Synthesis,Surface-Active Properties,and Antimicrobial Activities of New Neutral and Cationic Trimeric Surfactants

Neutral and cationic series of new trimeric β-hydroxy amino or ammonium surfactants were synthesized via a two-step process involving the Williamson etherification and regioselective oxirane ring opening with primary and tertiary amines, which afforded good to excellent yields. The synthesized compounds were obtained in high purity by a simple purification procedure on column chromatography. The critical micelle concentration (CMC), effectiveness of surface tension reduction (γ _CMC), surface excess concentration (Γ), and area per molecule at the interface (A) were determined and values indicate that the cationic series is characterized by good surface-active and self-aggregation properties. The antimicrobial activities are reported for the first time against representative bacteria and fungi for trimeric compounds. The antimicrobial potency was found to be dependent on the target microorganism (Gram-positive bacteria > fungi > Gram-negative bacteria), as well as both the neutral or ionic nature (cationic > neutral) and alkyl chain length (tri-C₁₂ > tri-C₁₈ > tri-C₈) of the compounds. The tri-C₈ and tri-C₁₈ compounds were found to be almost inactive and the tri-C₁₂ compounds, the most potent antimicrobial surface-active agents from the synthesized series. The trimeric C₁₂ cationic compound was found to be comparable to benzalkonium chloride against Gram-positive bacteria and fungi, in vitro. The antimicrobial effectiveness of this new compound and the facile two-step procedure for synthesizing it with an excellent overall yield (92%) provide a cost effective trimeric gemini surfactant.

Antimicrobial and SEM Studies of Sophorolipids Synthesized Using Lauryl Alcohol

In recent years, researchers have developed biosurfactants for industrial, pharmaceutical and medical applications revealing the promising biological activities of these biomolecules. One of the best studied microbial surfactants are glycolipids, especially sophorolipids (SLs) produced by selected non-pathogenic yeast species of Candida. They are biodegradable, non-toxic and are environmentally friendly. Sophorolipid production was carried out using glucose as the hydrophilic source and lauryl alcohol C_12–14, as the hydrophobic source using Candida bombicola ATCC 22214. Primary characterization of the SL obtained using lauryl alcohol (SLLA) was done by FTIR which depicted the presence of alkyl sophorosides/SLs. Antimicrobial activity testing revealed that SLLA showed complete inhibition against gram negative bacteria, Escherichia coli (ATCC 8739) Pseudomonas aeruginosa (ATCC 9027) at 30 and 1 μg/ml at a contact time of 2 and 4 h respectively. Whereas for gram positive bacteria Staphylococcus aureus (ATCC 6358), Bacillus subtilis (ATCC 6633), complete inhibition was observed at 6 and 1 μg/ml respectively at a contact time of 4 h. The formed SLLA showed noteworthy inhibition against the pathogenic yeast Candida albicans (ATCC 2091) at 50 μg/ml with a contact time of 4 h. These values are remarkably low compared to reported values of oleic acid SLs and linolenic acid SLs which were studied for antimicrobial properties. Scanning electron microscopy analysis of the treated cells revealed the changes in morphology and topography of the microorganisms.     

Preparation,Surface-Active Properties and Antimicrobial Activities of Bis(Ester Quaternary Ammonium) Salts

New cationic surfactants, bis-quaternary ammonium salts, were prepared from N,N-dimethylaminoalkyl esters of saturated fatty acids and products of the reactions of epichlorohydrin with primary amines: pentyl-, hexyl- and octylamine. The bis (ester–ammonium) salts obtained were examined in respect to their surface-active properties: critical micelle concentration (CMC), effectiveness of surface tension reduction (γ_CMC), and adsorption efficiency (pC₂₀). All these surfactants showed good water solubility and low critical micelle concentrations of more than two orders of magnitude lower than these of corresponding mono-alkylammonium salts. They also showed good wetting capability, but worse foaming properties. All the surfactants tested were nontoxic to gram-negative bacteria, but some of them inhibited the growth of gram-positive bacteria and yeast.

