Using flow to switch the valency of bacterial capture on engineered surfaces containing immobilized nanoparticles

Toward an understanding of nanoparticle-bacterial interactions and the development of sensors and other substrates for controlled bacterial adhesion, this article describes the influence of flow on the initial stages of bacterial capture (Staphylococcus aureus) on surfaces containing cationic nanoparticles. A PEG (poly(ethylene glycol)) brush on the surface around the nanoparticles sterically repels the bacteria. Variations in ionic strength tune the Debye length from 1 to 4 nm, increasing the strength and range of the nanoparticle attractions toward the bacteria. At relatively high ionic strengths (physiological conditions), bacterial capture requires several nanoparticle-bacterial contacts, termed "multivalent capture". At low ionic strength and gentle wall shear rates (on the order of 10 s(-1)), individual bacteria can be captured and held by single surface-immobilized nanoparticles. Increasing the flow rate to 50 s(-1) causes a shift from monovalent to divalent capture. A comparison of experimental capture efficiencies with statistically determined capture probabilities reveals the initial area of bacteria-surface interaction, here about 50 nm in diameter for a Debye length κ(-1) of 4 nm. Additionally, for κ(-1) = 4 nm, the net per nanoparticle binding energies are strong but highly shear-sensitive, as is the case for biological ligand-receptor interactions. Although these results have been obtained for a specific system, they represent a regime of behavior that could be achieved with different bacteria and different materials, presenting an opportunity for further tuning of selective interactions. These finding suggest the use of surface elements to manipulate individual bacteria and nonfouling designs with precise but finite bacterial interactions.     

Sensitivity of protein adsorption to architectural variations in a protein-resistant polymer brush containing engineered nanoscale adhesive sites

Patchy polymer brushes contain nanoscale (5-15 nm) adhesive elements, such as polymer coils or nanoparticles, embedded at their base at random positions on the surface. The competition between the brush's steric (protein resistant) repulsions and the attractions from the discrete adhesive elements provides a precise means to control bioadhesion. This differs from the classical approach, where functionality is placed on the brush's periphery. The current study demonstrates the impact of poly(etheylene glycol) (PEG) brush architecture and ionic strength on fibrinogen adsorption on brushes containing embedded poly-l-lysine (PLL, 20K MW) coils or "patches". The consistent appearance of a fibrinogen adsorption threshold, a minimum loading of patches on the surface, below which protein adsorption does not occur, suggests multivalent protein capture: Adsorbing proteins simultaneously engage several patches. The surface composition (patch loading) at the threshold is extremely sensitive to the brush height and ionic strength, varying up to a factor of 5 in the surface loading of the PLL patches (~50% of the range of possible surfaces). Variations in ionic strength have a similar effect, with the smallest thresholds seen for the largest Debye lengths. While trends with brush height were the clearest and most dominant, consideration of the PEG loading within the brush or its persistence length did not reveal a critical brush parameter for the onset of adsorption. The lack of straightforward correlation on brush physics was likely a result of multivalent binding, (producing an additional dependence on patch loading), and might be resolved for univalent adsorption onto more strongly binding patches. While studies with similar brushes placed uniformly on a surface revealed that the PEG loading within the brush is the best indicator of protein resistance, the current results suggest that brush height is more important for patchy brushes. Likely the interactions producing brush extension normal to the interface act similarly to drive lateral tether extension to obstruct patches.     

Single component and selective competitive protein adsorption in a patchy polymer brush: opposition between steric repulsions and electrostatic attractions

This work explores the use of "patchy" polymer brushes to control protein adsorption rates on engineered surfaces and to bind targeted species from protein mixtures with high selectivity but without invoking molecular recognition. The brushes of interest contain embedded cationic "patches" composed of isolated adsorbed poly(l-lysine) coils (PLL) that are about 10 nm in diameter and are randomly arranged on a silica substrate. Around these patches is a protein-resistant poly(ethylene glycol) (PEG) brush that is formed from the adsorption of a PLL-g-PEG graft copolymer on the remaining silica surface. Electrostatic attractions between individual cationic patches and the negative regions of approaching proteins may be energetically insufficient to bind proteins. Furthermore, protein-patch attractions are reduced by steric repulsions between proteins and the PEG brush. We show that protein adsorption, gauged by ultimate short-term coverages and by the initial protein adsorption rate, exhibits an adhesion threshold: pure PEG brushes of the architectures employed here and brushes containing sparse loadings of PLL patches do not adsorb protein. Above a critical PLL patch loading or threshold, protein adsorption proceeds, often dramatically. The PLL patch thresholds are specific to the protein of interest, allowing surfaces to be engineered to adhesively discriminate different proteins within a mixture. The separation achieved is remarkably sharp: one protein adsorbs, but the second is completely rejected from the interface. The surfaces in this study, by virtue of their well-controlled and well-characterized patchy nature, distinguish themselves from multicomponent brushes or brushes used to end-tether peptide sequences and nucleotides.     

