Polyurethane Surface Research Articles

Novel N-chloramine precursors for antimicrobial application: synthesis and facile covalent immobilization on polyurethane surface based on perfluorophenyl azide (PFPA) chemistry

To control the pathogen cross contaminations on medical material surface, there is a pressing need to develop antimicrobial materials with highly efficacious surface biocidal activity. In this work, N-chloramine precursors containing a quaternary ammonium unit and perfluorophenyl azide unit were synthesized and covalently immobilized on inert polyurethane (PU) film upon UV light irradiation. The surface modification was confirmed by contact angle, Fourier transform infrared (ATR FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) analyses. After bleaching treatment, satisfactory biocidal activity was achieved for the surface-modified PU films. It was found that the introduced surface QA center contributed an even faster surface contact killing behavior and that precursors with a longer structural linker caused higher surface chlorine content and higher antimicrobial efficacy. This approach provides a novel and facile method that enables the covalent immobilization of N-chloramine precursors on inert polymeric surface to produce durable antimicrobial materials.

UV sensor based on polyurethane foam

Ultraviolet light (UV) present in solar radiation has an important effect on the health of human skin. For that reason, we developed a disposable and easy-to-manufacture UV light sensor based on surface color change of a polyurethane (PU) film and examined its performance against radiation received from a lamp or from the sun. The chemical modification after UV exposition and the consequent color variation from light yellow to brown in PU sensor were studied by using RGB image analysis and a reflectance prototype containing an Arduino board. It was found that the photochemical modification of PU films increases absorption of visible radiation in the blue spectrum range. Furthermore, PU surface was more sensitive to UV (<390) than that found in visible light when exposed to sunlight, which was associated with the presence of a chromophore in the material modified. In addition, it was found that the extract obtained from irradiated PU showed its maximum absorption at 309 nm. Hence, the use of this economical light radiation sensor seems to be a very promising tool to determine exposure to UV light from the solar spectrum.

Surface modification of silica nanoparticle using dichlorodimethylsilane for preparation of self-cleaning coating based on polyurethane and polydimethylsiloxane

In this work, a superhydrophobic self-cleaning coating was prepared in three steps; firstly, silica nanoparticles were synthesized using stober method, secondly the surface of silica nanoparticles was modified using dichlorodimethylsilane (DDS), finally, surface modified silica nanoparticles were applied on the surface of un-cured polyurethane or polydimethylsiloxane resins which resulted in superhydrophobic coating with suitable self-cleaning properties. Surface modification of silica nanoparticles using different concentration of DDS lead to desired particle size and particle size distribution. The FTIR spectra showed that hydrogen of silica particles are substituted by SiCl(CH3)2 functional groups which are known as the origin of hydrophobicity of the surface. Furthermore, measuring the contact angle of water drop with the coated surface showed that by increasing the silica nanoparticles concentration, the hydrophobicity of the coating was increased. Electrochemical impedance spectroscopy (EIS) results indicated that corrosion resistance of coating depends directly on the concentration of nanoparticles in coating.

Grafting of niclosamide and salicylanilide onto hydrophilic polyurethane for the control of fungal and barnacle growth

Grafting of niclosamide or salicylanilide onto polyurethane (PU) was executed to develop antifungal effectiveness and barnacle repelling capability in seawater compared with underivatized PU. The PU surface was simultaneously modified to improve the surface hydrophilicity by inserting dimethylolpropionic acid into PU frame or by grafting recycled polyols onto PU. Surface modifications of PU significantly affected its properties, such as cross-link density, tensile and shape memory properties, and flexibility under freezing conditions relative to the unmodified PU. The modification of PU surface also notably influenced the glass transition and the melting and crystallization related to soft segments. The breaking tensile stress and the shape recovery were enhanced significantly after the grafting of polyol due to chemical cross-linking, whereas the breaking tensile strain was not reduced. Some PU samples demonstrated complete antifungal effectiveness against a mixture of fungi, and barnacle growth on PU films was limited in the specifically modified PUs.

Surface modification of polyurethane with a hydrophilic, antibacterial polymer for improved antifouling and antibacterial function.

