载自杀基因聚丙交酯乙交酯纳米粒的研制

目的 :对载自杀基因聚丙交酯乙交酯纳米粒的制备工艺进行考察 ,并评价其体外质量。方法 :以聚丙交酯乙交酯为载体材料 ,采用复乳溶媒蒸发法制备载 pEGFP TKAFB重组质粒纳米粒 ,并对其形态、包封率、体外释放、抗核酸酶抗超声的能力等进行研究。结果 :纳米粒形态圆整、大小均匀 ,平均粒径为 72nm ,平均包封率为 91.2 5 % ,体外释药速度依赖于载体材料的分子量 ,质粒制成纳米粒后对抗超声剪切及核酸酶降解的能力增强。结论 :本纳米粒制备工艺简单 ,质量可控。     

雷公藤提取物固体脂质纳米粒水分散体的制备及体外透皮吸收

制备雷公藤乙酸乙酯提取物固体脂质纳米粒水分散体,并初步研究了体外透皮行为.     

胰岛素固体脂质纳米粒的制备及其理化性质研究

 目的 制备胰岛素固体脂质纳米粒并考察其理化性质。方法 采用溶剂扩散法制备胰岛素固体脂质纳米粒,考察制备过程中加入多聚阴离子对纳米粒粒径、表面电位和药物包封率的影响;研究载药纳米粒的体外释放特性;荧光标记固体脂质纳米粒经大鼠口服给药,由荧光倒置显微镜观察血液和淋巴液中的荧光强度。结果胰岛素固体脂质纳米粒的平均粒径为(388.6±143.5)nm,水相中加入三聚磷酸钠对纳米粒粒径无明显影响,而表面电位下降,药物包封率明显增加;胰岛素固体脂质纳米粒最初1 h快速释放了药物包封总量的35.63％,随后以接近每小时1.5％的速度释放,呈明显的缓释特征,24 h体外累积释放量为药物包封量的67.30％;固体脂质纳米粒经大鼠口服研究发现,0.5 h时淋巴液中的荧光强度明显高于相同时间血液中的荧光强度。结论 采用溶剂扩散法制备得到的胰岛素固体脂质纳米粒,具有明显的药物缓释作用;通过调节纳米粒表面电位,可明显提高药物的包封率;固体脂质纳米粒口服给药,具有明显的纳米粒整体淋巴吸收特性。     

In-vitro anti-inflammatory and mosquito larvicidal efficacy of nickel nanoparticles phytofabricated from aqueous leaf extracts of Aegle marmelos Correa

In recent years there is a tremendous growth in the interdisciplinary world of nanotechnology across the globe and emergence of its potential applications remains as a big revolution to the industry. Fusion of green nanotechnology and medicine represents one of the major breakthroughs of modern science with the aim of developing nanomaterials for diagnosis, treatment, prevention of various diseases and overall improving health for the beneficial of mankind. In the present study phytofabrication of nickel nanoparticles (nickel NPs) was carried out by using indigenous Aegle marmelos Correa aqueous leaf extracts as a reducing, stabilizing and capping agents. Nickel NPs were characterized by UV-spectroscopy, FTIR, XRD, SEM, AFM and TGA studies. Phytosynthesis of nickel NPs was monitored both at room temperature (25 °C) and at 60 °C for 5 h. The green synthesis of triangular shape nickel NPs phytofabricated from A. marmelos Correa aqueous leaf extracts having face centered cubic structure showing an average particle size of 80–100 nm which is in consistent with the particle size calculated by XRD Scherer equation. We further explored and compared nickel NPs of A. marmelos Correa with crude leaf extracts of A. marmelos Correa for its in-vitro anti-inflammatory and mosquito larvicidal efficacy against three blood feeding parasites. The results obtained clearly gives an idea that nickel NPs of A. marmelos Correa (NiNPs of AmC) possess an enhanced anti-inflammatory and larvicidal activity when compared to crude leaf extracts of A. marmelos Correa.     

Fluorescent non-porous silica nanoparticles for long-term cell monitoring: Cytotoxicity and particle functionality

Inorganic nanoparticles such as silica particles offer many exciting possibilities for biomedical applications. However, the possible toxicity of these particles remains an issue of debate that seriously impedes their full exploitation. In the present work, commercially available fluorescent silica nanoparticles 25, 45 and 75 nm in diameter optimized for cell labelling (C-Spec® particles) are evaluated with regard to their effects on cultured cells using a novel multiparametric setup. The particles show clear concentration and size-dependent effects, where toxicity is caused by the number and total surface area of cell-associated particles. Cell-associated particles generate a short burst of oxidative stress that, next to inducing cell death, affects cell signalling and impedes cell functionality. For cell labelling purposes, 45 nm diameter silica particles were found to be optimally suited and no adverse effects were noticeable at concentrations of 50 μg ml^?1 or below. At this safe concentration, the particles were found to still allow fluorescence tracking of cultured cells over longer time periods. In conclusion, the data shown here provide a suitable concentration of silica particles for fluorescent cell labelling and demonstrate that at safe levels, silica particles remain perfectly suitable for fluorescent cell studies.     

Key challenges for nanotechnology: Standardization of ecotoxicity testing

Nanotechnology is expected to contribute to the protection of the environment, but many uncertainties exist regarding the environmental and human implications of manufactured nanomaterials (MNMs). Contradictory results have been reported for their ecotoxicity to aquatic organisms, which constitute one of the most important pathways for their entrance and transfer throughout the food web. The present review is focused on the international strategies that are laying the foundations of the ecotoxicological assessment of MNMs. Specific advice is provided on the preparation of MNM dispersions in the culture media of the organisms, which is considered a key factor to overcome the limitations in the standardization of the test methodologies.     

