Accurate mass analysis of N-acyl-homoserine-lactones and cognate lactone-opened compounds in bacterial isolates of Pseudomonas aeruginosa PAO1 by LC-ESI-LTQ-FTICR-MS

N-acyl-homoserine-lactones (AHSLs) are widely conserved signal molecules present in quorum sensing systems of Gram-negative bacteria such as Pseudomonas aeruginosa. We present here the results obtained with a hybrid linear trap/Fourier transform ion cyclotron resonance (LTQ-FTICR) mass spectrometer used to investigate the occurrence of AHSLs and cognate N-acyl-homoserines (AHSs) in bacterial isolates of P. aeruginosa (strain PAO1). Two hydrolysed AHSs were found in significant amounts, most likely formed through the lactone opening of N-3-oxo-decanoyl-L-homoserine-lactone (3OC10-HSL) and N-3-oxo-dodecanoyl-L-homoserine-lactone (3OC12-HSL). Structure elucidation of these ring-opened molecules, i.e. N-3-oxo-decanoyl-L-homoserine (3OC10-HS), and N-3-oxo-dodecanoyl-L-homoserine (3OC12-HS), which are not detected by bacterial biosensors, was performed by high-resolution and accurate mass measurements upon liquid chromatography (LC) and confirmed by tandem MS in the LTQ analyser. Assignment of chemical formula, with mass spectra in the form of [M+H]+, was significantly expedited by extracted ion chromatograms (XICs) because the number of potentially plausible formulae for each protonated signalling molecule was considerably reduced a priori by the LC behaviour, the high mass measurement accuracy available in FTICR mass spectra and the isotopic patterns. At least two concentration levels were observed in spent culture supernatants of P. aeruginosa: compounds at a relatively high content (5-15 microM) that is C4-HSL, 3OC10-HS, and 3OC12-HS and those occurring at a lower content (<0.2 microM) that is C6-HSL and C8-HSL. The implications of this work extend to a great variety of Gram-negative bacteria.     

Role of the Quorum Sensing Mechanism in the Response of Pseudomonas aeruginosa to Lethal and Sublethal UVA Irradiation

The role of quorum sensing (QS) in the response of Pseudomonas aeruginosa to UVA radiation was investigated in the PAO1 strain and derivatives defective in the synthesis of the QS signals 3OC12-HSL (lasI strain), C4-HSL (rhlI strain) or both (lasI rhlI strain). Cell viability measurements demonstrated that the double mutant was significantly more sensitive to UVA than single mutants, which in turn showed reduced cell survival with regard to the PAO1 strain. Irradiation under nitrogen atmosphere and chemiluminescence measurements indicated the oxidative nature of the UVA-induced damage. The activity of the antioxidant enzymes catalase and superoxide dismutase was assayed in these strains before and after irradiation, and a strong correlation between catalase levels and UVA sensitivity was observed. When a sublethal UVA dose was applied to PAO1, a growth delay was observed and this mechanism depended on the rhl system. Moreover, low doses of UVA irradiation triplicated the level of C4-HSL in log PAO1 cells. It is concluded that QS is fundamental in the defense against the toxic effects of UVA in P. aeruginosa. The induction of the QS system by UVA independently of cell density could function as an adaptative strategy to withstand this hostile environmental condition.     

Halogenated Phenazines that Potently Eradicate Biofilms,MRSA Persister Cells in Non‐Biofilm Cultures,and Mycobacterium tuberculosis

Conventional antibiotics are ineffective against non‐replicating bacteria (for example, bacteria within biofilms). We report a series of halogenated phenazines (HP), inspired by marine antibiotic 1 , that targets persistent bacteria. HP 14 demonstrated the most potent biofilm eradication activities to date against MRSA, MRSE, and VRE biofilms (MBEC=0.2–12.5 μM), as well as the effective killing of MRSA persister cells in non‐biofilm cultures. Frontline MRSA treatments, vancomycin and daptomycin, were unable to eradicate MRSA biofilms or non‐biofilm persisters alongside 14 . HP 13 displayed potent antibacterial activity against slow‐growing M. tuberculosis (MIC=3.13 μM), the leading cause of death by bacterial infection around the world. HP analogues effectively target persistent bacteria through a mechanism that is non‐toxic to mammalian cells and could have a significant impact on treatments for chronic bacterial infections.     

