Surfactant Molar Ratio Research Articles

Development and physicochemical characterization of Azadirachta indica seed oil loaded niosomes nanoparticles: A potential natural pesticide

Nanotechnology has helped for decades to transform the agricultural system to make it more effective and to ensure the worlds food supply is sustainable and secure. However, potential toxicological affects, interactions with the biotic or abiotic environment, high cost, unknown life cycles of nanomaterials, and their possible increased bioaccumulation effects are some of the barriers which needs to be addressed. This study evaluates development and potential agricultural application of niosomes nanoparticles loaded with Azadirachta indica seed oil. Niosomes are organic nanomaterials composed of non-ionic surfactants, which are inexpensive, have good encapsulation efficiency, more stability, relatively nontoxic, and biodegradable. Azadirachta indica seed oil loaded niosomes were prepared by thin-film hydration method utilizing different molar ratios of surfactant (Tween 80) and stabilizer (Soy lecithin). The characteristics of niosomes were determined by Fourier Transform Infra-Red Spectroscopy, Dynamic Light Scattering, Optical Microscope, and Transmission Electron Microscopy. Further, the prepared niosomes were statistically optimized using the Box-Behnken experimental design. The optimized condition displayed optimum particle size (<100 nm) and acceptable percentage entrapment efficiencies (> 80%). Anti-microbial efficacy of loaded niosomes were evaluated against plant pathogens Xanthomonas and Pantoea. The prepared niosomes displayed considerable antimicrobial properties and can be potentially used in agriculture for the targeted delivery of natural pesticides (Azadirachta indica seed oil) to combat agricultural diseases.

A dilute nematic gel produced by intramicellar segregation of two polyoxyethylene alkyl ether carboxylic acids

MotivationSurfactants like C8E8CH2COOH have such bulky headgroups that they cannot show the common sphere-to-cylinder transition, while surfactants like C18:1E2CH2COOH are mimicking lipids and form only bilayers. Mixing these two types of surfactants allows one to investigate the competition between intramicellar segregation leading to disc-like bicelles and the temperature dependent curvature constraints imposed by the mismatch between heads and tails. ExperimentsWe establish phase diagrams as a function of temperature, surfactant mole ratio, and active matter content. We locate the isotropic liquid-isotropic liquid phase separation common to all nonionic surfactant systems, as well as nematic and lamellar phases. The stability and rheology of the nematic phase is investigated. Texture determination by polarizing microscopy allows us to distinguish between the different phases. Finally, SANS and SAXS give intermicellar distances as well as micellar sizes and shapes present for different compositions in the phase diagrams. FindingsIn a defined mole ratio between the two components, intramicellar segregation wins and a viscoelastic discotic nematic phase is present at low temperature. Partial intramicellar mixing upon heating leads to disc growth and eventually to a pseudo-lamellar phase. Further heating leads to complete random mixing and an isotropic phase, showing the common liquid–liquid miscibility gap. This uncommon phase sequence, bicelles, lamellar phase, micelles, and water-poor packed micelles, is due to temperature induced mixing combined with dehydration of the headgroups. This general molecular mechanism explains also why a metastable water-poor lamellar phase quenched by cooling can be easily and reproducibly transformed into a nematic phase by gentle hand shaking at room temperature, as well as the entrapment of air bubbles of any size without encapsulation by bilayers or polymers.

Machine learning algorithms for prediction of entrapment efficiency in nanomaterials.

