Loading Cu-doped magnesium oxide onto surface of magnetic nanoparticles to prepare magnetic disinfectant with enhanced antibacterial activity.

In this article, Cu-doped magnesium oxide was loaded onto the surface of Fe3O4 magnetic nanoparticles via a hydrophilic carbon intermediate layer to synthesize Fe3O4@C@MgO-Cu magnetic composite. The potential application as disinfectant in water purification was investigated by examining the antibacterial activity of the Fe3O4@C@MgO-Cu composite toward Gram negative Escherichia coli and Gram positive Staphylococcus aureus. The practical bactericidal efficiency in inactivation experiment was also studied and the copper doping amount was optimized. The results show that the as-obtained magnetic composite, with good dispersion and typical multilayer structure, exhibited high antibacterial activity to both strains and the Cu-doping improved the antibacterial performance significantly. Moreover, an increasing bactericidal ability of the nanocomposite was observed with the increasing Cu-doping amount and 312.5mgL-1 of Fe3O4@C@MgO-Cu disinfectant with a 1.5% Cu-doping amount (wt% of MgO) could inactivate 99% of the tested bacteria in normal saline solution within 60minutes. The Fe3O4@C@MgO-Cu composite, with a high magnetic saturation value of 29.07emug-1, can be readily recovered from matrix solution for reuse with an external magnet, which simplified the disinfection operation greatly and avoided the waste of disinfectant.

Role of LM23 in cell proliferation and apoptosis and its expression during the testis development.

LM23, a gene expressed specifically in the testis in a stage-specific manner, has a diverse range of functions that are important in both the life and death of spermatogenic cells. The aim of this study was to further investigate the expression of LM23 in the developing rat testis and the biological function of LM23 in proliferation and antiapoptosis in vitro. Semiquantitative reverse transcription (RT)-PCR and real-time PCR were used to examine the expression of LM23 in testis at different developmental stages. The results suggested that LM23 mRNA levels in the testis increased progressively after birth. The role of LM23 in proliferation was analyzed with cell counting kit-8 (CCK8), colony-forming efficiency (CFE) and flow cytometry assays. The results indicated that ectopic expression of LM23 in 293T cells significantly promoted cell proliferation by increasing cell numbers in S phase. Several methods were used, including CCK8, annexin V and propidium iodide staining and western blotting, to determine the role of LM23 in apoptosis. The results showed that LM23 played a protective role in H2O2-induced apoptosis of 293T cells, mediated at least in part through the Akt/PI3K signal pathway. Taken together, these results provide new insights into the role of LM23 in the development of the testes and spermatogenesis.

Identification of 4,5-dihydro-4-hydroxygeldanamycins as shunt products of geldanamycin biosynthesis.

Two new geldanamycin (GDM) analogues, (4S)-4,5-dihydro-4-hydroxygeldanamycin (1) and (4R)-4,5-dihydro-4-hydroxygeldanamycin (2), were identified from Streptomyces hygroscopicus 17997. Compounds 1 and 2 were not normal intermediates of GDM biosynthesis but shunt products of C-4,5 oxidation catalyzed by GdmP, a cytochrome P450 oxidase acting as a desaturase in GDM biosynthesis. Preliminary assays implied that, compared with GDM, 1 and 2 exhibited decreased cytotoxicity.