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25 pages, 4393 KiB  
Article
Development and Preclinical Evaluation of Fixed-Dose Capsules Containing Nicergoline, Piracetam, and Hawthorn Extract for Sensorineural Hearing Loss
by Lucia Maria Rus, Andrei Uncu, Sergiu Parii, Alina Uifălean, Simona Codruța Hegheș, Cristina Adela Iuga, Ioan Tomuță, Ecaterina Mazur, Diana Șepeli, Irina Kacso, Fliur Macaev, Vladimir Valica and Livia Uncu
Pharmaceutics 2025, 17(8), 1017; https://doi.org/10.3390/pharmaceutics17081017 (registering DOI) - 5 Aug 2025
Abstract
Background: Fixed-dose combinations have advanced in many therapeutic areas, including otorhinolaryngology, where hearing disorders are increasingly prevalent. Objectives: The present study focuses on developing and evaluating a new capsule combining nicergoline (NIC), piracetam (PIR), and hawthorn extract (HE) for the management of sensorineural [...] Read more.
Background: Fixed-dose combinations have advanced in many therapeutic areas, including otorhinolaryngology, where hearing disorders are increasingly prevalent. Objectives: The present study focuses on developing and evaluating a new capsule combining nicergoline (NIC), piracetam (PIR), and hawthorn extract (HE) for the management of sensorineural hearing loss. Methods: The first phase methodology comprised preformulation studies (DSC, FTIR, and PXRD) to assess compatibility among active substances and excipients. Subsequently, four formulations were prepared and tested for flowability, dissolution behavior in acidic and neutral media, and stability under oxidative, thermal, and photolytic stress. Quantification of the active substances and flavonoids was performed using validated spectrophotometric and HPLC-UV methods. Results: Among the tested variants, the F1 formulation (4.5 mg NIC, 200 mg PIR, 50 mg HE, 2.5 mg magnesium stearate, 2.5 mg sodium starch glycolate, and 240.5 mg monohydrate lactose per capsule) displayed optimal technological properties, superior dissolution in acidic media, and was further selected for evaluation. The antioxidant activity of the formulation was confirmed through the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, Trolox Equivalent Antioxidant Capacity (TEAC), and iron chelation tests, and was primarily attributed to the flavonoid content of the HE. Acute toxicity tests in mice and rats indicated a high safety margin (LD50 > 2500 mg/kg), while ototoxicity assessments showed no adverse effects on auditory function. Conclusions: The developed formulation displayed good stability, safety, and therapeutic potential, while the applied workflow could represent a model for the development of future fixed-dose combinations. Full article
(This article belongs to the Special Issue Natural Product Pharmaceuticals, 2nd Edition)
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17 pages, 2479 KiB  
Article
Spectroscopic, Thermally Induced, and Theoretical Features of Neonicotinoids’ Competition for Adsorption Sites on Y Zeolite
by Bojana Nedić Vasiljević, Maja Milojević-Rakić, Maja Ranković, Anka Jevremović, Ljubiša Ignjatović, Nemanja Gavrilov, Snežana Uskoković-Marković, Aleksandra Janošević Ležaić, Hong Wang and Danica Bajuk-Bogdanović
Molecules 2025, 30(15), 3267; https://doi.org/10.3390/molecules30153267 - 4 Aug 2025
Abstract
The competitive retention of pollutants in water tables determines their environmental fate and guides routes for their removal. To distinguish the fine differences in competitive binding at zeolite adsorption centers, a group of neonicotinoid pesticides is compared, relying on theoretical (energy of adsorption, [...] Read more.