Exploitation of machine learning in predicting performance of nanomaterials is a rapidly growing dynamic area of research. For instance, incorporation of therapeutic cargoes into nanovesicles (i.e., entrapment efficiency) is one of the critical parameters that ensures proper entrapment of drugs in the developed nanosystems. Several factors affect the entrapment efficiency of drugs and thus multiple assessments are required to ensure drug retention, and to reduce cost and time. Supervised machine learning can allow for the construction of algorithms that can mine data available from earlier studies to predict performance of specific types of nanoparticles. Comparative studies that utilize multiple regression algorithms to predict entrapment efficiency in nanomaterials are scarce. Herein, we report on a detailed methodology for prediction of entrapment efficiency in nanomaterials (e.g., niosomes) using different regression algorithms (i.e., CatBoost, linear regression, support vector regression and artificial neural network) to select the model that demonstrates the best performance for estimation of entrapment efficiency. The study concluded that CatBoost algorithm demonstrated the best performance with maximum R2 score (0.98) and mean square error (< 10-4). Among the various parameters that possess a role in entrapment efficiency of drugs into niosomes, the results obtained from CatBoost model revealed that the drug:lipid ratio is the major contributing factor affecting entrapment efficiency, followed by the lipid:surfactant molar ratio. Hence, supervised machine learning may be applied for future selection of the components of niosomes that achieve high entrapment efficiency of drugs while minimizing experimental procedures and cost.

Controlled synthesis of samarium trifluoride nanoparticles in a water-in-oil microemulsion: Effects of water-to-surfactant ratio on particles and phosphate removal

SmF3 nanoparticles with a hexagonal closed pack structure were synthesised by W/O microemulsions of water/Tween 20/1-butanol/toluene. The crystal structure, composition and purity of the sample, as well as the morphology of the produced nanoparticles were studied using Powder X-ray Diffraction, Energy Dispersive X-ray, elemental mapping, Transmission Electron Microscope and Field Emission Scanning Electron Microscope. According to Dynamic Light Scattering study, particle size distribution is governed by the water to surfactant mole ratio (W0), and increasing W0 causes an increase in particle size distribution (PSD). PSD of SmF3 nanoparticles produced at W0 = 50 is the widest compared to W0 = 10. W/O microemulsion method provides formed nanoparticles to attain a spherical form at both W0. The so formed nanoparticles can adsorb phosphate ions from aqueous solution via electrostatic interactions, and their adsorption effectiveness is dependent on particle size and surface area. Small sized nanoparticles, at W0 = 10 removed 98.5% of the phosphate because of its greater surface area while the comparatively larger nanoparticle at W0 = 50 removed 84.5% of the phosphate. The adsorption kinetic data for both W0 are better fitted by pseudo second order model than by pseudo first order model and the calculated equilibrium adsorption capacities is higher for W0 = 10 than for 50. Consequently, this approach yields the most cost effective pure synthesis of high-cost, size and shape controlled rare earth nanoparticles and therefore used in size dependent applied field.

A Review on Silver Nanoparticles

Nanoparticles are defined as particulate dispersions or solid particles with a size between 10 and 1000 nm. A one billionth of a metre scale is the simplest unit of measurement for nanotechnology. Silver nanoparticles superiority over silver in bulk forms is primarily due to the size, shape, composition, crystallinity, and structure of AgNPs. Silver nanoparticles synthesis can be achieved by physical, chemical and green methods. Evaporation-condensation and laser ablation processes are used in the physical synthesis of silver nanoparticle. Evaporation-condensation has been used to create a number of metal nanoparticles in the past, including fullerene, lead sulphide, cadmium sulphide, gold, and silver. Chemical reduction, photo-induced reduction, micro-emulsion, microwave-assisted synthesis, UV-initiated photo-reduction, electrochemical synthetic technique, and irradiation procedures are some of the chemical processes utilised to create nanoparticles. The temperature, pH, concentration, type of precursor, reducing and stabilising agents, and the molar ratio of surfactant and precursor are some of the reaction parameters that control how NPs form and grow in the chemical method. Utilizing biological organisms like bacteria, mould, algae, and plants allows for one-step synthesis. Proteins and enzymes found in plants and microbes are used in the reduction process to create nanoparticles. Silver nanoparticles function as nanoscale antennas at the plasmon resonant wavelength, boosting the strength of a nearby electromagnetic field. Raman spectroscopy, which uses molecules distinctive vibrational modes to identify them, is one spectroscopic method that benefits from the strengthened electromagnetic field. The plasmonic Au/Ag hollow-shelled NIR SERS probes were put together on silica nanospheres, which showed a redshift in the plasmonic extinction band in the NIR optical window region (700–900 nm). Animal tissues that were 8 mm deep showed a measurable signal in the NIR-SERS nanoprobe signals for single particle detection. Silver nanoparticles size-tunable absorption spectra can be used to multiplex optical attributes for point-of-care diagnostics. Silver nanoparticles have antimicrobial, anti-neoplastic, antioxidant, and antidiabetic activity. Silver nanoparticles also shows some kind of toxicity like Oral toxicity, Immunotoxicity, Neurotoxicity, Environmental toxicity, Reproductive toxicity etc.

