Quaternary Ammonium Salts (QAS) Modified Polysiloxane Biocide Supported on Silica Materials

Three types of silica particles modified with vinyl groups were obtained: (i) xerogel formed by hydrolytic polycondensation of the mixture of tetramethoxysilane (TMOS) and 1,1,1,7−tetramethoxy-3,5,7-trimethyl-3,5,7-trivinyltetrasiloxane, (ii) mesoporous silica obtained from the same precursors in the presence of the cetyltrimethylammonium bromide (CTAB), and (iii) commercial Fluka silica gel 60A with a vinyltriethoxysilane-treated surface. Vinyl groups on these silica materials were transformed into silyl chloride by hydrosilylation with HMe₂SiCl. These groups were used to graft living polysiloxane that was synthesized by anionic ring-opening polymerization of 2,4,6-tri(3-chloropropyl)-2,4,6-trimethylcyclotrisiloxane and initiated by BuLi. Chloropropyl groups on the grafted polymer were used to quaternize N,N-dimethyl-n-octylamine. Silica particles with grafted polysiloxane having quaternary ammonium salt (QAS) groups pendant to polymer chains were obtained. Silica material with QAS groups directly attached to the surface were generated by the action of N,N-dimethyl-n-octylamine on particles obtained by the sol–gel process involving tetraethoxysilane (TEOS) with 3-chloropropyltriethoxysilane. The bacteriocidal properties of all these materials were tested in water suspension against five representative strains for Gram-positive and Gram-negative bacteria. Some of the silica–polysiloxane hybrid materials have good antibacterial properties against Gram-positive strains, but not as good as the non-tethered QAS-substituted polysiloxane in water solution. The QAS groups that are directly bonded to the silica material surface are inactive.     

Biologically active polymers. IV. Synthesis and antimicrobial activity of polymers containing 8‐hydroxyquinoline moiety

Polymers containing 8‐hydroxyquinoline moiety were prepared. Modifications of the base polymer of glycidyl methacrylate were carried out in order to introduce chloromethyl groups, either by the hydrolysis of the poly(glycidyl methacrylate) and the chloroacetylation of the hydrolyzed polymer by the reaction with chloroacetyl chloride or by aminating the poly(glycidyl methacrylate) either with ethylenediamine or with hexamethylenediamine, followed by reacting the aminated polymers with chloroacetyl chloride. The polymers containing 8‐hydroxyquinoline moiety were prepared by reacting the chloromethyl groups containing polymers with potassium salt of 8‐hydroxy quinoline. The antimicrobial activity of the polymers obtained was examined against gram‐negative bacteria (Escherichia coli) and gram‐positive bacteria (Bacillus subtilus) as well as the fungus Trichophyton rubrum. Generally, all three polymers proved effective against the tested microorganisms, but growth inhibitory effects varied from one another. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1364–1374, 2001     

Antimicrobial Siloxane Statistical and Graft Copolymers Substituted with t-Butylamine and t-Butylammonium Biocidal Functions

Two kinds of new biocidal siloxane copolymers were synthesized, poly-[3(t-butylamino)propyl]methylsiloxane-co-(3-chloropropyl)methylsiloxane] and poly[dimethylsiloxane-co-(3-mercaptopropyl)methylsiloxane]-g-poly-2(t-butylamino)ethyl methacrylate]. Water-soluble derivatives of these copolymers, having charged ammonium groups, were also obtained. The copolymers were tested against two Gram-positive and three Gram-negative bacterial strains. The antibacterial tests for the water-soluble copolymers with charged ammonium groups were performed in aqueous solutions. Both these copolymers were active against the Gram-positive bacterial strains and inactive or moderately active against Gram-negative bacteria. The uncharged, insoluble, t-butylamine substituted copolymers were tested using a two-phase water-copolymer system. In this test both copolymers having the uncharged t-butylamine functions showed a high biocidal potency against the bacteria studied including those Gram-negative ones.     

Antimicrobial and Hypoglycemic Activities of Novel N-Mannich Bases Derived from 5-(1-Adamantyl)-4-substituted-1,2,4-triazoline-3-thiones

The reaction of 5-(1-adamantyl)-4-ethyl or allyl-1,2,4-triazoline-3-thione with formaldehyde solution and various 1-substituted piperazines yielded the corresponding N-Mannich bases. The newly synthesized N-Mannich bases were tested for in vitro inhibitory activities against a panel of Gram-positive and Gram-negative bacteria and the yeast-like pathogenic fungus Candida albicans. Six compounds showed potent antibacterial activity against one or more of the tested microorganisms, while two compounds exhibited moderate activity against the tested Gram-positive bacteria. None of the newly synthesized compounds were proved to possess marked activity against Candida albicans. The oral hypoglycemic activity of six compounds was determined in streptozotocin (STZ)-induced diabetic rats. Four compounds produced significant strong dose-dependent reduction of serum glucose levels, compared to gliclazide at 10 mg/kg dose level (potency ratio > 75%).     