The competitive retention of pollutants in water tables determines their environmental fate and guides routes for their removal. To distinguish the fine differences in competitive binding at zeolite adsorption centers, a group of neonicotinoid pesticides is compared, relying on theoretical (energy of adsorption, orientation, charge distribution) and experimental (spectroscopic and thermogravimetric) analyses for quick, inexpensive, and reliable screening. The MOPAC/QuantumEspresso platform was used for theoretical calculation, indicating close adsorption energy values for acetamiprid and imidacloprid (−2.2 eV), with thiamethoxam having a lower binding energy of −1.7 eV. FTIR analysis confirmed hydrogen bonding, among different dipole-dipole interactions, as the dominant adsorption mechanism. Due to their comparable binding energies, when the mixture of all three pesticides is examined, comparative adsorption capacities are evident at low concentrations, owing to the excellent adsorption performance of the FAU zeotype. At higher concentrations, competition for adsorption centers occurs, with the expected thiamethoxam binding being diminished due to the lower bonding energy. The catalytic impact of zeolite on the thermal degradation of pesticides is evidenced through TG analysis, confirming the adsorption capacities found by UV/VIS and HPLC/UV measurements. Detailed analysis of spectroscopic results in conjunction with theoretical calculation, thermal profiles, and UV detection offers a comprehensive understanding of neonicotinoids’ adsorption and can help with the design of future adsorbents. Full article
(This article belongs to the Special Issue Design, Synthesis, and Application of Zeolite Materials)
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11 pages, 1745 KiB  
Article
Comprehensive Investigation of Structural and Photocatalytic Properties of Cobalt and Nickel Co-Doped Magnesium Oxide Nanoparticles
by Shafaq Arif, Amna Sarwar and M. S. Anwar
Condens. Matter 2025, 10(3), 41; https://doi.org/10.3390/condmat10030041 - 4 Aug 2025
Abstract
Cobalt and Nickel (Co, Ni) co-doped magnesium oxide (MgO) nanoparticles (NPs) have been synthesized using the coprecipitation method. The structural, chemical, and optical properties of the as-synthesized NPs are systematically investigated using X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and UV-visible spectroscopy. [...] Read more.
Cobalt and Nickel (Co, Ni) co-doped magnesium oxide (MgO) nanoparticles (NPs) have been synthesized using the coprecipitation method. The structural, chemical, and optical properties of the as-synthesized NPs are systematically investigated using X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and UV-visible spectroscopy. It is found that the optical bandgap of co-doped MgO NPs reduces from 2.30 to 1.98 eV (14%) with increasing Ni dopant concentrations up to 7%. The Co0.05Ni0.07Mg0.88O NPs exhibit a high photocatalytic degradation efficiency of 93% for methylene blue dye (MB) under natural sunlight irradiation for 240 min. Our findings indicate that the Co0.05NixMg0.95−xO NPs have strong potential for use as photocatalysts in industrial wastewater treatment. Full article
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19 pages, 9135 KiB  
Article
A Study on the Characterization of Asphalt Plant Reclaimed Powder Using Fourier Transform Infrared Spectroscopy
by Hao Wu, Daoan Yu, Wentao Wang, Chuanqi Yan, Rui Xiao, Rong Chen, Peng Zhang and Hengji Zhang
Materials 2025, 18(15), 3660; https://doi.org/10.3390/ma18153660 - 4 Aug 2025
Abstract
Asphalt plant reclaimed powder is a common solid waste in road engineering. Reusing reclaimed powder as filler holds significant importance for environmental protection and resource conservation. The key factors affecting the feasibility of reclaimed powder reuse are its acidity/alkalinity and cleanliness. Traditional evaluation [...] Read more.
Asphalt plant reclaimed powder is a common solid waste in road engineering. Reusing reclaimed powder as filler holds significant importance for environmental protection and resource conservation. The key factors affecting the feasibility of reclaimed powder reuse are its acidity/alkalinity and cleanliness. Traditional evaluation methods, such as the methylene blue test and plasticity index, can assess reclaimed powder properties to guide its recycling. However, these methods suffer from inefficiency, strong empirical dependence, and high variability. To address these limitations, this study proposes a rapid and precise evaluation method for reclaimed powder properties based on Fourier transform infrared spectroscopy (FTIR). To do so, five field-collected reclaimed powder samples and four artificial samples were evaluated. Scanning electron microscopy (SEM), X-ray fluorescence spectroscopy (XRF), and X-ray diffraction (XRD) were employed to characterize their microphase morphology, chemical composition, and crystal structure, respectively. Subsequently, FTIR was used to establish correlations between key acidity/alkalinity, cleanliness, and multiple characteristic peak intensities. Representative infrared