Oral Bioavailability Enhancement of Vancomycin Hydrochloride with Cationic Nanocarrier (Leciplex): Optimization, In Vitro, Ex Vivo, and In Vivo Studies

To explore the performance of the cationic nanocarrier leciplex (LPX) in escalating the oral bioavailability of vancomycin hydrochloride (VAN) by promoting its intestinal permeability. With the aid of a D-optimal design, the effect of numerous factors, including lipid molar ratio, cationic surfactant molar ratio, cationic surfactant type, and lipid type, on LPX characteristics, including entrapment efficacy (EE%), particle size (P.S.), polydispersity index (P.I.), zeta potential value (Z.P.), and steady-state flux (Jss) were assessed. The optimized formula was further evaluated in terms of morphology, ex vivo permeation, stability, cytotoxicity, and in vivo pharmacokinetic study. The optimized formula was spherical-shaped with an E.E. of 85.2 ± 0.95%, a P.S. of 52.74 ± 0.91 nm, a P.I. of 0.21 ± 0.02, a Z.P. of + 60.8 ± 1.75 mV, and a Jss of 175.03 ± 1.68 µg/cm2/h. Furthermore, the formula increased the intestinal permeability of VAN by 2.3-fold compared to the drug solution. Additionally, the formula was stable, revealed good mucoadhesive properties, and was well tolerated for oral administration. The in vivo pharmacokinetic study demonstrated that the VAN Cmax increased by 2.99-folds and AUC0-12 by 3.41-folds compared to the drug solution. These outcomes proved the potentiality of LPX in increasing the oral bioavailability of poorly absorbed drugs.

Sertaconazole-Nitrate-Loaded Leciplex for Treating Keratomycosis: Optimization Using D-Optimal Design and In Vitro, Ex Vivo, and In Vivo Studies.

This study aims to develop efficient topical therapy for keratomycosis using sertaconazolenitrate (STZN)-loaded leciplex (LP). The D-optimal design was used to optimize STZN-loaded LP by utilizing soy phosphatidylcholine (SPC) molar ratio (X1), cationic surfactant molar ratio (X2), and cationic surfactant type (X3) as the independent variables, whereas their impact was studied for entrapment efficiency percent (EE; Y1), particle size (PS; Y2), polydispersity index (PDI; Y3), zeta potential (ZP; Y4), and permeability coefficient (Kp; Y5). The optimized formula was evaluated regarding morphology, ex vivo permeation, mucoadhesion, stability, and in vivo studies. The optimized formula was spherical and showed EE of 84.87 ± 1.71%, PS of 39.70 ± 1.35 nm, PDI of 0.242 ± 0.006, ZP of +54.60 ± 0.24 mV, and Kp of 0.0577 ± 0.0001 cm/h. The ex vivo permeation study revealed that the optimized formula enhanced the Kp and corneal deposition by 2.78 and 12.49 folds, respectively, compared to the aqueous drug dispersion. Furthermore, the optimized formula was stable and revealed promising mucoadhesion properties. Finally, the in vivo studies showed that the optimized formula was superior to the drug dispersion in treating rats with induced keratomycosis. These results confirmed the capabilities of LP as a promising nanocarrier for treating ocular diseases topically.

Mechanism of the Micellar Solubilization of Curcumin by Mixed Surfactants of SDS and Brij35 via NMR Spectroscopy.