Towards the Prediction of Antimicrobial Efficacy for Hydrogen Bonded,Self-Associating Amphiphiles

Herein we report 50 structurally related supramolecular self-associating amphiphilic (SSA) salts and related compounds. These SSAs are shown to act as antimicrobial agents, active against model Gram-positive (methicillin-resistant Staphylococcus aureus) and/or Gram-negative (Escherichia coli) bacteria of clinical interest. Through a combination of solution-state, gas-phase, solid-state and in silico measurements, we determine 14 different physicochemical parameters for each of these 50 structurally related compounds. These parameter sets are then used to identify molecular structure-physicochemical property-antimicrobial activity relationships for our model Gram-negative and Gram-positive bacteria, while simultaneously providing insight towards the elucidation of SSA mode of antimicrobial action.     

Synthesis of some benzothiazoles by developing a new protocol using urea nitrate as a catalyst and their antimicrobial activities

The present communication demonstrates the development of urea nitrate as an effective and efficient catalyst for the synthesis of some 2-substituted benzothiazoles. Instant progress of reaction at room temperature under solvent-free condition, very high catalytic activity, inexpensive, clean reaction profile, operational simplicity, large-scale synthesis and appreciable yields are the main advantages of this protocol. These synthesized benzothiazoles have been evaluated for their antibacterial and antifungal activities against Gram-positive bacterium (Bacillus subtilis MTCC 121); two Gram-negative bacteria (Escherichia coli MTCC 1652 and Pseudomonas aeruginosa MTCC 741) and two fungi (Candida albicans MTCC 3017 and Saccharomyces cerevisiae MTCC 170). Compound 3n was found the most active against all the tested microbes.     

Synthesis and Modification of Amine-Terminated Maleic Anhydride-Ethylene Copolymers by Benzaldehyde Derivatives: Characterization and Antimicrobial Properties

Antimicrobial polymers based on poly(ethylene-alt-maleic anhydride) (PEMA) were prepared. Amination of poly(ethylene-alt-maleic anhydride) using diamines of different chain lengths such as ethylenediamine (EDA) and hexamethylenediamine (HMDA) afforded terminal amino groups on the polymers. Antimicrobial polymers were obtained by immobilization of benzaldehyde and its derivatives, which include 4-hydroxybenzaldehyde and 2,4-dihydroxybenzaldehyde onto amine-terminated polymers. The antimicrobial activity of the prepared polymers were examined against different types of microorganisms including Gram-positive and Gram-negative bacteria as well as some fungi. The obtained results revealed that the antimicrobial activity increased with increasing the number of phenolic hydroxyl group and with increasing the spacer length.     

Biocidal Polymers: Preparation and Antimicrobial Assessment of Immobilized Onium Salts onto Modified Chitosan

New derivatives of chitosan were synthesized by modification of chitosan (CTS) either with chloroacetyl chloride or with bromoacetyl chloride. The haloacetylated chitosan derivatives were quaternized by reaction with triethyl amine and triphenyl phosphine. The quaternized new derivatives of chitosan were tested against Gram-negative bacteria the Gram-positive bacteria Staphylococcus aureus, and the fungi by the cut plug method and viable cell counting methods. The results showed that the new chitosan derivatives have stronger antimicrobial activities than the chitosan itself. The examination of the treated cells by TEM showed complete discharge of cellular cytoplasm which led to the death of the cells.     

Preparation of antibacterial poly(methyl methacrylate) by solution blending with water-insoluble antibacterial agent poly[(tert-buty1amino) ethyl methacrylate]

A simple and effective way was developed to prepare antibacterial poly(methyl methacrylate) (PMMA) materials from commercial PMMA and synthesized poly[2-(tert-butylamino) ethyl methacrylate] (PTBAEMA) by solution blending and solvent evaporation methods. The chemical structure of as-synthesized PTBAEMA was characterized by FTIR and ¹H-NMR, and the molecular weight (M_w) and polydispersity index was determined by Gel Permeation Chromatograph. The two components, that is, PMMA and PTBAEMA, were partially miscible and of regular domain size and shape as revealed by SEM observation. Antibacterial assay revealed PMMA/PTBAEMA blends inherited the good antibacterial activity of PTBAEMA against both Staphylococcus aureus and Escherichia coli, no matter whether the bacteria were waterborne or airborne. Besides, the antibacterial performance of PMMA/PTBAEMA blends depended on the M_w and dosage of PTBAEMA, and type of bacteria strain. Furthermore, it was proved that PMMA/PTBAEMA blends killed bacteria on direct contact without releasing active component, which sufficiently met the demand of developing environment-friendly antibacterial materials. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Studies on the synthesis and antibacterial activities of polymeric quaternary ammonium salts from dimethylaminoethyl methacrylate