Antimicrobial surface is important for the inhibition of bacteria or biofilm formation on biomaterials. The objective of this study was to immobilize a novel hydrophilic polymer containing the antibacterial moiety onto polyurethane surface via a simple surface coating technology to make the surface not only antibacterial but also antifouling. The compound 3,4-dichloro-5-hydroxy-2(5H)-furanone was derivatized, characterized and incorporated onto polyvinylpyrrolidone containing succinimidyl functional groups, followed by coating onto the polyurethane surface. Contact angle, antibacterial function and protein adsorption of the modified surface were evaluated. The result shows that the modified surface exhibited significantly enhanced hydrophilicity with a 54-65% decrease in contact angle, increased antibacterial activity to Staphylococcus aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa with a 24-57% decrease in viability, and reduced human serum albumin adsorption with a 64-70% decrease in adsorption, as compared to the original polyurethane.

Influence of uniaxial deformation on structure of carbon-coated polyurethane surface

Plasma treatment of polymers is the promising technique for improving the quality of biomedical devices, in particular deformable implants. The influence of mechanical deformation on such coating has not been sufficiently studied. The effect of the uniaxial cyclic deformation on the surface structure of carbon nanolayer deposited (by the magnetron sputtering) on soft elastic polyurethane is investigated. The obtained coating is wrinkled. The mechanical load changes the structure of the surface (wavelength, amplitude and fractal dimension of the wrinkles, surface roughness); the cracks appear on the deposited layer. As the strain increases, the number of cracks rises and the strain-induced folds appear on the coating.

Direction-dependent stretchability of AgNW electrodes on microprism-mediated elastomeric substrates

Silver nanowires (AgNWs) have become an efficient electrode candidate for stretchable electronics. We report the effects of directional stretching in microprism-mediated AgNW stretchable electrodes on polyurethane (PU) substrates. The wavy substrate is fabricated using a customized microprism on polyethylene terephthalate. AgNWs on stretchable PU substrates show stable normalized resistance up to 35% strain under parallel uniaxial stretching. This performance is much better than AgNWs on bare PU substrate or on wavy PU under perpendicular stretching, which can only sustain 10%-15% strain before significant increase in normalized resistance. Finite element simulations were conducted to reveal the strain distribution and variation in the AgNW electrodes on both bare and wavy PU substrates when stretched along parallel and perpendicular directions. Comparing to AgNW electrodes on bare PU and on wavy PU under perpendicular stretching, the wavy PU surface relief features can effectively alleviate the strain in the AgNW network when stretched along parallel direction, leading to better performance.

Ses proteins as possible targets for vaccine development against Staphylococcus epidermidis infections

The opportunistic pathogen Staphylococcus epidermidis is progressively involved in device-related infections. Since these infections involve biofilm formation, antibiotics are not effective. Conversely, a vaccine can be advantageous to prevent these infections. In view of vaccine development, predicted surface proteins were evaluated on their potential as a vaccine target. Immunoglobulins directed against S. epidermidis surface proteins SesB, M, O, Q and R were used to firstly affirm their surface location. Further, inhibitory effects of these IgGs on biofilm formation were determined in vitro on polystyrene and polyurethane surfaces and in vivo using a subcutaneous catheter mouse model. We also examined the opsonophagocytotic capacity of these IgGs. Surface localization of the five Ses proteins was demonstrated both for planktonic and sessile cells, though to a variable extent. Ses-specific IgGs added to planktonic cells had a variable inhibitory effect on cell adhesion to polystyrene, while only anti-SesO IgGs decreased cell attachment to polyurethane catheters. Although phagocytic killing was only obtained after opsonization with SesB-specific IgGs, a significant reduction of in vivo formed biofilms was observed after administration of SesB-, SesM- and SesO-specific IgGs. Regardless of their characterization or function, S. epidermidis surface proteins can be adequate targets for vaccine development aiming the prevention of device-related infections caused by invasive S. epidermidis strains.