The micellar solubilization mechanism of curcumin by mixed surfactants of SDS and Brij35 was investigated at the molecular scale by NMR spectroscopy. Through the investigation of the micelle formation process, types and structures of mixed micelles and solubilization sites, the intrinsic factors influencing the solubilization capacity were revealed. For systems with αSDS = 0.5 and 0.2, the obtained molar solubilization ratios (MSRs) are consistent with the MSRideal values. However, for αSDS = 0.8, the solubilization capacity of curcumin is weakened compared to the MSRideal. Furthermore, only one single mixed SDS/Brij35 micelles are formed for αSDS = 0.5 and 0.2. However, for αSDS = 0.8, there are separate SDS-rich and Brij35-rich mixed micelles formed. In addition, NOESY spectra show that the interaction patterns of SDS and Brij35 in mixed micelles are similar for three systems, as are the solubilization sites of curcumin. Therefore, for αSDS = 0.5 and 0.2 with single mixed micelles formed, the solubility of curcumin depends only on the mixed micelle composition, which is almost equal to the surfactant molar ratio. Although curcumin is solubilized in both separate micelles at αSDS = 0.8, a less stable micelle structure may be responsible for the low solubility. This study provides new insights into the investigation and application of mixed micelle solubilization.

Targeting Colorectal Cancer Cells with Niosomes Systems Loaded with Two Anticancer Drugs Models; Comparative In Vitro and Anticancer Studies.

Colorectal cancer (CRC) is considered one of the most commonly diagnosed malignant diseases. Recently, there has been an increased focus on using nanotechnology to resolve most of the limitations in conventional chemotherapy. Niosomes have great advantages that overcome the drawbacks associated with other lipid drug delivery systems. They are simple, cheap, and highly stable nanocarriers. This study investigated the effectiveness of using niosomes with their amphiphilic characteristics in the incorporation of both hydrophilic and hydrophobic anticancer drugs for CRC treatment. Methods: Drug-free niosomes were formulated using a response surface D-optimal factorial design to study the cholesterol molar ratio, surfactant molar ratio and surfactant type effect on the particle size and Z-potential of the prepared niosomes. After numerical and statistical optimization, an optimized formulation having a particle size of 194.4 ± 15.5 nm and a Z-potential of 31.8 ± 1.9 mV was selected to be loaded with Oxaliplatin and Paclitaxel separately in different concentrations. The formulations with the highest entrapment efficiency (EE%) were evaluated for their drug release using the dialysis bag method, in vitro antitumor activity on HT-29 colon cancer cell line and apoptosis activity. Results: Niosomes prepared using d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) at a molar ratio 4, cholesterol (2 molar ratio) and loaded with 1 molar ratio of either Oxaliplatin or Paclitaxel provided nanosized vesicles (278.5 ± 19.7 and 251.6 ± 18.1 nm) with a Z-potential value (32.7 ± 1.01 and 31.69 ± 0.98 mV) with the highest EE% (90.57 ± 2.05 and 93.51 ± 2.97) for Oxaliplatin and Paclitaxel, respectively. These formulations demonstrated up to 48 h drug release and increased the in vitro cytotoxicity and apoptosis efficiency of both drugs up to twice as much as free drugs. Conclusion: These findings suggest that different formulation composition parameters can be adjusted to obtain nanosized niosomal vesicles with an accepted Z-potential. These niosomes could be loaded with either hydrophilic drugs such as Oxaliplatin or hydrophobic drugs such as Paclitaxel. Drug-loaded niosomes, as a unique nanomicellar system, could enhance the cellular uptake of both drugs, resulting in enhanced cytotoxic and apoptosis effects against HT-29 colon cancer cells. Oxaliplatin–niosomes and Paclitaxel–niosomes can be considered promising alternative drug delivery systems with enhanced bioavailability of these two anticancer drugs for colorectal cancer treatment.

