Preparation of antibacterial and antifungal breathable polyether block amide/chloropropane diol membranes via solution casting

A highly hydrophilic block copolymer polyether block amide (PEBA) is modified with chloropropane diol (CPD) to impart antibacterial and antifungal properties to it without compromising with its breathability. The antibacterial properties of modified membranes are evaluated against Staphylococcus aureus (S. aureus, Gram positive) and Escherichia coli (E. coli, Gram negative) bacteria by membrane culture method. CPD plays an important role in the antibacterial property with the inhibition rate reaching 99.99% for CPD modified membranes which was 27.55% and 16.82% for pristine membrane (against S. aureus and E. coli respectively). The antifungal properties studied against Aspergllus niger, Penicillium pinophilum, Aureobasidium pullulans, Chaetomium globosum, and Trichoderma virens show heavy‐growth of fungi for pristine PEBA membrane while no growth was observed in case of CPD modified membranes. Breathability of membrane is determined in terms of water vapor transmission rate (WVTR) and it increase from 1496 g/m²/day to 2354 g/m²/day after modification. The membranes are characterized by FTIR‐ATR, SEM‐EDX, DSC, and TGA. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46097.     

Antibacterial and biodegradable properties of polyhydroxyalkanoates grafted with chitosan and chitooligosaccharides via ozone treatment

Acrylic acid was grafted to ozone‐treated poly(3‐hydroxybutyric acid) (PHB) and poly(3‐hydroxybutyric acid‐co‐3‐hydroxyvaleric acid) (PHBV) membranes. The resulting membranes were further grafted with chitosan (CS) or chitooligosaccharide (COS) via esterification. These CS‐ or COS‐grafted membranes showed antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, methicilin‐resistant Staphylococcus aureus (MRSA), and S. aureus. The antibacterial activity to E. coli was the highest, whereas the antibacterial activity to MRSA was the lowest among these four bacteria tested. Acrylic acid grafting can increase the biodegradability with Alcaligens faecalis, whereas CS and COS grafting can reduce the biodegradability. In addition, CS‐grafted PHBV membrane showed higher antibacterial activity and lower biodegradability than COS‐grafted PHBV membrane. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 12: 2797–2803, 2003     

Antibacterial Activities of Five Cationic Gemini Surfactants with Ethylene Glycol Bisacetyl Spacers

A series of cationic gemini surfactants containing two dimethylalkylammonium chains linked by ethylene glycol bisacetyl spacers were synthesized [G_m‐AnA‐m, G = gemini surfactant, m = 12 (–C₁₂H₂₅), 14 (–C₁₄H₂₉), or 16 (–C₁₆H₃₃), A = acetyl, and n = 2, 3, or 4 is the number of ethylene glycol units in the spacers]. Because of the inductive effect of the oxygen atom in the spacer, acylation can take place using chloroacetyl chloride instead of bromoacetyl bromide which helps to limit the use of environmentally harmful reagents. Critical micelle concentrations were determined using conductivity measurements. The antibacterial activities of the surfactants against Gram‐positive bacterium Staphylococcus aureus and Gram‐negative bacterium Escherichia coli were evaluated from the minimum inhibitory concentration (MIC), minimum bacterial concentration, a time–kill study, and the inhibitory zone. Increasing the length of the spacer did not result in an obvious change of antibacterial activity. However, increasing the length of the alkyl chain apparently increased the antibacterial activity against S. aureus but decreased the antibacterial activity against E. coli. The G_{12‐A2A‐12} surfactant had the lowest CMC of 1.26 mmol L^?1 and exhibited the best antibacterial activity with a MIC of 32 μg mL^?1 toward S. aureus and 64 μg mL^?1 toward E. coli in the presence of 10⁵ CFU of bacteria. This work indicated that these cationic gemini surfactants have potential applications as antibacterial agents and emulsifiers.     

Efficiency of silver‐based antibacterial additives and its influence in thermoplastic elastomers

Styrene‐butylene/ethylene‐styrene‐based thermoplastic elastomers (TPE) are polymers with soft touch properties that are widely used for manufacturing devices that involve hand contact. However, when contaminated with microorganisms these products can contribute to spreading diseases. The incorporation of antibacterial additives can help maintain low bacteria counts. This work evaluated the antibacterial action of TPE loaded with silver ions and silver nanoparticles. The additives nanosilver on fumed silica (NpAg_silica), silver phosphate glass (Ag⁺_phosphate), and bentonite organomodified with silver (Ag⁺_bentonite) were added to the TPE formulation. The compounds were evaluated for tensile and thermal properties and antimicrobial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). All the additives eliminated over 90% of E. coli, but only NpAg_silica killed more than 80% of S. aureus population. The better effect of NpAg_silica was attributed to the additive's high specific surface area, which promoted greater contact with bacteria cells. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43956.     

