Surface modification of polyester fabric by corona discharge irradiation

Polyester fabric was treated by corona discharge irradiation at different voltages. The treated fabric showed increased wicking and hydrophilic properties and the properties can be preserved for a long time. Dyeing of the treated fabric showed that dyeing speed and the dye-uptake were improved. Surface affinity between the treated fabric surface with modified starch sizing was also confirmed to be increased. This is generally useful for the sizing of polyester staple yarn and the polyester fabric dyeing. All the results are supposed due to the improved hydrophilic properties produced by the corona discharge treatment.     

Asymmetrically superhydrophobic cotton fabrics fabricated by mist polymerization of lauryl methacrylate

A graft-polymerization process with atomized lauryl methacrylate as monomer is used to fabricate fluorine-less and asymmetrically superhydrophobic cotton fabrics. The polymers synthesized in the process can form nanoscale hierarchical structures on the cotton surface, and the surface morphology can be controlled by choosing a suitable solvent or by varying the feeding quantity of the monomer mist stream. After applying the surface modification to cotton fabrics, an asymmetrically superhydrophobic surface is achieved without any additional nanosized particles, and the solvent damages on the cotton fabrics are controllable at a very low level. Surface characterization reveals that the modified side of the cotton fabric has laundering-durable and mechanically stable superhydrophobicity with a water contact angle of more than 150°, whereas the opposite inherits the hydrophilic property of pristine cotton fabric. The modified cotton fabrics are found to have medium-level water-absorbing ability between pristine cotton and PET fabrics, as well as good vapor transmissibility similar to pristine cotton fabric. These properties are of great significance in textile and medical applications.     

Horseradish peroxidase activity in a reverse catanionic microemulsion

In this paper we present the first results of enzymatic activities in a reverse microemulsion medium based on a mixture of an anionic and a cationic surfactant, called catanionic microemulsion. The studied system is composed of sodium dodecyl sulfate (SDS)/dodecyltrimethylammonium bromide (DTAB)/n-hexanol/citrate buffer/n-dodecane, with high SDS/(SDS + DTAB) weight fractions. It turns out that the results are similar to those obtained in classical reverse microemulsions, except that the presence of DTAB exerts an inhibiting effect on the enzyme. Nevertheless, enzymatic superactivities are found even at a DTAB to total surfactant ratio of 15%, corresponding to 3% weight fraction of cationic surfactant in the microemulsion. The influence of pH and hexanol content on the enzymatic activities is also studied.     

Enhanced self-cleaning, antibacterial and UV protection properties of nano TiO2 treated textile through enzymatic pretreatment

Textile materials can be treated with some enzymes to improve their functionality. The usual enzymatic treatment hydrolyzes the textile surfaces that leads to increase the functional groups. Here, the polyester/wool fabric as a blend of fibers fabric was selected and treated with the two different types of enzymes to increase the surface activity with a propose of higher nano-TiO(2) adsorption. The fabric was first treated with proteases and lipases to hydrolyze the wool and the polyester surfaces, respectively. It has been then dipped into an ultrasound bath containing nano TiO(2) and cross-linking agent followed by curing. The cross-linking agent, butane tetracarboxylic acid (BTCA), also assisted to enhance the nano-particles adsorption and stabilization on the fabric surface. The self-cleaning properties of the fabrics were examined through evaluating the color removal from the stained fabric with Acid Blue 113. The antibacterial properties were determined by reduction growth of a Gram-negative bacteria E. coli. and the UV protection was assessed by UV-reflectance spectrum. The SEM pictures and EDX spectrums of some samples were also reported.     

Determination of drug and fatty acid binding capacity to pluronic f127 in microemulsions

