Search Results (222)

The rational design of mixed micellar systems has emerged as a cornerstone of modern nanomedicine, offering unprecedented control over the solubility and bioavailability of challenging therapeutic agents. This review provides a comprehensive analysis of the physicochemical principles governing the assembly of amphiphilic drugs and surfactants into synergistic nanostructures. By articulating the transition from traditional guest/host solubilization to “drug-as-component” models, we highlight the critical role of molecular interactions in achieving therapeutic precision. It further outlines the experimental methodologies used to investigate these systems and elucidates how they enhance the solubility, stability, and bioavailability of poorly water-soluble drugs. Special emphasis is placed on the practical applications of synergy in reducing systemic toxicity and optimizing drug release kinetics, providing a roadmap for the development of next-generation nano-pharmaceuticals. The functionality of these systems is significantly influenced by the molecular interactions among their constituents; thus, quantitative analysis of these interactions might enhance the formulation of more effective pharmaceuticals. This review outlines the key physicochemical principles of mixed micelle formation, including thermodynamics and synergistic interactions of amphiphiles, while emphasizing their relevance in current research and practical pharmaceutical applications. Various experimental methods, such as surface tension measurement, conductometric and calorimetric tests, and spectroscopic techniques, are compared in terms of their conditions of application and performance in understanding micelle formation and micelle structure. We clearly point out that the interpretation and evaluation of the properties of colloidal systems containing drug molecules solubilized by mixed micelles and an amphiphilic drug incorporated into micelles must be discussed and evaluated separately. Understanding the limitations and characteristics of the physical/chemical principles applied is essential for the rational design of mixed micelle carriers tailored to specific therapeutic needs. Full article

The present study extends the investigation of thermodynamic properties of phases in the silver–magnesium binary system, with particular emphasis on the κ-Ag₂Mg₅ phase, for which available literature data remain scarce. The work is divided into two parts. The experimental section comprises the synthesis of the κ phase from high-purity Ag and Mg, followed by its characterisation using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The synthesised material was subsequently used for calorimetric determination of the standard enthalpy of formation employing the drop solution method. Measurements were carried out in two experimental series (A and B), using two different metallic solvents (Al and Sn), at temperatures of 1020 K and 689 K. The enthalpy of formation obtained in both series was −14.4 ± 0.32 and −14.5 ± 0.42 kJ/mol at., respectively. In addition, the limiting partial enthalpy of solution of liquid Ag in liquid Al was determined calorimetrically and its average value is equal 7.1 ± 0.7 kJ/mol. The theoretical part of the study involved ab initio calculations of defect formation energies. The obtained results show good agreement with available literature data and provide a consistent interpretation of the observed non-stoichiometry of the κ-phase. Full article

Single-phase Cu₄Bi₄Se₉ was successfully synthesized through a simple and rapid process combining mechanical alloying (MA) and hot pressing (HP). The phase formation behavior, microstructural evolution, charge transport characteristics, and thermoelectric properties were systematically investigated. X-ray diffraction analysis as a function of MA time confirmed that all powders crystallized into a single orthorhombic phase with space group Pnma. No decompositions or secondary phases were observed after HP sintering, indicating high phase stability. Thermogravimetric and differential scanning calorimetric analyses revealed distinct endothermic peaks at 714–717 K for all samples, corresponding to the onset of the decomposition of Cu₄Bi₄Se₉. Microstructural observations showed that the relative density decreased with increasing HP temperature (>573 K), accompanied by grain growth and pore formation, reflecting the competition between Cu–Se interdiffusion and pore coarsening during high-temperature sintering. Hall effect measurements indicated p-type conduction for all samples, with carrier concentrations on the order of 10¹⁷ cm⁻³ and carrier mobilities of approximately 10² cm² V⁻¹ s⁻¹. With increasing temperature, the electrical conductivity increased monotonically, while the Seebeck coefficient gradually decreased, resulting in a maximum power factor of 0.12 mW m⁻¹ K⁻² at 573 K. The total thermal conductivity remained extremely low, ranging from 0.33 to 0.48 W m⁻¹ K⁻¹, with the electronic contribution accounting for less than 10%, indicating that lattice thermal transport is dominant. The suppressed lattice thermal conductivity is attributed to the combined effects of Cu atomic rattling, asymmetric bonding induced by Bi 6s² lone-pair electrons, and strong anharmonic phonon scattering arising from the complex crystal structure. Consequently, Cu₄Bi₄Se₉ achieved a peak dimensionless figure of merit ZT of 0.19 in the temperature range of 573–623 K, demonstrating that the MA–HP process enables stable phase formation and competitive thermoelectric performance without post-annealing. Full article

