Polypyrrole- and Polyaniline-Coated Cotton Fabrics as Efficient Adsorbents for the Pharmaceutical Water Contaminants Diclofenac and Salicylic Acid.

The emerging pharmaceutical contaminants diclofenac (DCF) and salicylic acid (SA) pose potential hazards to humans and living organisms due to their persistence in water environments. In this work, the conductive polymers polypyrrole (PPY) and polyaniline (PANI) were successfully coated on cotton fabrics, as confirmed by FTIR and SEM measurements. The coated fabrics efficiently removed DCF at pH 5.3 and SA at pH 4, with removal efficiencies that exceeded 90% and 70%, respectively. Adsorption was rapid for most of the tested contaminant-fabric systems and reached equilibrium within 20-30 min. The best adsorption performance for both contaminants was shown on the PPY-coated fabrics, which yielded adsorption capacities of about 65 and 21 mg/g for DCF and SA, respectively. This could be explained by molecular modeling simulations, which mostly estimated higher total cohesive energy densities for adsorption on the PPY-coated fabrics than on the PANI-coated ones. The adsorption mechanism involved both coulombic electrostatic attractions and non-coulombic van der Waals and π-π stacking. The fabrics could be reused for three adsorption-desorption cycles. Immobilization of the conductive polymers on cotton fabrics provides a facile method for their handling and collection during adsorption and regeneration cycles while maintaining their multi-functionality in adsorbing different contaminants.

Green synthesis of carbon quantum dots toward highly sensitive detection of formaldehyde vapors using QCM sensor.

In the present study, an eco-friendly method for the preparation of carbon quantum dots (CQDs) is demonstrated using hydrothermal treatment of laurel leaves. The optical and structural characteristics of the prepared CQDs are investigated using transmission electron microscopy (TEM), X-ray photoelectron (XPS), fluorescent and UV-visible spectroscopies, Fourier transform infrared (FTIR), and X-ray diffraction (XRD). The quartz crystal microbalance (QCM) sensor designed and modified with CQDs is capable of detecting formaldehyde vapors in the presence of other interfering chemical-vapor analytes. The changes in the frequency of the QCM sensor are linearly correlated with the injected formaldehyde concentrations. The sensing properties of formaldehyde, including sensitivity and reversibility, are investigated. Detection of formaldehyde in the presence of humidity is carefully discussed for home or workplace room environment use. The adsorption kinetics of various VOCs vapors are also calculated and discussed.

Aniline-co-o-anthranilic Acid Copolymer-Chitosan/Ag@AgCl Nanohybrid as a Carrier for (E)-N'-(Pyridin-2-ylmethylene) Hydrazinecarbothiohydrazide Release and Antimicrobial Activity.

Poly(aniline-co-o-anthranilic acid)-chitosan/silver@silver chloride (PAAN-CS/Ag@AgCl) nanohybrids were synthesized using different ratios of Ag@AgCl through a facile one-step process. The presence of CS led to the formation of the nanohybrid structure and prevented the aggregation of the copolymer efficiently. The synthesized nanohybrids were fully characterized by transmission electron microscopy, X-ray diffraction, Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis. (E)-N'-(Pyridin-2-ylmethylene) hydrazinecarbothiohydrazide I was prepared using thiosemicarbazide and confirmed by 1H-NMR, 13C-NMR, and FTIR analyses. Loading of the azine derivative I using various concentrations at different pH values onto the nanohybrid was followed by UV-vis spectroscopy. Langmuir and Freundlich adsorption isotherm models were used to describe the equilibrium isotherm, and the adsorption followed the Langmuir adsorption isotherm. A pseudo-second-order model was used to describe the kinetic data. A PAAN-CS/Ag@AgCl nanohybrid loaded with azine I interestingly showed efficient antimicrobial activity against Escherichia coli and Staphylococcus aureus more than the azine derivative I. The release of azine I at different pH values (2-7.4) was investigated and the kinetics of release were studied using zero-order, first-order, second-order, Higuchi, Hixson-Crowell, and Korsmeyer-Peppas equations.

Preparation of carbon quantum dots/polyaniline nanocomposite: Towards highly sensitive detection of picric acid.

