Search Results (268)

Recently, more sustainable and biodegradable packaging materials have begun to attract attention in food packaging due to major, rising concerns related to plastic usage. This study aims to develop and characterize biodegradable food packaging materials, namely poly(lactic acid) (PLA) and poly(ε-caprolactone) (PCL) enriched with pomegranate peel extract (PoPE). Firstly, the optimal extract selected was a 24 h maceration of PoPE with 60% ethanol, after production with different solvents and methods. PLA- and PCL-based films were produced via melt compounding with the addition of PoPE at different concentrations (1, 3, 5 and 10%, w/w). FTIR confirmed that the PoPE did not modify the chemical backbones of PLA or PCL, with only a more pronounced O–H band in PCL, suggesting mainly non-covalent/physical interactions. UV–Vis spectroscopy showed tunable warm coloration and strong UV shielding with reduced transparency; for PLA ~3–5 wt.%, PoPE enabled near-complete UV blocking, while PCL achieved very high UV protection even at low loadings. PoPE improved toughness in PLA (3–5 wt.%) and maintained ductility in PCL (1–10 wt.%). PoPE-added PLA and PCL films maintained thermal stability up to 10 wt.% according to TGA results. DSC/XRD indicated a matrix-dependent crystallization response. PLA remained largely amorphous, whereas PoPE promoted PCL crystallinity without changing polymer crystal polymorphs. SEM images revealed homogenous dispersion of PoPE in the films. Full article

Three multicomponent crystals of metformin were investigated to elucidate factors governing crystal architecture. Structures were determined by X-ray diffraction and analyzed using the Atoms-in-Molecules (AIM) approach, focusing on critical points and electron density topology. Three types of crystals were obtained: salt, cocrystal salt solvate and mixed salt with both organic and inorganic anions. Protonation of nitrogen atoms in metformin alters bond lengths and electron density, while strong intramolecular hydrogen bonds in hydrogenmaleate anions stabilize the structures and define the preferred anion geometry. Comparison with monoprotonated metformin revealed similar topological features despite differing protonation states. Mechanochemical synthesis via liquid-assisted grinding (LAG) enabled selective formation of specific crystalline forms, with the solvent type and acid polymorph influencing product distribution. These results highlight the critical roles of protonation, hydrogen bonding, and synthetic methodology in designing and controlling multicomponent metformin crystal structures. Full article

This study reports the valorization of oil palm empty fruit bunches into cellulose nanocrystals (CNCs) for the removal of the chemical oxygen demand (COD) from industrial wastewater generated by the same processing sector. Cellulose I_β was first isolated through sequential bleaching, delignification, and mercerization, and two hydrolysis routes were evaluated to obtain CNCs: a concentrated acid route (60% v/v H₂SO₄, 50 °C, 60 min) for CNCs-1 and a low-acid, long-duration route (1% v/v H₂SO₄, 80 °C, 12 h) for CNCs-2. Rietveld refinement of the X-ray diffractograms confirmed the polymorphic transition, assigning cellulose I_β to the intermediate materials and cellulose II to the CNC samples, with crystallite sizes of 4.99 nm for CNCs-1 and 5.43 nm for CNCs-2. Attenuated Total Reflectance–Fourier Transform Infrared (ATR-FTIR) spectroscopy analysis showed the progressive removal of lignin and hemicellulose and supported the cellulose I_β to II transition through changes in hydroxyl bonding and crystallinity-related bands. Preliminary adsorption tests showed better COD removal with CNCs-2, which were therefore selected for optimization using a Box–Behnken design with the adsorbent mass, pH, and contact time as variables. The quadratic model was significant (R² = 0.9675; predicted R² = 0.8908), and the maximum COD removal reached 91.47%, decreasing the COD concentration from 2459.0 to 209.85 mg L⁻¹ under the optimum conditions of 0.09 g CNCs-2, pH 3, and 20 min. These results highlight cellulose II nanocrystals derived from oil palm waste as a promising and scalable adsorbent for industrial wastewater treatment. Full article