We propose that one can deduce very insightful information regarding the drug and fatty acid binding capacity of microemulsions through simple turbidity experiments. Pluronic F127-based oil-in-water microemulsions of various compositions were synthesized and titrated to turbidity with concentrated amitriptyline, an antidepressant drug. We observed that, above certain Pluronic F127 concentrations, turbidity was never observed, irrespective of how much amitriptyline was added to the microemulsion. We also observed that whenever sodium caprylate fatty acid was not included in the microemulsion formulation, turbidity never occurred. On the basis of these findings, we were able to determine the point at which all sodium caprylate present in the microemulsion formulation was bound to the F127 in the microemulsion (i.e., no fatty acid was free in the bulk in monomer form). By the same logic we were also able to determine how much amitriptyline was binding to the microemulsions. We also measured the dynamic surface tension, foamability, and fabric wetting time of the microemulsion formulations to further prove the hypothesis that all fatty acid is bound to the F127 in the microemulsion above a critical Pluronic F127 concentration. On the basis of this research, we have concluded that there are approximately 11 molecules of sodium caprylate fatty acid bound per molecule of Pluronic F127 and approximately 12 molecules of amitriptyline bound per molecule of Pluronic F127 in the optimal microemulsion formulation. These findings give us valuable information about the charge density at the oil/water interface and about the mechanism of binding of the drug to the microemulsion.     

Effect of a nonionic surfactant on Trichoderma cellulase treatments of regenerated cellulose and cotton yarns

It has been shown that some surfactants affect the hydrolysis of cellulose by cellulase. In this study, the effect of the surfactant Tween 20 on the hydrolysis of different cellulosic fibers was investigated and related to the cellulose fiber structure. It was found that this non-ionic surfactant enhanced the enzymatic saccharification of highly crystalline cellulosics such as Avicel, Tencel and cotton but not of cuprammonium rayon. The enhanced saccha-rification effected by the surfactant is attributed to inhibition of non-productive sorption of the endoglucanase of the cellulose surface which gives greater access to the cellulose chain ends by the exoglucanase. Although all three fibers lost tensile strength as a result of the enzymatic treatment, no further decrease was effected by the presence of the surfactant.     

Staudinger–Vilarassa reaction versus Huisgen reaction for the control of surface hydrophobicity and water adhesion

Surface modifications are keys for a great number of applications. In order to perfectly control the surface properties, it is important to control the modification pathways. Two general pathways can be described in order to introduce modification on surfaces: the post‐strategies and the ante‐strategies. In this work, we focus on the comparison between the Huisgen and the Staudinger–Vilarrasa reaction for both post‐surface and ante‐surface modifications. Here, we focused on the possibility to use both two reactions to obtain superhydrophobic and oleophobic properties. This work includes monomer synthesis, surface modifications with alkyl, aryl or perfluoroalkyl chain. Copyright © 2016 John Wiley & Sons, Ltd.     

Bioconjugated nanoparticles for DNA protection from cleavage

We have developed a novel method to protect DNA from cleavage using bioconjugated nanoparticles. Positively charged amino-modified silica nanoparticles have been directly prepared using water-in-oil microemulsion. Plasmid DNA can be easily enriched onto the positively charged nanoparticle surface, and the DNA strands are well protected from enzymatic cleavage. When incubated with nuclease enzyme for enzymatic cleavage, free plasmid DNA strands are completely cleaved, while those on the nanoparticle surfaces are intact. Our results clearly demonstrate unique properties of nanomaterials when combined with biomolecules. Our simple bionanotechnology will be highly useful in DNA separation, manipulation, and detection, and possibly in genetic engineering and gene therapy, as plasmid DNA can be protected in cellular environments without any change in its property.     

Superhydrophobic properties of cotton woven fabrics with conducting 3D networks of multiwall carbon nanotubes,MWCNTs

This article presents the findings concerning the preparation and properties of cotton woven fabrics with a conductive network made of multiwall carbon nanotubes deposited on the fiber surface by the padding method. The next stage of treatment consisted of imparting superhydrophobic properties to the fabrics in solution with methyltrichlorosilane (MTCS) in a waterless medium. The tests performed show that the state of surface and water content in cotton fibers exerts a significant influence on the hydrophobic properties of the analyzed samples. In order to explain the differences in hydrophobic properties, the morphology of the cotton fabric surface was examined using samples with various water contents. The formation mechanism of MTCS coatings on cotton fabric has been proposed.     