characteristic peaks were selected, and a quantitative functional group index (Is) was proposed to simultaneously evaluate acidity/alkalinity and cleanliness. The results indicate that reclaimed powder primarily consists of tiny, crushed stone particles and dust, with significant variations in crystal structure and chemical composition, including calcium carbonate, silicon oxide, iron oxide, and aluminum oxide. Some samples also contained clay, which critically influenced the reclaimed powder properties. Since both filler acidity/alkalinity and cleanliness are affected by clay (silicon/carbon ratio determining acidity/alkalinity and aluminosilicate content affecting cleanliness), this study calculated four functional group indices based on FTIR absorption peaks, namely the Si-O-Si stretching vibration (1000 cm−1) and the CO32− asymmetric stretching vibration (1400 cm−1). These indices were correlated with conventional testing results (XRF for acidity/alkalinity, methylene blue value, and pull-off strength for cleanliness). The results show that the Is index exhibited strong correlations (R2 = 0.89 with XRF, R2 = 0.80 with methylene blue value, and R2 = 0.96 with pull-off strength), demonstrating its effectiveness in predicting both acidity/alkalinity and cleanliness. The developed method enhances reclaimed powder detection efficiency and facilitates high-value recycling in road engineering applications. Full article
(This article belongs to the Special Issue Innovative Approaches in Asphalt Binder Modification and Performance)
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24 pages, 5000 KiB  
Article
A Study of Methylene Blue Adsorption by a Synergistic Adsorbent Algae (Nostoc sphaericum)/Activated Clay
by Yakov Felipe Carhuarupay-Molleda, Noemí Melisa Ccasa Barboza, Sofía Pastor-Mina, Carlos Eduardo Dueñas Valcarcel, Ybar G. Palomino-Malpartida, Rolando Licapa Redolfo, Antonieta Mojo-Quisani, Miriam Calla-Florez, Rolando F. Aguilar-Salazar, Yovana Flores-Ccorisapra, Arturo Rojas Benites, Edward Arostegui León, David Choque-Quispe and Frida E. Fuentes Bernedo
Polymers 2025, 17(15), 2134; https://doi.org/10.3390/polym17152134 - 4 Aug 2025
Abstract
Dye residues from the textile industry constitute a critical wastewater problem. This study aimed to evaluate the removal capacity of methylene blue (MB) in aqueous media, using an adsorbent formulated from activated and sonicated nanoclay (NC) and microatomized Nostoc sphaericum (ANS). NC was [...] Read more.
Dye residues from the textile industry constitute a critical wastewater problem. This study aimed to evaluate the removal capacity of methylene blue (MB) in aqueous media, using an adsorbent formulated from activated and sonicated nanoclay (NC) and microatomized Nostoc sphaericum (ANS). NC was obtained by acid treatment, followed by activation with 1 M NaCl and sonication, while ANS was obtained by microatomization in an aqueous medium. NC/ANS was mixed in a 4:1 weight ratio. The NC/ANS synergistic adsorbent was characterized by the point of zero charge (PZC), zeta potential (ζ), particle size, FTIR spectroscopy, and scanning electron microscopy (SEM). NC/ANS exhibited good colloidal stability, as determined by pHPZC, particle size in the nanometer range, and heterogeneous morphology with functional groups (hydroxyl, carboxyl, and amide), removing between 72.59 and 97.98% from an initial concentration of 10 ppm of MB, for doses of 20 to 30 mg/L of NC/ANS and pH of 5 to 8. Optimal adsorption conditions are achieved at pH 6.8 and 32.9 mg/L of adsorbent NC/ANS. It was observed that the pseudo-first-order (PFO) and pseudo-second-order (PSO) kinetic models best described the adsorption kinetics, indicating a predominance of the physisorption process, with adsorption capacity around 20 mg/g. Isotherm models and thermodynamic parameters of adsorption, ΔS, ΔH, and ΔG, revealed that the adsorption process is spontaneous, favorable, thermodynamically stable, and occurs at the monolayer level, with a regeneration capacity of 90.35 to 37.54% at the fifth cycle. The application of physical activation methods, such as sonication of the clay and microatomization of the algae, allows proposing a novel and alternative synergistic material from organic and inorganic sources that is environmentally friendly and promotes sustainability, with a high capacity to remove cationic dyes in wastewater. Full article
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14 pages, 6988 KiB  
Article
Effect of Substrate Temperature on the Structural, Morphological, and Infrared Optical Properties of KBr Thin Films
by Teng Xu, Qingyuan Cai, Weibo Duan, Kaixuan Wang, Bojie Jia, Haihan Luo and Dingquan Liu
Materials 2025, 18(15), 3644; https://doi.org/10.3390/ma18153644 - 3 Aug 2025
Viewed by 96
Abstract
Potassium bromide (KBr) thin films were deposited by resistive thermal evaporation at substrate temperatures ranging from 50 °C to 250 °C to systematically elucidate the temperature-dependent evolution of their physical properties. Structural, morphological, and optical characteristics were examined by X-ray diffraction (XRD), scanning [...] Read more.