Synthesis and characterization of surface-grafted polyacrylamide brushes and their inhibition of microbial adhesion

A method is presented to prevent microbial adhesion to solid surfaces exploiting the unique properties of polymer brushes. Polyacrylamide (PAAm) brushes were grown from silicon wafers by atom transfer radical polymerization (ATRP) using a three-step reaction procedure consisting of immobilization of a coupling agent gamma-aminopropyltriethoxysilane, anchoring of an ATRP initiator 4-(chloromethyl)benzoyl chloride, and controlled radical polymerization of acrylamide. The surfaces were characterized by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, ellipsometry, and contact-angle measurements. The calculated grafting density pointed to the presence of a dense and homogeneous polymer brush. Initial deposition rates, adhesion after 4 h, and detachment of two bacterial strains (Staphylococcus aureus ATCC 12600 and Streptococcus salivarius GB 24/9) and one yeast strain (Candida albicans GB 1/2) to both PAAm-coated and untreated silicon surfaces were investigated in a parallel plate flow chamber. A high reduction (70-92%) in microbial adhesion to the surface-grafted PAAm brush was observed, as compared with untreated silicon surfaces. Application of the proposed grafting method to silicone rubbers may offer great potential to prevent biomaterials-centered infection of implants.     

Nanosegregated polymeric domains on the surface of Fe3O4@SiO2 particles

Multifunctional, biocompatible, and brush‐grafted poly(ethylene glycol)/poly(ε‐caprolactone) (PEG/PCL) nanoparticles have been synthesized, characterized, and used as vehicles for transporting hydrophobic substances in water. For anchoring the polymer mixed brushes, we used magnetic‐silica particles of 40 nm diameter produced by the reverse microemulsion method. The surface of the silica particle was functionalized with biocompatible polymer brushes, which were synthesized by the combination of “grafting to” and “grafting from” techniques. PEG was immobilized on the particles surface, by “grafting to,” whereas PCL was growth by ROP using the “grafting from” approach. By varying the synthetic conditions, it was possible to control the amount of PCL anchored on the surface of the nanoparticles and consequently the PEG/PCL ratio, which is a vital parameter connected with the arrangement of the polymer brushes as well as the hydrophobic/hydrophilic balance of the particles. Thus, adjusting the PEG/PCL ratio, it was possible to obtain a system formed by PEG and PCL chains grafted on the particle's surface that collapsed in segregated domains depending on the solvent used. For instance, the nanoparticles are colloidally stable in water due to the PEG domains and at the same time are able to transport, entrapped within the PCL portion, highly water‐insoluble drugs. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2966–2975     

Cellular responses to patterned poly(acrylic acid) brushes

We use patterned poly(acrylic acid) (PAA) polymer brushes to explore the effects of surface chemistry and topography on cell-surface interactions. Most past studies of surface topography effects on cell adhesion have focused on patterned feature sizes that are larger than the dimensions of a cell, and PAA brushes have been characterized as cell repellent. Here we report cell adhesion studies for RBL mast cells incubated on PAA brush surfaces patterned with a variety of different feature sizes. We find that when patterned at subcellular dimensions on silicon surfaces, PAA brushes that are 30 or 15 nm thick facilitate cell adhesion. This appears to be mediated by fibronectin, which is secreted by the cells, adsorbing to the brushes and then engaging cell-surface integrins. The result is detectable accumulation of plasma membrane within the brushes, and this involves cytoskeletal remodeling at the cell-surface interface. By decreasing brush thickness, we find that PAA can be 'tuned' to promote cell adhesion with down-modulated membrane accumulation. We exemplify the utility of patterned PAA brush arrays for spatially controlling the activation of cells by modifying brushes with ligands that specifically engage IgE bound to high-affinity receptors on mast cells.     

