Alanine and Lysine Scans of the LL‐37‐Derived Peptide Fragment KR‐12 Reveal Key Residues for Antimicrobial Activity

The human host defence peptide LL‐37 is a broad‐spectrum antibiotic with immunomodulatory functions. Residues 18–29 in LL‐37 have previously been identified as a minimal peptide (KR‐12) that retains antibacterial activity with decreased cytotoxicity. In this study, analogues of KR‐12 were generated by Ala and Lys scans to identify key elements for activity. These were tested against a panel of human pathogens and for membrane permeabilisation on liposomes. Replacements of hydrophobic and cationic residues with Ala were detrimental for antibiotic potency. Substitutions by Lys increased activity, as long as the increase in cationic density did not disrupt the amphiphilic disposition of the helical structure. Importantly, substitutions showed differential effects against different organisms. Replacement of Gln5 with Lys and Asp9 with Ala or Lys improved the broad‐spectrum activity most, each resulting in up to an eightfold increase in potency against Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans. The improved analogues displayed no significant toxicity against human cells, and thus, KR‐12 is a tuneable template for antibiotic development.     

Antibacterial and antifungal dressings obtained by photochemical deposition of silver nanoparticles

The antimicrobial activity of silver against a wide spectrum of bacteria, fungi and viruses is known since antiquity. Silver has been used as topical antimicrobial agent in the treatment of wounds since many years and advanced silver‐based dressings have been designed so far. The aim of this study was the development of low‐cost antibacterial and antifungal dressings through the surface modification of conventional cotton gauzes. Different percentages of silver were deposited on textile substrates by adopting an innovative silver deposition technique based on the photochemical deposition of silver nanoparticles. The uniformity of the coating and the distribution of the silver clusters on the surface were evaluated by scanning electron microscopy (SEM). The amount of silver was quantified by thermogravimetric analysis (TGA) and the presence of metallic silver nanoparticles was also assesses through UV–Vis–NIR with integrating sphere and energy dispersive X‐ray spectroscopy EDX. The effectiveness of the silver treated textile was verified on different microorganisms, namely Escherichia coli, Staphylococcus aureus, Pseudomonas p43 and Candida albicans derived from a clinical isolate. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40326.     

Chemical Synthesis of A Pore‐Forming Antimicrobial Protein,Caenopore‐5, by Using Native Chemical Ligation at a Glu‐Cys Site

The 2014 report from the World Health Organization (WHO) on antimicrobial resistance revealed an alarming rise in antibiotic resistance all around the world. Unlike classical antibiotics, with the exception of a few species, no acquired resistance towards antimicrobial peptides (AMPs) has been reported. Therefore, AMPs represent leads for the development of novel antibiotics. Caenopore‐5 is constitutively expressed in the intestine of the nematode Caenorhabditis elegans and is a pore‐forming AMP. The protein (82 amino acids) was successfully synthesised by using Boc solid‐phase peptide synthesis and native chemical ligation. No γ‐linked by‐product was observed despite the use of a C‐terminal Glu‐thioester. The folding of the synthetic protein was confirmed by ¹H NMR spectroscopy and circular dichroism and compared with data recorded for recombinant caenopore‐5. The permeabilisation activities of the protein and of shortened analogues were evaluated.     

Functionally modified,melt‐electrospun thermoplastic polyurethane mats for wound‐dressing applications

The electrospinning of a polymer melt is an interesting process for medical applications because it eliminates the cytotoxic effects of solvents in the electrospinning solution. Wound dressings made from thermoplastic polyurethane (TPU), particularly as a porous structured electrospun membrane, are currently the focus of scientific and commercial interest. In this study, we developed a functionalized fibrillar structure as a novel antibacterial wound‐dressing material with the melt‐electrospinning of TPU. The surface of the fibers was modified with poly(ethylene glycol) (PEG) and silver nanoparticles (nAg's) to improve their wettability and antimicrobial properties. TPU was processed into a porous, fibrous network of beadless fibers in the micrometer range (4.89 ± 0.94 μm). The X‐ray photoelectron spectroscopy results and scanning electron microscopy images confirmed the successful incorporation of nAg's onto the surface of the fiber structure. An antibacterial test indicated that the PEG‐modified nAg‐loaded TPU melt‐electrospun structure had excellent antibacterial effects against both a Gram‐positive Staphylococcus aureus strain and Gram‐negative Escherichia coli compared to unmodified and PEG‐modified TPU fiber mats. Moreover, modification with nAg's and PEG increased the water‐absorption ability in comparison to unmodified TPU. The cell viability and proliferation on the unmodified and modified TPU fiber mats were investigated with a mouse fibroblast cell line (L929). The results demonstrate that the PEG‐modified nAg‐loaded TPU mats had no cytotoxic effect on the fibroblast cells. Therefore, the melt‐electrospun TPU fiber mats modified with PEG and nAg have the potential to be used as antibacterial, humidity‐managing wound dressings. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40132.     