Optimization and Characterization of Lippia citriodora Essential Oil Loaded Niosomes: A Novel Plant-based Food Nano Preservative

The Lippia citriodora essential oil (LCEO) loaded nano-niosomes were prepared by thin-film hydration method utilizing different molar ratios of surfactants (Span 60/Tween 60) and stabilizers (cholesterol/vitamin D3) as well as different amounts of essential oil. The chemical composition of LCEO was evaluated with Gas chromatography mass spectrometry. α- curcumene (28.84%) and limonene (23.72%) were two major components of LCEO. The encapsulation efficiency, zeta potential, vesicle size, and PDI of niosome samples were investigated. All variables significantly affected the physicochemical properties of niosomes (P < 0.05). Based on the results, different ratios of Span 60/Tween 60 significantly affected the particle size, Zeta potential and PDI (P < 0.05). Besides, it was found that the amount of LCEO and cholesterol/vitamin D3 ratios had significant effects on the all investigated parameters. The niosome containing Span 60, cholesterol, and 5.5 mg/ml LCEO was chosen as the optimal formulation. The niosomes prepared by this formulation had high encapsulation efficiency (>85%) and a nanometric size of < 200 nm. Differential scanning calorimetry and Fourier transform infrared spectroscopy analyses confirmed the successful incorporation of LCEO into the niosome. The results of scanning electron microscopy indicated that the niosomes had good size distribution, quasi-spherical form, and smooth surface. According to the results of evaluating the antimicrobial activity of LCEO, using the well diffusion method, the antimicrobial effect of niosome incorporated LCEO was more than that of free LCEO. It was also found that the sensitivity of Staphylococcus aureus to the encapsulated LCEO was more than that of Escherichia coli. DPPH scavenging method was used to characterize the antioxidant activity of the essential oil, showing that niosome containing LCEO has good antioxidant activity. It could be concluded that these new colloidal systems have an interesting potential for application in food industry as a novel plant-based food nano preservative to deliver poorly-soluble bioactive compounds.

Determination of the influence of basic parameters on the solvent sublation of anionic dye

The object of research is wastewater contaminated with anionic dyes. Traditional methods of wastewater treatment from dyes are imperfect and inefficient or non-existent. Therefore, the need to develop and implement effective and inexpensive to use and operate dye removal technologies is important. The biggest problem in dye removal is when large volumes of low concentration wastewater have to be treated. To purify just such effluents, a combined method, solvent sublation, has been proposed. It combines flotation and extraction methods and has the benefits of both. The essence of the method is the passage of gas bubbles through the aqueous phase and the transport of a hydrophobic complex (sublate) formed by a dye and a surfactant into the organic phase. The study used imitates of wastewater contaminated with an anionic dye, active bright blue in the concentration range of 5–50 mg/dm3. The influence of the main parameters on the degree of dye removal was studied: the pH of the initial solution, the molar ratio of surfactant: dye, the size of air bubbles, the gas flow rate, the initial concentration of the dye, the duration of solvent sublation. Rational parameters of the process have been established, which are advisable to use in solvent sublation: – purification process must be carried out in the presence of a cationic collector hexadecyltrimethylammonium bromide; – extractant – isoamyl alcohol; – molar ratio Dye: surfactant=1:1.5; – pH 5.5; – generation of gas bubbles by a Schott filter with a porosity of 40 µm; – gas flow rate – 127 cm3/min. Under such conditions, the removal efficiency of active bright blue is 97 % at a process time of 10–25 min. The results obtained confirm the promise of the proposed method for the effective removal of dyes from low-concentration aqueous solutions. The method has a number of advantages: it requires a small amount of extractant compared to liquid extraction; ions are concentrated in small volumes of an organic solvent; the process proceeds without phase mixing, so no emulsions are formed.

Water effect in the reverse micellar formation of docusate sodium. A coarse-grained molecular dynamics approach

Improving understanding and characterization of complex fluid systems are crucial tasks of integral product and process design. Of particular interest is the development of enhanced surfactants for industrial and household applications. In this work, a coarse-grained molecular model is developed to study docusate sodium-water-cyclohexane microemulsion systems. Most of the model parameters are taken from a corresponding states treatment of the statistical associating fluid theory-γ-Mie equation of state, overcoming time-consuming simulations. A good agreement is found between model predictions and experimental data, including the phase boundary and reverse micellar aggregation numbers. The effect of water over the morphology of single reverse micelles was studied over the water:surfactant molar ratio range 1 – 14, where a predominant spherical shape was obtained with an average shape anisotropy value of 0.003. The gained molecular insights would be further exploited for the design of more efficient, effective and non-toxic surfactants.