Macroscale Chemotaxis from a Swarm of Bacteria‐Mimicking Nanoswimmers

Inspired by the dynamics of bacterial swarming, we report a swarm of polymer‐brush‐grafted, glucose‐oxidase‐powered Janus gold nanoswimmers with a positive, macroscale chemotactic behavior. These nanoswimmers are prepared through the grafting of polymer brushes onto one side of gold nanoparticles, followed by functionalization with glucose oxidase on the other side. The resulting polymer‐brush‐functionalized Janus gold nanoswimmers exhibit efficient propulsion with a velocity of up to approximately 120 body lengths s^?1 in the presence of glucose. The comparative analysis of their kinematic behavior reveals that the grafted polymer brushes significantly improve the translational diffusion of Janus gold nanoswimmers. Particularly, these bacteria‐mimicking Janus gold nanoswimmers display a collectively chemotactic motion along the concentration gradient of a glucose resource, which could be observed at the macroscale.     

Microbial adhesion to poly(ethylene oxide) brushes: influence of polymer chain length and temperature

Glass surfaces were modified by end-grafting poly(ethylene oxide) (PEO) chains having molecular weights of 526, 2000, or 9800 Da. Characterization using water contact angles, ellipsometry, and X-ray photoelectron spectroscopy confirmed the presence of the PEO brushes on the surface with estimated lengths in water of 2.8-, 7.5-, and 23.7-nm, respectively. Adhesion of two bacterial (Staphylococcus epidermidis and Pseudomonas aeruginosa) and two yeast (Candida albicans and Candida tropicalis) strains to these brushes was studied and compared to their adhesion to bare glass. For the bacterium P. aeruginosa and the yeast C. tropicalis, adhesion to the 2.8-nm brush was comparable to their adhesion on bare glass, whereas adhesion to the 7.5- and 23.7-nm brushes was greatly reduced. For S. epidermidis, adhesion was only slightly higher to the 2.8-nm brush than that to the longer brushes. Adhesion of the yeast C. albicans to the PEO brushes was lower than that to glass, but no differences in adhesion were found between the three brush lengths. After passage of an air bubble, nearly all microorganisms adhering to a brush were removed, irrespective of brush length, whereas retention of the adhering organisms on glass was much higher. No significant differences were found in adhesion nor retention between experiments conducted at 20 and those conducted at 37 degrees C.     

Influence of brush length of PVP chains immobilized on silicon wafers on their blood compatibility

In this study, the influence of variations in chain length of polyvinylpyrrolidone (PVP) brushes on the blood compatibility of silicon wafer surfaces to which they were chemically attached was studied. Si surfaces were functionalized with various lengths of PVP brush using atom transfer radical polymerization technology and confirmed by elliptical polarized light, atom force microscopy, and X‐ray photoelectron spectroscopy. The blood compatibility of these biointerfaces were systematically investigated by measuring protein adsorption, clotting time, platelet adhesion, contact activation, and complement activation. The results indicate that the hemocompatibility of the surfaces was highly related to PVP brush chain length and hydrophilicity of the surfaces. Our results contribute to rational biointerface design for specific biomedical applications. The results reveal that the PVP brushes with a long chain length have great potential for blood contacting applications due to their reduced protein absorption and cell activation following its contact with blood.     

Chemical Design of Non‐Ionic Polymer Brushes as Biointerfaces: Poly(2‐oxazine)s Outperform Both Poly(2‐oxazoline)s and PEG

The era of poly(ethylene glycol) (PEG) brushes as a universal panacea for preventing non‐specific protein adsorption and providing lubrication to surfaces is coming to an end. In the functionalization of medical devices and implants, in addition to preventing non‐specific protein adsorption and cell adhesion, polymer‐brush formulations are often required to generate highly lubricious films. Poly(2‐alkyl‐2‐oxazoline) (PAOXA) brushes meet these requirements, and depending on their side‐group composition, they can form films that match, and in some cases surpass, the bioinert and lubricious properties of PEG analogues. Poly(2‐methyl‐2‐oxazine) (PMOZI) provides an additional enhancement of brush hydration and main‐chain flexibility, leading to complete bioinertness and a further reduction in friction. These data redefine the combination of structural parameters necessary to design polymer‐brush‐based biointerfaces, identifying a novel, superior polymer formulation.     