Cytocompatible and regenerable antimicrobial cellulose modified by N‐halamine triazine ring

This study reports the formation of cyanuric chloride hydrolysate and its attachment onto cellulose fibers though covalent bonding. The hydrolysis product, 2,4‐dichloro‐6‐hydroxy‐1,3,5‐triazine, is prepared in water solution at ambient temperature, and directly used as a treatment solution for the treatment of cotton fabrics without any prior work‐up. The triazine treated fabrics are rendered antimicrobial through exposure to chlorine bleach. The oxidative chlorine bonded to the triazine‐treated cotton is very stable and regenerable to standard washing tests and UVA irradiation test. The N‐halamine modified cotton fabrics demonstrate excellent antimicrobial efficacy against Staphylococcus aureus ATCC 6538 and Escherichia coli O157:H7 ATCC 43895 with 7‐logs reductions within the contact time of 10 and 5 min, respectively. In addition, the results of in vitro cell viability test suggested that the N‐halamine modified fabrics have excellent cytocompatibility to mammalian cells. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40627.     

UV‐initiated copolymerization route for facile fabrication of epoxy‐functionalized micro‐zone plates

Bisphenol A‐based epoxy acrylate (BABEA), a commercial ultraviolet (UV)‐curable material, was introduced as a new manufacturing material for facile fabrication of epoxy‐functionalized micro‐zone plates through UV‐initiated copolymerization using glycidyl methacrylate (GMA) as the functional monomer. The poly (BABEA‐co‐GMA) was highly transparent in visible range while highly opaque when the wavelength is less than 295 nm, and of high replication fidelity. X‐ray photoelectron spectroscope (XPS) results indicated the existence of epoxy groups on the surface of the poly (BABEA‐co‐GMA), which allowed for binding protein through an epoxy‐amino group reaction. A fabrication procedure was proposed for manufacturing BABEA based epoxy‐functionalized micro‐zone plates. The fabrication procedure was very simple; obviating the need of micromachining equipments, wet etching or imprinting techniques. To evaluate the BABEA‐based epoxy‐functionalized micro‐zone plates, α‐fetoprotein (AFP) was immobilized onto the capture zone for chemiluminescent (CL) detection in a noncompetitive immune response format. The proposed AFP immunoaffinity micro‐zone plate was demonstrated as a low cost, flexible, homogeneous, and stable assay for α‐fetoprotein (AFP). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39787.     

Co‐Culture of Keratinocyte‐Staphylococcus aureus on Cu‐Ag‐Zn/CuO and Cu‐Ag‐W Nanoparticle Loaded Bacterial Cellulose:PMMA Bandages

Pressurized gyration and its sister processes are novel methods to produce polymeric fibers. Potential applications for such fibers include wound dressings, tissue engineering scaffolds, and filters. This study reports on a pressurized gyration technique that employs pressured N₂ gas to prepare biocompatible wound dressing bandages from bacterial cellulose and poly (methylmethacrylate) polymer blended with alloyed antimicrobial nanoparticles. Resulting bandages are manufactured with high product yield and characterized for their chemical, physical, and mechanical properties. Increased density in solutions with additional antimicrobial nanoparticles results in increased fiber diameters. Also, addition of antimicrobial nanoparticles enhances ultimate tensile strength and Young's modulus of the bandages. Typical molecular bonding in the bandages is confirmed by Fourier‐transform infrared spectroscopy, with peaks that have higher intensity and narrowing points being caused by additional antimicrobial nanoparticles. More so, the cellular response to the bandages and the accompanying antimicrobial activity are studied in detail by in vitro co‐culture of Staphylococcus aureus and keratinocytes. Antimicrobial nanoparticle‐loaded bandage samples show increased cell viability and bacteria inhibition during co‐culture and are found to have a promising future as epidermal wound dressing materials.     