Surface-Active Properties and Antimicrobial Study of Conventional Cationic and Synthesized Symmetrical Gemini Surfactants

Symmetrical gemini surfactants of cationic series α,ω-alkanediyl bis (dimethyl ammonium bromide) commonly referred as “m–s–m” have been synthesized. Spectral analysis was performed to confirm compound structures and purity. Conductivity and surface tension measurements provide better understanding of the micellization process. Their self-assembly behavior in aqueous solution is also discussed in detail. The antimicrobial efficacy was measured by bacterial and fungal growth inhibition expressed as minimal inhibitory concentration values against five strains of a representative group of microorganisms viz. Bacillus subtilis, Staphylococcus aureus, Klebsiella pneumonia, Salmonella paratyphi B and Aspergillus niger. All of the synthesized surfactants showed antimicrobial activity against them, but at different levels depending on their structures. The surfactants possessing longer alkyl chains (more hydrophobic environment) demonstrated better antimicrobial functionality. The antimicrobial potency was found to be dependent on the representative target microorganism (Gram-positive bacteria > fungi > Gram-negative bacteria), as well as on the ionic nature of the surfactant (cationic), alkyl chain length (m = 12, 16) and spacer length (s = 2, 4, 6) of the synthesized compounds. Gemini surfactants such as 12-2-12 and 12-4-12 were found to be weakly active whereas 16-2-16 and 16-4-16 compounds proved to be the most potent antimicrobial surface-active agents among the synthesized gemini homologues.     

Novel Ester-linked Anionic Gemini Surfactant: Synthesis,Surface-Active Properties and Antimicrobial Study

A novel anionic gemini surfactant containing an ester bond in the spacer group was synthesized using cardanol as the raw material and characterized by IR, ¹H NMR and ¹³C NMR. The surface properties of the gemini surfactant were investigated and compared with its corresponding single chain surfactant counterpart. It was found that this novel gemini surfactant exhibited a low critical micelle concentration value (1.9 mM) and good efficiency in reducing surface tension of water (33.6 mN/m). The gemini surfactant was found to have antimicrobial activity against Gram-negative (Escherichia coli and Pseudomonas aeruginosa), Gram-positive (Bacillus subtilis and Staphylococcus aureus) bacteria and fungi (Aspergillus niger, Aspergillus flavus, Candida albicans and Rhizopus stolonifer). The gemini as well as the corresponding single chain surfactant showed good antimicrobial activity against all pathogenic microorganisms studied and can be employed as an antimicrobial agent. The synthesized novel anionic gemini surfactant possesses an excellent wettability and low foamability.     

Antimicrobial Properties of Nanogold-Imprinted Starch Bionanocomposites

Nanogold-imprinted starch bionanocomposites of various compositions were synthesized by “one-pot reaction” with in situ generation of nanogold. Bionanocomposites were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscope and high-resolution transmission electron microscope. The electrical conductivity of nanocomposites was enhanced because of dispersion of nanogold in the starch. Antimicrobial activity of starch was increased due to incorporation of nanogold. The bionanocomposites were resistant towards dilute acid and alkali with little scarification in biodegradable properties. The enhanced thermal, gas barrier and antimicrobial properties may enable the synthesized materials for packaging applications.     

Preparation of a Novel Class of Cationic Gemini Imidazolium Surfactants Containing Amide Groups as the Spacer: Their Surface Properties and Antimicrobial Activity

A class of novel cationic Gemini imidazolium surfactants containing amide groups as the spacer were synthesized from ethylenediamine and 1-bromoalkane(C₈, C₁₀, C₁₂, C₁₄, C₁₆) by N-alkylation to get N,N′-dialkyl ethylenediamine (1a–e), 1a–e was further reacted with chloroacetyl chloride by N-acylation to get N,N′-(ethane-1,2-diyl)bis(2-chloro-N-alkylacetamide) (2a–e), which was further reacted respectively with 1-methyl imidazole by quaternized to form the surfactant molecule, N,N′-((ethane-1,2-diyl)bis(alkyl-azanediyl)bis(2-oxoethane-2,1-diyl)) bis(1-methyl-1H-imidazol-3-ium) dichloride. The structures of intermediates (1a–e) and (2a–e) were characterized by IR and ¹H NMR. The structures of the surfactants (3a–e) were characterized by IR, ¹H-NMR and ¹³C-NMR and element analysis. The critical micelle concentrations (CMC) of 3a–e were determined by the conductivity method at 25 °C. The CMC values decreased with increasing the length of the hydrophobic chain. The surfactants (3a–e) showed good foaming stability, emulsion ability and wetting ability. The surfactants (3a–e) also have good antimicrobial activity against Staphylococcus aureus, Escherichia coli and Bacillus subtilis.     

