Measurement of the adhesion between single melamine-formaldehyde resin microparticles and a flat fabric surface using AFM

An understanding of the adhesion of microparticles, particularly microcapsules, containing a functional component to a fabric surface is crucial to an effective application of this component to the fibre. Fabric surface is very rough; hence, direct measurement of the adhesion of single microparticles to surfaces with a roughness greater than the particle diameter is difficult. In the study reported here, cotton films were generated by dissolving cotton powder in an organic solvent and their properties including surface roughness, thickness, contact angle and purity were characterised. The adhesive forces between single melamineformaldehyde (MF) resin microparticles and a cotton film under ambient conditions with a relative humidity of above 40% were measured using atomic force microscopy; they are considered to be dominated by capillary forces. It was found that there was little adhesion between a MF microparticle and a cotton film in an aqueous solution of sodium dodecylbenzene sulphonate as surfactant. Repulsion between them was observed, but it reduced with increase in the surfactant concentration and decrease in the pH of the solution. The repulsion contributions are thought to originate mainly from electrostatic repulsion. It is believed that the studies on the adhesion between single MF microparticles and a cotton film under ambient conditions or dispersed in surfactant solutions, are beneficial to the attempts to enhance the adhesion of microcapsules to fabric surfaces via a modification of their surface composition and morphology

Sucrose Monoester Micelles Size Determined by Fluorescence Correlation Spectroscopy (FCS)

One of the several uses of sucrose detergents, as well as other micelle forming detergents, is the solubilization of different membrane proteins. Accurate knowledge of the micelle properties, including size and shape, are needed to optimize the surfactant conditions for protein purification and membrane characterization. We synthesized sucrose esters having different numbers of methylene subunits on the substituent to correlate the number of methylene groups with the size of the corresponding micelles. We used Fluorescence Correlation Spectroscopy (FCS) and two photon excitation to determine the translational D of the micelles and calculate their corresponding hydrodynamic radius, Rh. As a fluorescent probe we used LAURDAN (6-dodecanoyl-2-dimethylaminonaphthalene), a dye highly fluorescent when integrated in the micelle and non-fluorescent in aqueous media. We found a linear correlation between the size of the tail and the hydrodynamic radius of the micelle for the series of detergents measured

Effects of Transport Inhibitors on the Cellular Uptake of Carboxylated Polystyrene Nanoparticles in Different Cell Lines

Nanotechnology is expected to play a vital role in the rapidly developing field of nanomedicine, creating innovative solutions and therapies for currently untreatable diseases, and providing new tools for various biomedical applications, such as drug delivery and gene therapy. In order to optimize the efficacy of nanoparticle (NP) delivery to cells, it is necessary to understand the mechanisms by which NPs are internalized by cells, as this will likely determine their ultimate sub-cellular fate and localisation. Here we have used pharmacological inhibitors of some of the major endocytic pathways to investigate nanoparticle uptake mechanisms in a range of representative human cell lines, including HeLa (cervical cancer), A549 (lung carcinoma) and 1321N1 (brain astrocytoma). Chlorpromazine and genistein were used to inhibit clathrin and caveolin mediated endocytosis, respectively. Cytochalasin A and nocodazole were used to inhibit, respectively, the polymerisation of actin and microtubule cytoskeleton. Uptake experiments were performed systematically across the different cell lines, using carboxylated polystyrene NPs of 40 nm and 200 nm diameters, as model NPs of sizes comparable to typical endocytic cargoes. The results clearly indicated that, in all cases and cell types, NPs entered cells via active energy dependent processes. NP uptake in HeLa and 1321N1 cells was strongly affected by actin depolymerisation, while A549 cells showed a stronger inhibition of NP uptake (in comparison to the other cell types) after microtubule disruption and treatment with genistein. A strong reduction of NP uptake was observed after chlorpromazine treatment only in the case of 1321N1 cells. These outcomes suggested that the same NP might exploit different uptake mechanisms to enter different cell types

Protein-loaded poly(epsilon-caprolactone) microparticles III. Entrapment of superoxide dismutase by the (water-in-oil)-in water solvent evaporation method

This work investigated some process parameters involved in the entrapment of superoxide dismutase (model protein) in poly(epsilon-caprolactone) microparticles by a multiple emulsion solvent evaporation method. In optimal operating conditions, the particles were smooth and spherical (mean diameter 8.66 +/- 0.18 mu m) with entrapment efficiency and retained biological activity of 68 +/- 2% and 8.48 +/- 1.07% (n = 3), respectively. This dramatic activity loss was ascribed to the deleterious effect of the polymer solvent. The use of alpha-cyclodextrin decreased the entrapment efficiency and retained biological activity. These two parameters were not considerably influenced by the freeze-drying. Moreover, thermal analysis showed that superoxide dismutase did not form a true solution with the polymer and an increase in the polymer crystallization temperature after the entrapment process

Encapsulation of Hydrophilic and Lipophilic Compounds in Nanosomes Produced with a Supercritical Based Process

Liposomes are created when phospholipids self-assemble in an aqueous medium creating spherical closed structures. These vesicles can be loaded with hydrophilic active principles (AP) into the aqueous inner core or with lipophilic compounds in the lipidic double layer. In this work a new supercritical based process for the one-step continuous production of nanosomes is proposed for the encapsulation of hydrophilic and lipophilic compounds. This process is called Supercritical Assisted Liposome Formation (SuperLip). The innovation of this process consists in the inversion of the traditional phases of production of liposomes: water droplets are created by a spray atomization in a high pressure vessel, and then a double layer of phospholipids fast surrounds them. A systematic study on liposome size, morphology, encapsulation efficiency has been performed for several different hydrophilic AP (ampicillin, ofloxacin, bovine serum albumin, fluorescein, eugenol and theophylline). Some operative parameters were also optimized to achieve the production of nanometric liposomes with high encapsulation efficiencies. Operating in this way nanometric and monodispersed liposome suspensions were produced with EE up to 99%. To complete the study, other lipidic compounds were entrapped in the double lipidic layer, obtaining high entrapment efficiencies (TE), also in this case, up to 84.9%