Protein crystals are intrinsically hydrated systems, and their structural integrity is strongly influenced by environmental humidity. Understanding the effects of relative humidity (RH) variation on crystal stability is therefore essential for both fundamental research and applied studies. In this work, the structural response of tetragonal hen egg-white lysozyme (HEWL) to controlled RH variation was investigated using in situ X-ray powder diffraction (XRPD). Polycrystalline HEWL samples were subjected to systematic gradual dehydration and rehydration cycles, as well as to non-gradual RH variation protocols. Pawley analysis of the XRPD data enabled monitoring of the evolution of unit cell parameters and unit cell volume as a function of RH. Under all experimental conditions, the tetragonal polymorph (space group P4₃2₁2; a = 79.105 (4) Å, c = 38.231 (2) Å) was preserved. RH variation induced smooth, continuous and anisotropic lattice changes, characterized by a decrease in the a (=b)-axis and a concomitant increase in the c-axis upon dehydration, while rehydration resulted in the opposite behavior. The overall magnitude of lattice variation remained limited (within ±2%), indicating a high degree of structural stability. Partial degradation of crystallinity was observed only after prolonged exposure to low RH levels. These findings demonstrate the remarkable structural resilience of tetragonal HEWL and highlight the effectiveness of in situ XRPD as a powerful tool for probing hydration-driven lattice responses in protein crystals under realistic environmental conditions. Full article

Derivatives of 4,7-diphenyl-2,1,3-benzothiadiazole are highly stable compounds that fluoresce efficiently both in solutions and in the crystalline state. Thanks to their wide range of remarkable optoelectronic characteristics, they can rightly be called smart materials. This paper presents the results of an investigation into the polymorphism of 4,7-bis(4-(trimethylsilyl)phenyl)-2,1,3-benzothiadiazole (TMS-P-BTD) crystals under weakly and strongly non-equilibrium crystallization conditions from the vapor phase (PVD), solutions, and melt. Using single-crystal X-ray diffraction analysis at room temperature, two new polymorphic crystal modifications have been identified: orthorhombic II (sp. gr. Pnaa, Z/Z′ = 12/1.5) and triclinic III (sp. gr. P-1, Z/Z′ = 8/4). It was determined that the densest polymorph III melts at 154 °C. The least dense orthorhombic polymorph II dominates under kinetic growth conditions, melts independently at 151 °C, but transforms into polymorph III upon prolonged annealing. It has been established that the previously identified monoclinic polymorph I (P2₁/c, Z/Z′ = 32/8) transforms into polymorph III upon heating in the range of 75–110 °C. In the series of polymorphs I→II→III, a blue shift in the fluorescence spectrum maximum is observed: approximately 375 cm⁻¹ for polymorph II and ~635 cm⁻¹ for polymorph III relative to the position of the maximum λ_max,I = 497 nm for polymorph I. The observed spectral-fluorescence features of the TMS-P-BTD crystal polymorphic phases are consistent with the structure of the flattest molecular conformers within the crystal unit cells. Full article

Background/Objectives: The formulation development of Isotretinoin (ISN) is limited by its solubility and stability issues. This study aimed to characterise the BCS class II drug ISN, particularly the possible different solid state and formulate amorphous solid dispersion aiming for a supersaturation state. Methods: ISN’s physical states are investigated in its raw form, quench-cooled form, physical mixture with the polymer and corresponding solid dispersion form. Quench-cooled ISN was prepared in situ using DSC. Carrier stabilisation of ISN was attempted using the solid dispersion technique. Hereby, the solid dispersion of drug-polymer PVPVA at a ratio of 1:3 was prepared using the solvent evaporation method. Solid dispersion, physical mixture and raw ISN were characterised for the saturated solubility. Physical characterisation of the samples was performed using DSC, ATR-FTIR and a light microscope. Results: Two polymorphs of ISN (forms I and II) were found in the raw ISN, with form II being thermodynamically more stable. ISN possesses strong crystallinity and resistance to amorphisation under the applied quench-cooling condition without the presence of a carrier system. The conjugated polyene structure in ISN contributes to the polymorphic transformation and isomerisation. The incorporation of PVPVA in the solid dispersion system successfully improved the water solubility (sixfold) of ISN despite a combination of crystalline and amorphous components being present in the system. Conclusions: ISN is a class II drug crystal molecule. Taking advantage of solubility and possibility in the polymorphic transformation of ISN in a binary system, we concluded that ISN could potentially be formulated into its corresponding crystalline solid dispersion form. Full article

