Determination of silver nanoparticle release from antibacterial fabrics into artificial sweat

Silver nanoparticles have been used in numerous commercial products, including textiles, to prevent bacterial growth. Meanwhile, there is increasing concern that exposure to these nanoparticles may cause potential adverse effects on humans as well as the environment. This study determined the quantity of silver released from commercially claimed nanosilver and laboratory-prepared silver coated fabrics into various formulations of artificial sweat, each made according to AATCC, ISO and EN standards. For each fabric sample, the initial amount of silver and the antibacterial properties against the model Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria on each fabric was investigated. The results showed that silver was not detected in some commercial fabrics. Furthermore, antibacterial properties of the fabrics varied, ranging from 0% to greater than 99%. After incubation of the fabrics in artificial sweat, silver was released from the different fabrics to varying extents, ranging from 0 mg/kg to about 322 mg/kg of fabric weight. The quantity of silver released from the different fabrics was likely to be dependent on the amount of silver coating, the fabric quality and the artificial sweat formulations including its pH. This study is the unprecedented report on the release of silver nanoparticles from antibacterial fabrics into artificial sweat. This information might be useful to evaluate the potential human risk associated with the use of textiles containing silver nanoparticles.     

Synthesis and properties of solvent absorptive methyl methacrylate‐divinylbenzene copolymer beads

Methyl methacrylate‐divinylbenzene copolymer beads were synthesized by radical suspension polymerization. The effects of the divinylbenzene concentration and the composition of the toluene/heptane diluent were studied with regard to the polymer bead formation, surface morphology, solvent swelling ratio, and absorption kinetics. The crosslinking density and diluent composition were responsible for solvent swelling. The interaction between the polymer and the diluents is attributed to phase separation, which controls the formation of a network‐type or pore‐type polymer, or a combination. For the optimum bead swelling in toluene, a combined morphology of more flexible polymer networks and a small amount of pores is essential for the desired absorption–desorption behavior. Dynamic swelling behavior of the polymer beads was elucidated. The mechanism of toluene transport into the beads became more a relaxation control. POLYM. ENG. SCI., 47:447–459, 2007. © 2007 Society of Plastics Engineers.     

Effect of the third acrylated vinyl comonomer on absorption and desorption properties of styrene–divinylbenzene–alkyl acrylate terpolymers,imbibing solvent on a water surface

A series of imbiber terpolymer beads was prepared by radical suspension copolymerization of styrene–divinylbenzene with varied contents of acrylated vinyl monomers, n‐butyl acrylate and 2‐ethyl hexyl acrylate, as the third comonomer. A DVB content of 6 wt % and a mixture of 60/40 wt % toluene/n‐heptane as the diluent were used throughout this study. The influence of acrylated vinyl comonomers on bead properties and swelling properties was investigated. The imbiber beads are capable of absorption and desorption of organic solvents having solubility parameters in the range of 14.9–20.9 (MPa)^1/2. Styrenic imbiber beads were swelled in a toluene/n‐heptane mixture of 50% by volume and the kinetics of absorption was studied. The imbiber beads could absorb the toluene/n‐heptane mixture completely within 20 min and yielded a maximum swelling ratio of 6.8. The diffusion coefficient values of these beads were in the range of 6.40 × 10⁻⁶ to 1.52 × 10⁻⁵ cm² s⁻¹. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 504–516, 2001     

Kinetics of surface grafting on polyisoprene latexes by reaction calorimetry

The two-component redox-initiation system, cumene hydroperoxide (CHP) and tetraethylene pentamine (TEPA), was used to polymerize dimethylaminoethyl methacrylate (DMAEMA) in the presence of synthetic polyisoprene latexes. The modified latex particles are postulated to possess a ‘hairy layer’ of surface-grafted poly(DMAEMA) chains formed via an abstraction reaction between cumyloxy radicals and the isoprene moieties present in the seed polymer. The modified latexes exhibited enhanced colloidal stability to low pH, and dynamic light scattering showed that the apparent particle size was sensitive to pH. The rate of polymerization was followed by reaction calorimetry. No steady-state polymerization was observed, with a continual increase in the number of propagating chains at all initiator feed rates investigated. The data for particle size and colloidal stability, together with the calorimetric data, are consistent with radical production at the particle surface, and with abstraction near the interface being a rare event. Further, there is evidence that radical production by the redox couple is relatively slow. While this ‘topology-controlled’ reaction is responsible for the formation of the hairy layer and latex stability, the dominant polymerization process appears to be the formation of ungrafted poly(DMAEMA) in the water phase.     

Surface modification of electrospun chitosan nanofibrous mats for antibacterial activity

Chitosan (CS) blended with poly(ethylene oxide) (PEO) was electrospun into nanofibrous mats. The spinning solution of 6.7 : 0.3 (% w/v) of CS : PEO was dissolved in a 70 : 30 (v/v) trifluoroacetic acid/dichloromethane solution. The obtained fibers were smooth without beads on their surfaces and average diameter of the fiber was 272 ± 56 nm. N‐(2‐hydroxyl) propyl‐3‐trimethyl ammonium chitosan chloride (HTACC) and N‐benzyl‐N,N‐dimethyl chitosan iodide (QBzCS) were each prepared from the CS/PEO mats. They were identified by Fourier‐transform infrared and X‐ray photoelectron spectroscopy and degree of swelling in water. Both quaternized electrospun chitosan mats exhibited superior antibacterial activity to the unmodified electrospun CS/PEO against Staphylococcus aureus and Escherichia coli at short contact times. After 4 h of contact, the reduction of both bacterial strains by CS/PEO, HTACC, and QBzCS was equal at about 99–100%. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40981.     

Nanocapsules embedded in natural rubber latex gloves

To prepare medical gloves containing disinfectant agent, poly(methyl acrylate) (PMA) with _w of 550 K was synthesized via the iniferter technique and then used for encapsulating disinfectant agent, i.e., chlorhexidine digluconate (CHD), droplets. The CHD‐PMA nanocapsules suspended in a sodium dodecyl sulfate aqueous solution having 93% encapsulation efficiency were successfully embedded between the outermost and inner layers of γ‐radiation vulcanized natural rubber (RVNR) latex films by the coagulant dipping process. A RVNR/CHD‐PMA nanocapsules/RVNR three‐layer structure was revealed by the contact angle measurement, ATR‐FTIR and SEM. Both the tensile strength and elongation at break of the three‐layer film were also measured. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation of magnetic photocatalyst nanoparticles—TiO2/SiO2/Mn–Zn ferrite—and its photocatalytic activity influenced by silica interlayer

A magnetic photocatalyst, TiO₂/SiO₂/Mn–Zn ferrite, was prepared by stepwise synthesis involving the co-precipitation of Mn–Zn ferrite as a magnetic core, followed by a coating of silica as the interlayer, and titania as the top layer. The particle size and distribution of magnetic nanoparticles were found to depend on the addition rate of reagent and dispersing rate of reaction. The X-ray diffractometer and transmission electron microscope were used to examine the crystal structures and the morphologies of the prepared composites. Vibrating sample magnetometer was also used to reveal their superparamagnetic property. The UV–Vis spectrophotometer was employed to monitor the decomposition of methylene blue in the photocatalytic efficient study. It was found that at least a minimum thickness of the silica interlayer around 20 nm was necessary for the inhibition of electron transference initiated by TiO₂ and Mn–Zn ferrite.