Search Results (457)

This study presents the synthesis and characterization of novel kaolinite niobium and kaolinite titanium niobium nanocomposites and their application as heterogeneous photocatalysts. Utilizing a hydrolytic sol–gel route, we combined kaolinite with isopropyl alcohol, acetic acid, titanium (IV) isopropoxide, and ammonium niobium oxalate, followed by heat treatment at 400, 700, and 1000 °C. X-ray diffraction confirmed the retention of kaolinite’s characteristic reflections, with basal spacings indicating the presence of semiconductors on the external surfaces and edges. Heating treatment not allowing the crystallization of anatase until 1000 °C reveals that Nb⁵⁺ could inhibit the transition to titanium crystalline phases (anatase and rutile). The bandgap energies decreased with clay mineral support, averaging 2.50 eV, and absorbing up to 650 nm. The model reaction of terephthalic acid hydroxylation accomplished by photoluminescence spectroscopy demonstrated that KaolTiNb400 presented a higher rate of *OH production, achieving 591 mmol L⁻¹ min⁻¹ compared to pure KaolNb400 173 mmol L⁻¹ min⁻¹. Photodegradation studies revealed significant photocatalytic activity, with the KaolTiNb400 nanocomposite achieving the highest efficiency, demonstrating 90% removal of methylene blue (combining adsorption and degradation) after 24 h of UV light irradiation. These materials also exhibited promising results for the degradation of the antibiotics Triaxon^® (40%) and Loratadine (8%), highlighting their potential for organic pollutants’ removal. In both cases the presence of byproducts is detected. Full article

Background/Objectives: Wound healing requires simultaneous pain control, inflammation management, infection prevention, and tissue regeneration. This study aimed to develop and evaluate in vitro a non-contact thermosensitive spray hydrogel combining lidocaine for rapid analgesia and allantoin for tissue repair. Methods: The effects of chitosan and Poloxamer 407 on viscosity, spray diameter, and bioadhesion ability of hydrogels were optimized using response surface methodology. Lead formulations (S1 and S2) were selected via a desirability function within the software. The pH, gelation temperature (T_G), rheological behavior, sprayability, bioadhesion, and lidocaine release using the dialysis bag method were assessed. The in vitro cytotoxicity, anti-inflammatory activity (TNF-α), and cell migration (scratch assay) of the formulations were investigated. Results: The viscosity values (42.7–58.7 mPa·s) indicated suitability for spraying at room temperature. T_G was 28.7 ± 0.6 °C (S1) and 29.3 ± 0.3 °C (S2), enabling rapid sol–gel transition at skin temperature. The lidocaine release reached 95–100% within 120 min. S2 exhibited lower viscosity and wider spray diameter, improving applicability on larger wound areas. In vitro cytotoxicity, scratch assay, and inflammatory marker analyses demonstrated that the optimized sprayable hydrogels exhibited a biocompatible and cell-healing profile. Conclusions: The developed thermosensitive spray hydrogel enables the combined delivery of lidocaine and allantoin, rapid gelation at body temperature, and touch-free administration. Its suitable viscosity and sprayability, and fast lidocaine release profile indicate high patient compliance and a significant advantage over conventional cream/ointment formulations, particularly regarding painless application, reduced contamination risk, enhanced therapeutic potential, and confirmed in vitro biocompatibility with supportive effects on keratinocyte behavior. Full article

