Development of liposomes containing ethanol for skin delivery of temoporfin: Characterization and in vitro penetration studies

The aim of this study was to develop ethanol-containing (3.3–20%, w/v) liposomes loaded with temoporfin (mTHPC), which presents a highly hydrophobic photosensitizer with low percutaneous penetration, and to investigate their skin penetration enhancing effect. Characterization parameters of liposomes were measured by photon correlation spectroscopy, lamellarity was analyzed by cryo-electron microscopy and mTHPC-content in formulations was determined spectrofotometrically. In order to assess the stability of mTHPC–liposomes at 4 and 23 °C, at predetermined time intervals characterization parameters and mTHPC-content were measured. The in vitro skin penetration of mTHPC was investigated using human abdominal skin mounted in Franz cells. The results indicated that mTHPC–liposomes were of a small particle size, small polydispersity index, negative surface charge, unilamellar or oligolamellar, and of a spherical or oval shape. All liposomes were stable during 12 months’ storage at 4 °C. Increasing the amount of ethanol in mTHPC–liposomes the skin deposition of mTHPC increased also. Liposomes without ethanol delivered the lowest amount of mTHPC into the skin, while liposomes containing 20% ethanol showed the highest penetration enhancement. In conclusion, mTHPC–liposomes containing 20% ethanol could be a promising tool for delivering temoporfin to the skin, which would be beneficial for the photodynamic therapy of cutaneous malignant or non-malignant diseases.     

Topical application of temoporfin-loaded invasomes for photodynamic therapy of subcutaneously implanted tumours in mice: a pilot study

Temoporfin (mTHPC) represents a very potent second-generation synthetic photosensitizer. It has shown to be effective in the photodynamic therapy of early or recurrent oral carcinomas, in the palliative treatment of refractory oral carcinomas and in the treatment of primary non-melanomatous tumours of the skin of the head and neck. Until now for all positive findings an intravenous application of the photosensitizer was mandatory. In the case of cutaneous malignant or non-malignant diseases a topical application of the drug onto the site of the disease followed by illumination, would be advantageous. Unfortunately, mTHPC is a highly hydrophobic drug with a low percutaneous absorption. The purpose of this experiment was to investigate the photodynamic efficacy of novel mTHPC-loaded invasomes after their topical application onto the skin of mice bearing the subcutaneously implanted human colorectal tumour HT29 followed by photoirradiation. Invasomes are vesicles containing in addition to phospholipids a mixture of terpenes (cineole, citral and d-limonene) or only one terpene (citral) and ethanol, as penetration enhancers. This was a pilot study since until now no data are available about the efficacy of mTHPC in the photodynamic therapy of HT29 tumours after its topical application. The aim of this experiment was to investigate whether a mTHPC-loaded invasome formulation can reduce tumour size by photodynamic therapy or at least to find a formulation slowing down tumour growth compared to the control group (mice without any treatment). The groups of mice treated with mTHPC–invasomes containing 1% of the terpene mixture prior to photoirradiation showed a significantly smaller (p < 0.05) tumour increase compared to control groups (mice without any treatment and mice only photoirradiated).     

Development of a HPLC method for determination of four UV filters in sunscreen and its application to skin penetration studies

This study describes the development, validation and application of a high‐performance liquid chromatography (HPLC) method for the simultaneous determination of the in vitro skin penetration profile of four UV filters on porcine skin. Experiments were carried out on a gel‐cream formulation containing the following UV filters: diethylamino hydroxybenzoyl hexyl benzoate (DHHB), bis‐ ethylhexyloxyphenol methoxyphenyl triazine (BEMT), methylene bis‐ benzotriazolyl tetramethylbutylphenol (MBBT) and ethylhexyl triazone (EHT). The HPLC method demonstrated suitable selectivity, linearity (10.0–50.0 μg/mL), precision, accuracy and recovery from porcine skin and sunscreen formulation. The in vitro skin penetration profile was evaluated using Franz vertical diffusion cells for 24 h after application on porcine ear skin. None of the UV filters penetrated the porcine skin. Most of them stayed on the skin surface (>90%) and only BEMT, EHT and DHHB reached the dermis plus epidermis layer. These results are in agreement with previous results in the literature. Therefore, the analytical method was useful to evaluate the in vitro skin penetration of the UV filters and may help the development of safer and effective sunscreen products.     