Ultra-strong bio-glue from genetically engineered polypeptides

The development of biomedical glues is an important, yet challenging task as seemingly mutually exclusive properties need to be combined in one material, i.e. strong adhesion and adaption to remodeling processes in healing tissue. Here, we report a biocompatible and biodegradable protein-based adhesive with high adhesion strengths. The maximum strength reaches 16.5 ± 2.2 MPa on hard substrates, which is comparable to that of commercial cyanoacrylate superglue and higher than other protein-based adhesives by at least one order of magnitude. Moreover, the strong adhesion on soft tissues qualifies the adhesive as biomedical glue outperforming some commercial products. Robust mechanical properties are realized without covalent bond formation during the adhesion process. A complex consisting of cationic supercharged polypeptides and anionic aromatic surfactants with lysine to surfactant molar ratio of 1:0.9 is driven by multiple supramolecular interactions enabling such strong adhesion. We demonstrate the glue’s robust performance in vitro and in vivo for cosmetic and hemostasis applications and accelerated wound healing by comparison to surgical wound closures.

Novel Chitosan-Coated Niosomal Formulation for Improved Management of Bacterial Conjunctivitis: A Highly Permeable and Efficient Ocular Nanocarrier for Azithromycin.

In the present study, we aimed to formulate, optimize, and characterize azithromycin chitosan coated niosomes (AZM-CTS-NSM) as a novel colloidal system that increases precorneal residence period, eye permeation, and bioavailability. AZM-NSM was formulated via a modified thin-film hydration strategy and then coated with CTS. We assessed the influence of the cholesterol: surfactant molar ratio, CTS concentration, and surfactant type on particle diameter, entrapment, zeta potential, and NSM adhesion force to the corneal mucosal membrane and employed a central composite design (CCD). The resulting optimized AZM-CTS-NSM has a mean diameter of 376nm, entrapment of 74.2%, surface charge of 32.1mV, and mucoadhesion force of 3114 dyne/cm2. The optimized AZM-CTS-NSM demonstrated a prolonged in vitro release behavior. When compared with commercial eye drops, the optimized AZM-CTS-NSM produced a 2.61-fold increase in the apparent permeability coefficient, significantly improving corneal permeability. Additionally, ocular irritation was assessed, with no major irritant effects found to be induced by the formulated NSM. Compared with AZM commercial drops, the optimized AZM-CTS-NSM revealed ˃ 3-fold increase in AZM concentration in the rabbit eyes. Collectively, these findings indicate that CTS-NSM is a potentially valuable ocular nanocarrier that could augment the efficacy of AZM.

Enhancement of the Anti-inflammatory Efficacy of Betamethasone Valerate via Niosomal Encapsulation

Betamethasone valerate-loaded niosomes were formulated to improve drug anti-inflammatory efficacy and reduce its systemic side effects by providing prolonged and localized drug delivery into the skin. Niosomes were prepared by thin-film hydration using different molar ratios of surfactant, cholesterol, and charge inducers. Formulations were characterized for entrapment efficiency, morphology, size, and zeta potential. In-vitro release and stability studies were conducted on selected formulations. Two niosomal gels were evaluated for spreadability, pH, rheological behavior, ex-vivo skin permeation, and in-vivo anti-inflammatory efficacy. Formulations showed high encapsulation efficiency reaching 92.03±1.88%. Vesicles were spherical in shape, ranging from 123.1 to 782 nm, and had large negative values of zeta-potential. They showed a biphasic release pattern which was more sustained than free drug suspension. Niosomes demonstrated good physicochemical stability under refrigeration for up to 3 months. Niosomal gels exhibited good spreadability, suitable pH values, favorable rheological behavior, and higher skin permeation than the plain gel. In-vivo studies revealed that niosomal gels showed a better sustained anti-inflammatory effect than drug plain gel and the marketed product, which was confirmed by further histopathological examination of paw tissues. Niosomal gels are promising formulations for sustained local delivery of betamethasone valerate.

