Polyelectrolyte Multilayer Films Research Articles

Combinatorial Research of Molecular Technologies and Surface Nanostructures Applied to the Development of Antifouling Coatings.

Contact antimicrobial coatings have been a subject of increasing interest partly because of the contribution of biocide release coatings to antibiotic resistance. The surface hydrophobicity of these coatings can enhance their effectiveness and stability. In this work, polyethyleneimine (PEI) was quaternized with 1-bromoalkane and iodomethane, and a concept for antimicrobial coatings was developed on the basis of the polyelectrolyte multilayered films. The multilayered films were endowed with antibacterial property by grafting modified polycation (higher charge density) and with fouling-release property by constructing microstructures and nanostructures with low surface energy (long alkyl chains). The resultant polycation-coated substrates were able to kill the encountered bacterial cells on contact, and to release the dead bacteria and organic particles. The conclusion demonstrated that the microbicidal functionality could be imparted onto surfaces using layer-by-layer (LbL) self-assembly technology by using the right combination of molecular technologies and surface nanostructures, as well as the assembly and/or post-assembly experimental technical factors.

Controlled allylation of polyelectrolytes: a deep insight into chemical aspects and their applicability as building blocks for robust multilayer coatings

Abstract Polyelectrolytes (PEs) bearing easily derivatizable functions for possible post-modification under mild conditions can find a broad range of applications in various fields. The present paper describes the successful controlled side-chain allylation of two types of PEs: polyamine-based polycations, i.e. poly(allylamine hydrochloride) (PAH) and branched polyethyleneimine (PEI), and strong polyanions, i.e. poly(sodium vinyl sulfonate) (PVS) and poly(sodium 4-styrene sulfonate) (PSS). PSS has been largely investigated in the literature, while PVS is much less commonly explored. The allylation of each type presents its own drawback, i.e. heterogeneous reaction in the case of strong polyanions and instability of partially protonated allylated polyamine products. Nevertheless, all encountered difficulties could be solved and thoroughly elucidated by different experimental tests. This partial allyl-functionalization does not affect the electrolytic properties of the newly allylated PEs, as evidenced by the effective construction of two series of polyelectrolyte multilayer (PEM) films, namely PEI-ene (PSS-ene/PAH-ene)4 and PEI-ene (PVS-ene/PAH-ene)4, the latter being one of the rare examples developed in the literature. The presence of allyl groups on the PE side-chains allows for the stabilization of the resulting PEM films via thiol-ene photo-crosslinking in the presence of a water-soluble dithiol crosslinker. In order to fix permanently the resulting crosslinked PEM films on substrates, the covalent crosslinking occurs not only between different C=C bonds on PE layers but also with those present on substrates preliminarily functionalized with allyl groups via sulfur–gold chemistry. The robustness of both resulting crosslinked PEM films under strongly basic solution (pH 14) is validated by Quartz Crystal Microbalance (QCM) measurements. The versatility and effectiveness of the present approach is expected to find potential applications in different scientific and technological fields.

RETRACTED ARTICLE: Formation of polyelectrolyte multilayer films with controlled wettability via layer-by-layer electric-assembly

Taking the positive charged poly (diallyldimethylammonium chloride), PDDA, and negative charged polymaleic acid, PMA, as raw materials, the polyelectrolyte multilayer film, PMF, with oppositely charged surfaces was prepared by the layer-by-layer electric-assembly, LBLEA, method. Experimentally, the applied voltage was varied and the electrostatic force, EF, was controlled in enhancement or reduction, respectively. Results showed that these PMFs have oppositely surface wettability because the PDDA surface was sensitively responded to the voltage increase with EF enhancement to form the hydrophobic C=C structure, and the PMA surface was oppositely sensitively responded to the voltage increase with EF reduction to form the hydrophilic Cl−–COOH structure, respectively. A related mechanism has been discussed by investigating the effect of voltage increase on the surface tension of these two polyelectrolyte solutions.