Development and validation of HPLC method for imiquimod determination in skin penetration studies

A simple, rapid and sensitive analytical procedure for the measurement of imiquimod in skin samples after in vitro penetration studies has been developed and validated. In vitro penetration studies were carried out in Franz diffusion cells with porcine skin. Tape stripping technique was used to separate the stratum corneum (SC) from the viable epidermis and dermis. Imiquimod was extracted from skin samples using a 7:3 (v/v) methanol:acetate buffer (100 mM, pH 4.0) solution and ultrasonication. Imiquimod was analyzed by HPLC using C(8) column and UV detection at 242 nm. The mobile phase used was acetonitrile:acetate buffer (pH 4.0, 100 mM):diethylamine (30:69.85:0.15, v/v) with flow rate 1 mL/min. Imiquimod eluted at 4.1 min and the running time was limited to 6.0 min. The procedure was linear across the following concentration ranges: 100-2500 ng/mL for both SC and tape-stripped skin and 20-800 ng/mL for receptor solution. Intra-day and inter-day accuracy and precision values were lower than 20% at the limit of quantitation. The recovery values ranged from 80 to 100%. The method is adequate to assay imiquimod from skin samples, enabling the determination of the cutaneous penetration profile of imiquimod by in vitro studies.     

Novel Lanthanide Complexes of Ciprofloxacin: Synthesis,Characterization, Crystal Structure and in vitro Antibacterial Activity Studies

Novel lanthanide coordination compounds with ciprofloxacin (CPFX), including eleven complexes Ln(CPFX)₂Cl(H₂O), (Ln=Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb; n = 7, 8, 9) and crystalline [Ce(CPFX)₂ (H₂O)₄] Cl (H₂O)_3.25 (C₂H₅‐OH)_0.25, were synthesized. The crystal is of triclinic space group Pi with a= 1.3865(2) nm, b = 1.3899(3) nm, c = 1.6505(2) nm, a = 92.73(1)°, β= 114.39(1)°, γ=115.55 (1)°, Z = 2 and R = 0.0449. FT‐IR, electronic spectroscopy and X‐ray diffraction were employed to show that the lanthanide ion, which displays an eight‐coordinate structure, is chelated by 3‐carboxyl and 4‐keto oxygen donors of CPFX and two six‐membered chelate rings are formed. Test of in vitro antibacterial activity against E. coli, P. aeruginosa and S. aureus indicated that the in vitro antibacterial activity of the ligand can be improved by complexation with Ce(III).     

Fast and sensitive liquid chromatography/electrospray mass spectrometry method to study ocular penetration of EDL‐155, a novel antitumor agent for retinoblastoma in rats

Our group has used the tetrahydroisoquinoline derivative EDL‐155 to treat glioblastoma in animal models and it is currently being evaluated in the treatment of ocular cancers. The purpose of this study was to develop a rapid and sensitive liquid chromatography and tandem mass spectrometry (LC‐MS/MS) method to study the plasma and vitreous humor disposition of EDL‐155 in rats. Animals received a single periocular injection of EDL‐155 (20 mg/kg). Animals were sacrificed at specified times (5, 60, 120, 240 and 360 min) and plasma and vitreous humor samples were obtained. EDL‐155 was isolated by protein precipitation and the extracts were analyzed by reversed‐phase high‐pressure liquid chromatography (HPLC) with MS/MS detection. A structurally similar analog was used as internal standard (IS). The chromatographic run time was 3.5 min per injection. The mass spectrometer was operated in positive‐ion, multiple reaction monitoring (MRM) mode. The mass transitions monitored were m/z332.2 → 167.2 (EDL‐155) and m/z391.2 → 200.2 (IS). The lower limit of quantification (LLOQ) was 0.1 ng/ml in both vitreous humor and plasma. The method was validated for selectivity, linearity, accuracy and precision in rat vitreous humor and partially validated for accuracy and precision in rat plasma. The ion suppression, recovery and stability of the analyte in the biological matrix were also tested. The assay was rapid, sensitive and robust enough to support EDL‐155 ocular penetration studies in a rodent model of intraocular cancer. Application of this method revealed that EDL‐155 was rapidly passed into the vitreous humor following periocular administration. Further, vitreous humor exposure exceeded systemic exposure by approximately sevenfold. High local concentrations coupled with minimal systemic exposure supports further testing of EDL‐155 as localized therapy for intraocular cancers. Copyright © 2009 John Wiley & Sons, Ltd.     

