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21 pages, 3648 KiB  
Article
Preparation and Physicochemical Evaluation of Ionically Cross-Linked Chitosan Nanoparticles Intended for Agricultural Use
by Maria Karayianni, Emi Haladjova, Stanislav Rangelov and Stergios Pispas
Polysaccharides 2025, 6(3), 67; https://doi.org/10.3390/polysaccharides6030067 (registering DOI) - 1 Aug 2025
Abstract
The search for sustainable, economically viable, and effective plant protection strategies against pathogenic bacteria, fungi, and viruses is a major challenge in modern agricultural practices. Chitosan (CS) is an abundant cationic natural biopolymer known for its biocompatibility, low toxicity, and antimicrobial properties. Its [...] Read more.
The search for sustainable, economically viable, and effective plant protection strategies against pathogenic bacteria, fungi, and viruses is a major challenge in modern agricultural practices. Chitosan (CS) is an abundant cationic natural biopolymer known for its biocompatibility, low toxicity, and antimicrobial properties. Its potential use in agriculture for pathogen control is a promising alternative to traditional chemical fertilisers and pesticides, which raise concerns regarding public health, environmental protection, and pesticide resistance. This study focused on the preparation of chitosan nanoparticles (CS-NPs) through cross-linking with organic molecules, such as tannic acid (TA). Various formulations were explored for the development of stable nanoscale particles having encapsulation capabilities towards low compounds of varying polarity and with potential agricultural applications relevant to plant health and growth. The solution properties of the NPs were assessed using dynamic and electrophoretic light scattering (DLS and ELS); their morphology was observed through atomic force microscopy (AFM), while analytical ultracentrifugation (AUC) measurements provided insights into their molar mass. Their properties proved to be primarily influenced by the concentration of CS, which significantly affected its intrinsic conformation. Additional structural insights were obtained via infrared and UV–Vis spectroscopic measurements, while detailed fluorescence analysis with the use of three different probes, as model cargo molecules, provided information regarding the hydrophobic and hydrophilic microdomains within the particles. Full article
(This article belongs to the Collection Bioactive Polysaccharides)
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25 pages, 1473 KiB  
Review
Environmental Hazards and Glial Brain Tumors: Association or Causation?
by Robert P. Ostrowski, Albert Acewicz, Zhaohui He, Emanuela B. Pucko and Jakub Godlewski
Int. J. Mol. Sci. 2025, 26(15), 7425; https://doi.org/10.3390/ijms26157425 (registering DOI) - 1 Aug 2025
Abstract
Progress in establishing environmental risk factors and, consequently, prophylactic measures for glial tumors, particularly for glioblastomas, is of utmost importance, considering the dismal prognosis and limited treatment options. This report surveyed updates on established and recently identified factors that can predispose a patient [...] Read more.
Progress in establishing environmental risk factors and, consequently, prophylactic measures for glial tumors, particularly for glioblastomas, is of utmost importance, considering the dismal prognosis and limited treatment options. This report surveyed updates on established and recently identified factors that can predispose a patient to glioma formation while highlighting possible mechanistic links and further research directions. In addition to established factors that increase the risk of glioma, i.e., brain irradiation and several genetic syndromes, another group consists of likely factors contributing to such risks, such as the use of tobacco and those yielding ambiguous results (e.g., UV exposure). Oxidative stress is a common denominator for several types of exposure, and a mechanistic background for other factors remains elusive. Nevertheless, the analysis of clinical and basic research strongly suggests that, apart from the effect of environmental stressors on DNA alterations and mutation burden, the impact of modifying the tumor microenvironment should be considered. Identifying the involvement of environmental hazards in gliomagenesis and glial tumor progression would lower overall risk by modifying clinical practice, patient management, and lifestyle choices. Further verifying the environmental hazards in glioma formation and progression would have far-reaching implications for neurologists, neurosurgeons, and patients. Full article
(This article belongs to the Special Issue Latest Review Papers in Molecular Neurobiology 2025)
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20 pages, 4765 KiB  
Article
Ultrasonic EDM for External Cylindrical Surface Machining with Graphite Electrodes: Horn Design and Hybrid NSGA-II–AHP Optimization of MRR and Ra
by Van-Thanh Dinh, Thu-Quy Le, Duc-Binh Vu, Ngoc-Pi Vu and Tat-Loi Mai
Machines 2025, 13(8), 675; https://doi.org/10.3390/machines13080675 (registering DOI) - 1 Aug 2025
Abstract
This study presents the first investigation into the application of ultrasonic vibration-assisted electrical discharge machining (UV-EDM) using graphite electrodes for external cylindrical surface machining—an essential surface in the production of tablet punches and sheet metal-forming dies. A custom ultrasonic horn was designed and [...] Read more.
