Colloid Journal最新文献

For several decades, polymeric micelles remain to be objects actively studied in the field of nanomedicine, including the anticancer pharmacotherapy. Due to their “core–corona” structure, adjustable parameters (i.e., size, shape, sorption capacity, degradation rate, etc.), the possibility to impart stimuli-sensitive properties, etc., polymeric micelles have proven themselves to be promising carriers that can efficiently encapsulate various drugs and deliver them to targeted tissues and organs, providing controlled and prolonged release of the drugs. Despite the numerous studies, only four nanoforms of anticancer agents based on polymeric micelles have been approved in different regions of the world to date. This review discusses one of the significant disadvantages of polymeric micelles as drug carriers, namely the possibility of their disintegration into unassociated macromolecules upon an abrupt dilution and/or a change in ambient conditions (pH, temperature, solution ionic strength, etc.) due to their insufficient thermodynamic stability. Some strategies used to eliminate this disadvantage are considered. They include chemical cross-linking of polymeric chains that form the cores or coronas of micelles, physical crossl-inking of micelle segments via additional hydrophobic and electrostatic interactions or stereocomplexation, and the formation of so-called monomolecular micelles.

The Poisson–Helmholtz–Boltzmann model is used to study the properties of an electrical double layer formed near an individual weakly charged spherical particle surrounded by a 1 : 1 electrolyte solution. Dividing into Coulomb and non-Coulomb (specified by the Yukawa potential) interactions between ions in the solution, as well as between ions and the particle, mathematical expressions are obtained for the profiles of the corresponding potentials near the particle as functions of the main parameters of the model. When varying the values of key parameters, we find both monotonic and nonmonotonic profiles of the electrostatic potential, and we observe a change in the sign of the potential, resulting in the phenomena of inversion and reversal of charge. The conditions, under which the inversion and reversal of the particle potential sign occur, are determined. The dependences of the zero charge potential on the particle size, the concentration of the 1 : 1 electrolyte solution, and the surface density of a non-Coulomb force source are considered.

Composite nanoparticles (CNPs) with noble metal (Au or Ag) cores and silica shells serving as carriers for various target compounds are of considerable interest for solving various applied problems, including the tumor theranostics, the creation of highly sensitive sensors, super-bright emitters (including nanolasers), and various metamaterials. The conventional precursor for the synthesis of such shells is tetraethoxysilane (TEOS), which is, however, characterized by a low affinity for metal core surfaces and a poor solubility in water. Moreover, the hydrolytic condensation of TEOS yields a dense network of Si–O–Si bonds, which negatively affects the shell capacity for a target compound. All these drawbacks significantly complicate both the synthesis of CNPs and their subsequent loading. In this paper, the possibilities and advantages of alternative approaches to the creation of CNPs based on the replacement of TEOS with functionalized alkoxysilanes are analyzed. The main attention is focused on the particles obtained using γ-mercaptopropyltrimethoxysilane.

This review summarizes the data on the mechanisms and features of the application of commercially available crosslinking agents, such as aldehydes (glutaraldehyde, genipin, and aromatic monoaldehydes) and diglycidyl ethers, for the production of chitosan-based materials. It is shown that the choice of a crosslinking agent and a method and conditions (pH, temperature, nature of an acid in a chitosan solution) enables one to targetedly control the morphology, physicochemical properties, swelling, degradation kinetics, and biocompatibility of the resulting hydrogels, films, and porous materials. The development of crosslinking strategies, including the formation of dynamic covalent bonds and the use of macromolecular crosslinking agents, opens up the prospects for the production of injectable, self-healing, and stimulus-responsive systems for biomedical applications. Special attention is focused on the solution of the problem concerning the cytotoxicity of traditional crosslinking agents by using less toxic alternatives (genipin and diglycidyl ethers) and the methods that reduce the degree of crosslinking without significant deteriorating the mechanical properties of the materials.

Modernization raised many concerns for environment, growing industrialization created major issues for fresh water bodies. In this study, magnetite nanoparticle modified Pennisetum glaucum was employed for the adsorptive removal of Crystal violet (CV), Safranine O (SO), and Methylene blue (MB) dye in single, binary and ternary system. The optimization of adsorption parameters was evaluated with the help of Response Surface Methodology (RSM). Adsorption kinetics, isotherm, and thermodynamics study were employed to study the effect of time, concentration, and temperature respectively. Pseudo second order model was the best fitted kinetic model and Freundlich isotherm model was the best suited isotherm model for all the three dyes. The q_max values (maximum adsorption capacity) obtained from Langmuir model were 158.22 mg/g (SO), 217.39 mg/g (CV), and 122.10 mg/g (MB). The modified Langmuir isotherm model was explored to study the adsorption interaction mechanism in binary and ternary system. The competitive interactions between the co-existing dyes in the binary and ternary system resulted into the decreased maximum adsorption capacity. The adsorption mechanism was concluded as a result of electrostatic interactions, H-bonding, and π−π stacking. Overall, magnetite nanoparticle modified Pennisetum glaucum biosorbent can be helpful for reducing water pollution associated with dye pollutants.