Epoxy materials are an important class of thermosets whose properties strongly depend on the used formula, the curing parameters, and many available hardeners. Achieving desired properties such as enhanced thermal stability, extended lifetime, or self-regeneration requires selecting suitable precursors and carefully tuning curing conditions. In this work, a selected biphenyl epoxy precursor was used as a model compound to assess whether using different hardeners could be an effective factor in tailoring the elasticity of cured epoxy networks. We employed two chemically distinct hardeners—4,4′ diaminodiphenylmethane (DDM) and suberic acid—to generate materials with markedly different final properties. For instance, the glass transition temperature T_g varied within a range of over 35 °C. Two complementary experimental techniques were used in this paper to establish the optimal curing parameters: differential scanning calorimetry (DSC) and broadband dielectric spectroscopy (BDS). Both techniques supported tracking of changes in the mixture while curing and enabled determination of T_g in the obtained products. Dielectric relaxation spectroscopy revealed various molecular motions (α, β, and γ-processes) occurring in different phases, especially in glass-forming solids. BDS is therefore a good tool for testing new organic materials. The analytic route used in this work, based on a combination of calorimetric and electrical approaches, enables precise adjustment of the curing parameters to a specific hardener and helps verify the effects of using different hardeners on the elastic properties of the product. This allows the creation and modification of epoxy matrices towards modern materials, such as composites with self-healing properties or enhanced thermal stability. Full article

Gypsum is one of the main binding materials used in the construction industry. Its properties can be modified by the addition of chemical admixtures that may influence the hydration process and the microstructure of the hardened material. An important group of such admixtures comprises cellulose ethers. The aim of this study was to conduct an in-depth analysis of the effects of hydroxyethyl methylcellulose (HEMC) on the hydration and mechanical properties of gypsum. HEMC was applied in various amounts (ranging from 0.5 to 7% by mass of gypsum); the water-to-gypsum ratio was 0.75. The hydration process was investigated using calorimetry, thermal analysis, and infrared spectroscopy. Compressive and bending strength tests were also performed. The results of calorimetric measurements show that the presence of HEMC led to delayed hydration and prolonged gypsum crystallization, particularly at higher admixture dosages. No formation of new phases in the gypsum paste was observed in the presence of HEMC. However, the admixture modified the microstructure of the hardened material, as reflected by increased compressive and bending strength. This effect is most likely associated with the slower precipitation of gypsum crystals in the presence of HEMC. Full article

The aim of the article was to analyze the potential simultaneous use of magnetic nanoparticles as contrast agents in MRI imaging and for magnetic hyperthermia. The study proposed characterizing the nanoparticles using various measurement methods in order to investigate the relationships between different properties. The first stage involved measuring images of nanoparticle samples using scanning transmission electron microscopy (TEM) and dynamic light scattering (DLS). The diameter distribution of nanoparticles was determined based on image segmentation. The next step involved measuring relaxation properties of nanoparticles in low and high magnetic fields. The research was carried out for nanoparticle solutions of various concentrations and properties. The last step was measuring calorimetric properties of nanoparticles as a thermal source under alternating magnetic field excitation conditions. The range of nanoparticle diameters (20–25 nm) for which maximum losses occur in an alternating magnetic field corresponds to the diameter range in which the maximum r₂ relaxivity is observed. Full article