Fabrication of asymmetrically superhydrophobic cotton fabrics via mist copolymerization of 2,2,2‐trifluoroethyl methacrylate

We report here a simple strategy for fabricating asymmetrically superhydrophobic cotton fabric via a mist copolymerization of three monomers, 2,2,2‐trifluoroethyl methacrylate (TFMA), 2‐isocyanatoethyl methacrylate (IEM), and divinylbenzene (DVB). The copolymer layer on the cotton surface was confirmed by X‐ray photoelectron spectroscopy (XPS) analysis and attenuated total reflection (ATR) accessory, and the nanoscale hierarchical structures in the polymeric layer were demonstrated by observation of field emission scanning electron microscope (FE‐SEM). Surface characterization reveals that the modified surface is superhydrophobic, but the opposite side of the modified cotton fabric has the hydrophilic nature of cotton. More experimental data suggest that the good water adsorptivity and vapor transmissibility of the original cotton fabric were inherited after the surface modification. These properties are of great significance in textile and medical applications. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1862–1871     

Plasma-assisted regenerable chitosan antimicrobial finishing for cotton

In this study, nitrogen-plasma treatment was used to enhance the coating of chitosan onto cotton fabric and chlorine was introduced into nitrogen-containing groups on the chitosan coated fabric in order to make it antimicrobial by chlorination with sodium hypochlorite. The antimicrobial property and its rechargeability were investigated. FTIR, UV and scanning electron microscope were used to evaluate the surface properties, including the existence of chitosan on cotton fabric, the content of chitosan on cotton fabric and the surface topography of cotton fabric after modification. The results showed that nitrogen-plasma introduces nitrogen-containing groups into cotton fabric, the coating of chitosan on fabric was improved with nitrogen plasma treatment and chlorine was introduced into the chitosan coated fabric successfully which inhibits bacteria effectively and it is rechargeable. Thus, the antimicrobial property of cotton fabric coated with chitosan with the aid of nitrogen-plasma treatment after chlorination achieved good effects.     

LIDOCAINE IN MICROEMULSION - A DERMAL DELIVERY SYSTEM

In order to obtain a microemulsion that is stable at skin temperature, the regions of existence of microemulsions of water and isopropyl myristate were studied as a function of hydrophile-lipophile balance (HLB) of nonionic surfactant mixtures. The microemulsion dissolves large amount of the local anaesthetic - lidocaine. The amount of dissolved lidocaine in the microemulsion was proportional to the isopropyl myristate content and limited to its solubility in this solvent.

The addition of lidocaine lowered the phase inversion temperature (PIT) of the system and increased the temperature range for microemulsion stability.

The structure of the microemulsion, as investigated by proton Fourier transform pulsed-gradient spin-echo NMR spectroscopy, was found to be bicontinous. The physico - chemical properties of the microemulsion as well as the low toxicity of its components result in formulation intendend for topical administration.     

Coating of multiwalled carbon nanotubes with polymer nanospheres through microemulsion polymerization

We report a simple and noncovalent method for coating multiwalled carbon nanotubes (MWCNTs) with polyaniline (PANI) nanospheres using a microemulsion polymerization method. In this method, aniline polymerization is performed with MWCNTs in the presence of sodium dodecyl sulfate (SDS), which serves as both a surfactant and a dopant. Morphological, structural, thermal, and electrical properties of MWCNT–PANI nanocomposites were analyzed. The TEM results of the nanocomposites prepared with surfactant reveal that 30–50-nm-diameter PANI nanospheres were coated on the surface of the MWCNTs. Composites prepared without surfactant were found to be in core–sheath-type cable structures. The conductivities of the nanocomposites synthesized through microemulsion polymerization were found to be one order of magnitude higher than both the conductivities of pure PANI and the composites prepared via in situ chemical polymerization without an assisting SDS surfactant. The mechanism for the formation of nanostructured composites is presented.     

Probing the microstructure of nonionic microemulsions with ethyl oleate by viscosity, ROESY, DLS, SANS, and cyclic voltammetry