Halogenated Phenazines that Potently Eradicate Biofilms,MRSA Persister Cells in Non‐Biofilm Cultures,and Mycobacterium tuberculosis

Conventional antibiotics are ineffective against non‐replicating bacteria (for example, bacteria within biofilms). We report a series of halogenated phenazines (HP), inspired by marine antibiotic 1 , that targets persistent bacteria. HP 14 demonstrated the most potent biofilm eradication activities to date against MRSA, MRSE, and VRE biofilms (MBEC=0.2–12.5 μM), as well as the effective killing of MRSA persister cells in non‐biofilm cultures. Frontline MRSA treatments, vancomycin and daptomycin, were unable to eradicate MRSA biofilms or non‐biofilm persisters alongside 14 . HP 13 displayed potent antibacterial activity against slow‐growing M. tuberculosis (MIC=3.13 μM), the leading cause of death by bacterial infection around the world. HP analogues effectively target persistent bacteria through a mechanism that is non‐toxic to mammalian cells and could have a significant impact on treatments for chronic bacterial infections.     

Homogentisic acid γ-lactone suppresses the virulence factors of Pseudomonas aeruginosa by quenching its quorum sensing signal molecules

Homogentisic acid γ-lactone exhibited excellent anti-quorum sensing (QS) and anti-biofilm activities against Pseudomonas aeruginosa. Moreover, it suppressed the QS-dependent virulence factors in P. aeruginosa by quenching its QS signal molecules.     

Antiviral properties of lactoferrin--a natural immunity molecule

Lactoferrin, a multifunctional iron binding glycoprotein, plays an important role in immune regulation and defence mechanisms against bacteria, fungi and viruses. Lactoferrin's iron withholding ability is related to inhibition of microbial growth as well as to modulation of motility, aggregation and biofilm formation of pathogenic bacteria. Independently of iron binding capability, lactoferrin interacts with microbial, viral and cell surfaces thus inhibiting microbial and viral adhesion and entry into host cells. Lactoferrin can be considered not only a primary defense factor against mucosal infections, but also a polyvalent regulator which interacts in viral infectious processes. Its antiviral activity, demonstrated against both enveloped and naked viruses, lies in the early phase of infection, thus preventing entry of virus in the host cell. This activity is exerted by binding to heparan sulphate glycosaminoglycan cell receptors, or viral particles or both. Despite the antiviral effect of lactoferrin, widely demonstrated in vitro studies, few clinical trials have been carried out and the related mechanism of action is still under debate. The nuclear localization of lactoferrin in different epithelial human cells suggests that lactoferrin exerts its antiviral effect not only in the early phase of surface interaction virus-cell, but also intracellularly. The capability of lactoferrin to exert a potent antiviral activity, through its binding to host cells and/or viral particles, and its nuclear localization strengthens the idea that lactoferrin is an important brick in the mucosal wall, effective against viral attacks and it could be usefully applied as novel strategy for treatment of viral infections.     

Temperaturabhängiger Circulardichroismus von (3S, 3′R)- und (3S, 3′ S)-Adonixanthin

The temperature dependent CD. spectra of (3S, 3′R)- and (3S, 3′S)-adonixanthin are compared with those of (3R, 3′R)-zeaxanthin ( 1 ) and (3S, 3′S)-astaxanthin ( 2 ). The room temperature spectra of 1 and 2 are quite similar. On cooling to ?180° the CD. of 1 simply intensifies, the CD. of 2 changes sign and becomes also very intense. The room-temperature CD. of (3S, 3′R)-adonixanthin ( 3 ) resembles closely those of 1 and 2 at room temperature. On cooling, however, it becomes weak and changes strongly its shape. With (3S, 3′S)-adonixanthin ( 4 ) it is the low-temperature spectrum which resembles that of 2 at low temperature, whereas the room-temperature spectrum is weak and quite different in shape. These observations can be explained with temperature dependent equilibria where the end groups are twisted out of the plain of the chain thereby conferring chirality to the conjugated system.     