Potassium bromide (KBr) thin films were deposited by resistive thermal evaporation at substrate temperatures ranging from 50 °C to 250 °C to systematically elucidate the temperature-dependent evolution of their physical properties. Structural, morphological, and optical characteristics were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and Fourier transform infrared spectroscopy (FTIR). The results reveal a complex, non-monotonic response to temperature rather than a simple linear trend. As the substrate temperature increases, growth evolves from a mixed polycrystalline texture to a pronounced (200) preferred orientation. Morphological analysis shows that the film surface is smoothest at 150 °C, while the microstructure becomes densest at 200 °C. These structural variations directly modulate the optical constants: the refractive index attains its highest values in the 150–200 °C window, approaching that of bulk KBr. Cryogenic temperature (6 K) FTIR measurements further demonstrate that suppression of multi-phonon absorption markedly enhances the infrared transmittance of the films. Taken together, the data indicate that 150–200 °C constitutes an optimal process window for fabricating KBr films that combine superior crystallinity, low defect density, and high packing density. This study elucidates the temperature-driven structure–property coupling and offers valuable guidance for optimizing high-performance infrared and cryogenic optical components. Full article
(This article belongs to the Special Issue Obtaining and Characterization of New Materials (5th Edition))
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22 pages, 3797 KiB  
Article
Amygdalin-Doped Biopolymer Composites as Potential Wound Dressing Films: In Vitro Study on E. coli and S. aureus
by Dorinel Okolišan, Gabriela Vlase, Mihaela Maria Budiul, Mariana Adina Matica and Titus Vlase
Gels 2025, 11(8), 609; https://doi.org/10.3390/gels11080609 - 2 Aug 2025
Viewed by 403
Abstract
Biopolymer films doped with active substances may become a promising alternative to traditional dressings for skin wounds, as they can deliver drugs while maintaining wound moisture, thus contributing to the healing process. This article describes the preparation of amygdalin-doped biopolymer films for in [...] Read more.
Biopolymer films doped with active substances may become a promising alternative to traditional dressings for skin wounds, as they can deliver drugs while maintaining wound moisture, thus contributing to the healing process. This article describes the preparation of amygdalin-doped biopolymer films for in vitro testing against the bacterial strains typical of chronic wounds: E. coli and S. aureus. Thus, FTIR characterization suggests minimal chemical interaction between amygdalin and the biopolymer matrix components, indicating potential compatibility, while thermogravimetric analysis highlights the thermal behavior of the films as well as the influence of the polymer matrix composition on the amount of bound water and the shift of Tpeak value for the decomposition process of the base polymer. Moreover, the identity of the secondary biopolymer (gelatin or CMC) significantly influences film morphology and antibacterial performance. Full article
(This article belongs to the Special Issue Novel Functional Gels for Biomedical Applications (2nd Edition))
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18 pages, 2092 KiB  
Article
Predicting Adsorption Performance Based on the Properties of Activated Carbon: A Case Study of Shenqi Fuzheng System
by Zhilong Tang, Bo Chen, Wenhua Huang, Xuehua Liu, Xinyu Wang and Xingchu Gong
Chemosensors 2025, 13(8), 279; https://doi.org/10.3390/chemosensors13080279 - 1 Aug 2025
Viewed by 99
Abstract
This work aims to solve the problem of product quality fluctuations caused by batch-to-batch variations in the adsorption capacity of activated carbon during the production of traditional Chinese medicine (TCM) injections. In this work, Shenqi Fuzheng injection was selected as an example. Diluted [...] Read more.
