Silver nanoparticles (AgNP) undergo various transformations into different Ag species in the environment, which determines their toxicity in microorganisms. In aerobic condition, AgNPs release Ag+ that causes cell inactivation. Limited information is known about the AgNP-cell interaction in oxygen-free environment. Here we compared the transformation and antibacterial effects of AgNPs in aerobic and anaerobic environment. The bacterium Pseudomonas aeruginosa was relatively not susceptible to Ag+ or AgNP in anaerobic environment, indicated by near two orders of magnitude greater of anaerobic minimum inhibitory concentration (MIC) than the aerobic counterpart. In anaerobic environment, the dissolved Ag concentration decreased due to the reduction of Ag+. Electron microscopy images showed the formation of new AgNPs and aggregates, preferably on cell surface or associated with extracellular polymer substances (EPS) matrix. Accumulating AgNPs onto the cells could cause membrane damage, cytoplasm release or bacterial death. Meanwhile, EPS and cell lysate were very likely to bind AgNPs, facilitating the extensively assembling of AgNPs into large aggregates. This reduced the effective Ag exposure to cells and might contribute to the detoxification in anaerobic environment. Further, flow cytometry analysis quantified that bacterial membrane was largely intact under the treatment of AgNPs in anaerobic condition compared to the dose–response manner in aerobic condition. 相似文献
The replacement of oxide semiconducting TiO2 nano particles with one dimensional TiO2 nanotubes (TNTs) has been used for improving the electron transport in the dye-sensitized solar cells (DSSCs). Although use of one dimensional structure provides the enhanced photoelectrical performance, it tends to reduce the adsorption of dye on the TiO2 surface due to decrease of surface area. To overcome this problem, we investigate the effects of TiCl4 treatment on DSSCs which were constructed with composite films made of TiO2 nanoparticles and TNTs. To find optimum condition of TNTs concentration in TiO2 composites film, series of DSSCs with different TNTs concentration were made. In this optimum condition (DSSCs with 10 wt% of TNT), the effects of post treatment are compared for different TiCl4 concentrations. The results show that the DSSCs using a TiCl4 (90 mM) post treatment shows a maximum conversion efficiency of 7.83% due to effective electron transport and enhanced adsorption of dye on TiO2 surface. 相似文献
Liquid crystalline networks (LCNs) are a class of polymers, which are able to produce mechanical actuation in response to external stimuli. Recent creation of LCNs with exchangeable links (xLCNs) makes LCNs easy moldable. As the xLCNs need to be shaped at a high temperature, it is important to enhance their thermal and mechanical properties. In this paper, a series of xLCNs/SiO2 composites containing 1%–7% SiO2 nanoparitcles (SNP) were prepared and their thermal and mechanical properties were examined. The results show that xLCNs/SNP composites have lower liquid crystalline-isotropic phase transition temperature and higher decomposition temperature than pure LCN. The tensile strength and the elongation at break of xLCNs at high temperatures were also enhanced due to the addition of SNPs. 相似文献
One of the promises of nanoparticle (NP) carriers is the reformulation of promising therapeutics that have failed clinical development due to pharmacologic challenges. However, current nanomedicine research has been focused on the delivery of established and novel therapeutics. Here we demonstrate proof of the principle of using NPs to revive the clinical potential of abandoned compounds using wortmannin (Wtmn) as a model drug. Wtmn is a potent inhibitor of phosphatidylinositol 3' kinase-related kinases but failed clinical translation due to drug-delivery challenges. We engineered a NP formulation of Wtmn and demonstrated that NP Wtmn has higher solubility and lower toxicity compared with Wtmn. To establish the clinical translation potential of NP Wtmn, we evaluated the therapeutic as a radiosensitizer in vitro and in vivo. NP Wtmn was found to be a potent radiosensitizer and was significantly more effective than the commonly used radiosensitizer cisplatin in vitro in three cancer cell lines. The mechanism of action of NP Wtmn radiosensitization was found to be through the inhibition of DNA-dependent protein kinase phosphorylation. Finally, NP Wtmn was shown to be an effective radiosensitizer in vivo using two murine xenograft models of cancer. Our results demonstrate that NP drug-delivery systems can promote the readoption of abandoned drugs such as Wtmn by overcoming drug-delivery challenges. 相似文献