Mixed Pluronic-Cremophor Polymeric Micelles as Nanocarriers for Poorly Soluble Antibiotics-The Influence on the Antibacterial Activity.

In this work, novel polymeric mixed micelles from Pluronic F127 and Cremophor EL were investigated as drug delivery systems for Norfloxacin as model antibiotic drug. The optimal molar ratio of surfactants was determined, in order to decrease critical micellar concentration (CMC) and prepare carriers with minimal surfactant concentrations. The particle size, zeta potential, and encapsulation efficiency were determined for both pure and mixed micelles with selected composition. In vitro release kinetics of Norfloxacin from micelles show that the composition of surfactant mixture generates tunable extended release. The mixed micelles exhibit good biocompatibility against normal fibroblasts MRC-5 cells, while some cytotoxicity was found in all micellar systems at high concentrations. The influence of the surfactant components in the carrier on the antibacterial properties of Norfloxacin was investigated. The drug loaded mixed micellar formulation exhibit good activity against clinical isolated strains, compared with the CLSI recommended standard strains (Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 29213, Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922). P. aeruginosa 5399 clinical strain shows low sensitivity to Norfloxacin in all tested micelle systems. The results suggest that Cremophor EL-Pluronic F127 mixed micelles can be considered as novel controlled release delivery systems for hydrophobic antimicrobial drugs.

Anionic/nonionic surfactants for controlled synthesis of highly concentrated sub-50 nm polystyrene spheres.

Polystyrene nanospheres are of great importance in 3D hard templating along with many other fields like pharmaceuticals and coatings. Therefore, it is important to be able to prepare polystyrene beads with different sphere sizes that suit each application. In this work, the emulsion polymerization method was used to prepare monodispersed polystyrene (PS) spheres with an average size of 50 nm, using styrene monomer, sodium dodecyl sulfate (SDS) and polyvinylpyrrolidone (PVP) as surfactants, and potassium persulfate (KPS) as the initiator. The average size and size distribution of the PS spheres were controlled by optimizing the synthesis parameters such as the concentration of the monomer, initiator, and surfactant, the type of surfactant, and the time and temperature of polymerization. The shape, size, and size distribution of the prepared PS spheres were characterized using dynamic light scattering (DLS) and scanning electron microscopy (SEM). The preparation of perfectly spherical PS spheres as small as 50 nm with a narrow size distribution is obtained using 8% styrene with (5% SDS and 2% KPS of the styrene amount) at 90 °C, with the monomer and surfactant molar ratio and concentration and the polymerization temperature being the dominating factors that affect the PS bead size.

Optimization, physicochemical characterization, and antimicrobial activity of a novel simvastatin nano-niosomal gel against E. coli and S. aureus

Niosomes, as a kind of drug delivery system, is widely used for the topical delivery of lipophilic drugs. Optimization of niosomes plays an essential role in enhancing their therapeutic efficiencies. This study aims to prepare an optimized niosomal formulation of simvastatin (nSIM), a lipophilic member of statins, through the experiment (Response Surface methodology). Optimized niosomes were characterized in size, polydispersity index (PDI), entrapment efficiency (EE), stability, releasing pattern, and antimicrobial activity. The different molar ratio of surfactant and cholesterol were applied to prepare various formulation of simvastatin loaded niosome. Mean particle size and size distribution were analyzed by dynamic light scattering. Antibacterial activity was determined by MIC and MBC tests against Staphylococcus aureus and Escherichia coli. The release rate of simvastatin from noisome nanoparticles was studied by the Franz diffusion cell method. The release pattern was studied through zero order, first order, Higuchi, Korsmeyer-Peppas, and Hixson-Crowell kinetics models. Optimized niosomes were obtained by span 80, drug to cholesterol ratio of 0.4 with 7 min sonication time. Mean particle size, PDI, zeta potential, and entrapment efficiency (EE%) of optimized nSIM were obtained about 168 nm, 0.34, -32.40, and 96 %, respectively. The niosomes significantly decreased the drug's releasing rate and enhanced antibacterial activity against S. aureus and E. Coli. It was found that the release pattern of drug followed the Higuchi kinetic model which means drug release is by diffusion. Overall, our findings indicated that the prepared simvastatin loaded niosomes showed good stability and biological properties than free drug. Our study suggests that niosomal formulation could be considered as a promising strategy for the delivery of poor water-soluble drugs that enhance antibacterial activity.