Nanocomposite multifunctional polyelectrolyte thin films with copper nanoparticles as the antimicrobial coatings

The work presents the formation and physicochemical characterization of polyelectrolyte-copper nanocomposite coatings using: poly(diallyldimethylammonium chloride) (PDADMAC) as a polycation, poly(sodium 4-styrenesulfonate)(PSS) as a polyanion and negatively charged copper nanoparticles (CuNPs) to obtain biocompatible surfaces with an antibacterial functionality. The mass and thickness of composite films were investigated by the quartz crystal microbalance with dissipation monitoring (QCM-D) and the ellipsometry whereas, the structure and morphology of coatings were examined using scanning electron microscopy (SEM). The increase of the UV–Vis absorption confirmed the formation of the consecutive layers of the film. Antibacterial activity of the coatings was tested on a representative Gram-positive bacteria strain, Staphylococcus aureus. The microbiological tests were performed and bacteria visualized using fluorescent staining and microscopic technique. It was demonstrated that nanostructured films had antibacterial properties, which makes polyelectrolyte multilayer films containing copper an interesting material in biomedical applications area, e.g., for the prevention of microbial deposition on surfaces.

Surface modification of polyethylene naphthalate substrates by ultraviolet light-irradiation and assembling multilayers and their application in electroless deposition: The chemical and physical properties of the stratified structure

Electroless metal deposition on polymer surface is useful for fabricating metallic patterns. The surfaces of polyethylene naphthalate (PEN) substrates were modified by ultraviolet (UV) light -irradiation and layer-by-layer assembly of polyelectrolyte multilayer thin films, and then nickel and copper films were electrolessly deposited on the substrate surfaces to form the stratified structure, PEN-substrate/multilayer/metal-film. The chemical and physical properties of the modified layer in the substrate surfaces were studied by X-ray photoelectron spectroscopy, nanoindentation test, and measuring contact angle. The properties of the UV-irradiated surface layer depended on the condition of surface modification and affected the adhesion of the deposited metal film. Adhesive nickel films were deposited on the UV (254 nm)-irradiated PEN substrates that have thin modified layers compatible with the multilayers. In contrast, no adhesive nickel films were deposited on the substrate surfaces having thicker and fragile modified layers. These contrasting results are originated from the oxygenation and crosslinking of the polymer chains in the substrate surface layers, and reactive species formed by the UV irradiation induce the oxygenation and crosslinking. The properties of the modified substrate-surface play an important role for depositing adhesive metal films.

Alginate/chitosan multilayer films coated on IL-4-loaded TiO2 nanotubes for modulation of macrophage phenotype

Macrophage phenotype conversion is crucial for improving post-traumatic angiogenesis and tissue repair. Biomaterials with the ability of skewing macrophage phenotype have attracted widespread attention in the field of tissue engineering. The aim of this study was to transform macrophage phenotype by a three-step process; anodizing, drug loading and coating with polyelectrolyte multilayer (PEM) films. Interleukin (IL)-4, an anti-inflammatory cytokine, was loaded into titania nanotubes (TNTs) on the titanium surface. Subsequently, sodium alginate (ALG) and chitosan (CS) were alternately assembled onto IL-4-loaded TNTs and cross-linked with genipin/calcium chloride, finally forming cross-linked PEM films. The IL-4 release profile and cellular immune response of the modified surface was investigated. In the simulated biological solution, only 20% of IL-4 were detected in the first 3 days, with a sustained release of approximately 5 ng over 10 days. The results of gene expression and protein secretion in macrophages indicated that IL-4-loaded PEM films significantly attenuated the inflammatory activity of macrophages at the later stage through down-regulating the mRNA and protein levels of inflammatory markers. In summary, IL-4 was controlled released from the cross-linked PEM films deposited on the nanotubes, leading to the temporal conversion of macrophage phenotype.

Proliferation and osteogenic differentiation of human mesenchymal stem cells on cross‐linked polypeptide multilayer films

Polyelectrolyte multilayer film is an emerging method for substrate coating to regulate cellular behaviors. This material allows for modulation of thickness, stiffness, and adhesiveness. In this study, human mesenchymal stem cells (hMSCs) were cultured on polypeptide multilayer films built up by the alternate deposition of cationic poly‐L‐lysine (PLL) and anionic poly‐L‐glutamic acid (PLGA), cross‐linked with EDC/sulfo‐NHS, and coated with type I collagen. The in‐vitro degradation of the cross‐linked PLL/PLGA films in the presence or absence of hMSCs were followed by fluorimetry after labeling of the outermost PLL layer with FITC. Cell proliferation was measured by CyQuant proliferation assay and osteogenic differentiation was evaluated by q‐PCR of osteogenic specific genes such as ALP, OCN, and OPN. The results showed that these cross‐linked films, with or without hMSCs on top of them, were quite stable in the culture medium and not subjected to degradation at least for a few weeks. While hMSCs maintained similar attachment and spreading behavior regardless of layer number (1–6 layers) of films, they demonstrated better proliferation rate on even number layer of films, where the top layers are PLGA films. In addition, compared with cells cultured on polystyrene culture wells and treated with osteogenic induction medium, hMSCs cultured on 6‐layer cross‐linked PLL/PLGA films showed a significant increase in the osteogenic differentiation rate. Our observations indicate a feasible way to manipulate stem cell behavior on polypeptide multilayer films by changing the number of layers, the outermost polypeptide layer, and the concentration of cross‐linkers.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Alginate/chitosan multilayer films coated on IL-4-loaded TiO2 nanotubes for modulation of macrophage phenotype.