In recent years, the unsustainable consumption of fossil resources has been causing major ecological concerns, especially for the production of polymeric materials. 2,5-furandicarboxylic acid (FDCA) is one of the most appealing biobased chemical building blocks, because of its potential to replace the industrially widespread petrochemical, terephthalic acid. Camphoric acid (CA) is also an interesting biobased chemical derived from camphor, one of the most widespread fragrances. This work had the objective of combining CA, FDCA and biobased 1,6-hexanediol to synthesize random copolymers for sustainable food packaging applications by means of a solvent-free polycondensation process, obtaining poly(hexamethylene furanoate-co-camphorate)s (PHFC). The optimization of the synthesis made it possible to obtain high molecular weight polyesters with a percentage of camphoric acid up to 17 mol%, which could be compression-molded into films. They were subjected to molecular, structural, thermal and functional characterization via NMR, GPC, WAXS, DSC, and TGA analyses, as well as mechanical and gas permeability tests. Compared to the homopolymer of reference, it was possible to obtain higher flexibility, 430% higher elongation at break, and 223% higher toughness, with comparable, excellent gas permeability properties. Calorimetric evidence suggested that camphoric acid might have enhanced the formation of a partially ordered mesomorph phase in the copolymers under study. Full article

Background/Objectives: Phytochemicals are known to be active contributors to a healthy life, providing valuable wound healing benefits. Methods: This research took an innovative approach that successfully overcame the bioavailability limits of herbal extracts, by entrapping CentellaA with HypericumP in nanostructured lipid carriers (NLCs) and hybrid hyaluronic acid (HA-NLCs) as valuable formulations with enhanced bioactivity. Results: NLCs and HA-NLCs showed excellent entrapping efficiency values for CentellaA and HypericumP ranging from 89.5 to 95.3%. Co-entrapping of CentellaA:HypericumP in a weight ratio of 4:1 and 2:1 led to diameters of 221.4 ± 2.08 nm for NLC-CentellaA-HypericumP and 220.3 ± 1.74 nm for hybrid HA-NLC-CentellaA-HypericumP. The bimodal calorimetric profile of NLCs contributed to a lower degree of lipid core structural organization. HA-NLC-CentellaA showed the safest biocompatibility behavior with BJ skin cells. Conclusions: The cells treated with NLC-CentellaA exhibited a favorable scratch wound closure and promoted the fastest BJ cell migration. NLC- and HA-NLC herbal extracts remodeled the cytoskeleton of BJ fibroblast cells. The morphological fluorescence changes revealed that the fibroblast cells retained intact their cytoskeleton, characteristic of a viable cell with no obvious stress. An active motility of cells treated with NLCs in the wound area was detected, indicating strong pro-migratory properties; e.g., for NLC-CentellaA, the wound was almost closed after 30 h. Designing NLCs with HA adaptability to reinforce the skin wound healing action represents a desired step for the development of herbal products that meets the challenge of combining the benefits of phytochemicals and nanotechnology to create value-added herbal products. Full article

Since there is limited information available in the literature about the thermodynamic properties of the Cu-Mg-Ti system, this work aims to determine the mixing enthalpy change for several liquid alloys from this system. To achieve the intended purpose, the applied methods were divided into two stages. The first one covered a high-temperature calorimetric measurement of the enthalpy of mixing performed at 1123–1402 K for liquid solutions in six measurement series (A–F). The obtained experimental results indicate that the liquid solutions are characterized by negative deviations from ideal solutions across the whole measured concentration range. The second stage of the study includes thermodynamic modeling. At first, based on the calorimetrically obtained experimental data and thermodynamic properties of the binary systems described by the Redlich–Kister model, a set of ternary optimized parameters for the Cu-Mg-Ti system were calculated. Then, for the calculation of the mixing enthalpy change, two models were used—the symmetrical Muggianu model and the asymmetrical Toop model. This study complements the information available in the literature and the obtained results aim to fill the gap in the current knowledge on thermodynamic properties. Full article

