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The present study was conducted to prepare and characterize chitosan nanoparticle loaded copper ions, and evaluate their antibacterial activity. Chitosan nanoparticles were prepared based on ionotropic gelation, and then the copper ions were loaded. The particle size, zeta potential and morphology were determined. Antibacterial activity was evaluated against E. coli K(88) by determination of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) in vitro. Results showed that the antibacterial activity was significantly enhanced by the loading of copper ions compared to those of chitosan nanoparticles and copper ions. The MIC and MBC of chitosan nanoparticle loaded copper ions were 21 times and 42 times lower than those of copper ions, respectively. To confirm the antibacterial mechanism, morphological changes of E. coli K(88) treated by chitosan nanoparticle loaded copper ions were dynamically observed with an atomic force microscope (AFM). It was found that chitosan nanoparticle loaded copper ions killed E. coli K(88) through damage to the cell membrane.

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The TGF-β superfamily members are indicated to play key roles in ovarian follicular development, such as granulosa cell proliferation, estrogens, and progesterone production. However, little is known about the roles of TGF-β3 in follicular development. In this study, we found that TGF-β3 was predominantly expressed in granulosa cells of mouse ovarian follicles, and it significantly promoted 17β-estradiol (E(2)) release in a dose-dependent manner. The orphan nuclear receptor steroidogenic factor-1 (SF-1) was required in TGF-β3-induced Cyp19a1 (a key rate-limiting enzyme for estrogen biosynthesis) expression and E(2) release. Additionally, TGF-β3 enhanced the binding of SF-1 to endogenous ovary-specific Cyp19a1 type II promoter, as evidenced by chromatin immunoprecipitation assays. The enhanced effect of SF-1 by TGF-β3 may be mediated through functional interactions between SF-1 and mothers against decapentaplegic homolog (Smad)3 (a mediator of TGF-β signaling pathway), because disruption of the interaction abolished the synergistic effects of SF-1, Smad3, and TGF-β3 on Cyp19a1 mRNA expression. RNA interference and chromatin immunoprecipitation studies also demonstrated that Smad3 was required for SF-1 binding to Cyp19a1 type II promoter and activation of Cyp19a1. Smad3 thus acts as a point of convergence that involves integration of SF-1 and TGF-β signaling in affecting E(2) production. Taken together, our data provide mechanistic insights into the roles of SF-1 in TGF-β3-mediated E(2) synthesis. Understanding of potential cross-points between extracellular signals affecting estrogen production will help to discover new therapeutic targets in estrogen-related diseases.

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The chitosan microspheres crosslinked by formaldehyde were prepared by spray drying method and used as an adsorbent for copper (II) from aqueous solution. A batch adsorption system was applied to study the adsorption of copper (II) from aqueous solution by chitosan microspheres. The maximum adsorption capacity of the chitosan microspheres for copper (II) was 144.928 mg/g at pH 6.0. Langmuir adsorption model was found to be applicable in interpreting the adsorption process. To elucidate the adsorption mechanism, the chitosan microspheres before and after copper (II) adsorption were further characterized by Fourier transform infrared spectra, zeta potential analysis, and scanning electron microscope.