Carbon quantum dots/polyaniline (CQDs/PANI) nanocomposite was successfully prepared by in-situ polymerization of aniline. CQDs were synthesized hydrothermally from gelatin with a diameter size of 4.2 nm and a 17% quantum yield. FTIR, UV-vis absorption, fluorescence spectrophotometer, XRD, TEM, XPS and lifetime decay were used to characterize the obtained nanocomposite. The formation of PANI revealed a high quenching effect on CQDs where the TEM images showed that the formed CQDs were greatly embedded in PANI matrix. In this study, CQDs/PANI nanocomposite was used for the detection of picric acid (PA) in the range 0.37-1.42 µM with a low detection limit (LOD) of 0.056 µM. The prepared sensor showed good enhancement and sensitivity towards PA in comparison to pristine CQDs and other nanostructured materials. The mechanism of PA detection has been studied where it was observed that PA is electrostatically interacted to the nanocomposite through - OH group of PA and the protonated PANI salt formed in CQDs/PANI nanocomposite by fluorescence resonance energy transfer applications. The proposed CQDs/PANI sensor was then utilized in real water samples and successfully determined the different amounts of PA spiked into tap water.

Novel eco-friendly electrospun nanomagnetic zinc oxide hybridized PVA/alginate/chitosan nanofibers for enhanced phenol decontamination.

In the current study, poly(vinyl alcohol)/alginate/chitosan (PVA/Alg/CS) composite nanofiber was immobilized with six different ratios of nanomagnetic zinc oxide (M-ZnO) (0 wt%, 0.2 wt%, 0.4 wt%, 0.6 wt%, 0.8 wt%, and 1 wt%) via the electrospinning technique. The various fabricated composite (M-6) nanofibers were characterized using Fourier transform infrared (FTIR), X-ray diffractometer (XRD), vibrating sample magnetometer (VSM), scanning electron microscope (SEM), atomic force microscope (AFM), thermogravimetric analysis (TGA), mechanical testing machine, and optical contact angle measurement. The fabricated composite nanofibers were applied for the adsorption of phenol from aqueous solutions. The 1.0 wt% M-ZnO/PVA/Alg/CS composite nanofibers were selected as the best phenol adsorbent with removal percentage of 84.22%. The influence of different processing parameter such as contact time, composite nanofiber dosage, pH, initial pollutant concentration, and temperature were examined. Increasing nanofiber dosage and the solution temperature was found to enhance the phenol adsorption onto the prepared nanocomposites. The maximum percentage of phenol removal was achieved at 84.22% after 90 min. Meanwhile, the maximum monolayer adsorption capacity (at pH = 5.0) was estimated to be 10.03 mg g-1 at 25 °C. Kinetic, isotherm, and thermodynamic studies were designated to proof the endothermic, spontaneous, and thermodynamically nature of the phenol adsorption process. These outcomes indicate the effectiveness of the fabricated M-ZnO/PVA/Alg/CS nanofibers as adsorbent materials for phenol from aqueous solutions.

Rational design of a polypyrrole-based competent bifunctional magnetic nanocatalyst.

The combination of conducting polymers with semiconductors for the fabrication of organic/inorganic hybrid nanocatalysts is one of the most promising research areas for many applications. In this work, the synthesized nanocomposite combines several advantages such as the photoresponse shift from the UV region toward visible light by narrowing the band gap of the semiconductor, magnetic separation ability and dual applications including the catalytic reduction of p-nitrophenol (PNP) and the photocatalytic degradation of methylene blue (MB) dye. In addition to the core magnetite nanoparticles (NPs), the synthesized nanocomposite contains polypyrrole (PPY) and TiO2 shells that are decorated with silver metal NPs to prevent electron-hole recombination and to enhance the catalytic performance. Indeed, the catalytic PNP reduction experiments reveal that the synthesized nanocomposite exhibits significantly high catalytic activity with a rate constant of 0.1169 min-1. Moreover, the photocatalytic experiments show that the synthesized nanophotocatalyst has a boosting effect toward MB dye degradation under normal daytime visible light irradiation with a rate constant of 6.38 × 10-2 min-1. The synergetic effect between silver NPs, PPY and TiO2 is thought to play a fundamental role in enhancing the photocatalytic activity.

Cyclodextrin Functionalized Mesoporous Silica for Environmental Remediation of Methylene Blue Dye.

Functionalization of mesoporous silica KIT-6 with ß-cyclodextrin (ß-CD) was successfully realized via post-grafting method as a new adsorbent for environmental remediation of methylene blue (MB) dye from aqueous solutions. The mesostructure properties were characterized by transmission electron microscope (TEM), low-angel X-ray diffraction (XRD), Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA) and N2 sorption isotherm. The remarkable adsorption of MB into ß-CD-KIT-6 adsorbent was studied using UV-visible spectroscopy. The ß-CD-KIT-6 exhibited higher adsorption capacity compared with unmodified-KIT-6. The adsorption behavior of MB into the ß-CD-KIT-6 and unmodified-KIT-6 was carefully investigated using different kinetic and isotherm models. The adsorption process followed a pseudo-second order kinetic model and well-fitted to Langmuir isotherm. The thermodynamic parameters were evaluated and the adsorption of MB was found to be an exothermic and spontaneous process. The adsorption of MB into the ß-CD-KIT-6 was highly dependent on the solution pH.