Osteoporotic vertebrae are a uniquely challenging tissue for local delivery due to the complex geometry of cancellous bone, the proximity of the spinal cord, and the need for reliable site retention. These challenges can be met with the use of stimuli responsive, state transiting formulations by leveraging their unique capacity for minimally invasive implantation as a liquid, sol–gel transition in response to stimuli, and finally, release of a loaded therapeutic. Here, we present the formulation development of a thermosensitive methylcellulose–collagen hydrogel, functionalised with controlled release simvastatin, recently shown to enhance osteogenesis while also impeding osteoclast activity. We first optimised a formulation with collagen content of 0.4% w/v to achieve a thermosensitive system with sol–gel transition at 29 °C, shear-thinning/injectable properties, low cytotoxicity, and high biocompatibility. Incorporation of nano-hydroxyapatite for enhanced bone tissue mimicry revealed optimal performance at 100% w/collagen content, showing long-term hydrolytic stability, maintaining more than 100% of its mass after 28 days. A loading concentration of 1 mg of simvastatin to 1 g of hydrogel displayed sustained release of simvastatin over 35 days. Finally, the release of simvastatin from the hydrogel into in vitro conditions prevented the formation of osteoclasts but failed to boost osteogenesis. Together these findings reveal a series of desirable stimuli-responsive hydrogel properties, achieving minimally invasive application coupled with sustained release of a hydrophobic compound, which is potentially useful for spatially complex bone regeneration. Further this work demonstrates the challenge of dosing sustained release systems to achieve simultaneous osteogenesis and anti-osteoclastogenic effects. Full article

The synthesis and electrocatalytic properties of amorphous first- and third-row transition metal sulfides (a-TMS) for green hydrogen generation have been comprehensively reviewed. These electrocatalysts can be prepared by several solution processes, including chemical bath deposition, electrodeposition, sol–gel, hydrothermal reaction and thermolysis. The deposition method strongly influences the electrochemical properties of the synthesized a-TMS electrocatalyst. Based on overpotential at 10 mA/cm², the electrocatalytic activity of mono-metallic a-TMS for hydrogen evolution is ranked as follows: a-NiS_x > a-CuS_x > a-CoS_x > a-WS_x > a-FeS_x. The best performing a-NiS_x prepared by chemical bath deposition has an overpotential at 10 mA/cm² of 53 mV and Tafel slope of 68 mV/dec in 1 M KOH electrolyte. The integration of Ni into the a-TMS network structure is crucial to achieving high activity in multi-metallic a-TMS electrocatalyst, as demonstrated by the bifunctional (NiFe)S_x/NiFe(OH)_y nanocomposite catalyst. The critical role of Ni in a-TMS catalyst design can be attributed to the lower free energy change for hydrogen adsorption on Ni. Finally, the emerging catalyst design strategy of amorphous–crystalline heterostructures with a three-dimensional morphology will be discussed together with the need to identify hydrogen adsorption sites on a-TMS electrocatalysts in future. Full article

Magnesium metal boasts a high theoretical volumetric specific capacity and abundant reserves. Magnesium batteries offer high safety and environmental friendliness. In recent years, magnesium-ion batteries (MIBs) with Mg or Mg alloys as anodes have garnered extensive interest and emerged as promising candidates for next-generation competitive energy storage technologies. However, MIBs are plagued by issues such as sluggish desolvation kinetics and slow migration kinetics, which lead to limitations including a limited electrochemical window and poor magnesium storage reversibility. Herein, the sodium vanadium phosphate @ carbon (Na₃V₂(PO₄)₃@C, hereafter abbreviated as NVP@C) cathode material was synthesized via a sol–gel method. The electrochemical performance and magnesium storage mechanism of NVP@C in a 0.5 M magnesium bis(trifluoromethanesulfonyl)imide/ethylene glycol dimethyl ether (Mg(TFSI)₂/DME) electrolyte were investigated. The as-prepared NVP@C features a pure-phase orthorhombic structure with a porous microspherical morphology. The discharge voltage of NVP@C is 0.75 V vs. activated carbon (AC), corresponding to 3.5 V vs. Mg/Mg²⁺. The magnesium storage process of NVP@C is tentatively proposed to follow a ‘sodium extraction → magnesium intercalation → magnesium deintercalation’ three-step intercalation–deintercalation mechanism, based on the characterization results of ICP-OES, ex situ XRD, and FTIR. No abnormal phases are generated throughout the process, and the lattice parameter variation is below 0.5%. Additionally, the vibration peaks of PO₄ tetrahedrons and VO₆ octahedrons shift reversibly, and the valence state transitions between V³⁺ and V⁴⁺/V⁵⁺ are reversible. These results confirm the excellent reversibility of the material’s structure and chemical environment. At a current density of 50 mA/g, NVP@C delivers a maximum discharge specific capacity of 62 mAh/g, with a capacity retention rate of 66% after 200 cycles. The observed performance degradation is attributed to the gradual densification of the CEI film during cycling, leading to increased Mg²⁺ diffusion resistance. This work offers valuable insights for the development of high-voltage MIB systems. Full article