Four quaternary ammonium salt monomers were synthesized from dimethylaminoethyl methacrylate (DMAEMA) by quaternization with benzyl chloride (BC), butyl bromide (BB), dodecyl bromide (DB) or hexadecyl bromide (HB), respectively. And then, the monomers were homopolymerized to obtain four polymeric quaternary ammonium materials with different lengths of alkyl chain, which were referred to as poly(DMAEMA-BC), poly(DMAEMA-BB), poly(DMAEMA-DB) and poly(DMAEMA-HB), respectively. The resultant monomers and related polymers were characterized by elemental analysis, FTIR, NMR, thermogravimetric analysis (TGA) and so on. Their bactericidal activities were evaluated by determining minimum bactericidal concentration (MBC) values and inhibitory zone diameters against Gram-positive bacteria (S. aureus) and Gram-negative bacteria (E. coli), respectively. The results showed that the MBC values of monomer DMAEMA-DB and DMAEMA-HB were 12–24 μg/mL against E. coli and S. aureus. However, the MBC values of monomer DMAEMA-BC and DMAEMA-BB were higher than 50 mg/mL against test microbe. It was very interesting that poly(DMAEMA-BC) and poly(DMAEMA-BB) exhibited greater bactericidal activities than their precursory monomers, but poly(DMAEMA-DB) and poly(DMAEMA-HB) present contrary results.     

Preparation and properties of water‐soluble polyester surfactants. I. Preparation and surface activity of poly(ethylene glycol)‐dimethyl 5‐sulfo‐isophthalate sodium salt polyester surfactants

The reaction of poly(ethylene glycol) (PEG, number‐average molecular weight M_n = 400‐2000) and dimethyl 5‐sulfoisophthalate sodium salt (SIPM) synthesized a series of anionic polymeric surfactants having a range of molecular weights. ¹H‐NMR, FTIR, and elemental analysis were employed to characterize the structures of these compounds. Also, the influences of the PEG segment lengths of PEG/SIPM copolymers on the surface tension, foaming properties, wetting power, and dispersant properties were investigated. The experimental results indicated that the solution that contained the PEG/SIPM copolymer surfactants exhibited excellent surface‐active properties. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2727–2731, 2002     

Modification of Biphenolic Anti-Bacterial to Achieve Broad-Spectrum Activity

The Gram-positive bacteria, methicillin-resistant Staphylococcus aureus (MRSA) and Gram-negative bacteria, Acinetobacter baumannii, are pathogens responsible for millions of nosocomial infections worldwide. Due to the threat of bacteria evolving resistance to antibiotics, scientists are constantly looking for new classes of compounds to treat infectious diseases. The biphenolic analogs of honokiol that were most potent against oral bacteria had similar bioactivity against MRSA. However, all the compounds proved ineffective against A. baumannii. The inability to inhibit A. baumannii is due to the difficult-to-penetrate lipopolysaccharide-coated outer membrane that makes it challenging for antibiotics to enter Gram-negative bacteria. The C 2 scaffold was optimized from the inhibition of Gram-positive bacteria to broad-spectrum antibacterial compounds that inhibit the dangerous Gram-negative pathogen A. baumannii.     

Spermine Derivatives of Indole-3-carboxylic Acid,Indole-3-acetic Acid and Indole-3-acrylic Acid as Gram-Negative Antibiotic Adjuvants

The discovery of new antibiotic adjuvants is an attractive option for overcoming antimicrobial resistance. We have previously reported the discovery of a bis-6-bromoindolglyoxylamide derivative of spermine as being able to enhance the action of antibiotics against Gram-negative bacteria but suffers from being cytotoxic and red-blood cell haemolytic. A series of analogues was prepared exploring variation of the indolglyoxylamide unit, to include indole-3-acrylic, indole-3-acetic and indole-3-carboxylate units, and evaluated for antibiotic enhancing properties against a range of Gram-negative bacteria, and for intrinsic antimicrobial, cytotoxic and haemolytic properties. Two spermine derivatives, bearing 5-bromo-indole-3-acetic acid ( 17 ) and 5-methoxy-indole-3-acrylic acid ( 14 ) end groups were found to exhibit good to moderate antibiotic adjuvant activities for doxycycline towards the Gram-negative bacteria Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumoniae, but with more modest intrinsic antimicrobial activity and greatly reduced cytotoxic and haemolytic properties. The mechanism of action of the latter derivative identified its ability to disrupt the outer membranes of bacteria and to inhibit the AcrAB-TolC efflux pump directly or by inhibiting the proton gradient.     