A Process Model for Approximating the Production Costs of the Fermentative Synthesis of Sophorolipids

Sophorolipids are microbial glycolipids that possess surfactant-type properties. Sophorolipids have been tested successfully in a number of potential industrial and niche applications but are generally acknowledged to require higher production costs when compared to petroleum-based surfactants. The objective of this study was to develop a process economic model for the fermentative synthesis of sophorolipids using contemporary process simulation software and current reagent, equipment, and supply costs, following current production practices. Glucose (Glc) and either high oleic sunflower oil (HOSO) or oleic acid (OA) were used as feedstocks and the annual production capacity of the plant was set at 90.7 million kg/year with continuous operation of 24 h a day for 330 days per year. Major equipment costs were calculated to be US$17.1 million but other considerations such as capital, labor, material and utilities costs were also included. The single greatest contributor to the overall production/operating cost was raw materials, which accounted for 89 and 87 % of the total estimated production expenditures for the HOSO and OA-based fermentations, respectively. Based on this model and yields of 100 g/L, the cost of large-scale sophorolipid synthesis via fermentation from Glc:HOSO was calculated to be US$2.95/kg ($1.34/lb) and from Glc:OA to be US$2.54/kg ($1.15/lb). The model is flexible and can be adjusted to reflect changes in capital, production and feedstock costs as well as changes in the type of feedstocks used.     

Production and Characterization of Surface-Active Lipopeptides by Haloalkaliphilic Bacteria Salibacterium sp. 4CTb

Surface-Active Biomolecules (SAB) obtained from microbial sources are safe alternatives to chemically synthesized counterparts for many environmental and industrial applications. These applications frequently involve the exposure of the SAB to extreme factors making necessary to seek for molecules that are able to function under such conditions. In this work, the polyextremophilic bacterium Salibacterium sp. 4CTb is reported as a SAB producer. Its emulsifier activity increased almost twofold when the C/N ratio and culture conditions were modified. The partially purified molecule was able to form stable emulsions under extreme conditions (70 °C, pH 12, and 4 M NaCl) better than other commercial molecules, and reduced the surface tension of the water to 49.78 mN m⁻¹ with critical micelle concentration (CMC) of 15.1 mg L⁻¹. Carbohydrate, lipid, and protein assays, accompanied by the Fourier Transform Infra-Red (FTIR) and electrospray ionization mass spectroscopy (ESI-MS) results, indicate the lipopeptide nature of the compound with masses around 645 and 746 Da. The SAB obtained from Salibacterium sp. 4CTb may be suitable for electrical, food, pharmaceutical and cosmetic industries, agriculture, and environmental applications, among others.     

Mixed Stability and Antimicrobial Properties of Gluconamide-Type Cationic Surfactants

The stability of anionic-cationic surfactant solutions and the antimicrobial properties of novel N,N-dimethyl-N-[3-(gluconamide/lactobionamide)]propyl-N-alkylammonium bromides (CnDGPB and CnDLPB), N-methyl-N-hydroxyethyl group-N-[3-(gluconamide)-propyl]-N-alkylammonium bromide (CnMHGPB) and star-shaped gluconamide-type cationic surfactants N-dodecyl-N,N-bis[(3-d-gluconylamido)propyl]-N-alkylammonium bromide (CnDBGB) were investigated. Mixed stability in combination with sodium n-alkylbenzenesulfonate (LAS) was determined via transmittance; stability is achieved when percent transmittance was greater than 90 %. Transmittance results suggest that these cationic surfactants can form stable solutions with anionic surfactants over a broad concentration range. The inhibition activity of C _n DBGB is the best among the three kinds of glucocationic surfactants. Antimicrobial activity of C₁₂ surfactants was the best, C₁₄ was the second and C₁₀ was the worst. Moreover, antibacterial activity of glucose-based cationic surfactants was greater than lactose-based cationic surfactants.     

Friedel-Crafts Polyetherketones: Synthesis, Characterization and Antimicrobial Properties

Low molecular weight Friedel-Crafts polyetherketones (PEK) were prepared from o-chloro anisole, 1,4-phenylenedioxy diacetychloride (1,4-PDC), chloroacetylchloride (CAC), 1,2-dichloroethane (DEC) and dichloromethane (DCM) using anhydrous AlCl₃ as catalyst and CS₂ as solvent. The polyetherketones were characterized by IR spectra and Gel permeation chromatography (GPC). The kinetic parameters for the thermal behaviour of the resins were obtained from thermo gravimetric analysis (TGA) using the Broido and Doyle method. Differential scanning calorimetry (DSC) traces were employed to obtain heat of fusion. All the polyetherketones were tested for their biological activity against bacteria, fungi and yeast. It was observed that most of the polyetherketones synthesized can be used as antibacterial and antifungal agents. This revised version was published online in July 2006 with corrections to the Cover Date.     