This study presents the first investigation into the application of ultrasonic vibration-assisted electrical discharge machining (UV-EDM) using graphite electrodes for external cylindrical surface machining—an essential surface in the production of tablet punches and sheet metal-forming dies. A custom ultrasonic horn was designed and fabricated using 90CrSi material to operate effectively at a resonant frequency of 20 kHz, ensuring stable vibration transmission throughout the machining process. A Box–Behnken experimental design was employed to explore the effects of five process parameters—vibration amplitude (A), pulse-on time (Ton), pulse-off time (Toff), discharge current (Ip), and servo voltage (SV)—on two key performance indicators: material removal rate (MRR) and surface roughness (Ra). The optimization process was conducted in two stages: single-objective analysis to maximize MRR while ensuring Ra < 4 µm, followed by a hybrid multi-objective approach combining NSGA-II and the Analytic Hierarchy Process (AHP). The optimal solution achieved a high MRR of 9.28 g/h while maintaining Ra below the critical surface finish threshold, thus meeting the practical requirements for punch surface quality. The findings confirm the effectiveness of the proposed horn design and hybrid optimization strategy, offering a new direction for enhancing productivity and surface integrity in cylindrical EDM applications using graphite electrodes. Full article
(This article belongs to the Section Advanced Manufacturing)
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24 pages, 7997 KiB  
Article
Comparative Analysis of Habitat Expansion Mechanisms for Four Invasive Amaranthaceae Plants Under Current and Future Climates Using MaxEnt
by Mao Lin, Xingzhuang Ye, Zixin Zhao, Shipin Chen and Bao Liu
Plants 2025, 14(15), 2363; https://doi.org/10.3390/plants14152363 (registering DOI) - 1 Aug 2025
Abstract
As China’s first systematic assessment of high-risk Amaranthaceae invaders, this study addresses a critical knowledge gap identified in the National Invasive Species Inventory, in which four invasive Amaranthaceae species (Dysphania ambrosioides, Celosia argentea, Amaranthus palmeri, and Amaranthus spinosus) [...] Read more.