This work aims to solve the problem of product quality fluctuations caused by batch-to-batch variations in the adsorption capacity of activated carbon during the production of traditional Chinese medicine (TCM) injections. In this work, Shenqi Fuzheng injection was selected as an example. Diluted Shenqi Extract (DSE), an intermediate in the production process of Shenqi Fuzheng injection, was adsorbed with different batches of activated carbon. The adsorption capacities of adenine, adenosine, calycosin-7-glucoside, and astragaloside IV in DSE were selected as evaluation indices for activated carbon absorption. Characterization methods such as nitrogen adsorption, X-ray photoelectron spectrum (XPS), and Fourier transform infrared (FTIR) were chosen to explore the quantitative relationships between the properties of activated carbon (i.e., specific surface area, pore volume, surface elements, and spectrum) and the adsorption capacities of these four components. It was found that the characteristic wavelengths from FTIR characterization, i.e., 1560 cm−1, 2325 cm−1, 3050 cm−1, and 3442 cm−1, etc., showed the strongest correlation with the adsorption capacities of these four components. Prediction models based on the transmittance at characteristic wavelengths were successfully established via multiple linear regression. In validation experiments of models, the relative errors of predicted adsorption capacities of activated carbon were mostly within 5%, indicating good predictive ability of the models. The results of this work suggest that the prediction method of adsorption capacity based on the mid-infrared spectrum can provide a new way for the quality control of activated carbon. Full article
(This article belongs to the Section Analytical Methods, Instrumentation and Miniaturization)
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18 pages, 1621 KiB  
Article
The Evaluation of Cellulose from Agricultural Waste as a Polymer for the Controlled Release of Ibuprofen Through the Formulation of Multilayer Tablets
by David Sango-Parco, Lizbeth Zamora-Mendoza, Yuliana Valdiviezo-Cuenca, Camilo Zamora-Ledezma, Si Amar Dahoumane, Floralba López and Frank Alexis
Bioengineering 2025, 12(8), 838; https://doi.org/10.3390/bioengineering12080838 (registering DOI) - 1 Aug 2025
Viewed by 241
Abstract
This research demonstrates the potential of plant waste cellulose as a remarkable biomaterial for multilayer tablet formulation. Rice husks (RC) and orange peels (OC) were used as cellulose sources and characterized for a comparison with commercial cellulose. The FTIR characterization shows minimal differences [...] Read more.
This research demonstrates the potential of plant waste cellulose as a remarkable biomaterial for multilayer tablet formulation. Rice husks (RC) and orange peels (OC) were used as cellulose sources and characterized for a comparison with commercial cellulose. The FTIR characterization shows minimal differences in their chemical components, making them equivalent for compression into tablets containing ibuprofen. TGA measurements indicate that the RC is slightly better for multilayer formulations due to its favorable degradation profile. This is corroborated by an XRD analysis that reveals its higher crystalline fraction (~55%). The use of a heat press at combined high pressures and temperatures allows the layer-by-layer tablet formulation of ibuprofen, taken as a model drug. Additionally, this study compares the release profile of three types of tablets compressed with cellulose: mixed (MIX), two-layer (BL), and three-layer (TL). The MIX tablet shows a profile like that of conventional ibuprofen tablets. Although both BL and TL tablets significantly reduce their release percentage in the first hours, the TL ones have proven to be better in the long run. In fact, formulations made of extracted cellulose sandwiching ibuprofen display a zero-order release profile and prolonged release since the drug release amounts to ~70% after 120 h. This makes the TL formulations ideal for maintaining the therapeutic effect of the drug and improving patients’ wellbeing and compliance while reducing adverse effects. Full article
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22 pages, 5123 KiB  
Article
Tailored Effects of Plasma-Activated Water on Hair Structure Through Comparative Analysis of Nitrate-Rich and Peroxide-Rich Formulations Across Different Hair Types
by Antonia de Souza Leal, Michaela Shiotani Marcondes, Ariane Leite, Douglas Leite, Clodomiro Alves Junior, Laurita dos Santos and Rodrigo Pessoa
Appl. Sci. 2025, 15(15), 8573; https://doi.org/10.3390/app15158573 (registering DOI) - 1 Aug 2025
Viewed by 181
Abstract
Plasma-activated water (PAW), enriched with reactive oxygen and nitrogen species (RONS), presents oxidative and antimicrobial characteristics with potential in cosmetic applications. This study examined the effects of two PAW formulations—nitrate-rich (PAW-N) and peroxide-rich (PAW-P)—on human hair types classified as straight (Type 1), wavy [...] Read more.
