Improved antioxidant activity of pretreated lignin nanoparticles: Evaluation and self-assembly.

Lignin nanoparticles (LNPs) have gained significant attention for their potential as natural antioxidants. This study investigated the effect of various pretreatment methods on the lignin structure and subsequent antioxidant activity of LNPs. Among four pretreated LNPs, hydrothermal LNPs exhibited the highest antioxidant activity, surpassing unpretreated, acid-pretreated and kraft LNPs, with an impressive efficacy of 91.6%. The relationship between LNPs' structure and antioxidant activity was revealed by 2D heteronuclear singular quantum correlation (1H13C HSQC) and 31P nuclear magnetic resonance (NMR). 1H13C HSQC suggested the cleavage of ß-O-4 ether bonds, as well as a decrease in ferulic acid and p-coumaric acid, which directly influenced the antioxidant activity of LNPs. 31P NMR demonstrated a positive correlation between the total hydroxyl group content and the antioxidant activity. Besides, an isothermal kinetic model for scavenging free radicals was established based on Langmuir kinetic model instead of Freundlich model. Moreover, multilayer LNPs, based on layer-by-layer self-assembly, were prepared and exhibited remarkable antioxidant activity of 95.8%. More importantly, when blended with pure cosmetic cream, the multilayer LNPs maintained antioxidant activity of 86.7%. These finding may promote the practical applications of biomolecules, e.g. lignin additives in cosmetics and pharmaceuticals.

Aluminum ion intercalation in mesoporous multilayer carbocatalysts promotes the conversion of glucose to 5-hydroxymethylfurfural.

In this study, an efficient modification strategy was proposed by facile loading of trace aluminum ions and p-toluene sulfonic acid (p-TSA) in carbon materials to improve their catalytic activity. p-TSA is then proven to regulate the carbonization process and promote the formation of mesoporous and multilayer structures. The hexa-coordinated aluminum structure is characterized by 1H-27Al solid-state nuclear magnetic resonance (SSNMR) and X-ray photoelectron spectroscopy, which serves as the Lewis-Brønsted acid site in carbocatalysts. Accordingly, the resulting catalyst facilitates a yield of ∼70% for converting glucose to 5-hydroxymethylfurfural (HMF) with a maximum carbon balance of around 91.4% at 150 °C in 6 h. In situ NMR, electrospray ionization mass spectrometry and isotope labeling analysis reveal that the hexa-coordinated aluminum sites promote the isomerization of glucose, and the sulfonic groups facilitate the subsequent dehydration and rehydration of fructose and levoglucosan intermediates. Kinetic models further indicate the decreased energy barrier for glucose conversion over the Al3+/p-TSA intercalated carbocatalyst. This work provides a promising strategy for engineering waste-derived carbocatalysts toward effectively converting carbohydrates to precursors of biofuels and bioplastics.

Silica gel impregnated with deep eutectic solvent-based matrix solid-phase dispersion followed by high-performance liquid chromatography for extraction and detection of triazine herbicides in brown sugar.

A novel method was developed to determine six triazine herbicides from brown sugar samples using matrix solid-phase dispersion (MSPD) based on silica gel impregnated with deep eutectic solvent (DES) followed by high-performance liquid chromatography with photodiode array detector (HPLC/PDA). Several factors involved in the MSPD procedure such as DES type, DES content in impregnated silica gel, adsorbent-to-sample mass ratio, type and volume of washing solvent, type and volume of eluent, and grinding time were screened using single-factor experiments and then optimized using Box-Behnken design to accomplish the highest recoveries. The above method demonstrated a good linear range (20-1000 µg kg-1) with a determination coefficient exceeding 0.9962, low limits of determination (1.59-3.77 µg kg-1), acceptable limits of quantifications, and acceptable spiking recoveries (95.0-101.7%) for six triazines under optimized conditions. The proposed MSPD-HPLC/PDA method is a convenient, effective, and sensitive method for rapidly isolating and quantifying six triazines from brown sugar.

Novel recognition mechanism based on oxidative addition of Pt(II) complex-based luminescent probes for hypochlorite ion detection.

Platinum(II) complexes are the most commonly used anticancer drugs and potential optical materials, but the detectability of Pt(II) complex-based probes is seldom reported. In our previous work, a tetradentate Pt(II) complex Pt-CHO was utilised as a 'turn-off' probe to detect ClO- and image cancer cells. However, the recognition mechanism has not been completely clarified and there are still doubts. In this work, three Pt(II) complexes, Pt-H, Pt-CHO and Pt-COOH, were developed to elucidate the mechanism of this class of complexes and refine their property studies. As a result, the UV-visible absorption and luminescence emission experiments, as well as the mass spectrum, proved that the oxidation of Pt(II) to Pt(IV) was the real reason for luminescence quenching, which has nothing to do with aldehyde groups. This first reported mechanism introduces a new type of ClO- probe based on Pt(II) complexes, thereby expanding the application fields of platinum complexes. Moreover, the quantum yield measurements, the effect of biomolecules and reversibility were studied to improve the properties of the probes. Theoretical calculations were used to gain an in-depth understanding of optical characteristics and related mechanisms. The cell imaging of RAW264.7 cells under endogenous ClO- proved the potential of the probes in bioimaging.

Isomaltulose Exhibits Prebiotic Activity, and Modulates Gut Microbiota, the Production of Short Chain Fatty Acids, and Secondary Bile Acids in Rats.