Acid green crystal-based in situ synthesis of polyaniline hollow nanotubes for the adsorption of anionic and cationic dyes.

In this article, acid green (AG) dye played a dual pivotal role. The first role is as a structure-guiding agent and a soft template for the acid-free synthesis of polyaniline hollow nanotubes (PANI-HNTs) while the second role is as a target dye to be removed as a model of anionic dyes, alongside methylene blue (MB) as a model of cationic dyes. After characterization using X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy (TEM), nitrogen adsorption-desorption isotherms (BET), and UV-visible absorption spectroscopy techniques, the prepared PANI-HNTs were exploited for the adsorption of basic MB dye and acidic AG dye from aqueous media. To optimize the adsorption process, the effects of different variables, such as adsorbent dose, contact time and pH, were studied. Due to the structural differences between the MB and AG dyes, the obtained data revealed that the best pH for the medium for optimal adsorption was 9.0 and 3.0, respectively. The rapid sorption dynamics were found to proceed in a second-order kinetic model and the equilibrium data for the adsorption of MB and AG dyes were fitted well to the Langmuir isotherm. The maximum monolayer capacity, q max, for MB and AG was calculated from the Langmuir model and equalled 69.4 and 57.8 mg g-1, respectively. A thermodynamic study revealed that the adsorption of MB by PANI-HNTs was a feasible, spontaneous, and exothermic process. Investigation of the substrate regeneration revealed that PANI-HNTs can be reused for dye adsorption several times. Therefore, the synthesized PANI-NTs are highly efficient for the dual removal of basic and acidic dyes. TEM images showed that PANI-HNTs were formed with an external and internal diameter of 50-60 nm and 5-10 nm, respectively.

Sample Size for Tablet Compression and Capsule Filling Events During Process Validation.

During solid dosage form manufacturing, the uniformity of dosage units (UDU) is ensured by testing samples at 2 stages, that is, blend stage and tablet compression or capsule/powder filling stage. The aim of this work is to propose a sample size selection approach based on quality risk management principles for process performance qualification (PPQ) and continued process verification (CPV) stages by linking UDU to potential formulation and process risk factors. Bayes success run theorem appeared to be the most appropriate approach among various methods considered in this work for computing sample size for PPQ. The sample sizes for high-risk (reliability level of 99%), medium-risk (reliability level of 95%), and low-risk factors (reliability level of 90%) were estimated to be 299, 59, and 29, respectively. Risk-based assignment of reliability levels was supported by the fact that at low defect rate, the confidence to detect out-of-specification units would decrease which must be supplemented with an increase in sample size to enhance the confidence in estimation. Based on level of knowledge acquired during PPQ and the level of knowledge further required to comprehend process, sample size for CPV was calculated using Bayesian statistics to accomplish reduced sampling design for CPV.

Rational formulation strategy from drug discovery profiling to human proof of concept.

The objective of this paper is to introduce some strategic guidance to a rational formulation strategy of new molecules as oral dosage forms, based on a sound scientific understanding of factors determining the oral bioavailability. The critical implication of permeability and solubility is discussed along with the efficient dose of the drug. The concept of dose-solubility number is introduced as a tool for chemists to assess the develop-ability of different molecules very early during discovery stage. Based on this understanding, a rational formulation strategy for preclinical and early clinical phases is provided. The technical considerations and limitations of different formulation technologies are discussed and illustrated via concrete examples. This approach has the advantage of streamlining the formulation process in order to avoid delaying the development of new drugs due to formulation related issues.

Chemical design of a smart chitosan-polypyrrole-magnetite nanocomposite toward efficient water treatment.

A magnetic chitosan-polypyrrole-magnetite (Cs-PPy-Fe3O4) nanocomposite is prepared in a simple one-step method via in situ chemical polymerization of pyrrole using anhydrous FeCl3 as an oxidant in the presence of Cs. Magnetic Fe3O4 nanoparticles of size in the range of 10-20 nm are successfully introduced into the Cs-PPy matrix. Adsorption of an anionic dye (acid green 25, AG) from aqueous solution into the Cs-PPy-Fe3O4 nanocomposite is investigated. The nanocomposite exhibits high adsorption capacity compared to PPy and Cs themselves. After the adsorption, the Cs-PPy-Fe3O4 nanocomposite is easily separated from the reaction solution using an external magnet, which is very useful for practical applications.