Salmonella enterica growth and biofilm formation in flesh and peel cantaloupe extracts on four food-contact surfaces

Salmonella enterica is responsible for the highest number of foodborne disease outbreaks pertaining to cantaloupe industry. The objective of this study was to examine the growth and biofilm formation by outbreak strains of S. enterica ser. Poona (S. Poona), S. enterica ser. Stanley (S. Stanley) and S. enterica ser. Montevideo (S. Montevideo) on different food-contact processing surfaces in cantaloupe flesh and peel extracts at 22 °C and 10 °C. The generation time of all S. enterica strains tested was shorter in the high concentration (50 mg/ml) of cantaloupe extract and high temperature. In 50 mg/ml of cantaloupe flesh or peel extract, the populations of S. enterica were increased by 5 log CFU/ml in 24 h at 22 °C and 1 log CFU/ml in 72 h at 10 °C. In 2 mg/ml of cantaloupe flesh or peel extracts, the populations of S. enterica were increased by 3.5 log CFU/ml in 56 h at 22 °C, but there were no changes in 72 h at 10 °C. The biofilm production of S. enterica was greater at 50 mg/ml of cantaloupe extract and 22 °C, but no major differences (P ≥ 0.05) were found among the strains tested. In 50 mg/ml cantaloupe extract, S. enterica produced 5–6 log CFU/cm2 biofilm in 4–7 d at 22 °C and approximately 3.5–4 log CFU/cm2 in 7 d at 10 °C. In 2 mg/ml of cantaloupe extract, S. enterica produced 4–4.5 log CFU/cm2 biofilms in 4–7 d at 22 °C and 3 log CFU/cm2 in 7 d at 10 °C. Biofilm formation by S. Poona (01A4754) was lowest on buna-n rubber compared to stainless steel, polyethylene and polyurethane surfaces under the majority of conditions tested. Overall, these findings show that S. enterica strains can grow rapidly and form biofilms on different cantaloupe processing surfaces in the presence of low concentrations of cantaloupe flesh or peel extracts.

Polyurethane Modified with Plasma-Ion Implantation for Medical Applications

Medical polyurethane was treated with 20 keV nitrogen ions with a fluence of 1014–1016 ions/cm2. The modified polyurethane has a layered structure consisting of a 70-nm carbonized layer and a partly depolymerized layer below the carbonized layer. The high level of activity of the polyurethane due to free radicals provides stable adhesion of protein molecules to the surface layer of the polyurethane. The high level of hydrophilicity of the modified polyurethane surface preserves the biological activity of the attached proteins. This contributes to the attachment of endothelial cells to the polyurethane surface and their proliferation. Thus, this modified polyurethane can be used as a material for soft-tissue medical implants.

Preparation of ordered mesoporous and macroporous thermoplastic polyurethane surfaces for potential medical applications.

Thermoplastic polyurethanes are widely used in medical devices. In order to limit some of their shortfalls, like microbial attachment, surfaces modifications can be required. In this work, a two-step replication method was used to create ordered macroporous and mesoporous thermoplastic polyurethane surfaces using anodic aluminum oxide as master template. The intermediate mould materials that were tested were polystyrene and a polyacrylate resin with inorganic filler. All obtained surfaces were characterized by scanning electron microscopy. The initial anodic aluminum oxide surfaces possessed macro or mesopores, function of anodization conditions. The intermediate mould structure correctly replicated the pattern, but the polystyrene surface structures (pillars) were less resistant than the polyacrylate resin ones. The thermoplastic polyurethane pattern possessed macropores or mesopores of about 130 nm or 46 nm diameter and of about 300 nm or 99 nm interpore distances, respectively, in accordance with the initial pattern. Thermoplastic polyurethanes pore depth was however less than initial anodic aluminum oxide pore depth, linked to an incomplete replication during intermediate mould preparation (60 to 90% depth replication). The correct replication of the original pattern confirms that this novel fabrication method is a promising route for surface patterning of thermoplastic polyurethanes that could be used for medical applications.

Surface and bulk properties of waterborne polyurethane modified with fluorinated siloxane

ABSTRACTTwo series of polyester and polyether waterborne polyurethanes (WPUs) modified with poly[(3,3,3‐trifluoropropyl)methylsiloxane] (PTFPMS) were synthesized by prepolymerization method and the effect of PTFPMS on surface and bulk properties were investigated by a variety of experimental methods. FTIR and DSC results showed that the polyester WPU has better compatibility between soft segments and hard segments than polyether WPU in bulk and the degree of phase separation increased in polyester WPU but decreased in polyether WPU with increasing PTFPMS. ARXPS analysis revealed the migration of PTFPMS to WPU surface and the migration ability of Si element was better than F element. AFM images demonstrated that the surface of WPU films became rougher as PTFPMS content increased. The enrichment of PTFPMS with low surface energy and roughened surface imparted good hydrophobicity and oleophobicity to WPU films and polyether WPU has better surface properties compared with polyester WPU. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46473.