In vitro experiments have indicated prebiotic activity of isomaltulose, which stimulates the growth of probiotics and the production of short chain fatty acids (SCFAs). However, the absence of in vivo trials undermines these results. This study aims to investigate the effect of isomaltulose on composition and functionality of gut microbiota in rats. Twelve Sprague-Dawley rats were divided into two groups: the IsoMTL group was given free access to water containing 10% isomaltulose (w/w), and the control group was treated with normal water for five weeks. Moreover, 16S rRNA sequencing showed that ingestion of isomaltulose increased the abundances of beneficial microbiota, such as Faecalibacterium and Phascolarctobacterium, and decreased levels of pathogens, including Shuttleworthia. Bacterial functional prediction showed that isomaltulose affected gut microbial functionalities, including secondary bile acid biosynthesis. Targeted metabolomics demonstrated that isomaltulose supplementation enhanced cholic acid concentration, and reduced levels of lithocholic acid, deoxycholic acid, dehydrocholic acid, and hyodeoxycholic acid. Moreover, the concentrations of propionate and butyrate were elevated in the rats administered with isomaltulose. This work suggests that isomaltulose modulates gut microbiota and the production of SCFAs and secondary bile acids in rats, which provides a scientific basis on the use of isomaltulose as a prebiotic.

Development of magnetic porous carbon nano-fibers for application as adsorbents in the enrichment of trace Sudan dyes in foodstuffs.

A novel kind of magnetic porous carbon nano-fibers (Fe3O4@P-CNFs) materials was successfully prepared and used as an adsorbent. Based on the above-mentioned adsorbent, a simple and effective magnetic disperse solid-phase extraction (MSPE) method was developed and first utilized to the enrichment and purification of five Sudan dyes (including Sudan I, Sudan II, Sudan III, Sudan IV, and Sudan Red 7B) in foodstuffs for the first time. High-performance liquid chromatography was used to determine the content of the Sudan dyes. The parameters affecting the extraction performance were studied and optimized, including the amount of the adsorbent and inorganic salt, type and the volume of the eluent, pH of the sample solution and extraction time. Under the optimized experimental conditions, the results show that the proposed method has a good linear relationship (r≥ 0.9993). The limits of detection range from 0.88 µg L-1 to 1.27 µg L-1. The recoveries range from 86.6% to 99.7% with the relative standard deviations ranging from 0.6% to 7.9% in the methodology validation. The above-mentioned results indicate that the proposed method is a sensitive and reliable procedure with good reproducibility for the detection of Sudan dyes residues in foodstuffs.

The effect of spray drying on sucrose-glycine caramel powder preparation.

BACKGROUND: Caramel is used as food colorant in many parts of the world. However, there have been no studies investigating the effects of spray drying on sucrose and glycine solutions. In this study, model sucrose and glycine solutions at different pH levels (pH 4, 3, 2 and 1) were treated with different inlet air temperatures (160, 180, 200, 220 and 240 °C) for durations of 50 s in the spray drying process. RESULTS: With increasing inlet temperatures and decreasing pH, the morphology of the caramel agglomerates tended to be more scattered; however, the solubility of the caramel decreased. With increasing inlet temperature, the glycine and sucrose contents decreased but the fructose and glucose contents increased. CONCLUSION: The content of the intermediate products, browning intensity and amount of 5-hydroxymethyl-2-furaldehyde (HMF) increased with increasing inlet temperature and decreasing pH. Therefore, the amount of sucrose degradation and the change in pH can be used to evaluate caramel properties in the spray drying process. © 2015 Society of Chemical Industry.

[Analysis of 16 cases of uterine perforation during hysteroscopic electro-surgeries].

OBJECTIVE: To analyse the cause, diagnosis, treatment and preventive methods of uterine perforation resulting from hysteroscopic electro-surgeries. METHODS: Data of cases with uterine perforation were collected from 5 hospitals where overall 3,541 hysteroscopic electro-surgeries were done from May 1990 to July 2002. There were 1 468 transcervical resections of endometrium (TCRE), 797 cases of transcervical resection of myoma (TCRM), 783 cases of transcervical resection of endometrial polyp (TCRP), 189 cases of transcervical resection of uterine septa (TCRS), 112 cases of transcervical resection of uterine adhesion (TCRA) and 192 cases of transcervical removal of foreign body (TCRF). All operations were performed under B-ultrasonographic or laparoscopic monitoring. Cervical dilator stick was inserted into cervical canal or 200 micro g of misoprostol put in the posterior fornix the evening before operation. The procedures were done according to different indications and purposes. Cases of uterine perforation were divided into two groups: caused by approaching (entry-related) and by surgical instruments (technique-related). RESULTS: Totally sixteen cases (0.45%) of uterine perforation occurred. Seven cases occurred during cervical dilatation and 1 during hysteroscopy inserting lentry-related. Eight cases were technique-related caused by electrode. The incidences of uterine perforation of different operations were: TCRA 4.46% (5/112), TCRF 3.12% (6/192), TCRE 0.27% (4/1 468), TCRM 0.13% (1/797). TCRP and TCRS none. These 16 cases were all diagnosed during operations. 10 cases (62%) by B ultrasound and (or) laparoscopy, 6 cases (38%) by hysteroscopy and clinical features. 13 cases were complete uterine perforations, among them 2 were diagnosed by laparoscopic monitoring, 5 by B-ultrasonic monitoring, 4 by hysteroscopy and 2 by symptoms and B-ultrasound, 3 cases were incomplete uterine perforations in which 2 were diagnosed by laparoscopic monitoring and one by B-ultrasound monitoring. CONCLUSIONS: Half of uterine perforation cases were entry-related, so attention has to be paid to entry of Hegar or hysteroscopy (i.e., not dilate the cervix as possible and introduce the scope under direct vision). The other half were related to surgeons' experience and type of operation. TCRA and TCRF run more risks. B-ultrasound and (or) laparoscopy monitoring during hysteroscopic electro-surgery may help to prevent but not completely avoid uterine perforation.