1-(2′-Deoxy-β-D-xylofuranosyl)thymine Building Blocks for Solid-Phase Synthesis and Properties of Oligo(2′-Deoxyxylonucleotides)

1-(2′-Deoxy-β-D -threo-pentofuranosyl)thymine (= 1-(2′-deoxy-β-D -xylofuranosyl)thymine; xT_d; 2 ) was converted into its phosphonate 3b as well as its 2-cyanoethyl phosphoramidite 3c . Both compounds were used for solid-phase synthesis of d[(xT)₁₂-T] ( 5 ), representing the first DNA fragment build up from 3′–5′-linked 2′-deoxy--β-D -xylonucleosides. Moreover, xT_d was introduced into the innermost part of the self-complementary dodecamer d(G-T-A-G-A-A-xT-xT-C-T-A-C)₂ (9). The CD spectrum of d[(xT)₁₂–T] ( 5 ) exhibits reversed Cotton effects compared to d(T₁₂) ( 6 ; see Fig. 1), implying a left-handed single strand. With d(A₁₂) ( 7 ) it could be hybridized to form a propably Left-handed double strand d(A₁₂) · d[(xT)₁₂–T] ( 7 · 5 ) which was confirmed by melting experiments in combination with temperature-dependent CD spectroscopy. While 5 was hydrolyzed by snake-venom phosphodiesterase, it was resistant towards calf-spleen phosphodiesterase. The modified, self-complementary duplex 9 was hydrolyzed completely by snake-venom phosphodiesterase, at a twelvefold slower rate compared to unmodified 8 ; calf-spleen phosphodiesterase hydrolyzed 9 only partially.     

Photodynamic Activity on Biofilm in Endotracheal Tubes of Patients Admitted to an Intensive Care Unit

Ventilator-associated pneumonia (VAP) is an infection that arises after endotracheal intubation affecting patients under intensive care. The presence of the endotracheal tube (ETT) is a risk factor since it is colonized by multispecies biofilm. Antimicrobial photodynamic therapy (aPDT) could be a strategy to decontaminate ETTs. We verify if methylene blue (MB) associated with external illumination of the ETT could be an alternative to destroy biofilm. We performed an in vitro and ex vivo study. In vitro study was performed with P. aeruginosa biofilm grew over ETT for 7 days. After treatment, the surviving cells were cultured for 3 days and the biofilm was analyzed by crystal violet absorbance. Ex vivo study employed ETT obtained from extubated patients. aPDT was performed with MB (100 µm ) and red LED (λ = 640±20 nm). We quantified the biofilm thickness and used scanning electron microscopy and fluorescence technique to verify morphological and functional changes after aPDT. Our results showed that bacteria remain susceptible to aPDT after sequential treatments. We also attested that aPDT can reduce biofilm thickness, disrupt biofilm attachment from ETT surface and kill microbial cells. These data suggest that aPDT should be investigated to decrease VAP incidence via ETT decontamination.     

Nonisothermal crystallization and melting behavior of a luminescent conjugated polymer,poly(9,9‐dihexylfluorene‐alt‐co‐2,5‐didecyloxy‐1,4‐phenylene)

The nonisothermal crystallization kinetics of a luminescent conjugated polymer, poly(9,9‐dihexylfluorene‐alt‐co‐2,5‐didecyloxy‐1,4‐phenylene) (PF6OC10) with three different molecular weights was investigated by differential scanning calorimetry under different cooling rates from the melt. With increasing molecular weight of PF6OC10, the temperature range of crystallization peak steadily became narrower and shifted to higher temperature region and the crystallization rate increased. It was found that the Ozawa method failed to describe the nonisothermal crystallization behavior of PF6OC10. Although the Avrami method did not effectively describe the nonisothermal crystallization kinetics of PF6OC10 for overall process, it was valid for describing the early stage of crystallization with an Avrami exponent n of about 3. The combined method proposed in our previous report was able to satisfactorily describe the nonisothermal crystallization behavior of PF6OC10. The crystallization activation energies determined by Kissinger, Takhor, and Augis‐Bennett models were comparable. The melting temperature of PF6OC10 increased with increasing molecular weight. For low‐molecular‐weight sample, PF6OC10 showed the characteristic of double melting phenomenon. The interval between the two melting peaks decreased with increasing molecular weight, and only one melting peak was observed for the high‐molecular‐weight sample. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 976–987, 2007     

Deuterium-labelled N-acyl-L-homoserine lactones (AHLs)--inter-kingdom signalling molecules--synthesis, structural studies, and interactions with model lipid membranes

N-Acyl-l-homoserine lactones (AHLs) are synthesized by Gram-negative bacteria. These quorum-sensing molecules play an important role in the context of bacterial infection and biofilm formation. They also allow communication between microorganisms and eukaryotic cells (inter-kingdom signalling). However, very little is known about the entire mechanism of those interactions. Precise structural studies are required to analyse the different AHL isomers as only one form is biologically most active. Theoretical studies combined with experimental infrared and Raman spectroscopic data are therefore undertaken to characterise the obtained compounds. To mimic interactions between AHL and cell membranes, we studied the insertion of AHL in supported lipid bilayers, using vibrational sum-frequency-generation spectroscopy. Deuterium-labelled AHLs were thus synthesized. Starting from readily available deuterated fatty acids, a two-step procedure towards deuterated N-acyl-l-homoserine lactones with varying chain lengths is described. This included the acylation of Meldrum’s acid followed by amidation. Additionally, the detailed analytical evaluation of the products is presented herein.     