Scanning electron microscopy of Salmonella biofilms on various food-contact surfaces in catfish mucus

The objective of this study was to determine the growth and survival of Salmonella enterica in the presence of high and low concentrations (375 μg/ml and 15 μg/ml) of catfish mucus extract at 10 °C and 22 °C for 63 days. The second objective of this study was to investigate the biofilm formation of Salmonella enterica serovar Blockley (7175) in catfish mucus extract for 48 h at 22 °C on four food-contact surfaces and to observe the biofilm populations using Scanning Electron Microscopy (SEM). The surface properties, surface roughness and surface energies were determined using contact angle measurement and atomic force microscopy. In 375 μg/ml of catfish mucus extract that was inoculated with 3 log CFU/ml, the growth of Salmonella counts were increased to a maximum of 6–7 log CFU/ml at 10 °C and 7–8 log CFU/ml at 22 °C in 7–14 d and decreased by 1–2 log CFU/ml from these peak levels at both 10 °C and 22 °C from 21 to 63 d. In 15 μg/ml of catfish mucus extract, Salmonella counts were in the range of 4–5 log CFU/ml at 10 °C and 5–6 log CFU/ml at 22 °C over 7–63 d of storage. By contrast, Salmonella counts were non-detectable in the absence of catfish mucus by 21–28 d of storage at 10 °C or 22 °C. The biofilm counts of S. Blockley (7175) on a stainless steel surface were 4 log CFU/cm2 and 5.5 log CFU/cm2 in 15 μg/ml and 375 μg/ml of catfish mucus extract respectively after 48 h incubation at 22 °C. SEM revelead that biofilm formation by S. Blockley (7175) was less in 15 μg/ml than 375 μg/ml of catfish mucus extract on stainless steel. In addition, SEM indicated that the visible biofilms were least on buna-N rubber as compared to stainless steel, polyethylene and polyurethane surfaces. Contact angle and atomic force microscopy confirmed that buna-N rubber was highly hydrophobic with low surface energy and low roughness when compared to other three surfaces. These findings indicate that Salmonella can utilize catfish mucus as a nutrient source to survive for longer periods and promote biofilm formation for its persistence on different food-contact surfaces.

Passive treatment of arsenic and heavy metals contaminated circumneutral mine drainage using granular polyurethane impregnated by coal mine drainage sludge

Abstract A one-step and facile process was used to incorporate coal mine drainage sludge (CMDS) into granular polyurethane (PU), designated as PUCMDS, to remediate circumneutral mine drainages simultaneously contaminated by arsenic and heavy-metals. PUCMDS was characterized through physiochemical analyses. Several batch and column tests were carried out. CMDS was homogeneously stuck on the large-sized pore surface of PU. Based on the kinetic modeling, the low-range Biot number (BN, 0.86–2.63) indicated that external diffusion is a main rate-limiting step. Rapid small-scale column tests (RSSCTs) also showed this phenomenon, in which the empty bed contact time (EBCT) influenced the arsenic removal efficiency more than did the PUCMDS size. PUCMDS had 8190–14,330 bed volumes (BVs) of breakthrough (BT, 50 μg L−1) for As(V), while it did not have BTs for other heavy metals, except for Fe(III). Two pilot-scale columns were conducted to observe their outlets till 7644 and 3800 BVs. As a result, PUCMDS did not have any BTs for all regulations of As (total) and heavy metals. All results in this study demonstrated not only that PUCMDS can effectively remove arsenic and other heavy metals in circumneutral mine drainages, but also that it shows an example of sustainable development concept in mine sector.