Polyetherketones: Synthesis,Characterization and Antimicrobial Activity

ABSTRACT

Friedel-Crafts polyetherketones were prepared from o-chlorophenol, 1,4-phenylenedioxy diacetylchloride (1,4-PDC), chloroacetyl chloride (CAC), 1,2-dichloroethane (DCE), and dichloromethane (DCM) using anhydrous aluminium chloride (AlCl₃) as catalyst and carbon disulfide (CS₂) as solvent. These resins were characterized by IR spectroscopy and gel permeation chromatography. Carius method was employed to obtain the percentage of chlorine content in the resins. The kinetic parameters for the thermal behavior of the resins were evaluated from thermogravimetry (TG) using Broido method. Differential scanning calorimetry (DSC) thermograms of these resins were also obtained. All the polyetherketones were tested for their antimicrobial properties against bacteria, fungi, and yeast. It was observed that most of the polyetherketones synthesized could be used as antibacterial and antifungal agents.     

Synthesis,Characterization, and Surface-Active Properties of Carboxylbetaine and Sulfobetaine Surfactants based on Vegetable Oil

A novel series of carboxylbetaine-type and sulfobetaine-type zwitterionic surfactants (castor oil amidoethyl betaine, castor oil amidoethyl sulfobetaine [CAAS], cottonseed oil amidoethyl betaine, and cottonseed oil amidoethyl sulfobetaine [COAS]) were synthesized via the reactions of nonedible vegetable oils (castor oil and cottonseed oil) with dimethylaminoethylamine, followed by the reaction with sodium chloroacetate and sodium 2-hydroxy-3-chloropropane sulfonate, respectively. Their chemical structures were confirmed using the electrospray ionization mass spectrum (ESI-MS) and infrared (IR) spectra. The surface activities of the prepared compounds were measured by surface tension. It was noticed that the sulfobetaine-type surfactants in aqueous solution performed slightly better at reducing surface tension than the carboxylbetaine-type surfactants. Meanwhile, the synthesized surfactants possess a broad range of isoelectric points, superior foam properties, and exhibit some antibacterial activity on Gram-positive and Gram-negative bacteria.     

Biodegradable Polycaprolactone-Titania Nanocomposites: Preparation,Characterization and Antimicrobial Properties

Nanocomposites obtained from the incorporation of synthesized TiO₂ nanoparticles (≈10 nm average primary particle size) in different amounts, ranging from 0.5 to 5 wt.%, into a biodegradable polycaprolactone matrix are achieved via a straightforward and commercial melting processing. The resulting nanocomposites have been structurally and thermally characterized by transmission electron microscopy (TEM), wide/small angle X-ray diffraction (WAXS/SAXS, respectively) and differential scanning calorimetry (DSC). TEM evaluation provides evidence of an excellent nanometric dispersion of the oxide component in the polymeric matrix, with aggregates having an average size well below 100 nm. Presence of these TiO₂ nanoparticles induces a nucleant effect during polymer crystallization. Moreover, the antimicrobial activity of nanocomposites has been tested using both UV and visible light against Gram-negative Escherichia coli bacteria and Gram-positive Staphylococcus aureus. The bactericidal behavior has been explained through the analysis of the material optical properties, with a key role played by the creation of new electronic states within the polymer-based nanocomposites.     

Copolymers of Diallyldimethylammonium Chloride and Vinyl Ether of Monoethanolamine: Synthesis,Flocculating, and Antimicrobial Properties

N,N-diallyl-N,N-dimethylammonium chloride (DADMAC) and vinyl ether of monoethanolamine (VEMEA) copolymer P(DADMAC-VEMEA) were synthesized using radical polymerization in water media using ammonium persulfate as an initiator. The synthesis of this copolymer was investigated over a wide composition range at low conversion levels. The viscosity of the copolymers was measured in aqueous 1 M NaCl. Flocculating action and antimicrobial activities of the copolymers P(DADMAC-VEMEA) against microbacteria and sulfate-reducing bacteria (SRB) were studied. Synthesized copolymers had flocculating effects and can be used to purify wastewater from particles of bentonite clays. Also, the copolymer with a molar composition [DADMAC]: [VEMEA] = (80÷20):(20÷80) retarded the population of both bacteria, Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) in the diffusion zone. Furthermore, the copolymer with a molar composition [DADMAC]:[VEMEA] = (90÷10):(20÷80) had bactericidal properties against SRB. Minimum inhibitory concentration (MIC) of the copolymer varied from 0.01% to 0.1% depending on the molar composition of the copolymer.     