Polymer brushes grafted to "passivated" silicon substrates using click chemistry

We present herein a versatile method for grafting polymer brushes to passivated silicon surfaces based on the Cu(I)-catalyzed Huisgen 1,3-dipolar cycloaddition (click chemistry) of omega-azido polymers and alkynyl-functionalized silicon substrates. First, the "passivation" of the silicon substrates toward polymer adsorption was performed by the deposition of an alkyne functionalized self-assembled monolayer (SAM). Then, three tailor-made omega-azido linear brush precursors, i.e., PEG-N3, PMMA-N3, and PS-N3 (Mn approximately 20,000 g/mol), were grafted to alkyne-functionalized SAMs via click chemistry in tetrahydrofuran. The SAM, PEG, PMMA, and PS layers were characterized by ellipsometry, scanning probe microscopy, and water contact angle measurements. Results have shown that the grafting process follows the scaling laws developed for polymer brushes, with a significant dependence over the weight fraction of polymer in the grafting solution and the grafting time. The chemical nature of the brushes has only a weak influence on the click chemistry grafting reaction and morphologies observed, yielding polymer brushes with thickness of ca. 6 nm and grafting densities of ca. 0.2 chains/nm2. The examples developed herein have shown that this highly versatile and tunable approach can be extended to the grafting of a wide range of polymer (pseudo-) brushes to silicon substrates without changing the tethering strategy.     

Binary hairy nanoparticles: Recent progress in theory and simulations

Binary polymer brushes, including mixed homopolymer brushes and diblock copolymer brushes, are an attractive class of environmentally responsive nanostructured materials. Owing to microphase separation of the two chemically distinct components in the brush, multifaceted nanomaterials with functionalized and patterned surfaces can be obtained. This review summarizes recent progress on the theory and simulations related to binary polymer brushes grafted to flat, spherical, and cylindrical substrates, with a focus on patterned morphologies of multifaceted hairy nanoparticles, an intriguing class of hybrid nanostructured particles (e.g., nanospheres and nanorods). In particular, powerful field theory and particle-based simulations suitable for revealing novel structures on these patterned surfaces, including self-consistent field theory and dissipative particle dynamics simulations, are emphasized. The unsolved yet critical issues in this research field, such as dynamic response of binary polymer brushes to environmental stimuli and the hierarchical self-assembly of binary hairy nanoparticles, are briefly discussed. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 1583–1599     

Bioconjugation of protein-repellent zwitterionic polymer brushes grafted from silicon nitride

A new method for attaching antibodies to protein-repellent zwitterionic polymer brushes aimed at recognizing microorganisms while preventing the nonspecific adsorption of proteins is presented. The poly(sulfobetaine methacrylate) (SBMA) brushes were grafted from α-bromo isobutyryl initiator-functionalized silicon nitride (Si(x)N(4), x ≥ 3) surfaces via controlled atom-transfer radical polymerization (ATRP). A trifunctional tris(2-aminoethyl)amine linker was reacted with the terminal alkylbromide of polySBMA chains. N-Hydroxysuccinimide (NHS) functionalization was achieved by reacting the resultant amine-terminated polySBMA brush with bifunctional suberic acid bis(N-hydroxysuccinimide ester). Anti-Salmonella antibodies were subsequently immobilized onto polySBMA-grafted Si(x)N(4) surfaces through these NHS linkers. The protein-repellent properties of the polySBMA-grafted surface after antibody attachment were evaluated by exposing the surfaces to Alexa Fluor 488-labeled fibrinogen (FIB) solution (0.1 g·L(-1)) for 1 h at room temperature. Confocal laser scanning microscopy (CLSM) images revealed the minimal adsorption of FIB onto the antibody-coated polySBMA in comparison with that of antibody-coated epoxide monolayers and also bare Si(x)N(4) surfaces. Subsequently, the interaction of antibodies immobilized onto polySBMA with SYTO9-stained Salmonella solution without using blocking solution was examined by CLSM. The fluorescent images showed that antibody-coated polySBMA efficiently captured Salmonella with only low background noise as compared to antibody-coated monolayers lacking the polymer brush. Finally, the antibody-coated polySBMA surfaces were exposed to a mixture of Alexa Fluor 647-labeled FIB and Salmonella without the prior use of a blocking solution to evaluate the ability of the surfaces to capture bacteria while simultaneously repelling proteins. The fluorescent images showed the capture of Salmonella with no adsorption of FIB as compared to antibody-coated epoxide surfaces, demonstrating the potential of the zwitterionic layer in preventing the nonspecific adsorption of the proteins during the detection of bacteria in complex matrices.     