The role of functionalized graphene oxide on the mechanical and anti-corrosion properties of polyurethane coating

Polyurethane (PU) has been commonly used in a wide range of applications due to its high flexibility and good UV resistance. Attempts have been extensively carried out to improve the corrosion resistance and mechanical properties of this coating through inclusion of nanomaterials. In this study the graphene oxide nanosheets, covalently functionalized by (3-glycidyloxypropyl) trimethoxysilane, were introduced into the PU matrix to enhance the mentioned weaknesses. The modified (fGO) and unmodified-graphene oxide nanosheets (GO) were characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) analysis, field emission-scanning electron microscopy (FE-SEM), UV–vis and thermal gravimetric analysis (TGA). The physical–mechanical properties of the PU coatings reinforced with GO and fGO nanosheets were characterized by dynamic mechanical thermal analysis (DMTA) and tensile test. The influence of GO and fGO nanosheets on the fractured surface morphology of the PU coating after tensile test was studied by SEM analysis. In addition, the corrosion protection properties of the mild steel panels coated with PU coatings were characterized by salt spray test and electrochemical impedance spectroscopy (EIS). The results affirmed the physical–mechanical and anti-corrosion properties enhancement of the PU coating after incorporation of fGO nanosheets. The tensile stress, energy at break, loss factor and storage modulus values were significantly increased by addition of fGO nanosheets. The fGO stability and dispersion in the PU matrix was improved after modification with (3-glycidyloxypropyl) trimethoxysilane. The interfacial bonds between the polyurethane coating-fGO nanosheets were significantly enhanced. Besides the experiments, theoretical quantum mechanics approaches were utilized to examine the interactions of trimethoxysilane with polyurethane and GO surface.

Anchoring TGF-β1 on biomaterial surface via affinitive interactions: Effects on spatial structures and bioactivity.

Protein adsorption on biomaterial surfaces is clinically applied to increase therapeutic effects; however, this adsorption is possibly accompanied by conformational changes and results in loss of protein bioactivity or adverse reactions. In this research, a transforming growth factor β1 (TGF-β1) affinitive peptide HSNGLPL was grafted onto biopolymer surface to stabilize TGF-β1 spatial conformation after adhesion. The peptide with azide end group was combined with the propynyl pendant group on polyurethane via copper-catalyzed azide-alkyne cycloaddition (CuAAC) click reaction. The final polymer was characterized by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy, which indicated that the affinitive peptide was introduced to the polymer. Quartz crystal microbalance with dissipation (QCM-D) was performed to monitor TGF-β1 adsorption and desorption on the surfaces coated with polyurethane with and without peptide combination. Results showed that TGF-β1 adhered on polyurethane surface and formed a compact and rigid layer. This layer showed spatial structural change but presented a loose and diffuse layer on the peptide-grafted polyurethane surface, indicating stable spatial conformation after adherence. Similar regulations were observed on the two surfaces where BSA layer was coated in advance. In vivo animal experiments revealed that immune reactions and tissue regenerations occurred earlier on peptide-modified polyurethane than on polyurethane, which did not undergo peptide grafting. This finding confirmed that affinitive interactions may preserve TGF-β1 bioactivity on polymer surface after adsorption.

Sulfobetaine methacrylate hydrogel-coated anti-fouling surfaces for implantable biomedical devices

BackgroundZwitterionic molecules have been widely studied as coating materials for preparing anti-fouling surfaces because they possess strong hydration properties that can resist non-specific protein adsorption. Numerous studies on surface modification using zwitterionic molecules have been investigated, such as electrochemically mediated and photoinitiated radical polymerization. However, these methods have some limitations, including multi-step process, difficulties in producing thick and dense layers as well as the requirement of extra facilities. In this study, we report a novel zwitterionic hydrogel-coating method via Fenton reaction for the preparation of anti-fouling surfaces.MethodsSulfobetaine methacrylate (SBMA) hydrogel was coated on polyurethane (PU) by polymerization of SBMA molecules via the Fenton reaction. The coated surfaces were characterized by the measurements of water contact angle, SEM and XPS. The anti-fouling properties of the modified surfaces were evaluated by reductions of fibrinogen absorption and cell (human dermal fibroblasts, hDFBs) adhesion.ResultsSBMA hydrogel layers were coated on the PU substrates and these layers have a high affinity for water. The hydrogel coatings were highly stable for 7 days, without a significant change in surface wettability. Importantly, the hydrogel-coated PU substrates decrease 80% of surface-adsorbed fibrinogen and surface-attached hDFBs (compared with uncoated PU substrates), indicating the excellent anti-fouling activities of modified surfaces.ConclusionsThe hydrogel-coated PU surfaces prepared by Fenton reaction with anti-fouling properties could have potential uses for implantable biomedical devices.

