Display omitted
An understanding of the factors that affect liposome size, drug loading, stability and drug release is critical for the rational design of liposomes with desired pharmacokinetics and ...biodistribution. This article presents a report on the formulation and characterization of BIIB093 (glibenclamide) liposomes as well as a detailed analysis of the influence of formulation methods and parameters on encapsulation efficiency, liposome size, charge (zeta potential, ZP), polydispersity index (PDI), and drug release. PEGylated liposomes containing BIIB093 were made using ethanol injection and calcium acetate remote loading. The critical formulation parameters investigated include: the effect of lipid chain length, lipid unsaturation, lipid phase transition temperature (Tc) and the amount of cholesterol. Liposomes generated in this study had low average particle size (130 ± 20 nm), PDI (0.15 ± 0.1) and ZP (-2 ± 1 mV). Liposomes made from lipids with long acyl chains showed enhanced drug loading, encapsulation efficiency and drug retention. Similarly, liposomes made from lipids with high degree of unsaturation and low Tc exhibited faster drug release rates. Additionally, increasing the amount of cholesterol in the liposome bilayer improved PDI, decreased drug incorporation and accelerated drug release but had negligible impact on liposome size and ZP. Furthermore, encapsulating the drug in the liposome core enabled sustained drug release.
Display omitted
•Olefin emulsions with a saturated CaCl2 solution exhibit high stability.•Olefin emulsions with a saturated NaCl solution require less emulsifier;•Saturated NaCl solution is the most ...proper choice to compose the non-aqueous fluids;•Olefin emulsions with a saturated CaCl2 solution show high thixotropy.
Drilling fluids continue under development, being a challenge for the oil industry, which attempts to optimize technical performance, to comply with environmental laws, and to reduce fluid costs. A non-aqueous based drilling fluid widely used by Petrobras has been reformulated due to changes in Brazilian environmental legislation. The paraffinic base of the drilling fluid was replaced by an olefinic base, which is more biodegradable. Hence, to improve drilling fluid performance, the characteristics of olefin emulsions formulated with saturated NaCl and CaCl2 solutions were investigated. Therefore, for different emulsifier concentrations and stirring speeds, the droplet size distribution, the stability, and the rheological parameters of three emulsions were evaluated. All these emulsions had distinct dispersed phases, being these saturated solutions of NaCl, CaCl2, and 75% NaCl and 25% CaCl2. The increase of the stirring speed was followed by the emulsified systems apparent viscosities increase, but their polydispersity index and D50 values were reduced. The NaCl/Olefin emulsion exhibited lower stability, apparent viscosity, and emulsifier saturation concentration when compared to the CaCl2/Olefin emulsion. Besides, the CaCl2/Olefin emulsion showed more pronounced thixotropic behaviour.
Nanocrystals have exhibited great advantage for enhancing the dissolution rate of water insoluble drugs due to the reduced size to nanoscale. However, current pharmaceutical approaches for ...nanocrystals formulation development highly depend on the expert experience and trial-and-error attempts which remain time and resource consuming. In this research, we utilized machine learning techniques to predict the particle size and polydispersity index (PDI) of nanocrystals. Firstly, 910 nanocrystal size data and 341 PDI data by three preparation methods (ball wet milling (BWM) method, high-pressure homogenization (HPH) method and antisolvent precipitation (ASP) method) were collected for the construction of the prediction models. The results demonstrated that light gradient boosting machine (LightGBM) exhibited well performance for the nanocrystals size and PDI prediction with BWM and HPH methods, but relatively poor predictions for ASP method. The possible reasons for the poor prediction refer to low quality of data because of the poor reproducibility and instability of nanocrystals by ASP method, which also confirm that current commercialized products were mainly manufactured by BWM and HPH approaches. Notably, the contribution of the influence factors was ranked by the LightGBM, which demonstrated that milling time, cycle index and concentration of stabilizer are crucial factors for nanocrystals prepared by BWM, HPH and ASP, respectively. Furthermore, the model generalizations and prediction accuracies of LightGBM were confirmed experimentally by the newly prepared nanocrystals. In conclusion, the machine learning techniques can be successfully utilized for the predictions of nanocrystals prepared by BWM and HPH methods. Our research also reveals a new way for nanotechnology manufacture.
Display omitted
•Size and PDI data of drug nanocrystals were extracted for construction of prediction models.•LightGBM showed good prediction for nanocrystals prepared by top-down methods.•The contribution of the influence factors for nanocrystals was ranked by the LightGBM.•The model generalizations and prediction accuracies were confirmed by experiments.