Plasma-activated water (PAW), enriched with reactive oxygen and nitrogen species (RONS), presents oxidative and antimicrobial characteristics with potential in cosmetic applications. This study examined the effects of two PAW formulations—nitrate-rich (PAW-N) and peroxide-rich (PAW-P)—on human hair types classified as straight (Type 1), wavy (Type 2), and coily/kinky (Type 4). The impact of PAW on hair structure and chemistry was evaluated using Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), UV–Vis spectrophotometry, and physicochemical analyses of the liquids (pH, ORP, conductivity, and TDS). PAW-N, with high nitrate content (~500 mg/L), low pH (2.15), and elevated conductivity (6244 µS/cm), induced significant damage to porous hair types, including disulfide bond cleavage, protein oxidation, and lipid degradation, as indicated by FTIR and EDS data. SEM confirmed severe cuticle disruption. In contrast, PAW-P, containing >25 mg/L of hydrogen peroxide and exhibiting milder acidity and lower ionic strength, caused more localized and controlled oxidation with minimal morphological damage. Straight hair showed greater resistance to both treatments, while coily and wavy hair were more susceptible, particularly to PAW-N. These findings suggest that the formulation and ionic profile of PAW should be matched to hair porosity for safe oxidative treatments, supporting the use of PAW-P as a gentler alternative in hair care technologies. Full article
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18 pages, 2714 KiB  
Article
Assessing the Efficacy of Chemical and Green-Synthesized CuO Nanoparticles in Combatting Clinical Candida Species: A Comparative Study
by Hiba Younis Khalaf, Ferid Ben Nasr, Bashar Sadeq Noomi, Sami Mnif and Sami Aifa
Microbiol. Res. 2025, 16(8), 178; https://doi.org/10.3390/microbiolres16080178 - 1 Aug 2025
Viewed by 94
Abstract
The most prevalent growth of Candida cells is based on biofilm development, which causes the intensification of antifungal resistance against a large range of chemicals. Nanoparticles can be synthesized using green methods via various biological extracts and reducing agents to control Candida biofilms. [...] Read more.
The most prevalent growth of Candida cells is based on biofilm development, which causes the intensification of antifungal resistance against a large range of chemicals. Nanoparticles can be synthesized using green methods via various biological extracts and reducing agents to control Candida biofilms. This study aims to compare copper oxide nanoparticles (CuONPs) synthesized through chemical methods and those synthesized using Cinnamomum verum-based green methods against Candida infections and their biofilms isolated from Iraqi patients, with the potential to improve treatment outcomes. The physical and chemical properties of these nanoparticles were characterized using Fourier-transform infrared spectroscopy (FT-IR,) scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM) and X-ray diffraction (XRD). Four strains of Candida were isolated and characterized from Iraqi patients in Tikrit Hospital and selected based on their ability to form biofilm on polystyrene microplates. The activity of green-synthesized CuONPs using cinnamon extract was compared with both undoped and doped (Fe, Sn) chemically synthesized CuONPs. Four pathogenic Candida strains (Candida glabrata, Candida lusitaniae, Candida albicans, and Candida tropicalis) were isolated from Iraqi patients, demonstrating high biofilm formation capabilities. Chemically and green-synthesized CuONPs from Cinnamomum verum showed comparable significant antiplanktonic and antibiofilm activities against all strains. Doped CuONPs with iron or tin demonstrated lower minimum inhibitory concentration (MIC) values, indicating stronger antibacterial activity, but exhibited weaker anti-adhesive properties compared to other nanoparticles. The antiadhesive activity revealed that C. albicans strain seems to produce the most resistant biofilms while C. glabrata strain seems to be more resistant towards the doped CuONPs. Moreover, C. tropicalis was the most sensitive to all the CuONPs. Remarkably, at a concentration of 100 µg/mL, all CuONPs were effective in eradicating preformed biofilms by 47–66%. The findings suggest that CuONPs could be effective in controlling biofilm formation by Candida species resistant to treatment in healthcare settings. Full article
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25 pages, 2451 KiB  
Article
Complexation and Thermal Stabilization of Protein–Polyelectrolyte Systems via Experiments and Molecular Simulations: The Poly(acrylic acid)/Lysozyme Case
by Sokratis N. Tegopoulos, Sisem Ektirici, Vagelis Harmandaris, Apostolos Kyritsis, Anastassia N. Rissanou and Aristeidis Papagiannopoulos
Polymers 2025, 17(15), 2125; https://doi.org/10.3390/polym17152125 - 1 Aug 2025
Viewed by 252
Abstract
Protein–polyelectrolyte nanostructures assembled via electrostatic interactions offer versatile applications in biomedicine, tissue engineering, and food science. However, several open questions remain regarding their intermolecular interactions and the influence of external conditions—such as temperature and pH—on their assembly, stability, and responsiveness. This study explores [...] Read more.