Effects of enzyme treatment and skin extraction on varietal volatiles in Spanish wines made from Chardonnay, Muscat, Airén, and Macabeo grapes

Varietal compounds have been analyzed in wines prepared in the laboratory from four grape varieties grown in Spain. The possibilities for enhancing their aroma afforded by addition of glycosidase enzymes and steeping with the skin were studied. Both treatments increased substances responsible for varietal aroma in all wines, the effect being particularly significant for benzyl alcohol.     

Molecular structure and conformational stability of allylisocyanate—post-Hartree–Fock and density functional theory studies

The molecular structure and conformational stability of allylisocyanate (CH₂CHCH₂NCO) molecule was studied using the ab initio and DFT methods. The geometries of possible conformers, C-gauche (δ=120°, θ=0°) (δ=C=C–C–N and θ=C–C–N=C) and C-cis N-trans (δ=0° and θ=180°) were optimized employing HF/6-31G^*, MP2/6-31G^* levels of theory of ab initio and BLYP, B3LYP, BPW91 and B3PW91 methods of DFT implementing the atomic basis set 6-311+G(d,p). The structural and physical parameters of the above conformers were discussed with the experimental and theoretical values of the related molecules, methylisocyanate and 3-fluoropropene. It has been found that the N=C=O bond angle is not linear as the experimental result for both the conformers and the theoretical bond angle is 173°. The rotational potential energy surfaces have been performed at the HF/6-31G^*, and MP2/6-31G^* levels of theory. The Fourier decomposition potentials were analysed at the HF/6-31G^*, and MP2/6-31G^* levels of theory. The HF/6-31G^* level of theory predicted that the C-gauche conformer is more stable than the C-cis N-trans conformer by 0.41 kJ/mol, but the MP2 and DFT methods predicted the C-cis N-trans conformer is found to be more stable than the C-gauche conformer. The calculated chemical hardness value at the HF/6-31G^* level of theory predicted the C-cis N-trans form is more stable than C-gauche form, whereas the chemical hardness value at the MP2/6-31G^* level of theory favours the slight preference towards the C-gauge conformer.     

Quantitative investigation, stability and in vitro release studies of anti-TB drugs in Triton niosomes

The highly stable innocuous niosomes composed of four components (Triton X 100, polyethylene glycol 2000, water, Span 80) have been prepared successfully and characterized using particle size analyzer, transmission and scanning electron microscopy. The mean size has been found to be in the range 200-300 nm. The optimization of niosomes has been carried out using fluorescence spectroscopy. An attempt has been made to incorporate anti-tuberculosis drugs (ATD's) in the prepared niosomes. The stability and encapsulation efficiency of these drugs in the niosome have also been assessed and high encapsulation efficiency is observed. Such high encapsulation efficiency will serve as an advantage to solve the problem of multi-drug resistance in case of tuberculosis. Release studies and kinetics have been carried out to investigate the release behavior of drugs from the prepared niosomes. Fickian or diffusional release has been observed for rifampicin and isoniazid and a non-Fickian release mechanism for pyrazinamide. Fluorescence probe quenching technique has been used to determine the location and distribution coefficient of the ATD's in niosome/water system.     