Trypan blue exclusion assay by flow cytometry

Dye exclusion tests are used to determine the number of live and dead cells. These assays are based on the principle that intact plasma membranes in live cells exclude specific dyes, whereas dead cells do not. Although widely used, the trypan blue (TB) exclusion assay has limitations. The dye can be incorporated by live cells after a short exposure time, and personal reliability, related to the expertise of the analyst, can affect the results. We propose an alternative assay for evaluating cell viability that combines the TB exclusion test and the high sensitivity of the flow cytometry technique. Previous studies have demonstrated the ability of TB to emit fluorescence when complexed with proteins. According to our results, TB/bovine serum albumin and TB/cytoplasmic protein complexes emit fluorescence at 660 nm, which is detectable by flow cytometry using a 650-nm low-pass band filter. TB at 0.002% (w/v) was defined as the optimum concentration for distinguishing unstained living cells from fluorescent dead cells, and fluorescence emission was stable for 30 min after cell treatment. Although previous studies have shown that TB promotes green fluorescence quenching, TB at 0.002% did not interfere with green fluorescence in human live T-cells stained with anti-CD3/fluorescein isothiocyanate (FITC) monoclonal antibody. We observed a high correlation between the percentage of propidium iodide+CD3/FITC⁺ and TB+CD3/FITC⁺ cells, as well as similar double-stained cell profiles in flow cytometry dot-plot graphs. Taken together, the results indicate that a TB exclusion assay by flow cytometry can be employed as an alternative tool for quick and reliable cell viability analysis.     

Collagen-Carboxymethylcellulose Biocomposite Wound-Dressings with Antimicrobial Activity

Microbial infections associated with skin diseases are frequently investigated since they impact on the progress of pathology and healing. The present work proposes the development of freeze-dried, glutaraldehyde cross-linked, and non-cross-linked biocomposite dressings with a porous structure, which may assist the reepithelization process through the presence of collagen and carboxymethylcellulose, along with a therapeutic antimicrobial effect, due to silver nanoparticles (AgNPs) addition. Phisyco-chemical characterization revealed the porous morphology of the obtained freeze-dried composites, the presence of high crystalline silver nanoparticles with truncated triangular and polyhedral morphologies, as well as the characteristic absorption bands of collagen, silver, and carboxymethylcellulose. In vitro tests also assessed the stability, functionality, and the degradability rate of the obtained wound-dressings. Antimicrobial assay performed on Gram-negative (Escherichia coli), Gram-positive (Staphyloccocus aureus) bacteria, and yeast (Candida albicans) models demonstrated that composite wound dressings based on collagen, carboxymethylcellulose, and AgNPs are suitable for skin lesions because they prevent the risk of infection and have prospective wound healing capacity. Moreover, the cell toxicity studies proved that the obtained materials can be used in long time treatments, with no cytotoxic effects.     

Preparation of Nanoparticles by Solvent Displacement Using a Novel Recirculation System

Submicron colloidal suspensions of poly(ε-caprolactone) (PCL) were prepared by the solvent displacement method, using either the conventional form or a new recirculation device. In the latter case, a process that allows the recirculation of the aqueous phase into a device, providing a continuous flow, is proposed. The influence of the organic solution injection rate and polymer concentration on mean particle size and process yield were studied for both methods. The recirculation rate was also analyzed for the recirculation system. Nanoparticles (NPs) showed mean sizes that ranged from 156 to 381. The smallest particles were obtained when recirculation rate, injection rate and polymer concentration were maximized but at the expense of the yield. The only acceptable yields (83–96%) were obtained at the lowest PCL concentration (2.5% w/v). ANOVA tests (α = 0.05) showed that the variables implicated in the recirculation system significantly affected the mean particle size and the process yield. The entrapment efficiencies of NPs prepared by the conventional method were not significantly different (α = 0.05) from those obtained by the recirculation system.     

Inorganic Nanoparticle-Modified Poly(Phenylene Sulphide)/Carbon Fiber Laminates: Thermomechanical Behaviour

Carbon fiber (CF)-reinforced high-temperature thermoplastics such as poly(phenylene sulphide) (PPS) are widely used in structural composites for aerospace and automotive applications. The porosity of CF-reinforced polymers is a very important topic for practical applications since there is a direct correlation between void content and mechanical properties. In this study, inorganic fullerene-like tungsten disulphide (IF-WS₂) lubricant nanoparticles were used to manufacture PPS/IF-WS₂/CF laminates via melt-blending and hot-press processing, and the effect of IF-WS₂ loading on the quality, thermal and mechanical behaviour of the hybrid composites was investigated. The addition of IF-WS₂ improved fiber impregnation, resulting in lower degree of porosity and increased delamination resistance, compression and flexural properties; their reinforcement effect was greater at temperatures above the glass transition (T_g). IF-WS₂ contents higher than 0.5 wt % increased T_g and the heat deflection temperature while reduced the coefficient of thermal expansion. The multiscale laminates exhibited higher ignition point and notably reduced peak heat release rate compared to PPS/CF. The coexistence of micro- and nano-scale fillers resulted in synergistic effects that enhanced the stiffness, strength, thermal conductivity and flame retardancy of the matrix. The results presented herein demonstrate that the IF-WS₂ are very promising nanofillers to improve the thermomechanical properties of conventional thermoplastic/CF composites.