As China’s first systematic assessment of high-risk Amaranthaceae invaders, this study addresses a critical knowledge gap identified in the National Invasive Species Inventory, in which four invasive Amaranthaceae species (Dysphania ambrosioides, Celosia argentea, Amaranthus palmeri, and Amaranthus spinosus) are prioritized due to CNY 2.6 billion annual ecosystem damages in China. By coupling multi-species comparative analysis with a parameter-optimized Maximum Entropy (MaxEnt) model integrating climate, soil, and topographical variables in China under Shared Socioeconomic Pathways (SSP) 126/245/585 scenarios, we reveal divergent expansion mechanisms (e.g., 247 km faster northward shift in A. palmeri than D. ambrosioides) that redefine invasion corridors in the North China Plain. Under current conditions, the suitable habitats of these species span from 92° E to 129° E and 18° N to 49° N, with high-risk zones concentrated in central and southern China, including the Yunnan–Guizhou–Sichuan region and the North China Plain. Temperature variables (Bio: Bioclimatic Variables; Bio6, Bio11) were the primary contributors based on permutation importance (e.g., Bio11 explained 56.4% for C. argentea), while altitude (e.g., 27.3% for A. palmeri) and UV-B (e.g., 16.2% for A. palmeri) exerted lower influence. Model validation confirmed high accuracy (mean area under the curve (AUC) > 0.86 and true skill statistic (TSS) > 0.6). By the 2090s, all species showed net habitat expansion overall, although D. ambrosioides exhibited net total contractions during mid-century under the SSP126/245 scenarios, C. argentea experienced reduced total suitability during the 2050s–2070s despite high-suitability growth, and A. palmeri and A. spinosus expanded significantly in both total and highly suitable habitat. All species shifted their distribution centroids northward, aligning with warming trends. Overall, these findings highlight the critical role of temperature in driving range dynamics and underscore the need for latitude-specific monitoring strategies to mitigate invasion risks, providing a scientific basis for adaptive management under global climate change. Full article
(This article belongs to the Section Plant Ecology)
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26 pages, 3684 KiB  
Article
Creation of Zinc (II)-Complexed Green Tea and Its Effects on Gut Microbiota by Daily Green Tea Consumption
by Tsukasa Orita, Daichi Ijiri, De-Xing Hou and Kozue Sakao
Molecules 2025, 30(15), 3191; https://doi.org/10.3390/molecules30153191 - 30 Jul 2025
Viewed by 6
Abstract
Although Zn (II)-(−)-Epigallocatechin gallate (EGCg) complex (Zn-EGCg) is known for its promising bioactivities, little attention has been paid to its incorporation into daily green tea consumption. In this study, we aimed to incorporate Zn (II) into green tea extract to promote the formation [...] Read more.
Although Zn (II)-(−)-Epigallocatechin gallate (EGCg) complex (Zn-EGCg) is known for its promising bioactivities, little attention has been paid to its incorporation into daily green tea consumption. In this study, we aimed to incorporate Zn (II) into green tea extract to promote the formation of Zn-EGCg complex within the tea matrix. We then investigated how the formation of Zn-complexed green tea extract (Zn-GTE) influences the gut microbiota in a Western diet (WD)-fed mouse model. Structural analyses using ultraviolet–visible spectroscopy (UV–Vis), Fourier-transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (1H NMR), and powder X-ray diffraction (PXRD) suggested that Zn (II) interacted with hydroxyl groups of polyphenols within the extract, consistent with Zn-EGCg formation, although the complex could not be unequivocally identified. Under intake levels equivalent to daily consumption, Zn-GTE administration restored WD-induced reductions in alpha-diversity and resulted in a distinct microbial composition compared to treatment with green tea extract (GTE) or Zn alone, as shown by beta-diversity analysis. Linear discriminant analysis Effect Size (LEfSe) analysis revealed increased abundances of bacterial taxa belonging to o_Clostridiales, o_Bacteroidales, and f_Rikenellaceae, and decreased abundances of g_Akkermansia in the Zn-GTE group compared to the GTE group. These findings highlight that Zn-GTE, prepared via Zn (II) supplementation to green tea, may exert distinct microbiota-modulating effects compared to its individual components. This study provides new insights into the role of dietary metal–polyphenol complexes, offering a food-based platform for studying metal–polyphenol interactions under physiologically relevant conditions. Full article
(This article belongs to the Special Issue Health Benefits and Applications of Bioactive Phenolic Compounds)
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17 pages, 2736 KiB  
Article
Controlled Formation of α- and β-Bi2O3 with Tunable Morphologies for Visible-Light-Driven Photocatalysis
by Thomas Cadenbach, María Isabel Loyola-Plúa, Freddy Quijano Carrasco, Maria J. Benitez, Alexis Debut and Karla Vizuete
Molecules 2025, 30(15), 3190; https://doi.org/10.3390/molecules30153190 - 30 Jul 2025
Viewed by 40
Abstract
Water pollution caused by increasing industrial and human activity remains a serious environmental challenge, especially due to the persistence of organic contaminants in aquatic systems. Photocatalysis offers a promising and eco-friendly solution, but in the case of bismuth oxide (Bi2O3 [...] Read more.