Macrophage phenotype conversion is crucial for improving post-traumatic angiogenesis and tissue repair. Biomaterials with the ability of skewing macrophage phenotype have attracted widespread attention in the field of tissue engineering. The aim of this study was to transform macrophage phenotype by a three-step process; anodizing, drug loading and coating with polyelectrolyte multilayer (PEM) films. Interleukin (IL)-4, an anti-inflammatory cytokine, was loaded into titania nanotubes (TNTs) on the titanium surface. Subsequently, sodium alginate (ALG) and chitosan (CS) were alternately assembled onto IL-4-loaded TNTs and cross-linked with genipin/calcium chloride, finally forming cross-linked PEM films. The IL-4 release profile and cellular immune response of the modified surface was investigated. In the simulated biological solution, only 20% of IL-4 were detected in the first 3 days, with a sustained release of approximately 5 ng over 10 days. The results of gene expression and protein secretion in macrophages indicated that IL-4-loaded PEM films significantly attenuated the inflammatory activity of macrophages at the later stage through down-regulating the mRNA and protein levels of inflammatory markers. In summary, IL-4 was controlled released from the cross-linked PEM films deposited on the nanotubes, leading to the temporal conversion of macrophage phenotype.

Odd–Even Effect on Rotational Dynamics of Spin-Labeled Polyacid Chain Segments in Polyelectrolyte Multilayers

A nitroxide spin label has been covalently attached to the weak polyelectrolyte poly(ethylene-alt-maleic acid) (P(E-alt-MA)) to study the rotational dynamics of the polyacid backbone in swollen polyelectrolyte multilayers (PEMs) formed by P(E-alt-MA) and the oppositely charged weak polycation poly(allylamine hydrochloide) (PAH) by continuous wave electron paramagnetic resonance (EPR) spectroscopy. The growth of the PEM film with increasing number of layers has been monitored by quantitative EPR using the spin-labeled polyanion (SL-P(E-alt-MA)) for the preparation of every polyanion layer. A parabolic growth has been found for PEMs with up to 16 layers. In further experiments the SL-P(E-alt-MA) has been placed in selected layers, and the line shape has been analyzed. A pronounced odd–even effect has been observed, i.e., the rotational dynamics of the P(E-alt-MA) backbone in the PEMs is influenced by the chemical nature of the polyelectrolyte in the terminating layer.

Controlled growth of layer-by-layer assembled polyelectrolyte multilayer films under high electric fields

HypothesisThe application of an external electric Field (E-Field) to control layer-by-layer (LBL) growth of polyelectrolyte multilayers (PEM) typically involves hydrolysis of the water at the electrodes. We hypothesize that by isolating the electrodes from contact with the water, high E-Fields could be used to control the conformation of the polyelectrolytes in the solution phase and thus, enable non-chemical control of the LBL growth. ExperimentalAttenuated total reflectance infrared spectroscopy was used to monitor the bound fraction and adsorbed amount as a function of time for the sequential addition of polyacrylic acid and polydiallyldimethylammonium chloride adsorbed on a TiO2 film under the applied E–Field. FindingsThe direction of the E–Field relative to the TiO2 film controlled the PEM growth, resulting in non-linear growth or decay. In the case of non-linear LBL decay, there was a decrease in adsorbate mass in successive layers to a point of no growth.