Microbial Oxidation of Medium Chain Fatty Alcohol in the Synthesis of Sophorolipids by Candida bombicola and its Physicochemical Characterization

Sophorolipids (SL) are glycolipid biosurfactants abundantly produced from different feedstocks by yeasts and have been widely developed for various applications. The amphipathic structures of sophorolipids imparts to them surfactant type properties. These biosurfactants are readily isolated in high yield and are nontoxic and biodegradable, which make them industrially interesting as surfactants or emulsifiers. Sophorolipid production was carried out using glucose as a hydrophilic source and lauryl alcohol C_12–14, as a hydrophobic source by Candida bombicola (ATCC 22214). Process economics and environmental attractiveness was increased by using a low cost substrate. Optimization studies were carried out where the effect of glucose concentration, pH, temperature and metal ions on sophorolipid production was studied. Optimum production of sophorolipid obtained using lauryl alcohol (SLLA) was achieved after 96 h, the initial pH of the medium was 6.0 with 10 % glucose at 30 °C. Primary characterization of SLLA was done by FTIR. The SLLA showed high physicochemical properties in terms of the surface activities when compared with synthetic surfactants including dodecyl tetraethylene glycol ether and sodium lauryl sulfate. The surface tension of SLLA thus obtained was found to be 24 mN/m with a critical micellar concentration (CMC) value of 0.68 mg/L. Antimicrobial testing showed that SLLA have potent antimicrobial activity against both gram negative bacteria, Escherichia coli (ATCC 8739) and gram positive cocci, Staphylococcus aureuss (ATCC 2079).     

Synthesis of (R)‐ and (S)‐Ricinoleic Acid Amides and Evaluation of Their Antimicrobial Activity

A series of fatty acid amides derived from (R)‐ and (S)‐ricinoleic acid and 4 cyclic and acyclic amines were synthesized in a proecological solvent‐free process with yields ranging from 43 to 88%. All S‐configured compounds and both enantiomers of amide with 2‐amino‐2‐methyl‐1‐propanol were obtained and studied in terms of biological activity for the first time. The evaluation of antimicrobial activity of (R)‐ and (S)‐ricinoleic acid derivatives against 13 different microorganisms representing Gram‐negative and Gram‐positive bacteria, yeast, and molds showed significant inhibitory activity against Gram‐positive bacteria, especially Micrococcus luteus and Bacillus subtilis, and against selected molds. Ethanolamine‐ and pyrrolidine‐derived amides showed the most promising antibacterial and antimold potential. Derivatives from ricinoleic acid and pyrrolidine were the most active against both selected molds, Aspergillus brasiliensis and Penicillium expansum. Moreover, the R‐configured analog was the most potent against B. subtilis. The amides of ricinoleic acid with ethanolamine exhibited significant potential to Staphylococcus aureus, which distinguished them from the rest of tested derivatives to which this bacterium was very resistant.     

Bioactive Organotin Materials: Synthesis, Characterization and Antimicrobial Investigation

Antimicrobial properties of some newly prepared oil based organotin polymers by the condensation reaction between fatty amide diol (N,N′-bis(2-hydroxyethyl) castoroil fatty amide) obtained from castoroil and organotin dihydroxides (dibutyltin dihydroxide, dimethyltin dihydroxide and diphenyltin dihydroxide) have been studied by employing both Gram-positive (Lactobacillus, Staphylococcus aureus) and Gram-negative (Pseudomonas putida, Pseudomonas fluorescens, E. coli) bacteria. The structural studies of these three polymers were carried out by FTIR, ¹HNMR and ¹³ CNMR spectroscopic techniques. Standard laboratory methods were used to study the physiochemical characteristics like acid value, hydroxyl value, saponification value, iodine value, specific gravity and viscosity. A comparative study of the thermal stability was analysed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). All three polymers have been found fairly active against the tested bacterial species. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Novel Phospholium-Type Cationic Surfactants: Synthesis,Aggregation Properties and Antimicrobial Activity

A series of novel phospholium amphiphilic compounds with straight alkyl chains with different numbers of carbon atoms (12, 14, 15, 16, 17, 18) were synthesized. The quaternary phosphorus, phosphonium cation, is incorporated into a five-membered heterocyclic ring. Their physicochemical properties were investigated by measurements of surface tension, conductivity and dynamic light scattering. The critical micelle concentration (c _M), the surface tension value at the c _M (γ _cmc), the surface area at the surface saturation per head group (A _cmc), the ionization degree of micelle (α), the free energy of micellization (ΔG° _mic), and hydrodynamic diameter (d _h) were determined. Antimicrobial activity was tested against bacteria and yeast. The structure–activity relationship was determined.