Enhanced the dispersibility and permeability of silver nanoparticles over rGO grafted by positively-charged polyethyleneimine toward broad-spectrum sterilization

Silver nanoparticles (Ag NPs) are used as antimicrobial agents due to their high-efficiency, broad-spectrum disinfection activity. However, the agglomeration and stability problems caused by excessive release of silver ions (Ag⁺) have severely restricted their developments. Herein, a novel silver/polyethyleneimine/reduced graphene oxide (Ag/PEI/rGO) antibacterial material featuring good dispersibility and permeability was rationally designed, thus benefiting for the capture of bacteria due to the introducing of highly-cationic PEI modifier and controllable release of biocidal agents (Ag⁺). Compared with Ag/rGO, the Ag/PEI/rGO has excellent stability and shows a more efficient sterilization efficacy against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) with 100% germicidal efficiency with low orders of dozens of ppm. In addition, the outstanding biocompatibility of this Ag/PEI/rGO antibacterial material endows it with promising potential in sterilization applications, which is expected to solve the infection problem caused by bacterial biofilm formation.     

Adsorption and antibacterial activity of silver‐dispersed carbon aerogels

Silver‐dispersed carbon aerogels (Ag/CAs) were obtained by the direct immersion of organic aerogels in aqueous AgNO₃ solutions and then carbonization of the resulting material under a nitrogen atmosphere. The adsorption and antibacterial activity of Escherichia coli and Staphylococcus aureus on Ag/CAs were studied by the measurement of the amount of viable bacteria in suspensions and scanning electron microscopy (SEM) observations. The adsorbed amount of bacteria on samples without silver increased with an increase in the carbonization temperature and contact time. SEM studies showed that the adsorption capacity of Ag/CAs decreased with an increase in the silver content; this was considered to be mainly due to the dissolution behavior of bacteria by silver ions. The antibacterial test showed that 2.5 mg of Ag/CAs with more than 3.6% Ag could inhibit the growth of 10⁵ cfu/mL E. coli in 10 mL of a Mueller–Hinton broth culture, but in the case of S. aureus, 10‐mg samples just got the same antibacterial effect. An antibacterial persistency test showed that 25 mg of Ag/CAs with 6.5% Ag could kill 50 mL of 10⁵ cfu/mL E. coli eight times. These results indicate that Ag/CAs possess strong and long‐term antibacterial activity. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1030–1037, 2006     

Green cinnamaldehyde and thymol modified zinc oxide with double synergistic antibacterial effects in polypropylene

The green cinnamaldehyde (CA) and thymol (THY) separately or successively modified O-ZnO (O-ZnO-CA, O-ZnO-THY, and O-ZnO-CA-THY) were prepared after (3-aminopropyl) triethoxysilane (KH550) was grafted to the surface of ZnO (O-ZnO) and characterized by FTIR, TGA, and SEM. Polypropylene composites (PP/O-ZnO-CA, PP/O-ZnO-THY, and PP/O-ZnO-CA-THY) were prepared by melting the modified O-ZnO and PP. The antibacterial tests showed that the antibacterial rate of PP/O-ZnO-CA and PP/O-ZnO-THY against S. aureus and E. coli was obviously enhanced. It indicated an excellent synergetic antibacterial effect of O-ZnO and the little CA or THY grafted on the surface of O-ZnO. The antibacterial effect of O-ZnO-CA and O-ZnO-THY was related to the hydrophobic and hydrophilic groups contained in CA and THY. Importantly, CA and THY in O-ZnO-CA-THY exhibited another excellent synergetic antibacterial effect against both S. aureus and E. coli. The antibacterial rate of three PP composites containing 4 phr O-ZnO-CA-THY against S. aureus and E. coli reached 95% and 90%, respectively. The mechanism was regarded as that CA and THY grafted onto the same O-ZnO improved the contact probability between antibacterial agents and bacteria. Moreover, O-ZnO-CA, O-ZnO-THY, and O-ZnO-CA-THY had excellent migration resistance in the PP matrix.     