Research on the preparation and antibacterial properties of 2‐N‐thiosemicarbazide‐6‐O‐hydroxypropyl chitosan membranes with iodine

The 2‐N‐thiosemicarbazide‐6‐O‐hydroxypropyl chitosan (ATU‐HPCS) was prepared by chitosan grafted hydroxypropyl and thiosemicarbazide through the method of “amino protection‐graft‐deprotection,” while the ATU‐HPCS gel membranes were obtained from gelatin and polyvinyl pyrrolidone as additives, and the ATU‐HPCS membranes with iodine (ATU‐HPCS‐I₂‐M) were prepared by adding the ethanol solution of iodine in the ATU‐HPCS gel membranes. The ATU‐HPCS‐I₂‐M were characterized to evaluate their potential applications as antibacterial materials. The iodine releasing rule of ATU‐HPCS‐I₂‐M showed a sustained‐release effect of iodine, the maximum emission was approximately 0.80%. The inhibition zone diameters of ATU‐HPCS‐I₂‐M against Staphylococcus aureus (as Gram‐positive bacteria) and Escherichia coli (as Gram‐negative bacteria) were both greater than 15 mm, it demonstrated significant antibacterial activity compared with the ATU‐HPCS gel membranes. The double effects of the biocompatibility of chitosan and the sustained‐release of iodine provided an ideal healing environment for wound surface. These properties have made ATU‐HPCS‐I₂‐M highly potential as a novel natural macromolecule antimicrobial material preventing the bacteria from burns, surgery wounds, etc. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40535.     

Synthesis of novel pyridinium N‐chloramine precursors and its antimicrobial application on cotton fabrics

To control pathogenic microbial contamination on polymeric material surface, it is pivotal to develop materials with efficacious antimicrobial activity. Two pyridinium N‐chloramine precursors containing a siloxane handle were synthesized, characterized, and grafted onto cotton fabrics. The attenuated total reflectance spectra and scanning electron microscope photo analysis indicated that the cotton fabric surface was successfully modified. The resultant chlorinated fabric samples were challenged against bacteria Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 25923. Results showed that: (1) the surface modified cotton fabrics displayed satisfactory biocidal efficacy; (2) the precursor structure played a major role on surface grafting and antibacterial activity. This work provides two promising pyridinium N‐chloramine precursors which hold potential application for preparing antibacterial textile materials. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45323.     

Dissociation of Antimicrobial and Hemolytic Activities of Gramicidin S through N‐Methylation Modification

β‐Sheet antimicrobial peptides (AMPs) are well recognized as promising candidates for the treatment of multidrug‐resistant bacterial infections. To dissociate antimicrobial activity and hemolytic effect of β‐sheet AMPs, we hypothesize that N‐methylation of the intramolecular hydrogen bond(s)‐forming amides could improve their specificities for microbial cells over human erythrocytes. We utilized a model β‐sheet antimicrobial peptide, gramicidin S (GS), to study the N‐methylation effects on the antimicrobial and hemolytic activities. We synthesized twelve N‐methylated GS analogues by replacement of residues at the β‐strand and β‐turn regions with N‐methyl amino acids, and tested their antimicrobial and hemolytic activities. Our experiments showed that the HC₅₀ values increased fivefold compared with that of GS, when the internal hydrogen‐bonded leucine residue was methylated. Neither hemolytic effect nor antimicrobial activity changed when proline alone was replaced with N‐methylalanine in the β‐turn region. However, analogues containing N‐methylleucine at β‐strand and N‐methylalanine at β‐turn regions exhibited a fourfold increase in selectivity index compared to GS. We also examined the conformation of these N‐methylated GS analogues using ¹H NMR and circular dichroism (CD) spectroscopy in aqueous solution, and visualized the backbone structures and residue orientations using molecular dynamics simulations. The results show that N‐methylation of the internal hydrogen bond‐forming amide affected the conformation, backbone shape, and side chain orientation of GS.     