Ensuring food safety and quality has become increasingly critical due to the complexities introduced by globalization, industrialization, and extended supply chains. Traditional analytical methods for food quality control, such as chromatography and mass spectrometry, while accurate, face limitations including high costs, lengthy analysis times, and limited suitability for on-site rapid monitoring. Electrochemical sensors integrated with molecularly imprinted polymers (MIPs) have emerged as promising alternatives, combining high selectivity and sensitivity with portability and affordability. MIPs, often termed ‘plastic antibodies,’ are synthetic receptors capable of selective molecular recognition, tailored specifically for target analytes. This review comprehensively discusses recent advancements in MIP-based electrochemical sensing platforms, highlighting their applications in detecting various food quality markers. It particularly emphasizes the detection of antioxidants—both natural (e.g., vitamins, phenolics) and synthetic (e.g., BHA, TBHQ), artificial sweeteners (e.g., aspartame, acesulfame-K), colorants (e.g., azo dyes, anthocyanins), traditional contaminants (e.g., pesticides, heavy metals), and toxicants such as mycotoxins (e.g., aflatoxins, ochratoxins). The synthesis methods, including bulk, precipitation, surface imprinting, sol–gel polymerization, and electropolymerization (EP), are critically evaluated for their effectiveness in creating highly selective binding sites. Furthermore, the integration of advanced nanomaterials, such as graphene, carbon nanotubes, and metallic nanoparticles, into these platforms to enhance sensitivity, selectivity, and stability is examined. Practical challenges, including sensor reusability, regeneration strategies, and adaptability to complex food matrices, are addressed. Finally, the review provides an outlook on future developments and practical considerations necessary to transition these innovative MIP electrochemical sensors from laboratory research to widespread adoption in industry and regulatory settings, ultimately ensuring comprehensive food safety and consumer protection. Full article

Surgical site infections in oral and maxillofacial interventions are often exacerbated by biofilm formation, and current antimicrobial treatments are hampered by issues such as resistance and adverse effects. This article aimed to develop, characterize, and evaluate the antimicrobial activity of Lippia sidoides Cham. essential oil (LSEO) gel composed of poloxamer (P) and chitosan (C). Gas chromatography–mass spectrometry (GC-MS) analysis identified thymol as the major component of LSEO (71.04%). In situ P-gels containing LSEO (0.25–1.0%) were produced with and without C. The addition of C resulted in gels with nanometric particle sizes (263.8 ± 231 nm; PDI 0.39 ± 0.17) and a positive zeta potential (+4.81 ± 1.97 a + 8.19 ± 0.51 mV), exhibiting pseudoplastic behavior in rheological analysis. The sol–gel transition temperature (Tsol–gel) was found to be between 20 and 28 °C, with a transition time at 37 °C ranging from 18.76 ± 1.24 s to 46.46 ± 8.89 s. LSEO showed MIC values of 256, 128, and 128 µg/mL against Staphylococcus aureus, Escherichia coli, and Candida albicans, respectively, while in situ LSEO gels presented MIC values above 5 µg/mL for all tested strains. Therefore, the developed gel containing LSEO showed promising application in dentistry, offering a potential new treatment perspective for surgical site infections in oral and maxillofacial surgery. Full article