Microemulsions are important formulations in cosmetics and pharmaceutics and one peculiarity lies in the so-called "phase inversion" that takes place at a given water-to-oil concentration ratio and where the average curvature of the surfactant film is zero. In that context, we investigated the structural transitions occurring in Brij 96-based microemulsions with the cosmetic oil ethyl oleate and studied the influence of the short chain alcohol butanol on their structure and properties as a function of water addition. The characterization has been carried out by means of transport properties, spectroscopy, DLS, SANS, and electrochemical methods. The results confirm that the nonionic Brij 96 in combination with butanol as cosurfactant forms a U-type microemulsion that upon addition of water undergoes a continuous transition from swollen reverse micelles to oil-in-water (O/W) microemulsion via a bicontinuous region. After determining the structural transition through viscosity and surface tension, the 2D-ROESY studies give an insight into the microstructure, i.e., the oil component ethyl oleate mainly is located at the hydrophobic tails of surfactant while butanol molecules reside preferentially in the interface. SANS experiments show a continuous increase of the size of the structural units with increasing water content. The DLS results are more complex and show the presence of two relaxation modes in these microemulsions for low water content and a single diffusive mode only for the O/W microemulsion droplets. The fast relaxation reflects the size of the structural units while the slower one is attributed to the formation of a network of percolated microemulsion aggregates. Electrochemical studies using ferrocene have been carried out and successfully elucidated the structural transformations with the help of diffusion coefficients. An unusual behavior of ferrocene has been observed in the present microheterogeneous medium, giving a deeper insight into ferrocene electrochemistry. NMR-ROESY experiments give information regarding the internal organization of the microemulsion droplets. In general, one finds a continuous structural transition from a W/O over a bicontinuous to an O/W microemulsion, however with a peculiar network formation over an extended concentration range, which is attributed to the somewhat amphiphilic oil ethyl oleate. The detailed knowledge of the structural behavior of this type of system might be important for their future applications.     

High-speed microemulsion electrokinetic chromatography.

In previous reports of microemulsion electrokinetic chromatography (MEEKC), analysis times were typically in the order of 10 min as high-ionic strength buffers were used. These buffers produced high currents which limit the voltages which can be applied, therefore, analysis times could not be reduced. The primary cause of the high-ionic strength is the relatively high concentrations of surfactants required to form the microemulsion. The surfactant concentration can be lower when using an oil with a smaller surface tension. This preliminary study showed that migration times in MEEKC can be reduced to below 1 min by using a combination of an optimum microemulsion composition, high voltage, high temperature, short capillaries by injecting via the "short end", or by simultaneously applying pressure and voltage. Long injection sequences and quantitation were found to be possible with minimum buffer depletion effects.     

Interactions of a fungistatic antibiotic, griseofulvin, with phospholipid monolayers used as models of biological membranes

Griseofulvin (GF) is an oral antibiotic for widely occurring superficial mycosis in man and animals caused by dermaphyte fungi; it is also used in agriculture as a fungicide. The mechanism of the biological activity of GF is poorly understood. Here, the interactions of griseofulvin with lipid membranes were studied using 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC), and 1,2-myristoyl-sn-glycero-3-phosphoethanolamine (DMPE) monolayers spread at the air/water interface. Surface pressure (Pi), electric surface potential (Delta V), grazing incidence X-ray diffraction (GIXD), and Brewster angle microscopy (BAM) were used for studying pure phospholipid monolayers spread on GF aqueous solutions, as well as mixed phospholipid/GF monolayers spread on pure water subphase. Moreover, phospholipase A2 (PLA2) activity toward DLPC monolayers and molecular modeling of the GF surface and lipophilic properties were used to get more insight into the mechanisms of GF-membrane interactions. The results obtained show that GF has a meaningful impact on the film properties; we propose that nonpolar interactions are by and large responsible for GF retention in the monolayers. The modification of membrane properties can be detected using both physicochemical and enzymatic methods. The results obtained may be relevant for elaborating GF preparations with increased bioavailability.     

Preparation and in vitro Release Test of Insulin Loaded W/O Microemulsion

A W/O microemulsion of Tween‐80‐Span‐80/n‐butylalcohol/ethyl‐oleate/H₂O to envelop insulin (INS) was prepared. In order to obtain the maximum solved water, the components of microemulsion to envelop INS were chosen with the pseudo‐ternary phase diagram and the influences of temperature, salinity as well as the pH on microemulsion areas also were investigated. To test the properties of the microemulsion, the conductance was used to divide O/W, W/O and BC regions, the dynamic light scattering to evaluate the particle diameters of microemulsion, the ¹²⁵I isotope tracing method to measure the release rate of INS loaded in W/O microemulsion, and the growth inhibitory effect test to appraise the cytotoxicity on human normal cells. Results show that W/O microemulsion forms when water content below 50% in the microemulsion system. The microemulsion region decreases slightly with the increase of temperature, salinity and the decrease of pH. However, the viscosity measurements along certainly selected dilution lines to the microemulsion indicate that no phase invert occurred. Diameter of microemulsion particle increases with the addition of INS, and the increase is sharp in the first 5 days then very slightly at 68.6 nm within a month. The INS loaded W/O microemulsion possesses eminent sustaining release efficiency and the cytostatic as well as cytotoxic assays illustrate that the microemulsion can be used as drug delivery at small dosage.     