Rigidity-Activity Relationships of bisQPC Scaffolds against Pathogenic Bacteria

Biscationic quaternary phosphonium compounds (bisQPCs) represent a promising class of antimicrobials, displaying potent activity against both Gram-negative and Gram-positive bacteria. In this study, we explored the effects of structural rigidity on the antimicrobial activity of QPC structures bearing a two-carbon linker between phosphonium groups, testing against a panel of six bacteria, including multiple strains harboring known disinfectant resistance mechanisms. Using simple alkylation reactions, 21 novel compounds were prepared, although alkene isomerization as well as an alkyne reduction were observed during the respective syntheses. The resulting bisQPC compounds showed strong biological activity, but were hampered by diminished solubility of their iodide salts. One compound (P2P-10,10 I) showed single-digit micromolar activity against the entire panel of bacteria. Overall, intriguing biological activity was observed, with less rigid structures displaying better efficacy against Gram-negative strains and more rigid structures demonstrating slightly increased efficacy against S. aureus strains.     

One‐pot synthesis of cobalt‐incorporated polyglycerol ester as an antimicrobial agent for polyurethane coatings

Cobalt‐incorporated poly(glycerol ester) (Co–PGE) was synthesized by the polycondensation of glycerol and adipic acid followed by the reaction with cobalt(II) hydroxide under solvent‐free and noncatalyzed one‐pot synthesis conditions. The reaction was monitored through the acid value and hydroxyl value determination. The chemical structure and molecular weight of the poly(glycerol ester) (PGE) and Co–PGE were characterized by Fourier transform infrared spectroscopy, ¹³C‐NMR, gel permeation chromatography, and inductively coupled plasma mass spectrometry. Co–PGE with a 59.3% degree of branching was incorporated with up to 5.0% w/w cobalt, and it exhibited antimicrobial inhibition against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans in a broth microdilution study. Polyurethane (PU) coatings were prepared by the blending of 0.5–35% w/w Co‐PGE containing with 5% w/w of cobalt with blank PGE, poly(ethylene glycol) with a molecular weight of 6000, poly(caprolactone diol) with a molecular weight of 2000, and additives to react with isophorone diisocyanate. The prepared PUs demonstrated mild to high antimicrobial activities against E. coli, S. aureus, Bacillus subtilis, and C. albicans strains in a disc diffusion test. PU prepared with 0.5% w/w Co–PGE showed a mild inhibition activity against S. aureus, and PU prepared with 10% w/w Co–PGE demonstrated a high inhibition activity against C. albicans. This study demonstrated that value‐added Co–PGE synthesized from glycerol has the potential as an antimicrobial agent for polymer coatings in biomedical devices. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46045.     

Preparation and application of sulfonated poly(1‐octene‐co‐styrene)

In this article, 1‐octene and styrene was copolymerized by the supported catalyst (TiCl₄/ID/MgCl₂). Subsequently, by sulfonation reaction, sulfonated poly(1‐octene‐co‐styrene)s which were amphiphilic copolymers were prepared. The copolymerization behavior between 1‐octene and styrene is moderate ideal behavior. Copolymers prepared by this catalyst contain appreciable amounts of both 1‐octene and styrene. Increase in the feed ratio of styrene/1‐octene leads to increase in styrene content in copolymer and decrease in molecular weight. As the polymerization temperature increases, the styrene content in the copolymers increases, however, the molecular weight decreases. Hydrogen is an efficient regulator to lower the molecular weights of poly(1‐octene‐co‐styrene)s. The sulfonation degree of the sulfonated poly(1‐octene‐co‐styrene)s increased as the styrene content in copolymer increased or the molecular weight decreased. Thirty‐six hour is long enough for sulfonation reaction. The sulfonated poly(1‐octene‐co‐styrene)s can be used as effective and durable modifying agent to improve the wettability of polyethylene film and have potential application in emulsified fuels and for the stabilization of dispersions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthetic Method Development and Molecular Weight Control for Homo- and Co-Polysilynes,Silicon-Based Network-Backbone Polymers