Effects of UV weathering on the mechanical and antibacterial performance of peroxide‐cured silicone rubber containing biocide HPQM

2‐Hydroxypropyl‐3‐piperazinyl‐quinoline carboxylic acid methacrylate (HPQM) was used as a biocide in a silicone rubber compound. Antibacterial and mechanical performance of the compound was assessed before and after exposure to UV light for different times. Drop‐plate and halo tests were employed to evaluate qualitatively and quantitatively the antibacterial performance of the compound against Escherichia coli (E. coli, ATCC 25922) and Staphylococcus aureus (S. aureus, ATCC 25923). The results showed that the cure characteristics and the physical and mechanical properties of the HPQM‐containing rubber compound were strongly affected by the UV light. The tensile properties and hardness increased with UV aging. The lightness (L*) of the rubber compound without HPQM did not change with UV exposure, whereas that for the compound with HPQM decreased with UV exposure. The longer the contact time, the better the ability for killing the bacteria. After experiencing initial UV aging for 3 days, the rubber compound with HPQM showed an effective killing ability. However, after prolonged UV exposure, the antibacterial efficacy was reduced as a result of HPQM removal from the rubber surface during the condensation stage and a post‐curing reaction of the residual peroxide in the rubber compound. Under UV light, the silicone rubber compound with HPQM had a greater preference for killing the E. coli. J. VINYL ADDIT. TECHNOL., 20:49–56, 2014. © 2014 Society of Plastics Engineers     

Preparation and antimicrobial activity of Konjac Glucomannan modified with quaternary ammonium compound

Seven kind of graft copolymerization Konjac Glucomannan with quaternary ammonium group have been prepared, using Konjac Glucomannan (KGM) and methacryloxylethyl alkyl dimethyl ammonium bromide with c₈–c₁₈ alkyl and benzyl in water, ceric ammonium nitrate as initiator, the reaction temperature of 348 K, and the reaction period of 3 h. The structures were confirmed by FTIR. The 15 min inhibitory rates of all the graft copolymerization KGM against Escherichia coli and Staphylococcus aureus reached 99.99%, against Candida albicans somewhat lower, but 30 min inhibitory rate still reached 99.02% for graft copolymerization KGM with quaternary ammonium group having 14 alkyl. The antibacterial mechanism of the graft copolymerization KGM has been investigated by adsorption ability to E. coli, measure of 260 nm absorbing materials and SEM micrographs. Firstly, the bacteria were fastly adsorbed by graft copolymerization KGM. Interactions between bacterial membranes and antibacterial product cause fundamental changes in both membrane structure and function, induced leakage of cytoplasmic contents is a classic indication of damage to the bacterial cytoplasmic membrane. The loss of the connection between the outer membrane and the underlying peptidoglycan induces the abnormality of nodular structures and bleb formation of the cell envelope of E. coli. The antibacterial mechanism is in accordance with microbiologic findings identifying surface blebbing as the first morphologic change occurring in the permeability barrier of gram‐negative bacteria under mild heat stress and laser irradiation, etc. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Cure behavior and antimicrobial performance of sulfur‐cured natural rubber vulcanizates containing 2‐hydroxypropyl‐3‐piperazinylquinolinecarboxylic acid methacrylate or silver‐substituted zeolite

This work used 2‐hydroxypropyl‐3‐piperazinylquinolinecarboxylic acid methacrylate (HPQM) or silver‐substituted zeolite (SSZ) as antibacterial agents for natural rubber (NR) compounds vulcanized by conventional vulcanization (CV), semi‐efficient vulcanization, and efficient vulcanization (EV) systems. The cure behavior and antibacterial performance of the NR vulcanizates were studied by varying the loadings of HPQM or SSZ, contact times, and vulcanization systems. The antibacterial performance of the rubber compounds was examined by halo test and plate‐count‐agar methods against Escherichia coli (E. coli, ATCC 25922) and Staphylococcus aureus (S. aureus, ATCC 25923) as the testing bacteria. The cure time and crosslink density were dependent on the vulcanization recipe used but were not affected by the addition of HPQM or SSZ. Diphenylguanidine at the level of 1.0 phr (parts by weight per hundred parts of resin) in NR vulcanized by the EV system had the ability to kill the E. coli and S. aureus bacteria. The NR vulcanized by the CV system showed the most pronounced antibacterial performance, as compared with the other two vulcanization systems, via migration and diffusion of HPQM or SSZ onto the NR surfaces, this being identified by the relatively large reduction of contact angle values. The HPQM showed the most preference for NR compounds vulcanized with the CV system with a contact time of 120 min or longer to achieve a bacteria‐killing efficacy of 99.0–99.9%, the efficacy being more pronounced for E. coli bacteria. J. VINYL ADDIT. TECHNOL., 19:123–131, 2013. © 2013 Society of Plastics Engineers     