Ultra-slow diffusion of hexacyanoferrate anions in poly(diallyldimethyl ammonium chloride)-poly(acrylic acid sodium salt) multilayer films

Polyelectrolyte multilayer (PEM) films display either a linear or an exponential increase of their thickness with increasing the number of polycation/polyanion deposition cycles. Each of these growth regimes is further associated with a specific mode of internal PEM charge compensation: either intrinsic in the case of linearly growing films, or extrinsic for exponentially growing films with incorporation of small ions from the neighbouring electrolyte solution. In this report, we investigate by electrochemistry the charge compensation mechanism operational for poly(diallyldimethyl ammonium chloride)-poly(acrylic acid sodium salt) (PDAMAC-PAA)n films recently found to be out-of-equilibrium immediately after the deposition process despite of their exponential growth mode. It is found here that these films are defined by a negative Donnan potential drop (ca. −160 mV), thus evidencing an extrinsic charge compensation process, and most importantly, by a remarkably slow kinetics for loading of hexacyanoferrate anions, a very unusual property for PEMs with exponential growth. Depending on the film thickness, the diffusion coefficient of the redox probe in the film is found to be of the order of 10−13 − 10−15 cm2 s−1, i.e. about 8 to 10 orders of magnitude less than that typically measured in aqueous solution. This results in a steady state filling of e.g. a 2.8 µm thick PEM film with the redox probe that is achieved after more than 40 h, a feature in line with the typical 4 to 5 days relaxation timescale of the film structure previously determined by atomic force microscopy and Raman micro-spectroscopy analyses.

In vitro evaluation of drug release and antibacterial activity of a silver-loaded wound dressing coated with a multilayer system

The goal of the study was to elaborate an antibacterial silver wound dressing covered by a protective coating that would prevent silver diffusion toward skin without losing its biocide properties. Therefore, non woven polyethyleneterephtalate (PET) textiles were pre-treated by two types of polysaccharides – chitosan and cyclodextrin – both crosslinked with citric acid by a pad/dry/cure process. Both types of resulting thermofixed textiles carrying the citrate crosslinks were then impregnated in silver solution followed by a thermal treatment and were finally coated by Layer-by-Layer (L-b-L) deposition of a polyelectrolyte multilayer (PEM) film consisting of anionic water-soluble poly-cyclodextrin and cationic chitosan. The influence of the process parameters was investigated in terms of silver adsorption capacity, PEM system build-up, silver kinetics of release and antibacterial activity. We demonstrate i) the utility of the intermediate thermal treatment step in the reduction of silver leakage in the polyelectrolyte solutions used in the L-b-L process, ii) that silver adsorption on the preliminary thermofixed layers did not affect the PEM system build-up, iii) the slowing down of silver release kinetic thanks to the PEM coating, iv) the preservation of the antibacterial activity despite the PEM coating.

A Novel Soft Contact Piezo-Controlled Liquid Cell for Probing Polymer Films under Confinement using Synchrotron FTIR Microspectroscopy

Soft polymer films, such as polyelectrolyte multilayers (PEMs), are useful coatings in materials science. The properties of PEMs often rely on the degree of hydration, and therefore the study of these films in a hydrated state is critical to allow links to be drawn between their characteristics and performance in a particular application. In this work, we detail the development of a novel soft contact cell for studying hydrated PEMs (poly(sodium 4-styrenesulfonate)/poly(allylamine hydrochloride)) using FTIR microspectroscopy. FTIR spectroscopy can interrogate the nature of the polymer film and the hydration water contained therein. In addition to reporting spectra obtained for hydrated films confined at the solid-solid interface, we also report traditional ATR FTIR spectra of the multilayer. The spectra (microspectroscopy and ATR FTIR) reveal that the PEM film build-up proceeds as expected based on the layer-by-layer assembly methodology, with increasing signals from the polymer FTIR peaks with increasing bilayer number. In addition, the spectra obtained using the soft contact cell indicate that the PEM film hydration water has an environment/degree of hydrogen bonding that is affected by the chemistry of the multilayer polymers, based on differences in the spectra obtained for the hydration water within the film compared to that of bulk electrolyte.

Chitosan/hyaluronic acid multilayer films are biocompatible substrate for Wharton's jelly derived stem cells.