The rational design of transition metal oxides with tailored electronic structures and defect chemistries is critical for advancing high-performance supercapacitors. Herein, we report the engineering of cobalt oxide (Co₃O₄) gels through controlled sol–gel synthesis and rare earth (RE) incorporation using neodymium (Nd), gadolinium (Gd), and dual neodymium/gadolinium (Nd/Gd) doping. X-ray diffraction (XRD) confirmed the preservation of the cubic spinel structure with systematic peak shifts and broadening, evidencing lattice strain, oxygen vacancy generation, and defect enrichment. Field-emission scanning electron microscopy (FE-SEM) analyses revealed distinct morphological evolution from compact nanoparticle assemblies in pristine Co₃O₄ to highly porous, interconnected frameworks in Nd/Gd–Co₃O₄ (Nd/Gd-Co). X-ray photoelectron spectroscopy (XPS) verified the stable incorporation of RE ions, accompanied by electronic interaction with the Co–O matrix and enhanced oxygen defect states. Electrochemical measurements demonstrated that the Nd/Gd–Co electrode achieved a remarkable areal capacitance of 25 F/cm² at 8 mA/cm², superior ionic diffusion coefficients, and the lowest equivalent series resistance (0.26 Ω) among all samples. Long-term cycling confirmed 84.35% capacitance retention with 94.46% coulombic efficiency after 12,000 cycles. Furthermore, the asymmetric pouch-type supercapacitor (APSD) constructed with Nd/Gd–Co as the positive electrode and activated carbon as the negative electrode delivered a wide operational window of 1.5 V, an areal capacitance of 140 mF/cm², an energy density of 0.044 mWh/cm², and 89.44% retention after 7000 cycles. These findings establish Nd/Gd-Co gels as robust and scalable electrode materials and demonstrate that RE co-doping is an effective strategy for bridging high energy density with long-term electrochemical stability in asymmetric supercapacitors. Full article

This study compares the structural, morphological, magnetic, and photocatalytic properties of a pure SiO₂ matrix, a ZnFe₂O₄-doped SiO₂ nanocomposite (both synthesized via the sol-gel method), and bulk ZnFe₂O₄ produced by thermal decomposition. Thermogravimetric analysis (TGA) reveals that metal oxalates form below 200 °C and decompose into metal oxides, which subsequently form ferrite. Fourier-transform infrared (FTIR) spectroscopy confirms the embedding of both undoped and ZnFe₂O₄-doped nanoparticles into the SiO₂ matrix at all investigated annealing temperatures. X-ray diffraction (XRD) consistently reveals the formation of crystalline ZnFe₂O₄, with the crystallite size increasing from 48 to 93 nm upon annealing. Atomic force microscopy (AFM) shows spherical ferrite nanoparticles surrounded by an amorphous layer, with particle growth observed at higher temperatures. Structural parameters derived from XRD (e.g., crystallite size, density, porosity, lattice constant, unit cell volume) and AFM (e.g., particle size, coating thickness) as well as magnetic parameters (saturation magnetization, remanence, anisotropy, coercivity) demonstrate clear dependence on both dopant presence and annealing temperature. Magnetic measurements reveal enhanced properties with increasing ferrite content and heat treatment, with a transition from superparamagnetic behavior at 700 °C to ferrimagnetic behavior above 1000 °C. Scavenger experiments confirmed the involvement of holes, hydroxyl radicals, and superoxide radicals in the photocatalytic process. The photocatalytic efficiency, as evaluated by the Rhodamine B degradation under visible light, highlights the promising potential of the obtained nanocomposite for advanced environmental and technological applications. Full article