Insights into the methanol synthesis mechanism via CO2 hydrogenation over Cu-ZnO-ZrO2 catalysts: Effects of surfactant/Cu-Zn-Zr molar ratio

In this study, we evaluated aspects of the CO2 hydrogenation mechanism, correlating structure-activity relationships of Cu-ZnO-ZrO2 catalysts prepared by one-pot surfactant-assisted co-precipitation with different surfactant ratios. Identifying the CO2 hydrogenation pathway intermediates is key to controlling the reaction selectivity. Experimental evidence shows that the CO2 is dissociating into CO* and O* onto the surface of the Cu-ZnO-ZrO2 catalyst. The adsorption and dissociation of CO2 were evidenced by a combination of in situ ambient-pressure X-ray Photoelectron Spectroscopy (AP-XPS) and Fourier Transform Infrared Spectroscopy (FTIR) with a transmission cell. AP-XPS showed that the catalysts are composed of a Cu2+, Zr3+, and Zr4+ mixture and two kinds of Zn2+ species. After the H2 reduction process, only Cu2+ was reduced to Cu0. The Zn and Zr species were oxidized by the dissociated O* species. In situ transmission FTIR showed that CO was adsorbed onto the Cu+/0 sites. The catalyst with the higher surfactant molar ratio exhibited the highest CO2 conversion close to the equilibrium conversion, as well as a good methanol formation rate.

Wettability alteration and mitigating aqueous phase trapping damage in tight gas sandstone reservoirs using mixed cationic surfactant/nonionic fluoro-surfactant solution

During drilling, completion and fracturing operations, aqueous phase from working fluids can invade into rock formations and engender phase trapping damage in the near well region. This formation damage can diminish the gas relative permeability and hinder the gas well productivity in tight gas sandstone reservoirs. In this study, we investigated the mixed surfactants system of cationic surfactant (SDCSA-1) and nonionic fluorinated surfactant (FC-0) at varied mixing mole ratios and concentrations to reduce the formation damage. Results showed that the minimum surface tension of mixed surfactants solution was relatively low with around 20 mN/m. In addition, surfactant mixtures altered the wettability of sandstone rock from water wetting to intermediate wetting condition. An optimal mixed system was obtained when the concentration is 10-4 mol/L and mole ratio of individual surfactants is 1:1. The mechanism of wettability alteration of surfactants to liquid/rock interface was further determined by adsorption experiments, atomic force microscopy(AFM) tests, and energy dispersive spectrum(EDS) tests. Two sets of spontaneous imbibition experiments were conducted including parallel imbibition tests and sequential imbibition tests. We observed that mixed surfactants solution can prominently prevent liquid invasion into sandstone rocks. We further calculated the capillary pressure to quantitatively examine the capillary effects of different imbibed fluids. When sandstone sample was treated by mixed surfactants, the capillary pressure decreased from 7.81 MPa to 0.97 MPa. Core displacement tests revealed that the liquid saturation of core sample filled with surfactants mixture decreased from 100% to 35.48% and the its gas permeability recovered to 72.86% of the core without liquid after gas flooding. NMR tests also confirmed that surfactant mixtures can be more easily drained than brine from pores in tight sandstone. Consequently, we proposed an improved method to mitigate water blocking damage based on wettability alteration by mixed cationic surfactant and nonionic fluoro-surfactant system.