Metallorganische Verbindungen mit N-substituierten 3-Hydroxy-2-methyl-4-pyridon-Liganden: quadratisch-planare Rhodium(I)-, Iridium(I)- und Palladium(II)-Komplexe

Organometallic Compounds with N -substituted 3-Hydroxy-2-methyl-4-pyridone Ligands: square planar Rhodium(I), Iridium(I), and Palladium(II) Complexes Reactions of [(OC)₂MCl]₂ (M = Rh, Ir) or [(cod)RhCl]₂ with the anions of N-Aryl or N-Alkyl substituted 3-hydroxy-2-methyl-4-pyridones (O–O′) yield complexes of the general formula [L₂M(O–O′)]. Compounds of this type are also available from reactions of [(OC)₂Rh(acac)] with the corresponding neutral ligands. Substitution of one carbonyl-ligand of the N-phenyl complex [(OC)₂Rh(C₁₂H₁₀NO₂)] ( 2 ) with cyclooctene affords [(OC)(C₈H₁₄)Rh(C₁₂H₁₀NO₂)] ( 8 ). The palladium complexes [(R₃P)Pd(O–O′)Cl] (R = Et, Bu), [(C₆H₄CH₂NMe₂) · Pd(O–O′)] and [(Et₃P)₂Pd(O–O′)]BF₄ ( 9 – 12 ) were synthesized from [(R₃P)PdCl₂]₂, [(C₆H₄CH₂NMe₂)PdCl]₂ or [(Et₃P)PdCl₂]. The structures of the N-methyl compounds [(OC)₂Rh(C₇H₈NO₂)] ( 1 ) and [(Ph₃P)Pd(C₇H₈NO₂)Cl] ( 9 ) were determined by single crystal X-ray diffraction.     

Kinetics of the gas‐phase reaction of CF3OC(O)H with OH radicals at 242–328 K

The rate constants, k₁, of the reaction of CF₃OC(O)H with OH radicals were measured by using a Fourier transform infrared spectroscopic technique in an 11.5‐dm³ reaction chamber at 242–328 K. OH radicals were produced by UV photolysis of an O₃–H₂O–He mixture at an initial pressure of 200 Torr. Ozone was continuously introduced into the reaction chamber during UV irradiation. With CF₃OCH₃ as a reference compound, k₁ at 298 K was (1.65 ± 0.13) × 10^?14 cm³ molecule^?1 s^?1. The temperature dependence of k₁ was determined as (2.33 ± 0.42) × 10^?12 exp[?(1480 ± 60)/T] cm³ molecule^?1 s^?1; possible systematic uncertainty could add an additional 20% to the k₁ values. The atmospheric lifetime of CF₃OC(O)H with respect to reaction with OH radicals was calculated to be 3.6 years. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 337–344 2004     

Uptake, degradation and chiral discrimination of N-acyl-D/L-homoserine lactones by barley (Hordeum vulgare) and yam bean (Pachyrhizus erosus) plants

Bacterial intraspecies and interspecies communication in the rhizosphere is mediated by diffusible signal molecules. Many Gram-negative bacteria use N-acyl-homoserine lactones (AHLs) as autoinducers in the quorum sensing response. While bacterial signalling is well described, the fate of AHLs in contact with plants is much less known. Thus, adsorption, uptake and translocation of N-hexanoyl- (C6-HSL), N-octanoyl- (C8-HSL) and N-decanoyl-homoserine lactone (C10-HSL) were studied in axenic systems with barley (Hordeum vulgare L.) and the legume yam bean (Pachyrhizus erosus (L.) Urban) as model plants using ultra-performance liquid chromatography (UPLC), Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) and tritium-labelled AHLs. Decreases in AHL concentration due to abiotic adsorption or degradation were tolerable under the experimental conditions. The presence of plants enhanced AHL decline in media depending on the compounds' lipophilicity, whereby the legume caused stronger AHL decrease than barley. All tested AHLs were traceable in root extracts of both plants. While all AHLs except C10-HSL were detectable in barley shoots, only C6-HSL was found in shoots of yam bean. Furthermore, tritium-labelled AHLs were used to determine short-term uptake kinetics. Chiral separation by GC-MS revealed that both plants discriminated D-AHL stereoisomers to different extents. These results indicate substantial differences in uptake and degradation of different AHLs in the plants tested.     