Oxaceprol is well-defined therapeutic agent as an atypical inhibitor of inflammation in osteoarthritis. In the present study, we aimed to develop and characterize oxaceprol-loaded poly-lactide-co-glycolide (PLGA) nanoparticles for intra-articular administration in osteoarthritis. PLGA nanoparticles were prepared by double-emulsion solvent evaporation method. Meanwhile, a straightforward and generally applicable high performance liquid chromatography method was developed, and validated for the first time for the quantification of oxaceprol. To examine the drug carrying capacity of nanoparticles, varying amount of oxaceprol was entrapped into a constant amount of polymer matrix. Moreover, the efficacy of drug amount on nanoparticle characteristics such as particle size, zeta potential, morphology, drug entrapment, and in vitro drug release was investigated. Nanoparticle sizes were between 229 and 509 nm for different amount of oxaceprol with spherical smooth morphology. Encapsulation efficiency ranged between 39.73 and 63.83% by decreasing oxaceprol amount. The results of Fourier transform infrared and DSC showed absence of interaction between oxaceprol and PLGA. The in vitro drug release from these nanoparticles showed a sustained release of oxaceprol over 30 days. According to cell culture studies, oxaceprol-loaded nanoparticles had no cytotoxicity with high biocompatibility. This study was the first step of developing an intra-articular system in the treatment of osteoarthritis for the controlled release of oxaceprol. Our findings showed that these nanoparticles can be beneficial for an effective treatment of osteoarthritis avoiding side effects associated with oral administration. 相似文献
The aim of this study was to develop a novel nanosize drug candidate for cancer therapy. For this purpose, (S)-methyl 2-[(7-hydroxy-2-oxo-4-phenyl-2H-chromen-8-yl)methyleneamino]-3-(1H-indol-3-yl)propanoate (ND3) was synthesized by the condensation reaction of 8-formyl-7-hydroxy-4-phenylcoumarin with l -tryptophan methyl ester. Its controlled release formulation was prepared and characterized by different spectroscopic and imaging methods. The cytotoxic effects of ND3 and its controlled release formulation were evaluated against MCF-7 and A549 cancer cell lines, and it was found that both of them have a toxic effect on cancer cells. For drug design and process development, the molecular docking analysis technique helps to clarify the effects of some DNA-targeted anticancer drugs to determine the interaction mechanisms of these drugs on DNA in a shorter time and at a lower cost. By using the molecular docking analysis and DNA binding assays, the interaction between the synthesized compound and DNA was elucidated and non-binding interactions were also determined. To predict the pharmacokinetics, and thereby accelerate drug discovery, the absorption, distribution, metabolism, excretion and toxicity values of the synthesized compound were determined by in silico methods. 相似文献
Introduction: Nanomedicine has emerged as a major field of academic research with direct impact on human health. While a first generation of products has been successfully commercialized and has significantly contributed to enhance patient’s life, recent advances in material design and the emergence of new therapeutics are contributing to the development of more sophisticated systems. As the field matures, it is important to comprehend the challenges related to nanoparticle commercial development for a more efficient and predictable path to the clinic.
Areas covered: The review provides an overview of nanoparticle-based delivery systems currently on the market and in clinical trials, and discuss the principal challenges for their commercial development, both from a manufacturing and regulatory perspective, to help gain understanding of the translational path for these systems.
Expert opinion: Clinical translation of nanoparticle-based delivery systems remains challenging on account of their 3D nanostructure and requires robust nano-manufacturing process along with adequate analytical tools and methodologies. By identifying early enough in the development the product critical attributes and understanding their impact on the therapeutic performance, the developers of nanopharmaceuticals will be better equipped to develop efficient product pipelines. Second-generation products are expected to broaden nanopharmaceutical global market in the upcoming years. 相似文献