Water pollution caused by increasing industrial and human activity remains a serious environmental challenge, especially due to the persistence of organic contaminants in aquatic systems. Photocatalysis offers a promising and eco-friendly solution, but in the case of bismuth oxide (Bi2O3) there is still a limited understanding of how structural and morphological features influence photocatalytic performance. In this work, a straightforward hydrothermal synthesis method followed by controlled calcination was developed to produce phase-pure α- and β-Bi2O3 with tunable morphologies. By varying the hydrothermal temperature and reaction time, distinct structures were successfully obtained, including flower-like, broccoli-like, and fused morphologies. XRD analyses showed that the final crystal phase depends solely on the calcination temperature, with β-Bi2O3 forming at 350 °C and α-Bi2O3 at 500 °C. SEM and BET analyses confirmed that morphology and surface area are strongly influenced by the hydrothermal conditions, with the flower-like β-Bi2O3 exhibiting the highest surface area. UV–Vis spectroscopy revealed that β-Bi2O3 also has a lower bandgap than its α counterpart, making it more responsive to visible light. Photocatalytic tests using Rhodamine B showed that the flower-like β-Bi2O3 achieved the highest degradation efficiency (81% in 4 h). Kinetic analysis followed pseudo-first-order behavior, and radical scavenging experiments identified hydroxyl radicals, superoxide radicals, and holes as key active species. The catalyst also demonstrated excellent stability and reusability. Additionally, Methyl Orange (MO), a more stable and persistent azo dye, was selected as a second model pollutant. The flower-like β-Bi2O3 catalyst achieved 73% degradation of MO at pH = 7 and complete removal under acidic conditions (pH = 2) in less than 3 h. These findings underscore the importance of both phase and morphology in designing high-performance Bi2O3 photocatalysts for environmental remediation. Full article
(This article belongs to the Special Issue Green Catalysis Technology for Sustainable Energy Conversion)
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15 pages, 3436 KiB  
Article
Mohangic Acid H and Mohangiol: New p-Aminoacetophenone Derivatives from a Mudflat-Derived Streptomyces sp.
by Juwan Son, Ju Heon Lee, Yong-Joon Cho, Kyuho Moon and Munhyung Bae
Mar. Drugs 2025, 23(8), 307; https://doi.org/10.3390/md23080307 - 30 Jul 2025
Viewed by 140
Abstract
Streptomyces sp. AWH31-250, isolated from a tidal mudflat in the Nakdong River estuary in Busan, Republic of Korea, was found to produce two novel p-aminoacetophenone derivatives, mohangic acid H (1) and mohangiol (2). Their planar structures were established [...] Read more.