Complexation of dodecyl‐substituted poly(acrylate) by linked β‐cyclodextrin dimers and trimers in aqueous solution

Two‐dimensional NOESY ¹H NMR, isothermal titration calorimetric (ITC), and rheological studies of host–guest complexation by β‐cyclodextrin, β‐CD, and the β‐CD groups of the linked β‐CD dimers, β‐CD₂ur and β‐CD₂su and trimers, β‐CD₃bz and β‐CDen₃bz, of the dodecyl, C12, substituents of the 3.0% substituted poly(acrylate), PAAC12, in aqueous solution are reported. Complexations by β‐CD, β‐CD₂ur, β‐CD₂su, β‐CD₃bz, and β‐CDen₃bz of the C12 substituents of PAAC12 in 0.2 wt % solution exhibit complexation constants 10^?4K₁₁ (298.2 K) = 0.83, 5.80, 4.40, 15.0, and 1.50 dm³ mol^?1, respectively. (The corresponding ΔH₁₁ and TΔS₁₁ show a linear relationship.) The rheologically determined zero‐shear viscosities of 3.3 wt % aqueous solutions of PAAC12 alone and in the presence of β‐CD, β‐CD₂ur, β‐CD₂su, β‐CD₃bz, and β‐CDen₃bz (where the β‐CD groups and C12 substituents are equimolar) are 0.016, 0.03, 0.12, 0.25, 0.12, and 0.08 Pa s (298.2 K), respectively, and show PAAC12 to form interstrand cross‐links through complexation. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1278–1286     

Silver–Ethene Complexes [Ag(η2‐C2H4)n][Al(ORF)4] with n=1, 2, 3 (RF=Fluorine‐Substituted Group)

Compounds including the free or coordinated gas‐phase cations [Ag(η²‐C₂H₄)_n]⁺ (n=1–3) were stabilized with very weakly coordinating anions [A]^? (A=Al{OC(CH₃)(CF₃)₂}₄, n=1 ( 1 ); Al{OC(H)(CF₃)₂}₄, n=2 ( 3 ); Al{OC(CF₃)₃}₄, n=3 ( 5 ); {(F₃C)₃CO}₃Al‐F‐Al{OC(CF₃)₃}₃, n=3 ( 6 )). They were prepared by reaction of the respective silver(I) salts with stoichiometric amounts of ethene in CH₂Cl₂ solution. As a reference we also prepared the isobutene complex [(Me₂C?CH₂)Ag(Al{OC(CH₃)(CF₃)₂}₄)] ( 2 ). The compounds were characterized by multinuclear solution‐NMR, solid‐state MAS‐NMR, IR and Raman spectroscopy as well as by their single crystal X‐ray structures. MAS‐NMR spectroscopy shows that the [Ag(η²‐C₂H₄)₃]⁺ cation in its [Al{OC(CF₃)₃}₄]^? salt exhibits time‐averaged D_3h‐symmetry and freely rotates around its principal z‐axis in the solid state. All routine X‐ray structures (2θ_max.<55°) converged within the 3σ limit at C?C double bond lengths that were shorter or similar to that of free ethene. In contrast, the respective Raman active C?C stretching modes indicated red‐shifts of 38 to 45 cm^?1, suggesting a slight C?C bond elongation. This mismatch is owed to residual librational motion at 100 K, the temperature of the data collection, as well as the lack of high angular data owing to the anisotropic electron distribution in the ethene molecule. Therefore, a method for the extraction of the C?C distance in [M(C₂H₄)] complexes from experimental Raman data was developed and meaningful C?C distances were obtained. These spectroscopic C?C distances compare well to newly collected X‐ray data obtained at high resolution (2θ_max.=100°) and low temperature (100 K). To complement the experimental data as well as to obtain further insight into bond formation, the complexes with up to three ligands were studied theoretically. The calculations were performed with DFT (BP86/TZVPP, PBE0/TZVPP), MP2/TZVPP and partly CCSD(T)/AUG‐cc‐pVTZ methods. In most cases several isomers were considered. Additionally, [M(C₂H₄)₃] (M=Cu⁺, Ag⁺, Au⁺, Ni⁰, Pd⁰, Pt⁰, Na⁺) were investigated with AIM theory to substantiate the preference for a planar conformation and to estimate the importance of σ donation and π back donation. Comparing the group 10 and 11 analogues, we find that the lack of π back bonding in the group 11 cations is almost compensated by increased σ donation.     