Label-free gold nanoparticle-based sensing of cysteine: New peculiarities and prospects

In this article, some new peculiarities and prospects of cysteine determination using aggregation of label-free gold nanoparticles (AuNPs) are described. Features of the aggregation both in solution and on polyurethane surface are compared. Effects of ethylenediaminetetraacetate (EDTA) and cysteamine on the aggregation of AuNPs, which increase sensitivity, are considered. In case of EDTA, it was simultaneously possible to eliminate interferences from cations of metals. It is shown that attaching AuNPs onto polyurethane foam surface changes their sensitivity and selectivity, which can be used for the determination of cysteine. Based on found peculiarities, new methods for the determination of cysteine in a range 0.06–0.5 μg mL−1 (LOD = 0.04 μg mL−1) by spectrophotometry, and 0.02–0.15 μg mL−1 (LOD = 0.01 μg mL−1) by diffuse reflectance spectroscopy were developed.

Fabrication of highly hydrophobic two-component thermosetting polyurethane surfaces with silica nanoparticles

Highly hydrophobic thermosetting polyurethane (TSU) surfaces with micro-nano hierarchical structures were developed by a simple process combined with sandpaper templates and nano-silica embellishment. Sandpapers with grit sizes varying from 240 to 7000 grit were used to obtain micro-scale roughness on an intrinsic hydrophilic TSU surface. The surface wettability was investigated by contact angle measurement. It was found that the largest contact angle of the TSU surface without nanoparticles at 102 ± 3° was obtained when the template was 240-grit sandpaper and the molding progress started after 45 min curing of TSU. Silica nanoparticles modified with polydimethylsiloxane were scattered onto the surfaces of both the polymer and the template to construct the desirable nanostructures. The influences of the morphology, surface composition and the silica content on the TSU surface wettability were studied by scanning electron microscopy (SEM), attenuated total reflection (ATR) infrared (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and contact angle measurements. The surface of the TSU/SiO2 nanocomposites containing 4 wt% silica nanoparticles exhibited a distinctive dual-scale structure and excellent hydrophobicity with the contact angle above 150°. The mechanism of wettability was also discussed by Wenzel model and Cassie-Baxter model.

Growth and Biofilm Formation by Listeria monocytogenes in Catfish Mucus Extract on Four Food Contact Surfaces at 22 and 10°C and Their Reduction by Commercial Disinfectants

The objective of this study was to determine the effect of strain and temperature on growth and biofilm formation by Listeria monocytogenes in high and low concentrations of catfish mucus extract on various food contact surfaces at 10 and 22°C. The second objective of this study was to evaluate the efficacy of disinfectants at recommended concentrations and contact times for removing L. monocytogenes biofilm cells from a stainless steel surface covered with catfish mucus extract. Growth and biofilm formation of all L. monocytogenes strains increased with higher concentrations of catfish mucus extract at both 10 and 22°C. When 15 μg/mL catfish mucus extract was added to 3 log CFU/mL L. monocytogenes, the biofilm levels of L. monocytogenes on stainless steel reached 4 to 5 log CFU per coupon at 10°C and 5 to 6 log CFU per coupon at 22°C in 7 days. With 375 μg/mL catfish mucus extract, the biofilm levels of L. monocytogenes on stainless steel reached 5 to 6 log CFU per coupon at 10°C and 6 to 7.5 log CFU per coupon at 22°C in 7 days. No differences ( P > 0.05) were observed between L. monocytogenes strains tested for biofilm formation in catfish mucus extract on the stainless steel surface. The biofilm formation by L. monocytogenes catfish isolate HCC23 was lower on Buna-N rubber than on stainless steel, polyethylene, and polyurethane surfaces in the presence of catfish mucus extract ( P < 0.05). Contact angle analysis and atomic force microscopy confirmed that Buna-N rubber was highly hydrophobic, with lower surface energy and less roughness than the other three surfaces. The complete reduction of L. monocytogenes biofilm cells was achieved on the stainless steel coupons with a mixture of disinfectants, such as quaternary ammonium compounds with hydrogen peroxide or peracetic acid with hydrogen peroxide and octanoic acid at 25 or 50% of the recommended concentration, in 1 or 3 min compared with use of the quaternary ammonium compounds, chlorine, or acid disinfectants alone, which were ineffective for removing all the L. monocytogenes biofilm cells.