Photopatterned polymer brushes promoting cell adhesion gradients

The ability to spatially control cellular adhesion in a continuous manner on a biocompatible substrate is an important factor in designing new biomaterials for use in wound healing and tissue engineering applications. In this work, a novel method of engineering cell-adhesive RGD-ligand density gradients to control specific cell adhesion across a substrate is presented. Polymer brushes exhibiting spatially defined gradients in chain density are created and subsequently functionalized with RGD to create ligand density gradients capable of inducing cell adhesion on an otherwise weakly adhesive substrate. Cell studies indicate that these ligand-functionalized surfaces are noncytotoxic, with cellular adhesion increasing with RGD-ligand density across the gradient brush surface.     

Enhanced sampling of bacteria and their biofilms from food contact surfaces with robust cationic modified swabs

The swab sampling method combined with detection approaches is a common approach used to monitor pathogenic microbes in food facilities and to determine the adequateness of regular cleaning and sanitation processes. Thus, the efficiency of a swab material for both the capture and release of bacteria has a significant impact on the detection of pathogens. A novel functionalized cotton swab was developed based on cationic functionalization of the cotton swab for improving the sampling of bacteria from surfaces. The cationic modified swab was fabricated using UV-induced grafting of cationic monomer (METAC) onto a regular cotton swab. The prepared cationic cotton swabs displayed a persistent positive charge regardless of the pH conditions. The cationic swabs demonstrated 150–200% enhancement in the swab performance for Gram-positive and Gram-negative bacteria under any sampling conditions compared to the regular cotton swab as well as a significant enhancement in the bacteria sampling at the low bacterial concentrations. Furthermore, the cationic cotton swabs showed significant improvement at least 4 folds in the sampling performance of the bacterial biofilm from the stainless-steel surfaces compared to the cotton swabs. These results illustrate the role of modified swabs in enhancing the sampling of bacteria from contact surfaces and their potential impact on improved monitoring of microbial contamination and verification of surface sanitization.

     

Ionic effects in collapse of polyelectrolyte brushes

We investigated the effect of counterion valence on the structure and swelling behavior of polyelectrolyte brushes using a nonlocal density functional theory that accounts for the excluded-volume effects of all ionic species and intrachain and electrostatic correlations. It was shown that charge correlation in the presence of multivalent counterions results in collapse of a polyelectrolyte brush at an intermediate polyion grafting density. At high grafting density, the brush reswells in a way similar to that in a monovalent ionic solution. In the presence of multivalent counterions, the nonmonotonic swelling of a polyelectrolyte brush in response to the increase of the grafting density can be attributed to a competition of the counterion-mediated electrostatic attraction between polyions with the excluded-volume effect of all ionic species. While a polyelectrolyte brush exhibits an "osmotic brush" regime at low salt concentration and a "salted brush" regime at high salt concentration regardless of the counterion valence, we found a smoother transition as the valence of the counterions increases. As observed in recent experiments, a quasi-power-law dependence of the brush thickness on the concentration ratio can be identified when the monovalent counterions are replaced with trivalent counterions at a fixed ionic strength.     

Symmetric pH-dependent swelling and antibacterial properties of chitosan brushes

Charged polymer brushes grafted to surfaces are of great interest for antibacterial, biosensor, nanofluidic, and drug delivery applications. In this paper, chitosans with quaternary ammonium salts, CH-Q, were immobilized on silicon oxide and characterized by in situ quartz-crystal microbalance with dissipation, QCM-D, and in situ spectroscopic ellipsometry, SE. Both methods showed that the hydrated film exhibited a minimum thickness of ~40 nm near pH 5 that increased strongly (up to ~80 nm) at lower and higher pH. This symmetric swelling is surprising because CH-Q is a cationic polymer. The CH-Q grafted layer was stable for pH values from 3 to 8 and exhibited rapid, reversible swelling and contraction upon varying pH. The CH-Q layer also reduced S. aureus colonization by a factor of ~30× compared to bare silicon oxide and an amine terminated silane grafted to silicon oxide. This antibacterial characteristic of CH-Q is attributed to the quaternary ammonium salts and the flexible polymer brush.     