We used synchrotron X-ray diffraction (XRD) and ac-impedance spectroscopy (AIS) to uncover the structural and chemical modifications undergone by RbH₂PO₄ (RDP) at intermediate temperatures (150 °C < T < 300 °C) and investigate their relationship with RDP’s proton conductivity, σ. Nyquist plots collected on RDP samples sealed in a small volume (~50 mL) of dry air show a gradual increase in σ upon heating from 180 to 260 °C, but not the three-order-of-magnitude superprotonic jump observed in the Cs-based compound CsH₂PO₄ (CDP) within the same temperature range. Correspondingly, XRD measurements using synchrotron radiation (λ = 0.922 Å) on RDP crystalline powders sealed in a quartz capillary exhibit no evidence of a monoclinic-to-cubic superprotonic phase transition like the one observed in CDP. Instead, these temperature-resolved powder XRD patterns demonstrate that the intermediate-temperature RDP monoclinic phase (P2₁/m, a = 7.733 Å, b = 6.189 Å, c = 4.793 Å, and β = 109.21 deg) persists up to the melting point of the title compound. Our most significant finding comes from heating RDP under high pressure (P = 1 GPa), which leads to markedly different structural behavior. Indeed, our full profile refinements against XRD data collected on RDP crystals compressed at ~1 GPa show evidence of a polymorphic phase transition (at T_c = 300 °C) to a high-temperature cubic phase (Pm-3m, a = 4.784 Å) that is isomorphic with its CDP counterpart. This is significant, as it indicates that the superprotonic conduction in phosphate solid acids is not cation-specific, and a general highly efficient proton conduction mechanism is present in the high-temperature phases of these materials. Full article

From Palaeolithic ornaments to modern biomimetics, the use of nacre and shells has evolved. Initially utilised for jewellery and tools, they now inspire the development of advanced materials. This paper reviews the current knowledge on nacre’s composition, focusing on the highly regulated biomineralisation process wherein amorphous calcium carbonate (ACC) transforms into crystalline aragonite. It examines the important role of the organic matrix (specifically soluble, insoluble, and acidic proteins) in controlling crystal nucleation, growth, and polymorph selection. Scientists study natural nacre formation to create nacre-inspired composites for various applications. Charles Hatchett’s in 1799 shell categorisation, Sorby and Sowerby’s 19th-century microscopy, Taylor, Beedham, Bøggild, and Currey’s mid-20th-century research on bivalve structures, and mechanical property investigations in the 1970s are some of the major developments. The hierarchical structure, cooperative plastic deformation, surface asperities, organic–inorganic interactions, and interphase in such complex composite materials give rise to impressive mechanical properties. In the early 2000s, with the emergence of biomimetics, inspired by nacre, several macroscopic structural materials with uniform micro- and nanoscale architectures have been synthesised in recent decades, and their mechanical properties and potential applications have been explored. Modern nacre-inspired fabrication utilises 3D printing for precision, freeze casting for sustainability, and mineralisation for scalability. Techniques like layer-by-layer assembly and nanomaterial integration enhance mechanical performance through advanced interfacial engineering. Full article

Spray freeze-drying (SFD) is a novel technique for formulating dry powders, particularly for pulmonary drug delivery via dry powder inhalers (DPIs). Despite their low density and excellent aerodynamic properties, such powders are affected by high cohesiveness due to their surface properties. Sugars such as mannitol (MAN), trehalose, raffinose, and sucrose are commonly used in SFD. MAN is widely employed due to its high MAN—ice eutectic temperature—at which MAN and water (ice) form a stable eutectic mixture—and its crystallinity. However, crystallinity can impact the microparticles’ (MPs) cohesiveness, since MAN exhibits distinct polymorphs (α, β, δ) with peculiar properties. This study provides valuable insights for the development of DPI formulations by ensuring precise control over MAN polymorphism, ultimately enhancing formulation stability and performance. We introduced, for the first time, an intermediate freezing (IF) step within the SFD process to modulate MAN polymorphism, demonstrating its synergy with optimised storage temperature conditions. Furthermore, polyvinylpyrrolidone, 2-hydroxypropyl beta cyclodextrin, dextran, and polysorbate 80 were employed as polymorphism-controlling agents for MAN, contributing to the development of stable formulations with reduced particle cohesion and improved storage stability at room temperature. For the first time, this study shows that MAN polymorphism in SFD can be controlled to drive dry powder inhaler performance. Full article