Protein–polyelectrolyte nanostructures assembled via electrostatic interactions offer versatile applications in biomedicine, tissue engineering, and food science. However, several open questions remain regarding their intermolecular interactions and the influence of external conditions—such as temperature and pH—on their assembly, stability, and responsiveness. This study explores the formation and stability of networks between poly(acrylic acid) (PAA) and lysozyme (LYZ) at the nanoscale upon thermal treatment, using a combination of experimental and simulation measures. Experimental techniques of static and dynamic light scattering (SLS and DLS), Fourier transform infrared spectroscopy (FTIR), and circular dichroism (CD) are combined with all-atom molecular dynamics simulations. Model systems consisting of multiple PAA and LYZ molecules explore collective assembly and complexation in aqueous solution. Experimental results indicate that electrostatic complexation occurs between PAA and LYZ at pH values below LYZ’s isoelectric point. This leads to the formation of nanoparticles (NPs) with radii ranging from 100 to 200 nm, most pronounced at a PAA/LYZ mass ratio of 0.1. These complexes disassemble at pH 12, where both LYZ and PAA are negatively charged. However, when complexes are thermally treated (TT), they remain stable, which is consistent with earlier findings. Atomistic simulations demonstrate that thermal treatment induces partially reversible structural changes, revealing key microscopic features involved in the stabilization of the formed network. Although electrostatic interactions dominate under all pH and temperature conditions, thermally induced conformational changes reorganize the binding pattern, resulting in an increased number of contacts between LYZ and PAA upon thermal treatment. The altered hydration associated with conformational rearrangements emerges as a key contributor to the stability of the thermally treated complexes, particularly under conditions of strong electrostatic repulsion at pH 12. Moreover, enhanced polymer chain associations within the network are observed, which play a crucial role in complex stabilization. These insights contribute to the rational design of protein–polyelectrolyte materials, revealing the origins of association under thermally induced structural rearrangements. Full article
(This article belongs to the Section Polymer Physics and Theory)
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16 pages, 1365 KiB  
Article
Immobilization of Cd Through Biosorption by Bacillus altitudinis C10-4 and Remediation of Cd-Contaminated Soil
by Tianyu Gao, Chenlu Zhang, Xueqiang Hu, Tianqi Wang, Zhitang Lyu and Lei Sun
Microorganisms 2025, 13(8), 1798; https://doi.org/10.3390/microorganisms13081798 - 1 Aug 2025
Viewed by 139
Abstract
In this study, a highly cadmium (II)-resistant bacterium strain, C10-4, identified as Bacillus altitudinis, was isolated from a sediment sample collected from Baiyangdian Lake, China. The minimum inhibitory concentration (MIC) of Cd(II) for strain C10-4 was 1600 mg/L. Factors such as the [...] Read more.
In this study, a highly cadmium (II)-resistant bacterium strain, C10-4, identified as Bacillus altitudinis, was isolated from a sediment sample collected from Baiyangdian Lake, China. The minimum inhibitory concentration (MIC) of Cd(II) for strain C10-4 was 1600 mg/L. Factors such as the contact time, pH, Cd(II) concentration, and biomass dosage affected the adsorption of Cd(II) by strain C10-4. The adsorption process fit well to the Langmuir adsorption isotherm model and the pseudo-second-order kinetics model, based on the Cd(II) adsorption data obtained from the cells of strain C10-4. This suggests that Cd(II) is adsorbed by strain C10-4 cells via a single-layer homogeneous chemical adsorption process. According to the Langmuir model, the maximum biosorption capacity was 3.31 mg/g for fresh-strain C10-4 biomass. Cd(II) was shown to adhere to the bacterial cell wall through SEM-EDS analysis. FTIR spectroscopy further indicated that the main functional sites for the binding of Cd(II) ions on the cell surface of strain C10-4 were functional groups such as N-H, -OH, -CH-, C=O, C-O, P=O, sulfate, and phosphate. After the inoculation of strain C10-4 into Cd(II)-contaminated soils, there was a significant reduction (p < 0.01) in the exchangeable fraction of Cd and an increase (p < 0.01) in the sum of the reducible, oxidizable, and residual fractions of Cd. The results show that Bacillus altitudinis C10-4 has good potential for use in the remediation of Cd(II)-contaminated soils. Full article
(This article belongs to the Section Environmental Microbiology)
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14 pages, 3007 KiB  
Article
Bone-like Carbonated Apatite Titanium Anodization Coatings Produced in Citrus sinensis-Based Electrolytes
by Amisha Parekh, Amol V. Janorkar and Michael D. Roach
Appl. Sci. 2025, 15(15), 8548; https://doi.org/10.3390/app15158548 (registering DOI) - 31 Jul 2025
Viewed by 159
Abstract
Enhancing osseointegration is a common goal for many titanium implant coatings, since the naturally forming oxides are often bioinert and exhibit less than ideal bone-to-implant contact. Oxide coating surface topographies, chemistries, and crystallinities are known to play key roles in enhancing bone–implant interactions. [...] Read more.