Zinc oxide (ZnO) nanomaterials have emerged as promising candidates for gas sensing applications due to their high sensitivity, fast response–recovery cycles, thermal and chemical stability, and low fabrication cost. However, the performance of pristine ZnO remains limited by high operating temperatures, poor selectivity, and suboptimal detection at low gas concentrations. To address these limitations, significant research efforts have focused on dopant incorporation and polymer hybridization. This review summarizes recent advances in dopant engineering using elements such as Al, Ga, Mg, In, Sn, and transition metals (Co, Ni, Cu), which modulate ZnO’s crystal structure, defect density, carrier concentration, and surface activity—resulting in enhanced gas adsorption and electron transport. Furthermore, ZnO–polymer nanocomposites (e.g., with polyaniline, polypyrrole, PEG, and chitosan) exhibit improved flexibility, surface functionality, and room-temperature responsiveness due to the presence of active functional groups and tunable porosity. The synergistic combination of dopants and polymers facilitates enhanced charge transfer, increased surface area, and stronger gas–molecule interactions. Where applicable, sol–gel-based studies are explicitly highlighted and contrasted with non-sol–gel routes to show how synthesis controls defect chemistry, morphology, and sensing metrics. This review provides a comprehensive understanding of the structure–function relationships in doped ZnO and ZnO–polymer hybrids and offers guidelines for the rational design of next-generation, low-power, and selective gas sensors for environmental and industrial applications. Full article

Crystalline defects such as oxygen vacancies have been studied little by electron paramagnetic resonance (EPR) spectroscopy for silicate-based luminescent materials. In this study, lutetium oxyorthosilicate powders were prepared by the sol–gel method, using TEOS (silicon source) and rare earth salts as precursors. The cross-linking agent, Glymo, contributed silicon atoms to the precursor solution in all systems. The addition of Glymo to Lu₂SiO₅, Lu₂SiO₅:Eu and Lu₂SiO₅:Eu/Yb influenced the morphology and chemical structure of the powders, leading to Lu₂Si₂O₇ formation. The crystalline defects in the lutetium silicate systems were investigated by EPR spectroscopy, and several defects related to oxygen were identified, as well as impurities from the precursors. Photoluminescence emission spectra revealed Eu³⁺ transitions between ⁵D₀ → ⁷F₀, ⁵D₀ → ⁷F₁ and ⁵D₀ → ⁷F₂ under 258 nm excitation, in addition to oxygen vacancy emissions between 500 and 550 nm. Oxygen vacancies were identified and confirmed by correlating EPR and photoluminescence studies. Full article

With the rapid advancement of energy storage technologies, there is a growing demand for affordable, efficient, and environmentally benign battery systems. Sodium-ion batteries (SIBs) present a promising alternative to lithium-ion systems due to sodium’s high abundance and similar electrochemical properties. Particular attention is given to developing NASICON -sodium (Na) super ionic conductor, type cathode materials, especially Na3V2(PO4)3, which exhibits high thermal and structural stability. This study focuses on the sol–gel synthesis of Na₃V₂(PO₄)₃ using citric acid and ethylene glycol, as well as investigating the effect of annealing temperature (400–1000 °C) on its structural and electrochemical properties. Phase composition, morphology, textural characteristics, and electrochemical performance were systematically analyzed. Above 700 °C, a highly crystalline NASICON phase free of secondary impurities was formed, as confirmed by X-ray diffraction (XRD). Microstructural evolution revealed a transition from a loose amorphous structure to a dense granular morphology, accompanied by changes in specific surface area and porosity. The highest surface area (67.40 m²/g) was achieved at 700 °C, while increasing the temperature to 1000 °C caused pore collapse due to sintering. X-ray photoelectron spectroscopy (XPS) confirmed the predominant presence of V³⁺ ions and the formation of V⁴⁺ at the highest temperature. The optimal balance of high crystallinity, uniform elemental distribution, and stable texture was achieved at 900 °C. Electrochemical testing in a Na/NVP half-cell configuration delivered an initial capacity of 70 mAh/g, which decayed to 55 mAh/g by the 100th cycle, attributed to solid-electrolyte interphase (SEI) formation and irreversible Na⁺ trapping. These results demonstrate that the proposed approach yields high-quality Na₃V₂(PO₄)₃ cathode materials with promising potential for sodium-ion battery applications. Full article

