The potential risks of nano-materials and the spread of antibiotic resistance genes (ARGs) have become two major global public concerns. Studies have confirmed that nano-alumina can promote the spread of ARGs mediated by plasmids. Nano-titanium dioxide (TiO(2)), an excellent photocatalytic nano-material, has been widely used and is often present in aqueous environments. At various nano-material concentrations, bacterial density, matting time, and matting temperature, nano-TiO(2) can significantly promote the conjugation of RP4 plasmid in Escherichia coli. We developed a mathematical model to quantitatively describe the conjugation process and used this model to evaluate the effects of nano-TiO(2) on the spread of ARGs. We obtained analytical solutions for total and resistant bacteria, which were enumerated by the abundance of genetic loci unique to the plasmid and the chromosome using qPCR. Our results showed that the mathematic model was able to fit the experimental data well and can be used to quantitatively evaluate the effects of nano-TiO(2). According to our model, the presence of nano-TiO(2) decreased the bacterial growth rate from 0.0360 to 0.0323 min(-1) and increased the conjugative transfer rate from 6.69 × 10(-12) to 3.93 × 10(-10 )mL cell(-1) min(-1). These results indicate that nano-TiO(2) inhibited bacterial growth and promoted conjugation simultaneously. The data for morphology and mRNA expression also demonstrated this phenomenon. Our results confirm that environmental nano-TiO(2) may cause the spread of ARGs and thus poses an environmental risk. In addition, we provide a potential method for monitoring changes in ARGs that result from conjugation and evaluating the effects of antimicrobial substances on ARG expression.

Objective: In this study, β-cyclodextrin (β-CD) was chosen as the coating for ellagic acid to prepare ellagic acid microspheres, and the effect of microspheres on the growth of HepG2 cells was observed. Methods: Scanning electron microscopy, infrared spectroscopy, and release rate analysis were used to identify the formation of ellagic acid microspheres. Methyl thiazolyl tetrazolium (MTT) assay was used to detect the effect of different concentrations of ellagic acid microspheres on tumor cell proliferation at 6, 12, 24 and 36 h, and cell morphology and quantity were observed using hematoxylin-eosin (HE) staining. Single-cell gel electrophoresis was used to observe the effect of ellagic acid microspheres on the DNA damage of HepG2 cells, and the Olive tail moment and the mRNA expression of tumor suppressor protein gene p53 was measured. Results: β-CD could be used as wrapping material of ellagic acid to prepare ellagic acid microspheres. HepG2 cell proliferation could be inhibited by 0.1, 0.3 and 0.5 g/L of ellagic acid microspheres in a dose- and time-dependent manner, and the mechanism of proliferation inhibition was related to DNA damage and cell apoptosis. Conclusion: Preparing ellagic acid microspheres with β-CD is feasible, and ellagic acid microspheres have potential therapeutic value (anticancer).

Nanomaterial pollution and the spread of antibiotic resistance genes (ARGs) are global public health and environmental concerns. Whether nanomaterials could aid the transfer of ARGs released from dead bacteria into live bacteria to cause spread of ARGs is still unknown. Here, we demonstrated that nano-Al2O3 could significantly promote plasmid-mediated ARGs transformation into Gram-negative Escherichia coli strains and into Gram-positive Staphylococcus aureus; however, bulk Al2O3 did not have this effect. Under suitable conditions, 7.4 × 10(6) transformants of E. coli and 2.9 × 10(5) transformants of S. aureus were obtained from 100 ng of a pBR322-based plasmid when bacteria were treated with nano-Al2O3. Nanoparticles concentrations, plasmid concentrations, bacterial concentrations, interaction time between the nanomaterial and bacterial cells and the vortexing time affected the transformation efficiency. We also explored the mechanisms underlying this phenomenon. Using fluorescence in situ hybridization and scanning electron microscopy, we found that nano-Al2O3 damaged the cell membrane to produce pores, through which plasmid could enter bacterial cells. Results from reactive oxygen species (ROS) assays, genome-wide expression microarray profiling and quantitative real-time polymerase chain reactions suggested that intracellular ROS damaged the cell membrane, and that an SOS response promoted plasmid transformation. Our results indicated the environmental and health risk resulting from nanomaterials helping sensitive bacteria to obtain antibiotic resistance.

No abstract

Objective: In this study, chitosan/alginate-ellagic acid sustained-release microspheres were prepared, and the effect of sustained-release microspheres on preadipocyte adipogenic differentiation was analyzed. Methods: Chitosan/alginate-ellagic acid microspheres were prepared and identified by scanning electron microscopy (SEM) and infrared spectroscopy (IR). The drug release rates were measured at pH 6.8, 7.0, 7.2, 7.4 to determine sustained release of ellagic acid from microspheres. The effects of 0.1, 1, 10 mg/L chitosan/alginate-ellagic acid microsphere on 3T3-F442A preadipocyte proliferation were determined by Methyl thiazolyl tetrazolium assay (MTT), and cell morphology was checked by hematoxylin/ eosin staining (HE staining). The effect of chitosan/alginate-ellagic acid microspheres on preadipocyte adipogenic differentiation was also determined by Oil red O staining, and lipogenesis was measured by isopropanol extraction. The molecular mechanism was investigated by detecting the mRNA expression of CCAAT/enhancer binding protein alpha (C/EBPα) and peroxisome proliferatorsactivated receptor gamma (PPARγ). Results: Chitosan/alginate-ellagic acid sustained-release microspheres were successfully prepared, and the inhibition of proliferation and adipogenic differentiation of preadipocytes was found to be dosedependent. The mechanism of differentiation inhibition was found to be closely related to the expression of transcription factor C/EBPα and PPARγ. Conclusion: Chitosan/alginate can be used as a good material to prepare ellagic acid sustained-release microspheres, and these microspheres can be used for treating the obesity.