Activity and stability studies of verbascoside, a novel antioxidant, in dermo-cosmetic and pharmaceutical topical formulations

We here report the results of our investigations carried out on verbascoside, a phenylpropanoid glycoside known for its antioxidant, anti-inflammatory and photoprotective actions. Verbascoside was obtained from Buddleia davidii meristematic cells, obtained in turn using a sustainable biotechnology platform which employs an in vitro plant cell culture technology. Verbascoside was first investigated to assess the behaviour of the active ingredient in solution or in finished preparations, in view of its potential topical use, especially in skin protection. Stability studies were performed by HPLC, and a PCL assay was adopted to determine the radical scavenging activity toward superoxide anion. The high hydrophilic character of verbascoside, suggested in a somewhat limited range of possible applications, leading us to explore its derivatization to obtain the semi-synthetic derivative VPP, an acyl derivative of verbascoside, with an improved range of applications due to its lower hydrophilic profile. Alone, VPP revealed increased antioxidant activity, both as an active ingredient and in dermocosmetic preparations. Stability studies showed a greater stability of VPP in lipophilic vehicles, whereas the parent verbascoside proved more stable in an O/W emulsions. Verbascoside was also stable in suppositories, an interesting pharmaceutical form for possible applications in treatment of inflammation of the intestinal mucosa.     

Two novel diorganotin phosphonic diamides: syntheses,crystal structures,spectral properties and in vitro antibacterial studies

Two diorganotin complexes with general formulae SnCl₂(CH₃)₂[C₆H₅P(O)(NHCH(CH₃)₂)₂]₂ ( 1 ) and SnCl₂(CH₃)₂[C₆H₅P(O) (NHC(CH₃)₃)₂] ( 2 ) were prepared by the addition of one equivalent SnCl₂Me₂ to two equivalents of PhP(O)(NHⁱPr)₂ and PhP(O)(NH^tBu)₂, respectively. The compounds were characterized by elemental analysis, IR and multinuclear NMR (¹H, ¹³C, ³¹P and ¹¹⁹Sn) spectroscopy. The crystal structures of the complexes were determined by X‐ray single crystal analysis, which revealed that complex 1 has a distorted octahedral geometry and complex 2 has a distorted trigonal bipyramidal structure with non‐equivalent chlorine atoms. Preliminary antibacterial tests of the compounds against Gram‐positive and ‐negative bacteria were carried out using the filter paper disk method and chloroamphenicol was used as standard for comparison. Copyright © 2010 John Wiley & Sons, Ltd.     

A simple and high‐resolution HPLC‐PDA method for simultaneous quantification of local anesthetics in in vitro buccal permeation enhancement studies

A simple, isocratic, high‐resolution and prompt HPLC‐PDA method was developed and validated for the simultaneous quantification of prilocaine (PCL) and lidocaine (LCL) hydrochlorides in in vitro buccal iontophoresis‐driven permeation studies. A reversed‐phase C₁₈ column (250 mm x 4.6 mm, 3μm, 110Å) was used for the chromatographic separation. The mobile phase contained acetonitrile: 0.1M sodium phosphate buffer, pH 7.0 (1:1, v/v), plus 0.05% (v/v) diethylamine. The isocratic flow rate was set at 1 mL/min and the detection wavelength was 203 nm. PCL and LCL eluted in 8.9 min and 13 min, respectively, and the system suitability parameters varied within an acceptable range. The method was selective, sensitive, precise, accurate and robust, producing a linear plot at the concentration range of 0.25 to 10 µg/mL. The application of this method was demonstrated by a significant enhancement of the permeation of PCL and LCL with the application of iontophoresis (1 mA/cm² per 1 h) through isolated porcine esophageal epithelium. The amount of the drug retained in the epithelium also increased with the application of an electrical current. Copyright © 2015 John Wiley & Sons, Ltd.     

Organotin mefenamic complexes—preparations,spectroscopic studies and crystal structure of a triphenyltin ester of mefenamic acid: novel anti‐tuberculosis agents