Discovery of mesenchymal stem cells (MSCs) in various adult human tissues opened the way to new therapeutic strategies involving tissue engineering from these cells. More recently, vascular substitutes have opened the era of vascular engineering by making replacement vessels from purely biological material. The objective of our study was to create a vascular substitute from MSCs using a multilayer polyelectrolyte film based on natural polymers (Chitosan and Hyaluronic Acid). Biocompatibility and cellular behavior were evaluated in this study using MSCs from the Wharton's jelly (WJ) of human umbilical cords. WJ-MSCs adherence was assessed and cells morphology was investigated by Scanning Electron Microscopy (SEM) and actin visualization (Phalloidin). The number of WJ-MSCs seeded on the (CHI/HA)10 films was greater than the number of cells seeded on the collagen, as the spectrophotometric measurement showed a large cell proliferation on (CHI/HA)10 in comparison with collagen. After adhesion, WJ-MSCs showed a fibroblastic morphology on CHI/HA as for control (collagen I). These results were confirmed by cytoskeleton staining. The biocompatibility of WJ-MSCs and (CHI/HA)10 showed the possibility to combine the use of WJ-MSCs and (CHI/HA)10 films in vascular tissue engineering.

Enzymatically Active Polydopamine @ Alkaline Phosphatase Nanoparticles Produced by NaIO4 Oxidation of Dopamine.

Polydopamine (PDA) deposition, obtained from the oxidation of dopamine and other catecholamines, is a universal way to coat all known materials with a conformal coating which can subsequently be functionalized at will. The structural analogies between polydopamine and eumelanin, the black-brown pigment of the skin, were incited to produce stable polydopamine nanoparticles in solution, instead of amorphous precipitates obtained from the oxidation of dopamine. Herein, we demonstrate that size-controlled and colloidally stable PDA-based nanoparticles can be obtained in acidic conditions, where spontaneous auto-oxidation of dopamine is suppressed, using sodium periodate as the oxidant and a protein, like alkaline phosphatase (ALP), as a templating agent. The size of the PDA@ALP nanoparticles depends on the dopamine/enzyme ratio and the obtained particles display enzymatic activity of alkaline phosphatase, with an activity extending up to two weeks after particle synthesis. The PDA@ALP nanoparticles can be engineered in polyelectrolyte multilayered films to potentially design model biosensors.

Mesenchymal stem cell interacted with PLCL braided scaffold coated with poly-l-lysine/hyaluronic acid for ligament tissue engineering.

The challenge of finding an adapted scaffold for ligament tissue engineering remains unsolved after years of researches. A technology to fabricate a multilayer braided scaffold with flexible and elastic poly (l-lactide-co-caprolactone) (PLCL 85/15) has been recently pioneered by our team. In this study, polyelectrolyte multilayer films (PEM) with poly-l-lysine (PLL)/ hyaluronic acid (HA) were deposited on this scaffold. After PEM modification, polygonal (PLL) and particle-like (HA) structures were present on the braided scaffold with no significant variation of fibers Young's modulus. Wharton's jelly mesenchymal stem cells (WJ-MSC) and bone marrow mesenchymal stem cells (BM-MSC) showed good metabolic activity on scaffolds. They presented a spindled shape along the fiber longitudinal direction, and crossed the fibers to form cell bridges. Collagen type I, collagen type III, and tenascin-C secreted by MSCs were detected on day 14. Moreover, one-layer modified scaffold presented increased chemotaxis. As a conclusion, our results indicate that this braided PLCL scaffold with one-layer PEM modification shows inspiring potential with satisfying mechanical properties and biocompatibility. It opens new perspectives to incorporate growth factors within PEM-modified braided PLCL scaffold for ligament tissue engineering and to recruit endogenous cells after implantation. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 3042-3052, 2018.

On the Infectivity of Bacteriophages in Polyelectrolyte Multilayer Films: Inhibition or Preservation of Their Bacteriolytic Activity?

Antibiotic resistance in bacterial cells has motivated the scientific community to design new and efficient (bio)materials with targeted bacteriostatic and/or bactericide properties. In this work, a series of polyelectrolyte multilayer films differing in terms of polycation-polyanion combinations are constructed according to the layer-by-layer deposition method. Their capacities to host T4 and φx174 phage particles and maintain their infectivity and bacteriolytic activity are thoroughly examined. It is found that the macroscopic physicochemical properties of the films, which includes film thickness, swelling ratio, or mechanical stiffness (as derived by atomic force microscopy and spectroscopy measurements), do not predominantly control the selectivity of the films for hosting infective phages. Instead, it is evidenced that the intimate electrostatic interactions locally operational between the loaded phages and the polycationic and polyanionic PEM components may lead to phage activity reduction and preservation/enhancement, respectively. It is argued that the underlying mechanism involves the screening of the phage capsid receptors (operational in cell recognition/infection processes) because of the formation of either polymer-phage hetero-assemblies or polymer coating surrounding the bioactive phage surface.