As one of the polymorphs of the gallium oxide family, ε gallium oxide (ε-Ga₂O₃) demonstrates promising potential in high-power electronic devices and solar-blind photodetection applications. However, the synthesis of pure-phase ε-Ga₂O₃ remains challenging through low-energy consumption methods, due to its metastable phase of gallium oxide. In this study, we have fabricated pure-phase and highly oriented ε-Ga₂O₃ thin films on c-plane sapphire substrates via thermal atomic layer deposition (ALD) at a low temperature of 400 °C, utilizing low-reactive trimethylgallium (TMG) as the gallium precursor and ozone (O₃) as the oxygen source. X-ray diffraction (XRD) results revealed that the in situ-grown ε-Ga₂O₃ films exhibit a preferred orientation parallel to the (002) crystallographic plane, and the pure ε phase remains stable following a post-annealing up to 800 °C, but it completely transforms into β-Ga₂O₃ once the thermal treatment temperature reaches 900 °C. Notably, post-annealing at 800 °C significantly enhanced the crystalline quality of ε-Ga₂O₃. To evaluate the optoelectronic characteristics, metal–semiconductor–metal (MSM)-structured solar-blind photodetectors were fabricated using the ε-Ga₂O₃ films. The devices have an extremely low dark current (<1 pA), a high photo-to-dark current ratio (>10⁶), a maximum responsivity (>1 A/W), and the optoelectronic properties maintained stability under varying illumination intensities. This work provides valuable insights into the low-temperature synthesis of high-quality ε-Ga₂O₃ films and the development of ε-Ga₂O₃-based solar-blind photodetectors for practical applications. Full article

This study investigated the effects of tamarind seed polysaccharide (TSP) on the structural characteristics, digestibility, and emulsifying properties of waxy maize starch (WMS), as well as their interaction mechanisms. WMS-TSP complexes were prepared via complexes to improve starch’s physical and functional properties. Native WMS showed smooth spherical granules, while WMS-TSP samples formed freeze-drying-induced honeycomb structures (~200–250 μm). In vitro digestion indicated that WMS-TSP systems (5–15%) reduced RDS by 20.1–24.11% relative to native WMS (41% ± SD), suggesting a potential to attenuate postprandial glycemic responses. Fourier-transform infrared (FT-IR) spectroscopy revealed that TSP interacted with WMS mainly through non-covalent bonds such as hydrogen bonding, while influencing the degree of crystallinity without generating new crystalline polymorphs. In corn oil-based emulsions, the WMS-TSP composites showed strong viscoelastic behavior, with elevated storage (G′) and loss (G″) moduli, together with improved storage stability. These findings highlight the synergistic potential of WMS and TSP in enhancing the functionality of starch-based systems and provide insights into the role of polysaccharides in food structure and digestion regulation. Full article

Cerium-doped titania nanoflowers are obtained by hydrothermal synthesis, with different amounts of cerium (0.3, 0.5, and 1.0 at%). Both undoped nanoflowers (TNF) and Ce-doped TNF (Cex) are tested as photocatalysts in the degradation of the target pollutant (metronidazole) under simulated solar light. The samples are rutile polymorphs with high crystallinity and present a nanoflower-like morphology of about 1 µm in diameter and are made up of nanoscale petals (in the range of 100–300 nm). EDX spectroscopy was coupled with SEM and performed on the Ce-doped samples to determine the elemental composition of the catalysts and the Ce distribution in each sample. Optical and electronic spectroscopies reveal that Ce loading narrows the band gap from 3.0 to 2.8 eV, extending light absorption into the visible range of the spectrum and thus enhancing the photocatalytic activity. The best sample, Ce1, achieved 67% degradation of metronidazole after 360 min under solar irradiation at pH 4, compared to bare TNF, which reached 35%. Reusability tests confirm the chemical stability and photocatalytic efficiency of Ce1 over three cycles, and free-radical trapping experiments confirmed ·O₂⁻ and ·OH as major active species in metronidazole degradation. This study highlights the synergistic impact of morphology and doping on solar-driven organic pollutant degradation. Full article