Synthesis and ultraviolet‐curing behaviors of vinyl ether functionalized polyurethane oligomers

The vinyl ether functionalized oligomer is one of the most basic components of vinyl ether functionalized materials for cationic UV‐curable coatings. In this study, three types of vinyl ether functionalized polyurethane oligomers (i.e., polyether, polyester, and polydimethylsiloxane) were synthesized with diisocyanate, diol, and hydroxyethyl vinyl ether. These oligomers were characterized by IR, ¹H‐NMR, and ¹³C‐NMR spectroscopy. The effect of the raw material ratio on the oligomer, UV‐curing behaviors, and thermal properties of these oligomers were investigated. The UV‐curing behavior was analyzed by real‐time Fourier transform infrared spectroscopy. The vinyl ether terminated polyester urethane oligomer exhibited better UV curing, with a higher final conversion and maximum UV‐curing rates. In addition, the light intensity was enhanced for oligomers with better UV‐curing properties. Research on these vinyl ether functionalized oligomers is essential to the development and applications of cationic vinyl ethers systems. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40501.     

A facile dip‐coating approach to prepare SiO2/fluoropolymer coating for superhydrophobic and superoleophobic fabrics with self‐cleaning property

In this study, a facile, two‐step dip‐coating approach was reported for the fabrication of the superhydrophobic and superoleophobic cotton fabrics. It was confirmed that the superhydrophobic and superoleophobic composite thin film containing modified‐SiO₂ nanoparticles and fluoropolymer had been successfully fabricated on the cotton fabrics surface, the results demonstrated that the treated cotton fabrics showed good performances, such as superhydrophobicity and superoleophobicity, low water and oil absorption ability, self‐cleaning property and good laundering durability, so forth. The above approach can be applied to potentially advance superhydrophobic and superoleophobic fabrics materials for a variety of applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41458.     

Durable antimicrobial treatment of cotton fabrics using N‐(2‐hydroxy)propyl‐3‐trimethylammonium chitosan chloride and polycarboxylic acids

N‐(2‐hydroxy)propyl‐3‐trimethylammonium chitosan chloride (HTCC), a water‐soluble chitosan quaternary ammonium derivative, was used as an antimicrobial agent for cotton fabrics. HTCC has a lower minimum inhibition concentration (MIC) against Staphylococcus aureus, Klebsiella pneumoniae, and Escherichia coli compared to that of chitosan; however, the imparted antimicrobial activity is lost on laundering. Thus crosslinking agents were utilized to obtain a durable antimicrobial treatment by immobilizing HTCC. Several crosslinkers such as dimethyloldihydroxyethylene urea (DMDHEU), butanetetracarboxylic acid (BTCA), and citric acid (CA) were used with HTCC to improve the laundering durability of HTCC treatment by covalent bond formation between the crosslinker, HTCC and cellulose. The polycarboxylic acid treatment was superior to the DMDHEU treatment in terms of prolonged antimicrobial activity of the treated cotton after successive laundering. Also, the cotton treated with HTCC and BTCA showed improved durable press properties without excessive deterioration in mechanical strength or whiteness when compared to the citric acid treatment. With the addition of only 0.1% HTCC to BTCA solutions, the treated fabrics showed durable antimicrobial activity up to 20 laundering cycles. The wrinkle recovery angle and strength retention of the treated fabrics were not adversely affected with the addition of HTCC. Therefore, BTCA can be used with HTCC in one bath to impart durability of antimicrobial activity along with durable press properties to cotton fabric. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1567–1572, 2003     

Electrospun nylon 6 nanofibers incorporated with 2‐substituted N‐alkylimidazoles and their silver(I) complexes for antibacterial applications

The article presents the incorporation of biocides [2‐substituted N‐alkylimidazoles and their silver(I) complexes] into electrospun nylon 6 nanofibers for application as antimicrobial materials. The electrospun nylon 6/biocides nanofiber composites were characterized by IR spectroscopy (ATR‐FTIR) and scanning electron microscopy (SEM‐EDX). The antimicrobial activity of the electrospun nylon 6/biocides nanofiber composites was evaluated against Escherichia coli, Staphylococcus aureus, and Bacillus subtilis subsp. spizizenii using the disk diffusion method, the American Association for Textile Chemists and Colorists test method 100‐2004 and the dynamic shake flask method (American Society for Testing and Materials E2149‐10). The electrospun nylon 6 nanofibers incorporated with 2‐substituted N‐alkylimidazoles displayed moderate to excellent levels of growth reduction against S. aureus (73.2–99.8%). For the electrospun nylon 6 nanofibers incorporated with silver(I) complexes, the levels of growth reduction were >99.99%, for both E. coli and S. aureus, after the antimicrobial activity evaluation using the shake flask method. The study demonstrated that the electrospun nanofibers, fabricated using the incorporation strategy, have the potential to be used as attractive antimicrobial materials. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39783.     