Selective Adsorption of Functionalized Nanoparticles to Patterned Polymer Brush Surfaces and Its Probing with an Optical Trap

The site‐specific attachment of nanoparticles is of interest for biomaterials or biosensor applications. Polymer brushes can be used to regulate this adsorption, so the conditions for selective adsorption of phosphonate‐functionalized nanoparticles onto micropatterned polymer brushes with different functional groups are optimized. By choosing the strong polyelectrolytes poly(3‐sulfopropyl methacrylate), poly(sulfobetaine methacrylate), and poly[2‐(methacryloyloxy)ethyl trimethylammonium chloride], it is possible to direct the adsorption of nanoparticles to specific regions of the patterned substrates. A pH‐dependent adsorption can be achieved by using the polycarboxylate brush poly(methacrylic acid) (PMAA) as substrate coating. On PMAA brushes, the nanoparticles switch from attachment to the brush regions to attachment to the grooves of a patterned substrate on changing the pH from 3 to 7. In this manner, patterned substrates are realized that assemble nanoparticles in pattern grooves, in polymer brush areas, or substrates that resist the deposition of the nanoparticles. The nanoparticle deposition can be directed in a pH‐dependent manner on a weak polyelectrolyte, or is solely charge‐dependent on strong polyelectrolytes. These results are correlated with surface potential measurements and show that an optical trap is a versatile method to directly probe interactions between nanoparticles and polymer brushes. A model for these interactions is proposed based on the optical trap measurements.     

Effects of Grafting Density and Film Thickness on the Adhesion of Staphylococcus epidermidis to Poly(2‐hydroxy ethyl methacrylate) and Poly(poly(ethylene glycol)methacrylate) Brushes

Thin polymer films that prevent the adhesion of bacteria are of interest as coatings for the development of infection‐resistant biomaterials. This study investigates the influence of grafting density and film thickness on the adhesion of Staphylococcus epidermidis to poly(poly(ethylene glycol)methacrylate) (PPEGMA) and poly(2‐hydroxyethyl methacrylate) (PHEMA) brushes prepared via surface‐initiated atom transfer radical polymerization (SI‐ATRP). These brushes are compared with poly(ethylene glycol) (PEG) brushes, which are obtained by grafting PEG onto an epoxide‐modified substrate. Except for very low grafting densities (ρ = 1%), crystal violet staining experiments show that the PHEMA and PPEGMA brushes are equally effective as the PEG‐modified surfaces in preventing S. epidermis adhesion and do not reveal any significant variations as a function of film thickness or grafting density. These results indicate that brushes generated by SI‐ATRP are an attractive alternative to grafted‐onto PEG films for the preparation of surface coatings that resist bacterial adhesion.

     

Bacterial capture efficiency and antimicrobial activity of phage-functionalized model surfaces

The rise of antibiotic-resistant bacteria has directed substantial attention toward the use of bacteriophages as a means to control bacterial populations. It has been proposed that bacteriophages can be applied as a coating on surfaces in healthcare settings or on indwelling medical devices to create an antimicrobial surface. In this study, antimicrobial model surfaces functionalized with five different types of bacteriophage were prepared and characterized with X-ray photoelectron spectroscopy and atomic force microscopy. The bacterial capture efficiency of these functionalized surfaces was studied for two common bacteria, Escherichia coli and Salmonella typhimurium. Binding of the phages to a solid surface affected their biofunctionality as expressed by the capture efficiency and rate of host membrane disruption. Moreover, the size and shape of the bacteriophage and positioning of its specific binding proteins significantly affected its bacterial capture capability in the immobilized state. Symmetric bacteriophages were found to be a better choice for antibacterial surfaces compared to more asymmetric tailed bacteriophages. Immobilized phages were found to disrupt the membranes of attached bacteria and are thus proposed as a candidate for antimicrobial surfaces.