Colloid Journal最新文献

The applicability of various approximations of the electrophoresis theory to calculating the electrokinetic potentials in real nanodisperse systems has been estimated by the example of aqueous polydispersed thermooxidized detonation nanodiamond sols containing nanoparticle aggregates as depending on the concentration and pH of background electrolyte (NaCl) solutions. It has been found that, at low potentials |ζ^W| < 25 mV calculated for primary particles within the framework of the Wiersema model, allowance for particle aggregation and aggregate porosity has almost no effect on the electrokinetic potential. In the range of |ζ^W| = 25−50 mV, the most reliable values of the electrokinetic potentials of the aggregates can, seemingly, be obtained using the Miller equation for ion-conducting particles taking into account their real porosities, provided that the potential is constant. At |ζ^W| > 50 mV, knowing the real sizes of the aggregates, the Overbeek equation with the Oshima analytical expressions for the f₃(κr) and f₄(κr) functions can be used to calculate the electrokinetic potentials under the assumption that the aggregates are monolithic.

The paper presents the results of molecular dynamics simulating microscopic collective excitations in low-density amorphous ice, with the simulation being based on the monatomic ML-mW model of the intermolecular interaction potential. The calculated spectra of longitudinal ({{C}_{{text{L}}}}(k,omega )) and transverse ({{C}_{{text{T}}}}(k,omega )) current spectra have revealed the propagation of collective excitations of the longitudinal and transverse polarizations in amorphous ice within a wide range of wavenumbers. The region of mixing the longitudinal and transverse collective modes in low-density amorphous ice has been found. It has been shown that, in terms of the dispersion law of transverse acoustic-like modes, the temperature dependence of gap width k_gap is described by a linear dependence.

The paper presents the results of experimental studying colloidal structure and rheology of dilute aqueous Na⁺-montmorillonite dispersions by the capillary and rotational viscometry methods. Aqueous dispersions of clay particles undergo significant structural changes, which markedly affect the character of the flow of such systems. All these changes are managed by alterations in indifferent electrolyte concentration within a narrow concentration range. Certain critical concentration has been found to appear at a NaCl concentration of about 3 mM for the series of dispersions with solid contents of 0.25–3.0 wt %. This critical concentration is significantly lower than the coagulation thresholds reported in the experimental and theoretical works devoted to this scope. The substantial changes in the rheological behavior within this electrolyte concentration range may reflect both the processes of formation/disruption of aggregates and changes in the mechanism of either aggregation or structure formation. The obtained rheological data have been compared with theoretical calculations and the results of dispersion analysis (by the dynamic light scattering method) of aqueous dispersions. The data obtained widen the conceptions of the structuring processes in clay dispersions.

Paradoxically, but the humans cannot survive at ultralow temperatures, while individual cells such as the spermatozoa can be stored at cryogenic conditions. This facilitates the in-vitro fertilization in cases of male infertility, but the success of assisted reproduction is not guaranteed due to cryodamage of part of the gametes. Recent innovations in carbon nanotechnologies provide perspectives to resolve the existing problems in reproductive medicine, since the flame deposition of rapeseed oil soot on the surfaces of freezing tools favors the cryopreservation of human semen. The water-repellent soot supports heat exchange rates allowing timely osmotic removal of the intracellular water and retained chemical equilibrium in the cells. It is unknown, however, whether the non-wettability of soot is responsible for the enhanced cryopreservation or the dynamics of sperm freezing and thawing influences the outcome. To understand this, 50 µL semen without and with 50 vol % cryoprotectant SpermFreeze^TM are frozen within twenty minutes on two types of soot coatings by simultaneously cooling all components of the cryogenic chamber, leading to ice-liquid content in the droplets that eliminates the singular tip, followed by uniform melting via thermocapillary convection. The pre-cooling of soot-coated substrates and the absence of cryoprotectant generates an abrupt upward-moving freezing front and increases the total ice mass in the semen, creating a cone tip—processes, presumably worsening the cells’ viability. These novel results reveal that the fraction of ice crystals and their spatial distribution could be adjusted by selecting appropriate carbon nanostructures and cooling regimes, targeting future harmless sperm freezing.