Mixed β2/β3‐Hexapeptides and β2/β3‐Nonapeptides Folding to (P)‐Helices with Alternating Twelve‐ and Ten‐Membered Hydrogen‐Bonded Rings

The structural properties of four mixed β‐peptides with alternating β²/β³‐ or β³/β²‐sequences have been analyzed by two‐dimensional homonuclear ¹H‐NMR‐ and CD spectroscopic measurements. All four β‐peptides fold into (P)‐helices with twelve‐ and ten‐membered H‐bonded rings (Figs. 3–6). CD Spectra (Fig. 2) of the mixed β³/β²‐hexapeptide 4a and β³/β²‐nonapeptide 5a , indicating that peptides of this type also adopt the 12/10‐helical conformation, were confirmed by NMR structural analysis. For the deprotected β³/β²‐nonapeptide 5d , NOEs not consistent with the 10/12 helix have been observed, showing that the stability of the helix decreases upon N‐terminal deprotection. From the NMR structures obtained, an idealized helical‐wheel representation was generated (Fig. 7), which will be used for the design of further 12/10 or 10/12 helices.     

Gallium tris­(iodate), Ga(IO3)3

Ga(IO₃)₃ crystallizes in the space group P6₃, with the Ga atom at a site with imposed threefold symmetry. The crystal structure consists of slightly distorted GaO₆ octa­hedra that are bridged by I atoms of IO₃⁻ groups, giving rise to a three‐dimensional polar network. The framework contains unoccupied hexa­gonal channels running parallel to the hexa­gonal [001] direction. The iodate groups have their stereochemically active non‐bonded electron pairs pointing in the same direction along [001], which creates the polarity in the structure. The I—O bond distances and O—I—O angles are normal, being in the ranges 1.783 (3)–1.847 (2) Å and 94.68 (11)–99.61 (12)°, respectively.     

Preparation of New Derivatives of the closo-Dodecaborate Anion [B12H10(OC(O)CH3){OC(O)(CH2)3CH3}]2–, [B12H10(OH){OC(O)(CH2)3CH3}]2–, [B12H10(SCN){OC(O)(CH2)3CH3}]2–, and [B12H10(I){OC(O)(CH2)3CH3}]2–

Nucleophilic substitution reactions of the monosubstituted anions [B₁₂H₁₁X]^2–, where X = OC(O)CH₃, OH, SCN, and I, with pentanoic acid were studied. The obtained compounds were shown to contain the [B₁₂H₁₀X{OC(O)(CH₂)₃CH₃}]^2– anions.     

Preparation and characterization of poly(ethylene oxide)‐loaded hydroxypropyl‐β‐cyclodextrin nanofibers

Hydroxypropyl‐β‐cyclodextrin (HP‐β‐CD) is a modified β‐cyclodextrin (β‐CD) derivative, which is toxicologically harmless to mammals and other animals. HP‐β‐CD is electrospun from an aqueous solution by blending with a non‐toxic, biocompatible, synthetic polymer poly(ethylene oxide) (PEO). Aqueous solutions containing different HP‐β‐CD/PEO blends (50:50–80:20) with variable concentrations (4 wt%–12 wt%) were used. Scanning electron microscope was used to investigate the morphology of the fibers, and Fourier transform infrared spectroscopy analysis confirmed the presence of HP‐β‐CD in the fiber. Uniform nanofibers with an average diameter of 264, 244, and 236 nm were obtained from 8 wt% solution of 50:50, 60:40, and 70:30 HP‐β‐CD/PEO, respectively. The average diameter of the fiber was decreased with increasing of HP‐β‐CD/PEO ratio. However, a higher proportion of HP‐β‐CD in the spinning solution increased beads in the fibers. The polymer concentration had no significant effect on the fiber diameter. The most uniform fibers with the narrowest diameter distribution were obtained from the 8 wt% of 50:50 solution. Copyright © 2015 John Wiley & Sons, Ltd.