Optimized methods for the syntheses of polyaryl, polyalkyl, and co-polysilynes, using sonochemically-emulsified NaK alloy reductions of trichlorosilanes, are reported. The methods give oxygen and solvent-impurity free polymers, by FTIR and ¹H NMR, for poly(phenylsilyne) 1, poly(n-butylsilyne) 2, poly(ethylsilyne) 3, poly(n-propylsilyne) 4, and poly(cyclohexylsilyne) 5. Syntheses of the novel polysilynes poly(isobutylsilyne) 6, poly(amylsilyne) 7, and poly(phenyl-co-butylsilyne) 8 are also reported. The polymers were assessed for the photooxidation behavior that is characteristic of these inorganic network-backbone polymers. A method of molecular weight control for polysilynes, by combining monomers that bear substituents of differing steric size (n-butyltrichlorosilane and cyclohexyltrichlorosilane), is also reported.     

Adenine functionalized antibacterial PVC with both photo and thermal stability

Adenine was used as a precursor to obtain antibacterial poly(vinyl chloride) (PVC). Adenine functionalized PVC has been prepared, characterized, and its antibacterial activity was evaluated. Chemical modification reaction of PVC was performed with adenine in two molar ratios (2:1 and 4:1). Fourier-transform infrared spectroscopy and ¹HNMR spectroscopic analyses confirmed the chemical structure of the adenine-modified PVC and indicated the incorporation of adenine molecule in the backbone chains of PVC. Photostability of the prepared modified PVC was determined by measuring the changes in molecular weights using Gel permeation chromatography technique as well as the extent of discoloration of UV irradiated samples while thermal stability was studied by measuring the rate of dehydrochlorination and thermogravimetric analysis. Morphological investigation in terms of scanning electron microscopy was studied. Antibacterial activities of the two modified PVC samples were investigated against two types of Gram-positive bacterial strains (Bacillus subtitles, Staphylococcus aurous, and Streptococcus faecalis) while the other types (Escherichia coli, Neisseria gonorrhea, and Pseudomonas aeruginosa) represented the Gram-negative type bacteria. Antibacterial activity of PVC-adenine blend was also investigated for comparison. Minimum inhibition concentration was performed for some PVC samples under study.     

Synthesis,Characterization, Evaluation of Interfacial Properties and Antibacterial Activities of Dicarboxylate Anacardic Acid Derivatives from Cashew Nut Shell Liquid of Anacardium occidentale L.

Anacardic acid, 2-hydroxy-6-[(8Z,11Z-pentadeca-8,11,14-trienyl]-benzoic acid, extracted from cashew nut shell liquid (CNSL), has been structurally modified to obtain the 2-(O-carboxymethyl)-6-[(8Z,11Z)-pentadeca-8,11,14-trienyl]-benzoic acid and its disodium carboxylate salt. Our separation method allows to easily obtain anacardic acid, which has been of interest for the fabrication of green products. These methods proposed for the first time to synthesize these derivatives are short and cheap, and with a high yield. The elucidation of its structure was carried out by means of infrared spectroscopy (IR) and nuclear magnetic resonance (NMR) techniques. Interfacial rheology properties of surfactant-air-water and surfactant-heptane-water systems were determined by using a new oscillating spinning drop rheometer apparatus. Physicochemical characterization was performed with a salinity scan in a surfactant-heptane-brine system, obtaining a value of the surfactant characteristic parameter σ = −4.3 for the disodium salt and a critical micellar concentration (cmc) of 0.08 wt%, showing high surface activity. The biological activity of both compounds was determined and measurements of their potential antimicrobial activity against Gram-positive and Gram-negative bacteria were performed, exhibiting high effectiveness, especially for the disodium salt against Gram-positive bacteria.     

Gold(I) and Gold(III) N-Heterocyclic Carbene Complexes as Antibacterial Agents and Inhibitors of Bacterial Thioredoxin Reductase

A series of (NHC)Au(I)Cl monocarbene complexes and their gold(III) analogues (NHC)Au(III)Cl₃ were prepared and investigated as antibacterial agents and inhibitors of bacterial TrxR. The complexes showed stronger antibacterial effects against the Gram-positive MRSA and E. faecium strains than against several Gram-negative bacteria. All complexes were efficient inhibitors of bacterial thioredoxin reductase, indicating that inhibition of this enzyme might be involved in their mechanism of action. The efficacy of gold(I) and gold(III) analogues was comparable in most of the assays. The cytotoxicity of the gold NHC compounds against cancer and human cells was overall weaker than the activity against the Gram-positive bacteria, suggesting that their optimization as antibacterials warrants further investigation.