Enhancing osseointegration is a common goal for many titanium implant coatings, since the naturally forming oxides are often bioinert and exhibit less than ideal bone-to-implant contact. Oxide coating surface topographies, chemistries, and crystallinities are known to play key roles in enhancing bone–implant interactions. In the present study, two novel anodization processes were developed in electrolytes based on juiced navel oranges to create bioactive oxide coatings on commercially pure titanium (CPTi) surfaces. Both oxide groups revealed multi-scaled micro and nano surface topographies, significant Ca and P-dopant incorporation exhibiting Ca/P ratios similar to human bone (1.7 and 1.8), and physiologically relevant Mg uptake levels of <0.1% and 1.4 at%. XRD and FTIR analyses of each oxide revealed a combination of tricalcium phosphate and hydroxyapatite phases that showed carbonate substitutions indicative of bone-like apatite formation. Finally, VDI indentation testing revealed good adhesion strengths, minimal cracking, and no visible delamination for both oxides. In summary, the anodization processes in the present study were shown to produce carbonated tricalcium phosphate and apatite containing oxides with contrasting levels of Mg uptake that show much promise to improve future implant clinical outcomes. Full article
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21 pages, 5017 KiB  
Article
Effects of Phase Structure Regulation on Properties of Hydroxyl-Terminated Polyphenylpropylsiloxane-Modified Epoxy Resin
by Yundong Ji, Jun Pan, Chengxin Xu and Dongfeng Cao
Polymers 2025, 17(15), 2099; https://doi.org/10.3390/polym17152099 - 30 Jul 2025
Viewed by 191
Abstract
4,4’-Methylenebis(N,N-diglycidylaniline) (AG80), as a high-performance thermosetting material, holds significant application value due to the enhancement of its strength, toughness, and thermal stability. However, conventional toughening methods often lead to a decrease in material strength, limiting their application. Modification of AG80 epoxy resin was [...] Read more.
4,4’-Methylenebis(N,N-diglycidylaniline) (AG80), as a high-performance thermosetting material, holds significant application value due to the enhancement of its strength, toughness, and thermal stability. However, conventional toughening methods often lead to a decrease in material strength, limiting their application. Modification of AG80 epoxy resin was performed using hydroxy-terminated polyphenylpropylsiloxane (Z-6018) and a self-synthesized epoxy compatibilizer (P/E30) to regulate the phase structure of the modified resin, achieving a synergistic enhancement in both strength and toughness. The modified resin was characterized by Fourier transform infrared analysis (FTIR), proton nuclear magnetic resonance (1H NMR) spectroscopy, silicon-29 nuclear magnetic resonance (29Si NMR) spectroscopy, and epoxy value titration. It was found that the phase structure of the modified resin significantly affects mechanical properties. Thus, P/E30 was introduced to regulate the phase structure, achieving enhanced toughness and strength. At 20 wt.% P/E30 addition, the tensile strength, impact strength, and fracture toughness increased by 50.89%, 454.79%, and 152.43%, respectively, compared to AG80. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses indicate that P/E30 regulates the silicon-rich spherical phase and interfacial compatibility, establishing a bicontinuous structure within the spherical phase, which is crucial for excellent mechanical properties. Additionally, the introduction of Z-6018 enhances the thermal stability of the resin. Full article
(This article belongs to the Section Polymer Analysis and Characterization)
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