Elastic to Plastic Deformation in Uniaxially Stressed Polylelectrolyte Multilayer Films

Polyelectrolyte multilayer (PEM) are thin polymeric films produced by alternating adsorption of positively and negatively charged polyelectrolytes (PE) on a substrate. These films are considered drug delivery agents as well as coating material for implants, due to their antibiofouling and biologically benign properties. For these reasons the film mechanical properties as well as response to mechanical stress are important measurement parameters. Especially intriguing is the correlation of the mechanical properties of PEM on macroscopic level with the structure of PEM on molecular level, which is addressed here for the first time. This study investigates PEM from PDADMA/PSS produced by spraying technique with neutron and X-ray reflectometry. Reflectometry technique provides precise information on thickness and density (i.e., electron density or scattering length density, respectively), and, this way, allows to conclude on changes in film composition. Thus, neutron and X-ray reflectometry technique is suitable to investigate the overall and the internal transformations, which PEM films might undergo upon exposure to mechanical load. During uniaxial elongation two regimes of PEM-deformation can be observed: An elastic regime at small elongations (below ca. 0.2%), which is characterized by a reversible change of film thickness, and a plastic regime with a permanent change above this limit. Both regimes have in common, that the mechanical load induces an increase of the film thickness, which is accompanied by an uptake of water from the surrounding atmosphere. The strain causes a molecular rearrangement within the PEM-structure of stratified layers, which, even in elastic regime, is permanent, although the thickness change remains reversible.

Electrical conductivity enhancement and wettability modification of (PDDA/PEDOT:PSS)n multilayer film

Conductive polyelectrolyte multilayer films composed of conductive anionic poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) and insulating cationic polydiallyldimethylammonium chloride (PDDA) were successfully prepared by layer-by-layer method. The (PDDA/PEDOT:PSS)n multilayer thickness is affected by the PDDA concentration ranging from 0.25 g.L−1 to 1 g.L−1 as well as the number of deposited bilayers and the type of salts used as electrolyte (BaCl2 or NaCl). More precisely, film thickness measured by profilometry increases with PDDA concentration, number of adsorbed bilayers and with the presence of Ba2+ cations. From UV–Visible absorbance spectroscopy, we showed that the amount of adsorbed PEDOT:PSS is greater when PDDA concentration increases and that PEDOT is still incorporated into the multilayer film especially when divalent ions are employed to improve the film growth. Water contact angles were measured on (PDDA/PEDOT:PSS)n films with PEDOT:PSS as the outerlayer. Films are more hydrophobic in the presence of Ba2+ which is probably due to a modification of the PEDOT:PSS core/shell structure. A percolation threshold leading to electrical conduction was determined as a function of the number of adsorbed bilayers. The effect of several parameters such as PDDA concentration, type of salt and temperature on conductivity and activation energy was investigated.

Inhibiting Pathogen Surface Adherence by Multilayer Polyelectrolyte Films Functionalized with Glucofuranose Derivatives.

Inhibiting pathogenic bacterial adherence on surfaces is an ongoing challenge to prevent the development of biofilms. Multilayer polyelectrolyte films are feasible antibacterial materials. Here, we have designed new films made of carbohydrate polyelectrolytes to obtain antibacterial coatings that prevent biofilm formation. The polyelectrolyte films were constructed from poly(maleic anhydride- alt-styrene) functionalized with glucofuranose derivatives and quaternized poly(4-vinylpyridine) N-alkyl. These films prevent Pseudomonas aeruginosa and Salmonella Typhimurium, two important bacterial contaminants in clinical environments, from adhering to surfaces. When the film was composed of more than 10 layers, the bacterial population was greatly reduced, while the bacteria remaining on the film were morphologically damaged, as atomic force microscopy revealed. The antibacterial capacity of the polyelectrolyte films was determined by the combination of thickness, wettability, surface energy, and most importantly, the conformation that polyelectrolytes adopt the function of nature of the carbohydrate group. This polyelectrolyte film constitutes the first green approach to preventing pathogenic bacterial surface adherence and proliferation without killing the bacterial pathogen.