The triphenyltin adduct of mefenamic acid, [SnPh₃L] ( 1 ), the monophenyltin complex [PhSnOL] _n ( 2 ), and the dibutyltin complex [SnBu₂L₂] (3), where HL is 2‐[bis(2,3‐dimethylphenyl)amino]benzoic acid (mefenamic acid), have been prepared and structurally characterized by means of vibrational, ¹H and ¹³C NMR spectroscopies. The crystal structure of 1 has been determined by X‐ray crystallography. X‐ray analysis revealed a pseudo‐pentacoordinated structure containing Ph₃Sn coordinated to the carboxylato group. The structural distortion is a displacement from the tetrahedron toward the trigonal bipyramid. Significant C? H–π interactions and intramolecular hydrogen bonds stabilize the structure 1. The polar imino hydrogen atom participates in intramolecular hydrogen bonds. Complex 1 is self‐assembled via C? H–π and stacking interactions. Vibrational and NMR data are discussed in terms of the crystal structure and the proposed structures for 1–3. Compounds 1 and 3 were tested for antimycobacterial activity against Mycobacterium tuberculosis H37Rv. Copyright © 2002 John Wiley & Sons, Ltd.     

Chitosan–hyaluronic acid hybrid film as a novel wound dressing: in vitro and in vivo studies

Wound dressing with high quality is a kind of highly demanded wound‐repairing products. In this article, chitosan (CS) and hyaluronic acid (HA) were used to fabricate a novel wound dressing. CS/HA composite films with high transparency could be fabricated on glass or poly(methyl methacrylate) (PMMA) substrates, but not on poly(tetrafluoroethylene) (PTFE) plate. Along with the increase of HA amount, the resulting films became rougher as detected by atomic force microscopy (AFM). Increased also are water contact angle and water‐uptake ratio. By contrast, increase of the HA amount weakened the water vapor permeability (WVP), bovine albumin adsorption, and fibroblast adhesion, which are desirable characteristics for wound dressing. In vivo animal test revealed that compared with the vaseline gauge the CS/HA film could more effectively accelerate the wound healing, and reduce the occurrence of re‐injury when peeling off the dressing again. These results demonstrate that the CS mixed with a little amount of HA may produce inexpensive wound dressing with good properties for practical applications. Copyright © 2007 John Wiley & Sons, Ltd.     

Development of NAMI-A-loaded PLGA-mPEG Nanoparticles: Physicochemical Characterization,in vitro Drug Release and in vivo Antitumor Efficacy

NAMI-A has showed extraordinary activities against metastatic tumors. However, the hydrolysis of DMSO from NAMI-A could reduce anti-metastatic activity. To enhance the circulation time and the anti-metastatic effect of NAMI-A, we first synthesized the NAMI-A-loaded nanoparticles. NAMI-A-loaded nanoparticles were prepared by the double emulsion method and characterized by scanning electron microscopy for surface morphology, laser light scattering for size and zeta potential for surface charge. Controlled release of NAMI-A was observed in a sustained manner. Compared with free NAMI-A, NAMI-A -loaded nanoparticles exhibited superior antitumor effect by delaying tumor growth in T739 mice. PLGA-mPEG nanoparticles are promising for further studies as drug delivery carriers.     

Characterization and in vitro phase I microsomal metabolism of designer benzodiazepines — an update comprising adinazolam,cloniprazepam, fonazepam, 3‐hydroxyphenazepam,metizolam and nitrazolam

Designer benzodiazepines represent an emerging class of new psychoactive substances. While other classes of new psychoactive substances such as cannabinoid receptor agonists and designer stimulants are mainly consumed for hedonistic reasons, designer benzodiazepines may also be consumed as ‘self‐medication’ by persons suffering from anxiety or other psychiatric disorders or as stand‐by ‘antidote’ by users of stimulant and hallucinogenic drugs. In the present study, five benzodiazepines (adinazolam, cloniprazepam, fonazepam, 3‐hydroxyphenazepam and nitrazolam) and one thienodiazepine (metizolam) offered as ‘research chemicals’ on the Internet were characterized and their main in vitro phase I metabolites tentatively identified after incubation with pooled human liver microsomes. For all compounds, the structural formula declared by the vendor was confirmed by nuclear magnetic resonance spectroscopy, gas chromatography–mass spectrometry (MS), liquid chromatography MS/MS and liquid chromatography quadrupole time‐of‐flight MS analysis. The detected in vitro phase I metabolites of adinazolam were N‐desmethyladinazolam and N‐didesmethyladinazolam. Metizolam showed a similar metabolism to other thienodiazepines comprising monohydroxylations and dihydroxylation. Cloniprazepam was metabolized to numerous metabolites with the main metabolic steps being N‐dealkylation, hydroxylation and reduction of the nitro function. It has to be noted that clonazepam is a metabolite of cloniprazepam, which may lead to difficulties when interpreting analytical findings. Nitrazolam and fonazepam both underwent monohydroxylation and reduction of the nitro function. In the case of 3‐OH‐phenazepam, no in vitro phase I metabolites were detected. Formation of licensed benzodiazepines (clonazepam after uptake of cloniprazepam) and the sale of metabolites of prescribed benzodiazepines (fonazepam, identical to norflunitrazepam, and 3‐hydroxyphenazepam) present the risk of incorrect interpretation of analytical findings. Copyright © 2016 John Wiley & Sons, Ltd.     