Melanoma is one of the most dangerous skin cancers, with a high mortality rate and an incidence that has increased radically in the past few years. This has led to a huge demand for new more ...effective forms of treatment. Nanoemulsions have been investigated as potential drug delivery vehicles to target cancer cells, since they are a promising alternative to increase the solubility and the skin permeation and retention of hydrophobic drugs. The purpose of this work was to incorporate miconazole, a hydrophobic antifungal drug with potential anticancer activity, into an oil-in-water (O/W) nanoemulsion for topical administration for the treatment of melanoma. Seventeen O/W nanoemulsions were prepared via spontaneous emulsification. The preconcentrate was composed of Plurol® Diisostearique, Transcutol® HP and Kolliphor® RH 40, while the aqueous phase was water. A visual examination was performed to confirm the absence of phase separation and heterogeneity. Analysis using dynamic light scattering (Zetasizer Nano ZS apparatus, Malvern, UK) followed to determine the droplet size and polydispersity index (PDI). Nanoemulsions with a PDI below 0.300 and a droplet size between 100 and 200 nm were selected for solubility assays. After drug incorporation, at 5 mg/mL, only one out of the seventeen nanoemulsions showed characteristics within the intended parameters. In conclusion, this study showed that the incorporation of miconazole in nanoemulsions allows us to greatly increase its solubility when compared to water (up to 6550 times). Future studies will include the determination of viscosity, stability, in vitro drug release, ex vivo drug permeation and in vitro cytotoxicity in melanoma cells.
In the present study, we have tried to establish the correlation between changes in Zeta potential with that of cell surface permeability using bacteria (
Escherichia coli
and
Staphylococcus aureus
...). An effort has been made to establish Zeta potential as a possible marker for the assessment of membrane damage, with a scope for predicting alteration of cell viability. Cationic agents like, cetyl trimethyl ammonium bromide and polymyxin B were used for inducing alteration of Zeta potential, and the changes occurring in the membrane permeability were studied. In addition, assessment of poly-dispersity index (PDI), cell viability along with confocal microscopic analysis were performed. Based on our results, it can be suggested that alteration of Zeta potential may be correlated to the enhancement of membrane permeability and PDI, and it was observed that beyond a critical point, it leads to cell death (both Gram-positive and Gram-negative bacteria). The present findings can not only be used for studying membrane active molecules but also for understanding the surface potential versus permeability relationship.
Display omitted
•The dispersibility of GO and highly graphitized RGO, in various solvents was reported.•Hansen Solubility Parameters (HSP) of the materials were determined.•High concentrations for GO ...and RGO were achieved, in DH2O and o-DCB respectively.•Stability, particles’ size and PDI of GO and RGO dispersions were evaluated through DLS.
The formation of highly concentrated and stable graphene derivatives dispersions remains a challenge towards their exploitation in various applications, including flexible optoelectronics, photovoltaics, 3D-printing, and biomedicine. Here, we demonstrate our extensive investigation on the dispersibility of graphene oxide (GO) and reduced graphene oxide (RGO) in 25 different solvents, without the use of any surfactant or stabilizer. Although there is a significant amount of work covering the general field, this is the first report on the dispersibility of: a) RGO prepared by a HI/AcOH assisted reduction process, the method which yields RGO of higher graphitization degree than the other well-known reductants met in the literature, b) both GO and RGO, explored in such a great range of solvents, with some of them not previously reported. In addition, through calculation of their Hansen Solubility Parameters (HSP), we confirmed their dispersibility behavior in each solvent, while we indirectly validated the most advanced graphitization degree of the studied RGO compared to other reported RGOs, since its HSPs exhibit the highest similarity with the respective ones of pure graphene. Finally, high concentrations of up to 189 μg mL−1 for GO and ~ 87.5 μg mL−1 for RGO were achieved, in deionized water and o-Dichlorobenzene respectively, followed by flakes size distribution and polydispersity indices estimation, through dynamic light scattering as a quality control of the effect of a solvent’s nature on the dispersion behavior of these graphene-based materials.
The objectives of this paper were to investigate the existence of Listeria monocytogenes (L. monocytogenes) in different types of cheese (Mozzarella, Thalaga, and Romy cheeses, 40 samples each) sold ...in Assiut dairy shops and to evalute antibacterial properties of chitosan and its nanoparticles against isolated strains. L. monocytogenes was isolated in higher percentage from Mozzarella cheese (25%) followed by Thalaga and Romy cheese samples. L. monocytogenes isolates were validated by PCR utilising the 16S rRNA gene. Zeta-sizer and TEM were used to characterise nano-chitosan. The minimum inhibitory concentrations of chitosan and nano-chitosan on L. monocytogenes were detected by MIC test. Nano-chitosan (3.125%) could prevent organism growth in cheese as early as the third week. The findings revealed that 3.125% nano-chitosan had a sufficient effect on L. monocytogenes while also providing good consumer satisfaction; therefore, nano-chitosan should be utilised as a natural food additive in Egyptian dairy products.
Display omitted
•A guide in using method of moments for modeling of polymerization kinetics.•Step-by-step derivation is provided in the worked examples.•Commonly encountered problems in derivation ...process are discussed and tackled.
Method of moments is a simple deterministic method widely applicable in modeling various polymerization processes. This method is easy to use and computationally inexpensive. Although the mathematics involved is simple and elementary, the derivation step is often lengthy and thus it may be intimidating. This paper aims to serve as a tutorial by providing step-by-step guide on how to apply the method of moments to different polymerization and polymer modification systems. The basics behind method of moments, the limitation related to it, and common problems encountered in derivation with ways to counter them are described in details. Several examples are presented to clearly elucidate these concepts.
PDF