Surface grafting of polyester fiber with chitosan and the antibacterial activity of pathogenic bacteria

Three polyesters—poly(ethylene terephthalate), poly(2‐methyl‐1,3‐propylene terephthalate‐co‐ethylene terephthalate), and poly(1,4‐cyclohexylene terephthalate‐co‐ethylene terephthalate)—were preirradiated with ⁶⁰Co‐γ‐rays. Then, acrylic acid and N‐vinylformamide were grafted to these irradiated fibers. Fibers grafted with N‐vinylformamide were further hydrolyzed with acid so that the amide groups would convert into amino groups, and they were treated with glutaraldehyde so that aldehyde groups would be introduced. Chitosan or chitooligosaccharide was then grafted to these fibers via either esterification or imine formation. Four pathogenic bacteria—methicillin‐resistant Staphylococcus aureus‐1 (MRSA), Staphylococcus aureus‐2, Escherichid coli, and Pseudomonas aeruginosa—were tested to determine the antibacterial activities of chitosan‐grafted and chitooligosaccharide‐grafted fibers. The results showed that grafting chitosan via imine formation could achieve a higher surface density for amino groups and give higher antibacterial activity to those four bacteria tested. The antibacterial activity for E. coli was the highest and that for MRSA was the lowest among the four bacteria tested. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2977–2983, 2002     

Enhanced functionality of colloidal polyaniline/polyvinyl alcohol nanocomposite as an antibacterial agent

This study describes the preparation of colloidal polyaniline/polyvinyl alcohol (PAn/PVA) nanocomposite by chemical polymerization of aniline (AN) in the presence of ammonium peroxydisulphate (APS) as an oxidant and PVA as a stabilizer. The product was characterized morphologically using a scanning electron microscope (SEM) and transmission electron microscopy (TEM), chemically using Fourier transform infrared (FTIR) and optically UV–visible. The prepared polymer was then tested for the antibacterial properties against gram‐negative bacteria: Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa); and gram‐positive bacteria: Staphylococcus aureus (S. aureus). The antibacterial properties were assessed by disk diffusion, minimum inhibitory concentration (MIC), minimum bactericidal concentrations (MBCs), and the bactericidal effect methods. The results clearly showed that colloidal PAn/PVA nanocomposite strongly inhibits the growth of wild‐type E. coli (19 ± 0.5) mm followed by P. aeruginosa (17 ± 0.5 mm) and S. aureus (17.5 ± 0.5 mm) bacteria. S. aureus was completely killed after exposure for only 15 min, whereas S. aureus and E. coli were completely killed after exposure for 25 min. J. VINYL ADDIT. TECHNOL., 22:267–272, 2016. © 2014 Society of Plastics Engineers     

Synthesis and Evaluation of N‐Phenylpyrrolamides as DNA Gyrase B Inhibitors

ATP‐competitive inhibitors of DNA gyrase and topoisomerase IV are among the most interesting classes of antibacterial drugs that are unrepresented in the antibacterial pipeline. We developed 32 new N‐phenylpyrrolamides and evaluated them against DNA gyrase and topoisomerase IV from E. coli and Staphylococcus aureus. Antibacterial activities were studied against Gram‐positive and Gram‐negative bacterial strains. The most potent compound displayed an IC₅₀ of 47 nm against E. coli DNA gyrase, and a minimum inhibitory concentration (MIC) of 12.5 μm against the Gram‐positive Enterococcus faecalis. Some compounds displayed good antibacterial activities against an efflux‐pump‐deficient E. coli strain (MIC=6.25 μm ) and against wild‐type E. coli in the presence of efflux pump inhibitor PAβN (MIC=3.13 μm ). Here we describe new findings regarding the structure–activity relationships of N‐phenylpyrrolamide DNA gyrase B inhibitors and investigate the factors that are important for the antibacterial activity of this class of compounds.     

