Deposition Of Polyanions Research Articles

Release-killing properties of a textile modified by a layer-by-layer coating based on two oppositely charged cyclodextrin polyelectrolytes.

Infections represent a major medical concern and have severe impact on the public health economy. Antimicrobial coatings represent one major solution and are the subject of many investigations in academic and industrial research. Polyelectrolyte multilayers (PEMs) consist in the step-by-step deposition of polyanions and polycations films on surfaces. The wide range of disposable polyelectrolytes makes this approach among the most versatile methods as it allows to design surfaces that prevent bacterial adhesion, and kill bacteria by contact or by releasing antibacterial agents. The present work focused on the release-killing effect of an active PEM coating of a polyethylene terephthalate (PET) textile support. This activity was obtained thanks to the PEM film build up using cationic and anionic polyelectrolytes both based on cyclodextrins (PCD- and PCD+) that provided a reservoir property and prolonged release of triclosan (TCS). To this effect, a PET non-woven preliminarily modified with carboxylate groups by applying a thermofixation process was then treated by dip-coating, alternating soaking cycles in cationic PCD+ and in anionic PCD- solutions. Samples coated with such PEM film were then loaded with TCS whose release was assessed in dynamic mode in a phosphate buffered saline solution (PBS) at 37°C. In parallel, TCS/PCD+ and TCS/PCD- interactions were investigated by Nuclear Magnetic Resonance (NMR) and phase solubility study, and the biocide activity was assessed against S. aureus and E. coli. Finally, the present study has demonstrated that our PCD+/PCD- PEM system presented release-killing properties that supplement the contact-killing effect of this system that was reported in a previous paper.

Preparation of polyaniline/nylon conducting fabric by layer‐by‐layer assembly method

AbstractIn this article, layer‐by‐layer assembly technology was used to prepare polyaniline (PANI)/nylon conducting fabrics. PANI/nylon conductive composite fabrics were prepared by deposition of polyanion (PSS) and polycation (aniline cation) alternately. The pretreatment with PSS was discussed. The influence of the reaction time, aniline concentration, acid concentration and assembly time on the conductivity, and K/S values of composite fabric was studied. The optical reaction condition of assembly should be: the concentration of PSS was 20 g/L, the PSS‐treated nylon immersion in blended bath for 24 min, ammonium persulfate 0.1 mol/L, aniline 0.1 mol/L, p‐toluene sulfonic acid 0.3 mol/L. In the end, the conductive composite fabrics were characterized by fourier transformed Infrared‐attenuated total reflection spectroscopy and compared with pure nylon fabrics. At the same time, scanning electron microscopy, atomic force microscope (AFM), thermogravimetric analysis (TG), and mechanical properties were studied. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Ion-induced cell sheet detachment from standard cell culture surfaces coated with polyelectrolytes

Polyelectrolyte multilayers (PEMs), formed by alternating layer-by-layer deposition of polyanions and polycations, are an ideal substrate for controlling cellular adhesion and behavior. In the present study we propose a simple mechanism for the controlled detachment of C2C12 myoblasts cell sheets from PEMs consisting of poly(l-lysine) and hyaluronic acid with a topmost layer of fibronectin. The multilayers were deposited on two standard cell culture surfaces: glass and polystyrene. Adding a low concentration of nontoxic ferrocyanide to the cell culture medium resulted in erosion of the polyelectrolyte multilayer and rapid detachment of viable cell sheets. Additional Quartz Crystal Microbalance and Atomic Force Microscopy measurements indicated that the detached cells retained their extracellular matrix and that no polyelectrolyte molecules remained bound to the cell sheets. The dissolution of polyelectrolyte multilayers by multivalent ions is a promising approach to cell sheet engineering that could potentially be used for regenerative medicine.

Electrical Detection of Self-Assembled Polyelectrolyte Multilayers by a Thin Film Resistor

The build up of polyelectrolyte multilayers (PEMs) was observed by a silicon-on-insulator (SOI) based thin film resistor. Differently charged polyelectrolytes adsorbing to the sensor surface result in defined potential shifts, which decrease with the number of layers deposited. We model the response of the device assuming electrostatic screening of polyelectrolyte charges by mobile ions within the PEMs. The Debye screening length inside the PEMs was found to be increased compared to the value corresponding to the bulk solution. Furthermore the partitioning of mobile ions between the bulk phase and the polyelectrolyte film was employed to calculate the dielectric constant of the PEMs and the concentration of mobile charges.