Site-selective surface modification using enzymatic soft lithography

Surface modification with functional polymers or molecules offers great promise for the development of smart materials and applications. Here, we describe a versatile and easy-to-use method of site-selective surface modification based on the ease of microcontact printing and the exquisite selectivity of enzymatic degradation. A micropatterned poly-L-lysine (PLL) layer on solid substrates was prepared by enzymatic degradation using trypsin enzyme immobilized on a prestructured poly(dimethlylsiloxane) (PDMS) stamp. After the enzymatic degradation of PLL and the removal of the degradation products, very well defined patterning was revealed over a large scale by fluorescence microscopy and atomic force microscopy (AFM). We investigate the advantage of our method by comparison with traditional microcontact printing and found that lateral diffusion was reduced, yielding a more accurate reproduction of the master. We also demonstrate that the stamp can be reused without reinking. The patterned surface was used for site-selective modification. The strategy was applied to two applications: the first is dedicated to the creation of amino-silane patterned surfaces, and the second illustrates the possibility of patterning polyelectrolyte multilayered thin films.     

Preparation and Characterization of Polyhydroxyalkanoates Macroporous Scaffold Through Enzyme-Mediated Modifications

Polyhydroxyalkanoates (PHAs) are hydrophobic biodegradable thermoplastics that have received considerable attention in biomedical applications due to their biocompatibility, mechanical properties, and biodegradability. In this study, the degradation rate was regulated by optimizing the interaction of parameters that influence the enzymatic degradation of P(3HB) film using response surface methodology (RSM). The RSM model was experimentally validated yielding a maximum 21 % weight loss, which represents onefold increment in percentage weight loss in comparison with the conventional method. By using the optimized condition, the enzymatic degradation by an extracellular PHA depolymerase from Acidovorax sp. DP5 was studied at 37 °C and pH 9.0 on different types of PHA films with various monomer compositions. Surface modification of scaffold was employed using enzymatic technique to create highly porous scaffold with a large surface to volume ratio, which makes them attractive as potential tissue scaffold in biomedical field. Scanning electron microscopy revealed that the surface of salt-leached films was more porous compared with the solvent-cast films, and hence, increased the degradation rate of salt-leached films. Apparently, enzymatic degradation behaviors of PHA films were determined by several factors such as monomer composition, crystallinity, molecular weight, porosity, and roughness of the surface. The hydrophilicity and water uptake of degraded salt-leached film of P(3HB-co-70%4HB) were enhanced by incorporating chitosan or alginate. Salt-leached technique followed by partial enzymatic degradation would enhance the cell attachment and suitable for biomedical as a scaffold.     

Study of properties of modified silicones at solid-liquid interface: fabric-silicone interactions

Silicones are special reagents that impart desired surface properties such as softness, bounciness and antiwrinkle properties to fabrics and related materials. Although these finishing processes have been practiced routinely, very little is known about the mechanisms involved in modification so that they could be improved. The current study was undertaken to develop basic understanding of the mechanisms responsible for surface modification of fibers using silicones. PDMS based amino silicone emulsions, quaternized to various degrees using dimethyl sulphate, were used in the present study. The electrokinetic properties of the modified silicones were studied as a function of pH. It was expected that the silicone emulsions would show a steady positive zeta potential throughout the pH range due to the quaternization by dimethyl sulphate. Surprisingly, a sudden drop in the zeta potential was observed around pH 8 with the samples turning hazy in the pH range of 8-10. Turbidimetric studies also showed a sudden increase in the turbidity in the pH range 8-10 where commercial processes also encounter problems. It was concluded that the emulsions were destabilized at pH 8-10 thus rendering them ineffective for surface treatment. In order to identify reason for the improvement in fabric properties, fiber structure was monitored using atomic force microscopy. It was observed that the treated fibers were far smoother, relaxed and uniform as compared to the untreated fibers. Thus the morphology of the fabric is modified in a specific way by treatment with specialty silicones.