Antibacterial activities of novel nanocomposite biofilms of chitosan/phosphoramide/Ag NPs

Novel nanocomposite films of chitosan/phosphoramide/Ag NPs were prepared containing 1–5% of silver nanoparticles. The Ag NPs were synthesized according to the citrate reduction method. The XRD and SEM analysis of Ag NPs, chitosan (CS), phosphoramide (Ph), CS/Ph, CS/Ag NPs films and the nanocomposite films 1–5 containing CS/Ph/1–5% Ag NPs were investigated. The in vitro antibacterial activities were evaluated against four bacteria including two Gram‐positive Staphylococcus aureus (S. aureus), Bacillus cereus (B. cereus) and two Gram‐negative Escherchia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa) bacteria. Results revealed greater antibacterial effects of the films against Gram‐positive bacteria. Also, nanocomposite films containing higher percent of Ag NPs showed more antibacterial activities. POLYM. COMPOS. 36:454–466, 2015. © 2014 Society of Plastics Engineers     

Enhanced mechanical properties and bactericidal activity of polypropylene nanocomposite with dual‐function silica–silver core‐shell nanoparticles

Dual‐function silica–silver core‐shell (SiO₂@Ag) nanoparticles (NPs) with the core diameter of 17 ± 2 nm and the shell thickness of about 1.5 nm were produced using a green chemistry. The SiO₂@Ag NPs were tested in vitro against gram‐positive Staphylococcus aureus (S. aureus) and gram‐negative Escherichia coli (E. coli), both of which are human pathogens. Minimal inhibitory concentrations of the SiO₂@Ag NPs based on Ag content are 4 and 10 μg mL^?1 against S. aureus and E. coli, respectively. These values are similar to those of Ag NPs. SiO₂@Ag NPs were for the first time incorporated to a commodity polypropylene (PP) polymer. This yielded an advanced multifunctional polymer using current compounding technologies i.e., melt blending by twin‐screw extruder and solvent (toluene) blending. The composite containing 5 wt % SiO₂@Ag NPs (0.05 wt % Ag) exhibited efficient bactericidal activity with over 99.99% reduction in bacterial cell viability and significantly improved the flexural modulus of the PP. Anodic stripping voltammetry, used to investigate the antibacterial mechanism of the composite, indicated that a bactericidal Ag⁺ agent was released from the composite in an aqueous environment. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis and Antimicrobial Activities of Oximes Derived from O-Benzylhydroxylamine as FabH Inhibitors

Forty‐three oxime derivatives were synthesized by allowing O‐benzylhydroxylamines to react with primary benzaldehydes or salicylaldehydes; these products were gauged as potential inhibitors of β‐ketoacyl‐(acyl‐carrier‐protein) synthase III (FabH). Among the 43 compounds, 38 are reported herein for the first time. These compounds were assayed for antimicrobial activities against Escherichia coli, Pseudomonas aeruginosa, Pseudomonas fluorescens, Bacillus subtilis, Staphylococcus aureus, and Enterococcus faecalis. Compounds with prominent antibacterial activities were tested for their E. coli FabH inhibitory activities. 3‐((2,4‐Dichlorobenzyloxyimino)methyl)benzaldehyde O‐2,4‐dichlorobenzyl oxime ( 44 ) showed the best antibacterial activity, with minimum inhibitory concentrations of 3.13–6.25 μg mL^?1 against the tested bacterial strains, exhibiting the best E. coli FabH inhibitory activity, with an IC₅₀ value of 1.7 mM . Docking simulations were performed to position compound 44 into the E. coli FabH active site in order to determine the most probable binding conformation.     

Effect of blending sodium polyethylene‐5‐sulfoisophthalate on adhesion of clinical bacteria on polyethylene terephthalate

This work studies the adhesion of clinical infecting bacteria, S. aureus and E. coli, on prosthetic polymeric materials. Membranes were prepared from polyethylene terephthalate (PET) blending at various ratios with sodium polyethylene‐5‐sulfoisophthalate (SPES). The membranes were characterized by measuring the contact angle, equilibrium water content, and the surface concentration of sodium sulfonate. The results show that sulfonate makes the membrane more hydrophilic. The surface properties of bacteria were determined by measuring the adhesion to n‐octane (B%) and the contact angles to water and α‐bromonaphthalene. For the four bacteria studied, encapsulated S. aureus was the most hydrophobic and had the highest amount of bacteria attached to the surface of SPES/PET membrane. Furthermore, the attached amount decreased with the increase of the content of SPES. Empirical correlations for predicting the attached amount from the surface properties of both polymer and bacteria were obtained from linear regression. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3587–3594, 2004     