The manufacturing techniques, structural features, and optical attributes of titanium dioxide (TiO₂) nanoparticles are highlighted in this study. These nanoparticles are notable for their remarkable photocatalytic activity, cheap cost, chemical stability, and biocompatibility. TiO₂ consists of three polymorph structures: anatase, rutile, and brookite. Because of its electrical characteristics and large surface area, anatase is the most efficient for photocatalysis when exposed to UV light. The crystallinity, size, and shape of titania nanoparticles (NPs) are influenced by diverse production techniques. Sol-gel, hydrothermal, solvothermal, microwave-assisted, and green synthesis with plant extracts are examples of common methods. Different degrees of control over morphology and surface properties are possible with each approach, and these factors ultimately affect functioning. For example, microwave synthesis provides quick reaction rates, whereas sol-gel enables the creation of homogeneous nanoparticles. XRD and SEM structural investigations validate nanostructures with crystallite sizes between 15 and 70 nm. Particle size, synthesis technique, and annealing temperature all affect optical characteristics such as bandgap (3.0–3.3 eV), fluorescence emission, and UV-visible absorbance. Generally speaking, anatase has a smaller crystallite size and a greater bandgap than rutile. TiO₂ nanoparticles are used in gas sensing, food packaging, biomedical coatings, dye-sensitized solar cells (DSSCs), photocatalysis for wastewater treatment, and agriculture. Researchers are actively exploring methods like adding metals or non-metals, making new composite materials, and changing the surface to improve how well they absorb visible light. Full article

The photocatalytic activity of Bi₂WO₆ Aurivillius phase has been widely exploited for the degradation of a wide range of gaseous and aqueous molecules, as well as microorganisms, under the influence of visible irradiation. Strategies for the development of doped and co-doped bismuth tungstate materials require the thermodynamic data on this phase. The heat capacity of bismuth tungstate, Bi₂WO₆, was investigated using a DSC microcalorimeter on polycrystalline powder samples in the temperature range from 313 to 1103 K (40–830 °C) in two separate runs. The samples were synthesized by solid-state reaction from pure binary oxides at 1033 K (760 °C) in a platinum crucible with cover. The high temperature C_p(T) data were fitted by the Maier–Kelley equation and, from this relation, the standard molar heat capacity of γ-Bi₂WO₆ polymorph was estimated to be at 298.15 K 176.8 ± 3.9 J·K⁻¹·mol⁻¹. A reversible second-order transition of Bi₂WO₆ phase was observed in the experimental temperature range, with a peak close to 940 K (667 °C). Additionally, the extrapolation of C_p(T) to 0 K was proposed using a method based on the multiple Einstein model. Thermodynamic properties (heat capacity C_p(T), entropy S°(T), enthalpy H°(T), Gibbs energy G°(T)) of crystalline γ-Bi₂WO₆ were calculated in the temperature range of 298.15–1123 K (25–850 °C). Full article

Chitin, one of the most abundant natural polysaccharides, has gained increasing attention for its structural diversity and potential in biomedicine, agriculture, food packaging, and advanced materials. Conventional chitin production from crustacean shell waste faces limitations, including seasonal availability, allergenic protein contamination, heavy metal residues, and environmentally harmful demineralization processes. Chitin from fungi and microalgae provides a sustainable and chemically versatile alternative. Fungal chitin, generally present in the α-polymorph, is embedded in a chitin–glucan–protein matrix that ensures high crystallinity, mechanical stability, and compatibility for biomedical applications. Microalgal β-chitin, particularly from diatoms, is secreted as high-aspect-ratio microrods and nanofibrils with parallel chain packing, providing enhanced reactivity and structural integrity that are highly attractive for functional materials. Recent progress in green extraction technologies, including enzymatic treatments, ionic liquids, and deep eutectic solvents, enables the recovery of chitin with reduced environmental burden while preserving its native morphology. By integrating sustainable sources with environmentally friendly processing methods, fungal and microalgal chitin offer unique structural polymorphs and tunable properties, positioning them as a promising alternative to crustacean-derived chitin. Full article