. The particles were used as photocatalysts for degrading RhB, MO dyes, and TC antibiotics, as well as for reducing toxic 4-NP to useful 4-AP. The synthesized nanoparticles were characterized using several state-of-the-art tools. The formation of perovskite structure and the presence of biomolecules on the surface of BiFeO3 nanoparticles was confirmed by FTIR analysis. Raman spectrum revealed a rhombohedral structure of BiFeO3 nanoparticles, corroborating the XRD analysis. FESEM micrograph demonstrated irregularly shaped agglomerated nanoparticles. The average hydrodynamic diameter was estimated to be 51 nm using the DLS technique. The optical energy bandgap of the bismuth ferrite was estimated using Tauc’s relation for direct bandgap semiconductors. SQUID measurements revealed that these nanoparticles exhibit a weak ferromagnetic ordering. Furthermore, these nanomaterials degraded the cationic and anionic dyes effectively because of the formation of hydroxyl radicals, confirmed by the scavenger test. The photocatalytic degradation pathway of RhB dye was investigated through LC-MS analysis, and the intermediate degradation products were identified. The prepared material also exhibited excellent catalytic efficiency in a short duration of time. This study proclaims that these nanoparticles can be used as potential catalysts for the purification of water.

Experimental and theoretical insights into the influence of gamma irradiation degradation products of N,N,N′,N′-tetraoctyl diglycolamide on extraction efficiency toward trivalent f-elements

Understanding the effect of radiation rays on N,N,N′,N′-tetraoctyl diglycolamide (TODGA) based solvent extraction systems is an essential task for establishing and optimizing related extraction processes in nuclear industries. However, the influence of various radiolysis degradation products on extraction efficiency and the mechanism involved still remain elusive. In this work, the radiolysis degradation products of TODGA were analyzed with the aid of high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) technique and documented results, followed by the successful synthesis of ten radiolysis degradation products P1–P10. The extraction ability of each main degradation product towards Eu(III) and their effects on the extraction performance of TODGA system were systematically studied. These radiolysis degradation products with diverse chemical structures were found to reveal different roles in extraction such as serving as co-extractant and synergist, in which P2 resemblance in structure to TODGA offers the highest extraction ability among others, thus mitigating the decrease of extraction efficiency. Mechanism investigations including slope analysis and density functional theory (DFT) calculations reveal that P2 is involved as one of the extracted species in the complexation with Eu(III) in its first coordination sphere. These findings provide in-depth experimental and theoretical guidance on the molecular scale for designing TODGA-based metal separation processes.

Green stability-indicating RP-HPTLC technique for determining croconazole hydrochloride

Abstract The objective of the proposed investigation is the development and validation of a green stability-indicating reverse-phase high-performance thin-layer chromatographic method to determine croconazole hydrochloride (CCZ). The developing system used was an 80:20 v/v mixture of acetone and water. The measurement of CCZ was done at 198 nm. With the use of the Analytical Eco-Scale (AES), ChlorTox, and Analytical GREEnness (AGREE) tools, greenness was evaluated. The linearity was demonstrated by the present method in the 25–1,200 ng/band range. The present approach was additionally reliable, accurate, sensitive, precise, and green. An exceptional greenness profile was demonstrated by the AES, total ChlorTox, and AGREE scales, which were determined to be 89, 1.08 g, and 0.82, respectively. The greenness metrics of the present method were much better than the reported high-performance liquid chromatography approach. Under acid and oxidative degradation circumstances, CCZ was shown to be unstable, while under alkaline and thermal-stress settings, it was sufficiently stable. Furthermore, the stability-indicating component determined by analytical method identified CCZ in the presence of its degradation products. Commercial CCZ cream was found to contain 0.98% w/w of CCZ. The investigation’s results suggested that CCZ in commercially available creams might be regularly examined with the help of the recommended green technology.

Accurate Visualization of C4d Complement Fragment in Immunohistochemistry by C-Terminal Linear Neoepitope-Specific Antibodies

C4d is the end degradation product of activated complement component C4b that appears during the early steps of the classical and lectin complement pathways. Within the primary sequence of C4d, there is a reactive thioester group that binds covalently to nearby surfaces, thus labeling the locations of complement activation. This feature makes C4d a target for immunohistochemical staining aimed to aid the diagnosis of, among others, the antibody-mediated rejection of transplanted organs, membranous glomerulonephritis, bullous pemphigoid, or inflammatory myopathies. However, the credibility of C4d immunostaining is debatable, as a high background in surrounding tissues and body fluids and diffused patterns of deposits in target structures are experienced with some of the available anti-C4d antibodies. Herein, we present an improved version of a rabbit anti-C4d antibody, originally raised against the C-terminal linear neoepitope of this complement fragment. Minor cross-reactivity with C4b and native C4 proteins, measured by ELISAs, as well as relatively low concentrations necessary for obtaining a specific signal in immunohistochemical analyses of formalin-fixed paraffin-embedded material, makes the improved antibody superior to commercially available rabbit monoclonal anti-C4d antibody SP91 dedicated to ex vivo diagnostics, as demonstrated by the staining of a panel of kidney transplant biopsies.

Evolution of the biochemistry underpinning purine alkaloid metabolism in plants.