The present study focuses on the formulation and evaluation of a nanoemulsion-based cream (nanocream) using green ingredients, aimed at enhancing performance, stability, and sustainability. The nanoemulsion was developed through the low-energy phase inversion temperature (PIT) method, which successfully protected green bioactive compounds like vitamin E, cinnamon oil, jojoba oil, and peppermint oil from degradation. A series of nanoemulsions were prepared using varying ratios of oils and surfactants and evaluated for stability, transparency, and droplet size. The optimized nanoemulsion, with a mean droplet size of 121.3 ± 1.1 nm and a low polydispersity index (PDI) of 0.094 ± 0.001, demonstrated high uniformity and stability. This optimized nanoemulsion was further used as the cream’s aqueous phase, forming a nanocream that exhibits enhanced permeation of nanoscale bioactives through a membrane and improved overall performance characteristics. In vitro membrane permeation studies revealed that the optimized nanocream achieved a permeation rate of 97.1%, substantially outperforming the control cream. In vitro antimicrobial studies showed comparable efficacy to standard market preparations containing synthetic agents. The nanocream also demonstrated long-term stability over six months, maintaining structural integrity without phase separation or significant changes in pH and spreadability. The nanoemulsion-based cream formulated with eco-friendly ingredients hence offers enhanced skin permeation, superior bioactive delivery, and stable performance, making it a promising candidate for topical skincare and antimicrobial applications.

In this study, we have utilized the base treated Saccharum munja for the removal of Safranine O (SO) and Crystal Violet (CV) dyes from water. The as-synthesized composite was characterized by using various techniques to study the morphological and functional features. Response surface methodology was used to optimize the effect of various parameters such as pH, dosage, and concentration on the adsorption process. Moreover, the kinetics and isotherm of the adsorption process were evaluated using various models. The best-fitted kinetic model was the pseudo-second-order model for both the dyes. The Freundlich isotherm model was found to be the most appropriate for SO and CV dyes suggesting the multilayer adsorption. Further, the adsorption process was favorable as the value of 1/n falls between 0–1. The Langmuir maximum adsorption capacity (q_max) for SO and CV dyes was found to be 121.80 and 143.67 mg/g, respectively. The regeneration study was performed to check out the reusable capability of the composite and it showed a good regeneration stability upto five adsorption-desorption cycles. In conclusion, Saccharum munja can effectively reduce environmental pollution and offer a sustainable solution for dye removal.

Biosurfactants are one of the recently investigated biomolecules that have enormous applications in many fields including agriculture. As there is a need to develop less toxic, and environmentally friendly surfactants, therefore, amino acid-based biosurfactants that are produced from renewable raw materials are of great demand nowadays and can be used as an alternative to conventional chemical surfactants. The negative effects of chemical surfactants present in agrochemicals and modern detergents can damage human health and the environment, thus there is a crucial requirement to explore innovative, well planned, as well as cost-effective natural products for the welfare of humanity. Biodegradable surfactants created through green chemistry, specifically amino acid-based surfactants, are a favourable alternative to avoid these risks. Since amino acids (AAs) are inexhaustible compounds, therefore biosurfactants based on AAs have abundant potential as eco-friendly and environmentally friendly substances. Their higher biodegradation ability, low or even no toxicity, temperature stability, and tolerance to pH fluctuations make these biosurfactants preferable over chemical surfactants. In modern agriculture, most chemical pesticides and fertilizers used are frequently associated with numerous environmental issues. Hence, the development of green molecules as biosurfactants has a promising role in this regard to ensure agricultural sustainability. Biosurfactants can be harnessed for plant pathogen management, plant growth elevation, improving the quality of agricultural soil by soil remediation, degradation of complex hydrocarbons, increasing bioavailability of nutrients for advantageous plant-microbe interactions, and improving plant immunity, hence, they can supersede the grim synthetic surfactants which are presently being used.

