A field-applicable colorimetric assay for notorious explosive triacetone triperoxide through nanozyme-catalyzed irreversible oxidation of 3, 3'-diaminobenzidine

A field-applicable colorimetric assay for fast detection of notorious explosive triacetone triperoxide (TATP) has been developed through the selective irreversible oxidation of 3, 3'-diaminobenzidine by hydrogen peroxide (HP) liberated during the acidic hydrolysis/degradation of TATP in the presence of MnO₂ nanozymes. The generated HP was detected by probing the absorbance of the product (indamine polymer) of the 3, 3'-diaminobenzidine (DAB) oxidation reaction at 460.0 nm. The UV-Vis measurements provided a linear range from 1.57 to 10.50 mg L^-1 TATP with a detection limit of 0.34 mg L^-1. The oxidation of DAB cannot proceed by molecular oxygen, thus it is selectively oxidized by H₂O₂; this prevents false-positive results from laundry detergents (containing O₂-releasing substances). Moreover, a naked-eye field test was developed, and a fast spot test analyzing time of 5 s was achieved. The selectivity of the assay was checked by analyzing some synthetic samples prepared with a laundry detergent as camouflage. The results of the developed assay revealed quantitative recoveries for TATP whereas the standard nanozyme-based method showed significant false-positive results. Graphical abstract.

Obesity accelerates ovarian follicle development and follicle loss in rats

OBJECTIVE

Studies have shown that excess body fat negatively affects reproductive functions in females. However, whether obesity affects the ovarian follicle development and ovarian lifespan and the underlying mechanism has not been well elucidated. The aim of the present study was to investigate the association between obesity and ovarian follicle development.

METHODS

Adult female Sprague-Dawley rats (n = 36) were randomly divided into three groups: the normal control (NC) group, the caloric restriction (CR) group (fed 70% food of the NC group) and the high-fat diet (HF) group. They were maintained on these regimens for 18 weeks.

RESULTS

The body weight, ovary weight and visceral fat in the HF group were significantly higher than those in the NC group and the CR group at the end of treatment. Histological analysis showed that the HF rats had significantly less number and percentage of primordial follicles, but greater number and percentage of developing and atretic follicles than the NC rats and CR rats. Western blot analysis demonstrated that the level of mTORC1 and p-S6K1 proteins significantly increased in the ovaries of HF rats, whereas that of SIRT1, SIRT6, FOXO3a and NRF-1 decreased compared to the NC rats. In contrast, the expression of mTORC1 and p-S6K1 dramatically declined, while that of SIRT1, SIRT6, FOXO3a and NRF1 increased in the ovaries of CR rats.

CONCLUSIONS

Our study suggests that the HF diet induced obesity may accelerate the ovarian follicle development and rate of follicle loss through activating mTOR and suppressing SIRT1 signaling, thus leading to POF, and that CR may inhibit the activation of primordial follicles, follicular development and loss, thus extending the ovarian lifespan through suppressing mTOR and activating SIRT1 signaling.

Maturation inside and outside bone marrow dendritic cells (BMDCs) modulated by interferon-α (IFN-α)

Interferons are made by cells in response to appropriate stimuli such as viruses, bacteria, parasites or tumor cells and are released into the surrounding medium. They then bind to receptors on target cells to allow for communication between cells to trigger the protective defenses of the immune system that eradicate pathogens or tumors. IFN-α is produced by leukocytes and is mainly involved in innate immune response against viral or bacterial infections and for tumor control. The aim of this work is to explore the detailed modulation of IFN-α on phenotypic and functional maturation inside and outside murine bone marrow derived dendritic cells (BMDCs). The maturity of BMDCs post treatment with IFN-α was evaluated with conventional light microscope and transmission electron microscopy (TEM) for morphology changes; flow cytometry (FCM) for changes of surface molecules on BMDCs; cytochemistry, acid phosphatase activity (ACP) test, and FITC-dextran bio-assay for biochemistry analysis and enzyme-linked immunosorbent assay (ELISA) for cytokine production by BMDCs. We have shown that IFN-α 1) up-regulates the expression of MHC II, CD40, CD83, CD80 and CD86 molecules on BMDCs; 2) down-regulates the rates of pinocytosis and phagocytosis by BMDCs as evidenced by the results of decreased ACP, and FITC-dextran bio-assay; 3) enhances the ability of BMDCs to drive T cell function; and 4) induces higher levels of IL-12 and TNF-α secreted by BMDCs. Therefore, we conclude that IFN-α can efficiently promote the maturation of BMDCs through detailed modulation inside and outside BMDCs. Our study has provided more detailed data on changes of BMDCs modulated by IFN-α, and rationale on future application of IFN-α for enhancing host immunity and potent adjuvant administration in the design of DC-based vaccines.

Detailed modulation of phenotypes and functions of bone marrow dendritic cells (BMDCs) by interferon-gamma (IFN-γ)

IFN-γ is a cytokine that plays crucial role in innate and adaptive immunity against viral and intracellular bacterial infections and for tumor control. IFN-γ is also a key activator of macrophages [1,2]. In the present study, we studied detailed modulation of IFN-γ on phenotypic and functional maturation of murine bone marrow derived dendritic cells (BMDCs). Phenotypic and functional maturation of BMDCs was evaluated by light microscope, flow cytometry(FCM), transmission electron microscopy (TEM), cytochemistry method, acid phosphatase activity(ACP), FITC-dextran bio-assay and enzyme linked immunosorbent assay (ELISA). We elucidated that IFN-γ up-regulated the expression of MHC II, CD40, CD80, CD83 and CD86 molecules on BMDCs, down-regulated the activity of pinocytosis and phagocytosis by BMDCs, and induced higher levels of IL-12 and TNF-α secreted by BMDCs. It is therefore confirmed that IFN-γ can effectively promote the maturation of BMDCs. Our study provides more evidence and rationale on future application of IFN-γ for enhancing host immunity.