The physico-chemical and electrophysical properties of carbon coke obtained by coking composite mixtures of pitches isolated from coal tar coking plants of JSC “Shubarkol Komir” and “Qarmet” are investigated. The component composition of the initial resins and the obtained pitches was determined by gas–liquid chromatography methods. The purpose of this study was to identify the patterns of influence of the composition of composite mixtures of pitches isolated from coal tar coking plants of JSC “Shubarkol Komir” and “Qarmet”, as well as heat treatment parameters (temperature 800–1000 °C, duration 4–6 h), on the thermophysical and electrophysical properties of electrode coke, with the determination of optimal conditions for obtaining a material combining low ash content and high carbon content. It was found that the content of phenols and paraffins in the resin of “Shubarkol Komir” is approximately 25% of each component. It is shown that the properties of the final coke depend on the ratio of the mixed pitches (1:1, 1:2, 2:1) and coking conditions (temperature 800–1000 °C, duration 4–6 h). Optimal characteristics (minimal ash content of 0.4%, maximal carbon content of 97.75%) were achieved with a pitch ratio of 1:2 and a temperature of 1000 °C for 6 h. A specific heat capacity in the range of 298–448 K was measured calorimetrically for this sample, where a type II phase transition was detected at 373 K. Electrophysical measurements in the range of 293–483 K revealed a complex temperature dependence of the resistance characteristic of a semiconductor with two sections of a narrow band gap (~0.67 eV and ~0.55 eV). The novelty of the work consists in a comprehensive study of composite mixtures of coal tar pitches and the influence of heat treatment parameters on the formation of thermophysical and electrophysical properties of electrode coke. For the first time, signs of a type II phase transition have been identified for this type of coke material and gigantic permittivity values (up to 10⁹) have been recorded, indicating its potential as a functional carbon material. Full article

Background: Cancer therapeutics development has been a challenge in medical and scientific areas due to their toxicity, limited biocompatibility, and unfortunate side effects. However, despite advances in early detection and the study of novel treatments, the mortality rate for breast cancer remains high, making it a significant global health concern. Objectives: In this study, poly(methyl methacrylate) (PMMA) nanoparticles functionalized with acrylic acid (AA), fumaramide (FA), and curcumin (CUR) as chelating and inhibitor agents were synthesized by emulsion polymerization techniques. Methods and Results: Comprehensive physiochemical characterization studies based on gravimetry, dynamic light scattering (DLS), electrophoresis, Fourier transform infrared (FT-IR), ultraviolet–visible (UV–Vis) and photoluminescence (PL) spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM) revealed a pH dependence of nanoparticles that exhibit structural changes upon interaction with calcium (Ca²⁺) and magnesium (Mg²⁺) ions. Calorimetric thermodynamic properties measured by isothermal titration calorimetry (ITC) confirmed chelating coordination and positive cooperativity between the nanoparticles and metal ions. In vitro studies showed the low cytotoxicity of nanoparticles by fibroblast proliferation, and their chelation process was observed by fluorescence microscopy, with the loss of interaction between cells. Conclusions: These results suggest that the functionalized nanoparticles have potential in drug delivery systems (DDS) for targeted breast cancer therapies, providing a promising polymer material for more efficient and less toxic treatments. Full article

This paper presents a study of the thermal and rheological properties of isosorbide, showing that its degradation temperature (around 100 °C) is much lower than values previously proposed in the literature. Furthermore, remarkable calorimetric and viscoelastic behaviors, with features usually observed in semi-crystalline systems are presented. The onset of the melting is measured at 45 °C, while a glass transition occurs at −45 °C, followed by cold crystallization. Wide-angle X-ray diffraction confirmed the coexistence of crystalline domains and an amorphous fraction, which behaves as a molecular glass, with an estimated crystallinity of approximately 70%. Thermogravimetric analyses conducted under both air and nitrogen and at multiple heating rates, in line with ICTAC recommendations, established the robustness of the 100 °C degradation onset. These findings provide new structure–property relationships for isosorbide and open up new avenues for further research and development in this area. Full article