Purine alkaloids are naturally occurring nitrogenous methylated derivatives of purine nucleotide degradation products, having essential roles in medicine, food and various other aspects of our daily lives. They are generated through convergent evolution in different plant species. The pivotal reaction steps within the purine alkaloid metabolic pathways have been largely elucidated, and the convergent evolution of purine alkaloids has been substantiated through bioinformatic, biochemical and other research perspectives within S-adenosyl-ʟ-methionine-dependent N-methyltransferases. Currently, the biological and ecological roles of purine alkaloids, further refinement of the purine alkaloid metabolic pathways and the investigation of purine alkaloid adaptive evolutionary mechanisms continue to attract widespread research interest. The exploration of the purine alkaloid metabolic pathways also enhances our comprehension of the biochemical mechanism, providing insights into inter-species interactions and adaptive evolution and offering potential value in drug development and agricultural applications. Here, we review the progress of research in the distribution, metabolic pathway elucidation and regulation, evolutionary mechanism and ecological roles of purine alkaloids in plants. The opportunities and challenges involved in elucidating the biochemical basis and evolutionary mechanisms of the purine alkaloid metabolic pathways, as well as other research aspects, are also discussed. This article is part of the theme issue 'The evolution of plant meta-bolism'.

Oxidative stress-induced degradation of Brinzolamide: Isolation and in-depth characterization of unique hydroxylamine and oxime degradation products

Since the safety and efficacy of therapeutic products are strongly related to their stability and purity, impurities including the unavoidable degradation products may affect the pharmacological effect. The International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) guidelines Q3A requires the identification of process impurities and as well as degradation products in any drug substance to assess the inherent stability of the drug. The present work involves an ICH-guided degradation study for the Brinzolamide (BRZ), a topical ophthalmic drug which is generally used to lower the intraocular pressure (IOP) during glaucoma. Under oxidative stress at room temperature for 20 h, four degradation products (namely BRZ-Pk1, BRZ-PK2, BRZ-Pk3, and BRZ-Pk4) are isolated using advanced chromatographic techniques. Upon confirming the masses of the compounds using High-resolution mass spectrometry (HRMS), functional groups are identified with the help of Fourier-transform infrared spectroscopy (FT-IR). Extensive 1-dimensional (1D) and 2-dimensional (2D) Nuclear Magnetic Resonance spectroscopic (NMR) experiments especially 1D nOe, 1H-13C-HSQC and 1H-13C-HMBC unequivocally confirm the structures. Among the four compounds analyzed, three (BRZ-Pk1, BRZ-Pk2, and BRZ-Pk4) are novel, while BRZ-Pk3 was previously reported solely with mass spectrometric data. Nitrogen-based 2D NMR experiments are crucial for determining the oxidation state of hydroxylamine and oxime products within the molecules, and 1D nOe measurements help confirming E/Z isomerism (geometrical isomerism) for BRZ-Pk2 and BRZ-Pk4. All the proposed structures are justified with appropriate analytical data. The proposed mechanisms are expected to help in identifying the possible degradation pathways for similar pharmaceutical candidates.

Ethoxy Acetalated Dextran-Based Biomaterials for Therapeutic Applications.

A novel class of pH-responsive polymers, acetalated dextran, has emerged in the field of biomaterials. These versatile materials are derived from dextran through a simple acetalation reaction, allowing for the creation of polymers with a tunable release profile which allows the controlled release of encapsulated therapeutics in response to acidic environments. Despite their recent introduction, acetalated dextran has rapidly garnered significant interest due to its potential for various therapeutic applications. This review delves specifically into the recent advancements of ethoxy acetalated dextran or Ace-DEX, a particular acetalated dextran with a distinct advantage: its degradation products (acetone and ethanol) are less toxic compared to other variants that produce methanol. The focus of this review is the diverse range of biomedical applications currently being explored for Ace-DEX-based scaffolds. Finally, this review concludes by addressing the existing challenges associated with Ace-DEX and outlining potential future research directions within this promising field.

Insight into HTPB pyrolysis mechanism under high-temperature: A reactive molecular dynamics study

Hydroxyl-terminated polybutadiene (HTPB) is widely utilized in solid and hybrid rocket propellants due to its mechanical properties and combustion performance. Insight into its pyrolysis process is key to enhancing combustion efficiency in rocket engines. This study employs ReaxFF molecular dynamics (MD) simulations to explore the pyrolysis mechanism of HTPB under extreme conditions, with temperatures ranging from 1000 K to 2000 K. The results identify the primary degradation products and elucidate their formation mechanisms. The simulation reveals that C-C bond cleavage at polymerization sites is the initial step, followed by the formation of linear oligomers and butadiene. Subsequent reactions, including hydrogenation and dehydrogenation, lead to the generation of smaller molecular species. The kinetic analysis confirms that HTPB pyrolysis follows first-order reaction kinetics, with an activation energy of 8.12 kcal/mol. The findings are compared with existing experimental data, highlighting the influence of thermal environments on pyrolysis mechanisms and product distributions.

Elucidation of a specific alginate lyase Aly7Rm: The products demonstrated the strict recognition of G residue at subsites ±2

An alginate lyase Aly7Rm with novel subsite specificity was cloned, expressed and characterized in this article. Aly7Rm was a G-specific alginate lyase, exhibiting optimum reaction conditions at 30 °C and pH 5.0. UPSEC-VWD-MS analysis revealed that Aly7Rm degraded polysaccharides in a random endo-acting manner. The main degradation products of alginate were trisaccharide to octasaccharide and those of PG were disaccharide to hexasaccharide. The product distribution was related to the specificity of enzyme and the structure of substrates. By utilizing the HPAEC-PAD/MS method, the structure of products was identified and the specificities of subsite were defined. Aly7Rm accommodated both G and M at subsites −1 and strictly recognized G at subsite −2 and +2. This is the first report on the alginate lyase exhibiting G specificity at subsites ±2, which shed light on the diversity in subsite specificity of alginate lyases. The Aly7Rm with clear action pattern could serve as an efficient tool in the specific degradation of alginate and targeted preparation of oligosaccharides.