This study focuses on the synthesis and characterization of thermoresponsive hydrogels of poly(lactic acid) (PLA) and poly(ethylene glycol) (PEG), PLA–PEG copolymers, aiming at the targeted and controlled release of deferoxamine (DFO), a clinically applied iron-chelating drug. Triblock (PLA-PEG-PLA) and diblock (mPEG-PLA) copolymers were synthesized using ring-opening polymerization (ROP) with five different PEGs with molecular weights of 1000, 1500, 2000, 4000, and 6000 g/mol and two types of lactide (L-lactide and D-lactide). Emulsions of the polymers in phosphate-buffered saline (PBS) were prepared at concentrations ranging from 10% to 50% w/w to study the sol–gel transition properties of the copolymers. Amongst the synthesized copolymers, only those that demonstrated thermoresponsive sol-to-gel transitions near physiological temperature (37 °C) were selected for further analysis. Structural and molecular confirmation was performed by Nuclear Magnetic Resonance (NMR) and Fourier-transform infrared spectroscopy (FTIR), while the molecular weights were determined via Gel Permeation Chromatography (GPC). The thermal transitions were studied by calorimetry (DSC) and crystallinity via X-ray diffraction (XRD) analysis. DFO-loaded hydrogels were prepared, and their drug release profiles were investigated under simulated physiological conditions (37 °C) for seven days using HPLC analysis. The thermoresponsive characteristics of these systems can offer a promising strategy for injectable drug delivery applications, where micelles serve as drug carriers and undergo in situ gelation, enabling controlled release. This alternative procedure may significantly improve the bioavailability of DFO and enhance patient compliance by addressing key limitations of conventional administration routes. Full article

Thermoresponsive hydrogels that undergo reversible sol-gel transitions near physiological temperatures are highly attractive for biomedical applications, such as injectable drug delivery and embolization therapies. In this study, a library of polyurethane-based hydrogels was synthesized via step-growth polymerization using polyethylene glycol (PEG) of varying molecular weights, different diisocyanates, and a series of functional diols derived from diethanolamine with increasing hydrophobicity. The resulting polymers exhibited sol–gel transition behaviors without the need for external crosslinkers, relying solely on non-covalent interactions. The thermal responsiveness was systematically investigated using UV–Vis turbidimetry, and the cloud point temperature (T_CP) was found to be tunable within a range of 26–49 °C by modulating the monomer composition. Statistical modeling identified PEG molecular weight and diol structure as the primary determinants of T_CP, while diisocyanate type and diol-to-PEG ratio had negligible effects. Only diethanolamine (DEA)-based polymers formed stable hydrogels above a critical gelation temperature (LCGT), attributed to enhanced intermolecular interactions via free amine groups. In vitro degradation assays confirmed good hydrolytic stability under physiological conditions over four weeks, with degradation profiles strongly influenced by the PEG chain length and hydrophobic content. These findings establish a structure–property framework for the rational design of injectable, thermoresponsive polyurethane hydrogels with tailored sol–gel behavior for biomedical applications. Full article

The use of solid products deriving from the pyrolysis of wastes as potential substitute of traditional binders in asphalt preparation is investigated with the final goal of reducing production costs, preserving non-renewable resources, and promoting an effective resource use as well as recovery and recycling procedures, thus implementing a regenerative circular economy approach. Char derived from the pyrolysis of agricultural and aquaculture wastes has been explored as a novel alternative additive for asphalt production. Different feedstocks were used for the preparation of biochar by pyrolysis. The produced char samples, after an in-depth chemical and structural characterization, have been implemented in the preparation of asphalt mixtures, with their potential use as a binder evaluated by performing conventional rheological tests. To evaluate the potential anti-aging effect of char as an additive, bituminous formulations containing 3 to 6 wt.% char were subjected to short-term simulated aging using the Rolling Thin-Film Oven Test (RTFOT) method. The resulting mechanical properties were then assessed. The results indicate that the all the tested char samples have limited modifying properties towards the gel-to-sol transition temperature. Among the samples, lemon peel-derived char (LP-char) showed superior antioxidant properties against bitumen oxidative aging. This study suggests that certain chemical characteristics can serve as predictive indicators of antioxidant activity in biochars produced from biomass pyrolysis. Full article