Amorphous solid dispersion successfully improved oral exposure of ADX71943 in support of toxicology studies.

ADX71943 is a potent and selective GABA(b) receptor positive allosteric modulator (PAM) which exhibits poor aqueous solubility at all physiologically relevant pHs. The aim of this study was to identify an adequate formulation to improve the solubility of ADX71943 to achieve a sufficiently high plasma exposure after oral administration to support the toxicology program. Considering the overall physicochemical properties and the low solubility of ADX71943 in a variety of solvents, solid dispersion, and particle size reduction have been successfully chosen as potential strategies to improve its oral bioavailability. Both technologies have proven useful in improving the in vitro dissolution profile and as a result of the solubility enhancement, higher bioavailability was obtained in vivo. As the solid dispersion gave better bioavailability (30-fold compared with the neat active pharmaceutical ingredient (API)), this formulation was selected for the toxicology study. Changing the crystalline form of ADX71943 into amorphous state by preparing a solid dispersion has greatly improved its oral bioavailability and has allowed achieving the required plasma concentration needed in toxicology studies.

Alcohol vapours sensor based on thin polyaniline salt film and quartz crystal microbalance.

A sensor based on the quartz crystal microbalance (QCM) technique was developed for detection of a number of primary aliphatic alcohols such as ethanol, methanol, 1-propanol, and 2-propanol vapours. Detection was based on a sensitive and a thin film of polyaniline, emeraldine salt (ES), coated the QCM electrode. The frequency shifts (Delta f) of the QCM were increased due to the vapour absorption into the ES film. The values of Delta f were found to be linearly correlated with the concentrations of alcohols vapour in mg L(-1). The changes in frequency are due to the hydrophilic character of the ES and the electrostatic interaction as well as the type of the alcohol. The sensor shows a good reproducibility and reversibility. The diffusion and diffusion coefficient (D) of different alcohols vapour were determined. It was found that the sensor follows Fickian kinetics.

A sensor of alcohol vapours based on thin polyaniline base film and quartz crystal microbalance.

Thin films of polyaniline base, emeraldine base (EB), coating on the quartz crystal microbalance (QCM) electrode were used as a sensitive layer for the detection of a number of primary aliphatic alcohols such as ethanol, methanol, 2-propanol and 1-propanol vapours. The frequency shifts (Deltaf) of the QCM were increased due to the vapour adsorption into the EB film. Deltaf were found to be linearly correlated with the concentrations of alcohols vapour in part per million (ppm). The sensitivity of the sensor was found to be governed by the chemical structure of the alcohol. The sensor shows a good reproducibility and reversibility. The diffusions of different alcohols vapour were studied and the diffusion coefficients (D) were calculated. It is concluded that the diffusion of the vapours into the EB film follows Fickian kinetics.

Quartz crystal microbalance and spectroscopy measurements for acid doping in polyaniline films.

We investigated the doping of thin polyaniline (PANI) films, prepared by the chemical oxidation of aniline, with different acids. The initial step in the investigation is the preparation of PANI films from aqueous hydrochloric acid solution. This is followed by dedoping with ammonia to obtain a PANI base, which is subsequently doped with strong acids (e.g. hydrochloric, sulfuric, phosphoric and trichloroacetic acids) and with a weak acid (acetic acid). The dopant weight fraction ( w ), which is connected with the gain of mass during the doping of PANI, was determined in situ using a quartz crystal microbalance (QCM). The behavior of PANI upon doping with different anions derived from strong acids indicates that both proton and the anion uptake into the polymer chains occur sharply, rapidly, completely, and reversibly. However the uptake in the case in acetic acid is characterized by slow diffusion. The doping was studied at different concentrations of acetic acid. A second cycle of dedoping-redoping was also performed. The kinetics of the doping reaction is dominated by Fickian diffusion kinetics. The diffusion coefficients (D) of the dopant ions into the PANI chains were determined using the QCM and by UV-Vis absorption spectroscopy in the range of (0.076-1.64)× 10-15 cm2 s-1. It was found that D in the second cycle of doping is larger than that evaluated from the first cycle of doping for high concentrations of acetic acid. D for the diffusion and for the dopant ion expulsion from the PANI chains was also determined during the redoping process. It was found that D for acetic acid ions in the doping process is larger than that calculated for the dedoping process.