Transition metal complexes of a novel quinoxaline‐based tridentate ONO donor ligand: synthesis,spectral characterization,thermal, in vitro pharmacological and molecular modeling studies

Co(II), Ni(II), Cu(II) and Zn(II) complexes of a novel tridentate heterocyclic ligand, 3‐{[(2‐benzoyl‐4‐chlorophenyl)imino]methyl}quinoxalin‐2(1H)‐one, have been synthesized. The ligand and the metal complexes were characterized using elemental analysis, molar conductance and magnetic susceptibility measurements, and UV–visible, Fourier transform infrared, ¹H NMR, ¹³C NMR, electron spin resonance and DART mass spectral data. The ligand behaves as a tridentate one, coordinating through two oxygen atoms from two keto groups and through the azomethine nitrogen atom. The thermal properties of the newly synthesized compounds were determined using thermogravimetric analysis. The ligand and its metal complexes were subjected to powder X‐ray diffraction analysis by which average crystallite size and unit cell parameters were calculated. The electrochemical behaviour of the compounds was studied using cyclic voltammetry. The ligand and the metal complexes were screened for their in vitro antimicrobial activities against the bacterial strains E. coli, K. pneumoniae, S. pneumoniae and S. aureus and the fungal species A. niger, A. flavus, P. chrysogenum and R. stolonifer. DNA binding, DNA cleavage and antioxidant activities of the compounds were also evaluated. The compounds bind with DNA through groove binding. The Cu(II) and Zn(II) complexes exhibit higher superoxide anion and hydrogen peroxide scavenging activities, respectively. The Cu(II) complex exhibits better anticancer activity against the MCF7 cell line. The compounds were subjected to molecular docking study against B‐DNA dodecamer d(CGCGAATTCGCG)₂ and vascular endothelial growth factor receptor kinase to justify the experimental DNA binding and MTT assay. Density functional theory studies were used to optimize the geometry of the compounds and to calculate the nonlinear optical properties. Copyright © 2016 John Wiley & Sons, Ltd.     

Development of nanoformulation for hyperpigmentation disorders: Experimental evaluations,in vitro efficacy and in silico molecular docking studies

Hyperpigmentation is a crucial dermatological disorder. This study aims to formulate a nanoemulsion formulation containing chlorogenic acid (CA) for hyperpigmentation treatment, to carry out characterization studies, and to investigate its efficacy and safety in vitro and in silico analysis.In line with this purpose, CA nanoemulsions (CA-NEs) were developed using the ultrasonic homogenization method. Accelerated stability tests were performed to examine the kinetic and thermodynamic stability of the CA-NEs to ascertain the presence of any stability issues. After the heating–cooling test, appropriate CA-NEs were stored for 60 days in three different stability environments to examine the physicochemical stability and determine the finalized formulation. The toxicity of the finalized CA-NE formulation was evaluated by genotoxicity/mutagenicity and cytotoxicity tests. The tyrosinase and melanogenesis activities of the finalized CA-NE formulation were determined on the Melanoma B16F0 cell line. Finally, the molecular docking method was used to reveal interactions of CA that play an essential role in tyrosinase inhibition. Additionally, the mushroom and human tyrosinase enzymes were used to determine the activity of CA. In addition, the comparison study with the molecular docking method was carried out using kojic acid as a reference molecule.In conclusion, the molecular docking study, pharmacokinetic analyses, and in vitro studies showed that F4P1 coded CA-NE formulation might hold promise as an innovative formulation in cosmetic applications such as skin-lightening effects with its high efficacy and safety profile.     