Influence of the Multivalency of Ultrashort Arg‐Trp‐Based Antimicrobial Peptides (AMP) on Their Antibacterial Activity

Peptide dendrimers are a class of molecules of high interest in the search for new antibiotics. We used microwave‐assisted, copper(I)‐catalyzed alkyne–azide cycloaddition (CuAAC; “click” chemistry) for the simple and versatile synthesis of a new class of multivalent antimicrobial peptides (AMPs) containing solely arginine and tryptophan residues. To investigate the influence of multivalency on antibacterial activity, short solid‐phase‐ synthesized azide‐modified Arg‐Trp‐containing peptides were “clicked” to three different alkyne‐modified benzene scaffolds to access scaffolds with one, two, or three peptides. The antibacterial activity of 15 new AMPs was investigated by minimal inhibitory concentration (MIC) assays on five different bacterial strains, including a multidrug‐resistant Staphylococcus aureus (MRSA) strain. With ultrashort (2–3 residues) peptides, a clear synergistic effect of the trivalent display was observed, whereas this effect was not apparent with longer peptides. The best candidates showed activities in the low‐micromolar range against Gram‐positive MRSA. Surprisingly, the best activity against Gram‐negative Acinetobacter baumannii was observed with an ultrashort dipeptide on the trivalent scaffold (MIC: 7.5 μM ). The hemolytic activity was explored for the three most active peptides. At concentrations ten times the MIC values, <1 % hemolysis of red blood cells was observed.     

Modification of silica gel,cellulose, and polyurethane with a sterically hindered N‐halamine moiety to produce antimicrobial activity

The sterically hindered amine monomer 4‐[3‐triethoxysilylpropoxyl]‐2,2,6,6‐tetramethylpiperidine has been synthesized and covalently bonded to the surfaces of silica gel particles and cellulose (cotton) and copolymerized in a polyurethane coating formulation. Upon exposure to dilute sodium hypochlorite (household bleach), a very stable N‐Cl bond is formed in situ at the hindered amine nitrogen site. This source of oxidative chlorine provides an antimicrobial function to the silica gel, cotton, and polyurethane. Stability, regenerability, and biocidal efficacy data are presented. The new N‐halamine materials were remarkably effective against Staphylococcus aureus and Escherichia coli O157 : H7 in brief periods of contact. The materials should find application in water treatment and medical applications. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Chitosan hydrogel‐coated cotton fabric: Antibacterial,pH‐responsiveness,and physical properties

In this work, chitosan hydrogel has been synthesized and used to impart pH‐sensitivity and antimicrobial finish to cotton fabric. In order to enhance the incorporation rate of hydrogel, anionic, and cationic activation of the textile surface was applied and then compared. The antibacterial activity of the fabric was then studied. The results revealed an enhancement of the antibacterial activities of the modified fabrics against Escherichia coli, Listeria monocytogene, and Staphylococcus aureus bacteria's. The capacity of material to respond to pH change was studied and confirmed using contact angle method. The anionic fabric treated with hydrogel showed a better pH‐responsiveness. Scanning electron microscopic testing results has also confirmed that the deposition of hydrogel was clearly better with the anionic activation. The characteristics of breathability of the fabrics were analyzed. The results show that the moisture management behavior of the finished materials is significantly better than the control one. Although the permeability to air has reduced by 10%, the permeability to water vapor remained practically unchanged. Furthermore, the effects of the antibacterial finishing on the physical properties of the cotton fabrics were also investigated. It was established that the functionalized samples have changed structure parameters, thickness, air permeability, tensile strength, and resistance to wrinkles. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46645.     