Galactomannans, like locust bean gum, are polysaccharides widely used in the food and pharmaceutical industries because of their rheological and functional properties. However, their optical and thermal characterization is challenging due to their viscous and highly dispersive nature, which hinders the applicability of conventional spectroscopic and calorimetric techniques. In this study, photopyroelectric techniques were used to simultaneously determine, for the first time, the optical absorption coefficients and thermal diffusivity of locust bean gum in aqueous suspension at various concentrations. Optical characterization was performed at 660 nm (visible) and 1550 nm (near-infrared), revealing strong absorption at 1550 nm associated with hydroxyl group overtones and allowing reliable quantification at concentrations as low as 0.5 g/100 mL. Thermal characterization yielded diffusivity values ranging from 1.50 × 10⁻³ to 1.47 × 10⁻³ cm²/s, with a slight decreasing trend as concentration increased. These results confirm the applicability of photopyroelectric methods for the dual optical and thermal characterization of galactomannans and highlight their potential for analyzing complex biopolymer suspensions where traditional methods fall short. Full article

Alloys from the Ag-Ti system are extremely promising and offer the possibility of versatile applications owing to their attractive properties. However, due to the experimental difficulties caused, among others, by the significant difference in melting points of the components, most of the information on the thermodynamic properties available in the literature has been obtained by computer methods. Therefore, the main aim of this work is to extend the current knowledge about the experimentally determined thermodynamic properties of selected alloys from the Ag-Ti system. Within the scope of this work, calorimetric studies were carried out using Differential Scanning Calorimetry (DSC) and high-temperature drop calorimetry measurements. The first of the aforementioned methods was used to determine the characteristic temperature of the Ag_0.43Ti_0.57 alloy synthesized by mechanical alloying. Using titanium hydride instead of titanium for the preparation of alloys from the Ag-Ti system has not yet been reported in the literature. This paper presents a complete structural characterization (SEM, XRD studies) of the above alloy produced by this method. The second technique was applied to ascertain the mixing enthalpy change in the alloys in the composition range between x_Ti = 0.02–0.226, and for the measurements of the formation enthalpy of the AgTi intermetallic phase. Based on the calorimetric results obtained in this study, along with the relevant thermodynamic data from the literature, the Ag-Ti phase diagram was reoptimized. Full article

Blocking the MAPK pathway is a strategy to stop cancer cells proliferation. Despite all the successes, the acquisition of drug resistance by cells, as well as the mutational status of the downstream protein KRAS, reduces the tumor response to therapy. Ribonuclease binase from Bacillus pumilus is among the agents that block this pathway through direct interaction with EGFR and RAS. The present study is aimed at the design, optimization, and characterization of a novel complex based on antitumor binase immobilized on microgranular clinoptilolite-containing rock to ensure its prolonged release in the gastrointestinal tract. A set of modern methods including transmission electron microscopy, scanning electron microscopy, and computed tomography was used to characterize the granularity, porosity and elemental composition of the carrier. The size of binase particles, measured by atomic force microscopy at 7 nm, allows enzyme penetration into meso- and macropores of the carrier. Calorimetric results confirm that binase is stable at high temperatures, even exceeding those in the body, and retains catalytic activity in the model fluids of the gastrointestinal tract. The parameters for processing a natural clinoptilolite-containing rock and the conditions for binase sorption were selected. The gradual release of the enzyme from the carrier lasts over 20 h, which provides cytotoxicity towards human adenocarcinoma cells during movement through the gastrointestinal tract. Thus, for the first time a promising long-acting complex with antitumor and detoxifying properties was successfully created. Full article