The study examines the micellization of sodium dodecyl sulfate (SDS) with methylene blue (MB) in a propanol-water mixed solvent system within a temperature spanning from 298.15–313.15 K. The conductivity measurements of SDS-MB complex was carried out at 5, 10, and 15% volume fraction of propanol in water both in absence and presence of dye. The variation of CMC with temperature was analyzed to assess thermodynamic parameters of micellization. This approach offers valuable insights on the behavior of surfactant in mixed solvent system and sheds lights on different interactions occurring within the system. Spectrophotometric analysis was conducted to investigate the interactions between SDS-MB complex at 5, 10, and 15% volume fraction of propanol in aqueous medium. An increment in volume fraction of propanol hinders the process of micellization. However, in the presence of MB increases the efficiency of micellization and rendering the process more spontaneous. Consequently, MB monomers become associated with micelle which is the case of dye solubilization.

Plant extracts are powerful agents in the green synthesis of metal or metal oxide nanoparticles for biomedical applications, as they are environmentally friendly and contain no toxic chemicals. This study used the electrochemical method with the Camellia chrysantha flower extract to synthesize green silver nanoparticles (AgNPs). The extract served as an electrolyte, reducing agent, and stabilizer. Without chemicals, the synthesized nanoparticles were characterized by ultraviolet-visible spectroscopy (UV-Vis), X-ray diffraction (XRD), transmission electron microscopy (TEM), and zeta potential methods. The antibacterial activity of AgNPs against Escherichia coli and Staphylococcus aureus was evaluated using minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) methods. The results indicate successful synthesis of AgNPs with a size distribution of 4–14 nm, an average size of 8.20 nm, and spherical morphology. The AgNPs synthesized by the electrochemical method using C. chrysantha flower extract exhibited a zeta potential of −29.7 mV, indicating good dispersion, and demonstrated high antibacterial activity against both Gram-positive and Gram-negative bacterial strains. Given the traditional use of C. chrysantha flowers in food and cosmetics, the synthesis of AgNPs from this extract offers potential applications in various fields including cosmetics, food, and medicine.

Felodipine, a Dihydropyridine calcium channel antagonist, is widely used to treat hypertension and angina pectoris. Its highly lipophilic nature and low aqueous solubility classify it as a Biopharmaceutics Classification System Class II Drug. When administered orally, Felodipine undergoes extensive first-pass hepatic metabolism, resulting in low oral bioavailability (15%) and posing challenges for effective antihypertensive therapy. This study aimed to formulate drug-loaded nanovesicular Spanlastics within oral fast-dissolving films, enabling buccal mucosa delivery to bypass hepatic metabolism and enhance drug bioavailability. Felodipine nanovesicular Spanlastics were formulated using a modified Ethanol Injection method. Design Expert® Software Version 13 and a 2³ factorial design model determined the effect of formulation variables on response variables. The Spanlastics, characterized for particle size (ranging from 155.7 to 308.9 nm) and entrapment efficiencies (84.68 to 88.36%), showed lamellar, circularly shaped vesicles as observed through Optical and Transmission Electron Microscopy. These optimized Spanlastics were incorporated into oral fast-dissolving films, which exhibited substantial flexibility, sufficient mechanical strength, a disintegration time of 35 s, and rapid drug release of 95.99% within 5 min. Scanning Electron Microscopy imaging confirmed a smooth, porous, and uniform surface of the films. Short-term stability studies indicated that the films maintained stable physical and structural attributes. This research confirmed that Felodipine Spanlastic vesicles, due to their nanosize, enhance mucosal permeation and act as effective nanocarriers. Their incorporation into fast-dissolving oral films improves bioavailability through oro-mucosal tissue absorption for buccal delivery.