Synthesis,characterization and in vitro antimicrobial and anti‐breast cancer activity studies of metal complexes of novel pentadentate azo dye ligand

A new azo dye with N3O2 donor set of atoms has been synthesized via coupling reaction of 2,6‐diaminopyridine with p‐methoxybenzaldehyde. The molecular and electronic structure of the azo dye ligand (L) was optimized theoretically and the quantum chemical parameters were calculated. Molecular docking was used to predict the binding between L and the receptors of breast cancer mutant 3hb5‐oxidoreductase, crystal structure of Escherichia coli (3 T88) and crystal structure of Staphylococcus aureus (3q8u). The newly synthesized L was used for complex formation with Cr(III), Mn(II), Fe(III), Co.(II), Ni(II), Cu(II), Zn(II) and Cd(II) ions. The nature of bonding and the stoichiometry of L and its mononuclear complexes were deduced from elemental analyses, spectroscopic, magnetic susceptibility, molar conductance, electron spin resonance and conductivity measurements, thermogravimetric analyses and powder X‐ray diffraction. Elemental analysis data show that the complexes have composition of ML type with an octahedral geometry for all the complexes. The activation thermodynamic parameters were calculated. The prepared azo dye and its metal complexes were tested against various Gram‐positive and Gram‐negative bacteria and a fungus. Most complexes exhibit antibacterial and antifungal activities against these organisms. Anticancer evaluation studies against standard breast cancer cell line were performed using various concentrations. The activity index was calculated. Copyright © 2016 John Wiley & Sons, Ltd.     

Free‐volume variation in polyethylenes of different crystallinities: Positron lifetime,density, and X‐ray studies

High‐quality positron lifetime measurements (70 million total counts) are reported for polyethylenes (PEs) of different crystallinities (X_c = 3–82%). The specific volumes of the crystalline and amorphous phases (V_c and V_a, respectively) were estimated from density and wide‐angle X‐ray scattering (WAXS) experiments. Some samples (those with low values of X_c) were branched PEs, and those with high values of X_c were linear PEs for which X_c was varied with changes in the crystallization temperature. Both V_c and V_a increase with decreasing X_c in the range 0% ≤ X_c ≤ 56% (the branched PEs) but are constant for X_c ≥ 56% (the linear PEs). The lifetime spectra were analyzed with the MELT and LIFSPECFIT routines. Artifacts that can appear in the spectrum analysis were checked via an analysis of computer‐generated spectra. Four lifetime components appeared in all of the PEs; the two long‐lived ones are attributed to pick‐off annihilation of ortho‐positronium (o‐Ps) in crystalline regions (τ₃) and in holes of the amorphous phase (τ₄). With increasing X_c, τ₃ decreases from about 1.2 to 1 ns, τ₄ decreases from 3.0 to 2.5 ns, and the intensity I₄ decreases from 29 to 0%. An increase in I₃ from 6 to 12% was observed. A comparison with simulations shows that the true I₃ value approaches 0 for X_c → 0%. The decrease in I₄ is weaker than the increase in X_c; this leads to the conclusion that the apparent specific o‐Ps yield in the amorphous phase I₄^Xc increases with X_c. Possible reasons for this surprising results are discussed. The fractional free hole volume [h = (V_a ? V_occ)/V_a, where V_occ is the crystalline occupied volume] was estimated from density and WAXS results. Between X_c = 0 and 56%, h decreases from 0.151 to 0.090, but it does not change further above X_c = 56%. The mean size (v) of the local free volumes (holes) estimated from τ₄ decreases from 200 to 150 ų. The number density of holes (N_h) calculated from these values (N_h = h/v) also decreases from 0.8 to 0.6 nm^?3 in the range 0% ≤ X_c ≤ 56%. The values of V_a, V_c, h, and N_h increase with an increasing degree of branching but do not vary for linear PEs. The possible influence of a crystalline–amorphous interfacial phase (three‐phase model) on the observed lifetime parameters is also discussed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 65–81, 2002