Effect of organoclay and silver‐substituted zeolite on the mechanical and antibacterial properties of a silicone rubber filled with 2‐hydroxypropyl‐3‐piperazinyl‐quinoline carboxylic acid methacrylate

Silicone rubber compounds filled with different loadings of organoclay (OC) and silver substituted zeolite (SSZ) solid fillers were prepared and cured with 2,5‐dimethyl‐2,5‐di(tert‐butylperoxy) hexane. The rubber vulcanizates contained an antimicrobial agent to protect them against Escherichia coli (E. coli ATCC 25922) and Staphylococcus aureus (S. aureus ATCC 25923) bacteria. The tensile strength, elongation at break, stored energy density at break, Young's modulus, modulus at 100% elongation, cyclic fatigue life, and glass transition temperature of the rubber vulcanizates were subsequently measured. The antimicrobial performance of the rubber surfaces were determined by disk diffusion testing and plate count agar method. The antimicrobial agent had an adverse effect on the mechanical properties, but the cyclic fatigue life of the rubber vulcanizate improved. The addition of OC and SSZ could improve the tensile strength, elongation at break and stored energy density at break, but deteriorated the tear energy, Young's modulus and modulus at 100% elongation. The inclusion of the fillers was not beneficial to the antimicrobial activity of the rubber against bacteria. The HPQM in the rubber was effective more against E. coli. than against S. aureus. Furthermore, the antimicrobial activity increased when the contact time in the test solution was increased. POLYM. ENG. SCI., 54:932–941, 2014. © 2013 Society of Plastics Engineers     

Polyamide‐montmorillonite nanocomposites as a drug delivery system: Preparation,release of 1,3,4‐oxa(thia)diazoles,and antimicrobial activity

New microbicidal polyamides were prepared by the reaction of 5‐phenyl‐1,3,4,‐oxadiazole‐2‐thiol, 5‐phenyl‐1,3,4‐oxadiazole‐2‐amine, and 5‐(4‐chlorophenyl)?1,3,4‐thiadiazole‐2‐thiol with ethyl chloroformate followed by polycondensation with polyoxypropylenetriamine (Jeffamine T₄₀₃). The polyamides were modified to yield amine hydrochloride. The intercalation of polyamides into montmorillonite (MMT) was achieved through an ion exchange process between sodium cations in MMT and amine hydrochloride in the polyamides. The structure of the resulting materials was characterized with elemental analysis, proton nuclear magnetic resonance, Fourier transform infrared‐spectroscopy, X‐ray diffraction, thermogravimetric analysis, and transmission electron microscope. The release behavior of 1,3,4‐oxa(thia)diazoles was investigated in buffered aqueous solution at different pH values (2.3, 5.8, and 7.4). A slow release was recorded from the nanocomposites whereas; the release reaches almost 90% from polyamides. The in vitro antimicrobial activity of the polyamides and nanocomposites was studied against Gram‐negative bacteria, Gram‐positive bacteria, Yeast and the filamentous fungi by well diffusion method. The polymers showed good or moderate antimicrobial activities. However, nanocomposites showed no antimicrobial effect. Furthermore, in vivo study showed that nanocomposites had good antimicrobial activity. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41177.     

Polyimide films with antibacterial surfaces from surface‐initiated atom‐transfer radical polymerization

BACKGROUND: Materials with antibacterial surface properties have attracted extensive scientific interest for research and development in the battle against microbial contamination. The application of antimicrobial polymers minimizes environmental problems and enhances the efficiency, selectivity and lifetime of the antimicrobial agents. In this paper polyimide (PI) films are chosen as the polymeric substrate to be modified due to the good thermal, mechanical and physicochemical properties of PI. The method of preparing PI films with antibacterial surfaces using surface‐initiated atom‐transfer radical polymerization (ATRP) is described. RESULTS: The results from X‐ray photoelectron spectroscopy showed that the surfaces at each stage were modified successfully. The pyridinium groups introduced on the PI surface possessed antibacterial properties and the bactericidal effect of the functionalized PI films on Escherichia coli was evaluated. Quaternization of the pyridine rings of the poly(4‐vinylpyridine) (P4VP) brushes gave rise to a high concentration of quaternary pyridinium groups on the PI film surfaces. The antibacterial efficiency of the modified PI film was dependent on the amount of quaternary pyridinium groups on the surface. CONCLUSION: In this research, functional polymer brushes of P4VP were prepared via surface‐initiated ATRP from PI films, followed by alkylation of the grafted P4VP with hexyl bromide. The surface functionalization method described has the advantage of being effective in conferring antibacterial properties on polymeric materials. Copyright © 2008 Society of Chemical Industry