Synthesis and water absorbency of polyampholytic hydrogels with antibacterial activity

Amphoteric terpolymers of acrylic acid (AA), acrylamide (AM), and N,N′‐dimethyl‐N‐ethylmeth‐acryloxylethylammoniumbromide (DMAEA‐EB) with varied compositions P[AA‐AM‐(DMAEA‐EB)] were synthesized by inverse suspension polymerization. The components of P[AA‐AM‐(DMAEA‐EB)] were verified by FTIR spectroscopy. The water absorption ability and antibacterial activity of the copolymer against Escherichia coli(E. coli) and Staphylococcus hyicus(S. hyicus) suspended in sterilized physiological saline were investigated. The introduction of  N⁺R₄ may increase the water absorbency of P[AA‐AM‐(DMAEA‐EB)] in some degree because of the excellent hydrophilicity of  N⁺R₄. The AA‐AM‐(DMAEA‐EB) hydrogels exhibited high antibacterial activity against bacteria tested. The process of adsorption between live bacteria cells and resins was at least partially reversible. A peak of antibacterial efficiency existed with increasing contact time. The resin killed 96.6% E. coli organisms and 90.3% S. hyicus organisms, respectively, within 30 min of contact at dosage of 0.1g. The concentration of DMAEA‐EB has a special effect on the antibacterial activity of the polyampholytic hydrogels, which is different from polycation. It was observed that the antibacterial activity of the resin with 2 mol % of DMAEA‐EB is superior to the copolymers tested with other compositions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Poly(ether imide) membranes modified with charged surface‐modifying macromolecule—Its performance characteristics as ultrafiltration membranes

Modification of poly (ether imide) (PEI) ultrafiltration (UF) membranes was attempted by blending charged surface modifying macromolecule (cSMM). Compared to the pure PEI membrane, blending of PEI with cSMM resulted in blend membranes with enhanced UF characteristics such as lower hydraulic resistance (R_m) and higher pure water flux (PWF) coupled with higher water content (WC). Among the various modified membranes, blend membranes with 5 wt % cSMM concentration exhibited higher PWF (60.38 L m^?2 h^?1), WC (73.6%), protein permeate flux (27.12 L m^?2 h^?1) and lower flux decline rate (R_fd) (55.1%), R_m (5.21 kPa/L m^?2 h^?1), bovine serum albumin (BSA) rejection (87.1%). Meanwhile, the fouling resistant ability was studied by flux recovery ratio (FRR) after water and alkali cleaning, irreversible and reversible fouling rate. Higher FRR after water cleaning (95.07%), FRR after alkali cleaning (97.1%), reversible fouling rate (50.14%) and lower irreversible fouling rate (5%) exhibited by 5 wt % cSMM membranes showed its better antifouling ability compared to pure PEI and other blend membranes because of its higher hydrophilic nature. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40320.     

Electrospun Sandwich‐Structure Composite Membranes for Wound Dressing Scaffolds with High Antioxidant and Antibacterial Activity

In this study, the sandwich‐structured composite (SSC) membranes with well‐antibacterial and antioxidant properties, which have the promising application as wound dressing, are successfully fabricated by combining an electrospinning process. The SSC membranes are composed of three layers, including the bottom polyvinylidene fluoride fibrous layer, the middle curcumin/polylactic acid (PLA) microsphere layer, and the top enrofloxacin/PLA fibrous layer, respectively. The obtained SSC membranes are characterized in terms of morphology, component, and mechanical property using scanning electronic microscope, X‐ray diffractometer, Fourier transform infrared spectroscopy, and universal electronic testing machine, respectively. Moreover, in vitro drug release, antioxidant activity, antimicrobial activity, and biocompatibility of the SSC membranes are also evaluated. The results showed that the obtained composite membranes indeed possess the sandwich structure, where the middle microsphere layer is located between two fibrous surface layers. It is found that the drug‐loaded SSC membranes show excellent antioxidant activity against ^?OH and DPPH free radicals and antibacterial activity against Staphylococcus aureus, Escherichia coli, Streptococcus pneumoniae, Pseudomonas aeruginosa, and Candida albicans. The combination of electrospinning and electrospraying opens up a new way to fabricate a variety of composite membranes with a sandwich structure, which have promising potential application as wound dressing scaffolds.