Reduced graphene oxide nanosheets were synthesized using Asparagus officinalis (shatavari) leaves plant extract. Plant extract containing functional groups involvement in reduction of graphene oxide identified using functional group detection technique Fourier-Transform Infrared Spectroscopy (FTIR). The pure crystal structure of reduced graphene oxide (rGO) nanosheets (NSs) was confirmed using X-ray diffraction (XRD) pattern. Scanning electron microscopy (SEM) showed ultrathin graphene nanosheets morphology having thickness less than 7.5 nm. UV-Visible spectra of rGO shows absorption peak mainly at 279 nm. The elemental composition of rGO was studied by energy dispersive spectroscopy (EDS) confirms phytochemical reduction graphene oxide (GO). Specific surface area of rGO is 135 m²/g measured by Brunauer-Emmett-Teller (BET) technique. rGO NSs showed enhanced anticancer activity against human breast cancer cell line MDA-MB-231 tumour cells with 45 μg/mL. IC₅₀ value emphasizing its role in biomedical field.

Amorphous titanium dioxide (TiO₂) nanoparticles were synthesized via a sol–gel reaction using titanium tetrachloride (TiCl₄) as the precursor. Acrylic acid (AA) was introduced to modify the particle surface, preventing aggregation and enabling functionalization. Fourier transform infrared analysis revealed that a reaction time of 48 h was necessary to complete the surface modification through chelation and condensation. To optimize processing conditions, reactions were performed at 25 and 50°C with varied TiO₂ : AA molar ratios. Results showed that at 50°C, excessive AA (1 : 14) led to over-polymerization, while insufficient AA (1 : 6) failed to stabilize the particles. In contrast, the intermediate concentration (1 : 10) produced well-dispersed spherical nanoparticles (10–15 nm), as confirmed by dynamic light scattering (DLS) and transmission electron microscope (TEM). This study demonstrates that tuning AA concentration and reaction temperature enables kinetic control over surface modification, effectively stabilizing amorphous TiO₂ in aqueous media. It offers a simple and scalable approach for preparing size-controlled, surface-functionalized amorphous TiO₂ nanoparticles with potential optical and functional applications.

The paper proposes a capillary model of a charged membrane, which consists of a set of plane-parallel slitlike hydrophilic and hydrophobic pores separated by an impermeable material. The zeta potential or fixed charge density and the condition of liquid no-slip can be preset on the surface of the hydrophilic pores. The hydrophobic pores differ from the hydrophilic ones in the size, zeta potential (density of the fixed charge), and the Navier slip condition. Relations are derived for the hydrodynamic and electroosmotic permeabilities and electrical conductivity of the membrane as functions of the relative hydrophilic and hydrophobic porosities, electrolyte concentration, surface charge or potential, dielectric properties of a solution, diffusion coefficients and charge numbers of ions, and the sizes of the pores of both types. In all cases, compliance with the Onsager reciprocity principle has been shown for cross coefficients L₁₂ and L₂₁, which are responsible for the electroosmosis velocity and the streaming current. All boundary problems for the four types of pores are solved analytically under the Debye–Hückel approximation. It has been found that, in the case of aqueous organic mixtures against the background of a weak electrolyte solution, differently directed flows of components may occur through the hydrophilic and hydrophobic pores of the membrane under the action of external pressure and electric potential gradients. The results obtained enable one to predict the transport properties of a charged membrane as depending on the ratio between the shares of the hydrophilic and hydrophobic pores.

Janus particles represent one of the forms of existence of heterogeneous micro- and nanoparticles. A convenient mathematical prototype of Janus particles is a double bubble, which was described by Plateau when solving the problem of minimal surfaces. The main difference between a double bubble and a Janus particle is an additional condition that interfaces can have different elastic properties. The solution for this case has been obtained using the Young’s method. The limits of the existence of this solution have been revealed. The dependence of the configuration of Janus particles on the relation between the surface properties and the volumes that form the particles has been shown.

A novel method has been proposed for preparing stable highly concentrated Pickering emulsions stabilized with 2D particles of carbon nitride (g-C₃N₄) and its mixtures with graphene oxide (GO) in a water/n-hexane system due to electrostatic interactions with zinc acetate (Zn(OAc)₂). Optical microscopy and sedimentation stability analysis have been employed to determine optimal conditions for preparing emulsions with g-C₃N₄ concentrations up to 6 mg/mL. The formation of oil-in-water (o/w) emulsions stabilized with either g-C₃N₄ particles or GO/g-C₃N₄ binary dispersions has been confirmed by fluorescence microscopy using a water-soluble dye, fluorescein. Measurements of the ζ-potentials of g-C₃N₄ sols and emulsions stabilized with g-C₃N₄ have made it possible to determine the main stabilization mechanism of the highly concentrated Pickering emulsions. It has been found that acetate ions (CH₃COO⁻) promote migration of negatively charged g-C₃N₄ particles from the aqueous phase to the interfaces, while zinc cations (Zn²⁺) are adsorbed on the g-C₃N₄ surface, thereby suppressing the mutual repulsion of the particles in the shells of emulsion droplets. During the formation of Pickering emulsions based on GO/g-C₃N₄ binary disperse systems, metal clusters contribute to the stabilization of emulsions due to coordination bonding between GO carboxyl groups and g-C₃N₄ particles. This mechanism provides efficient particle integration at the interfaces and prevents the highly concentrated Pickering emulsions from separation. The results obtained open up prospects for developing universal catalytic systems with controllable properties to be used for the degradation of organic pollutants and the synthesis of functional materials.