Streptomyces sp. AWH31-250, isolated from a tidal mudflat in the Nakdong River estuary in Busan, Republic of Korea, was found to produce two novel p-aminoacetophenone derivatives, mohangic acid H (1) and mohangiol (2). Their planar structures were established by comprehensive 1D and 2D NMR spectroscopy, mass spectrometry, and UV analysis, possessing a shorter carbon-chain with a diene moiety, whereas known mohangic acids A–F bear a longer carbon-chain with a triene moiety. The absolute configurations of the key stereogenic centers were determined via computational DP4+ calculations and bioinformatic analysis of the ketoreductase domain sequence from the biosynthetic gene cluster. Based on the careful gene analysis along with whole-genome sequencing, the first plausible biosynthetic pathway of mohangic acids A–G and mohangiol was proposed. Mohangic acid H (1) and mohangiol (2) displayed moderate inhibitory activity against Candida albicans isocitrate lyase with IC50 values of 21.37 and 21.12 µg/mL, respectively. Full article
(This article belongs to the Section Structural Studies on Marine Natural Products)
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12 pages, 2396 KiB  
Article
Helical Airflow Synthesis of Quinoxalines: A Continuous and Efficient Mechanochemical Approach
by Jiawei Zhang, Zeli Xiao, Qi Huang, Yang Zhao, Bo Jin and Rufang Peng
Chemistry 2025, 7(4), 121; https://doi.org/10.3390/chemistry7040121 - 29 Jul 2025
Viewed by 145
Abstract
In this work, we report a novel mechanochemical synthesis method for the synthesis of quinoxaline derivatives—a spiral gas–solid two-phase flow approach, which enables the efficient preparation of quinoxaline compounds. Compared to conventional synthetic methods, this approach eliminates the need for heating or solvents [...] Read more.
In this work, we report a novel mechanochemical synthesis method for the synthesis of quinoxaline derivatives—a spiral gas–solid two-phase flow approach, which enables the efficient preparation of quinoxaline compounds. Compared to conventional synthetic methods, this approach eliminates the need for heating or solvents while significantly reducing reaction time. The structures of the synthesized compounds were characterized using nuclear magnetic resonance (NMR), Fourier-transform infrared spectroscopy (FT-IR), ultraviolet-visible (UV–Vis) absorption spectroscopy, powder X-ray diffraction (XRD), differential scanning calorimetry (DSC), and high-performance liquid chromatography (HPLC). Using the synthesis of 2,3-diphenylquinoxaline (1) as a model reaction, the synthetic process was investigated with UV–Vis spectroscopy. The results demonstrate that when the total feed amount was 2 g with a carrier gas pressure of 0.8 MPa, the reaction completed within 2 min, achieving a yield of 93%. Furthermore, kinetic analysis of the reaction mechanism was performed by monitoring the UV–Vis spectra of the products at different time intervals. The results indicate that the synthesis of 1 follows the A4 kinetic model, which describes a two-dimensional diffusion-controlled product growth process following decelerated nucleation. Full article
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13 pages, 2697 KiB  
Communication
Oxidation-Active Radical TTM-DMODPA for Catalysis-Free Hydrogen Peroxide Colorimetric Sensing
by Qingmei Zhong, Xiaomei Rong, Tingting Wu and Chuan Yan
Biosensors 2025, 15(8), 490; https://doi.org/10.3390/bios15080490 - 29 Jul 2025
Viewed by 203
Abstract
As a crucial reactive oxygen species, hydrogen peroxide (H2O2) serves as both a physiological regulator and a pathological indicator in human systems. Its urinary concentration has emerged as a valuable biomarker for assessing metabolic disorders and renal function. While [...] Read more.
As a crucial reactive oxygen species, hydrogen peroxide (H2O2) serves as both a physiological regulator and a pathological indicator in human systems. Its urinary concentration has emerged as a valuable biomarker for assessing metabolic disorders and renal function. While conventional colorimetric determination methods predominantly employ enzymatic or nanozyme catalysts, we present an innovative non-catalytic approach utilizing the redox-responsive properties of organic neutral radicals. Specifically, we designed and synthesized a novel radical TTM-DMODPA based on the tris (2,4,6-trichlorophenyl) methyl (TTM) scaffold, which exhibits remarkable optical tunability and oxidative sensitivity. This system enables dual-mode H2O2 quantification: (1) UV-vis spectrophotometry (linear range: 2.5–250 μmol/L, LOD: 1.275 μmol/L) and (2) smartphone-based visual analysis (linear range: 2.5–250 μmol/L, LOD: 3.633 μmol/L), the latter being particularly suitable for point-of-care testing. Validation studies using urine samples demonstrated excellent recovery rates (96–104%), confirming the method’s reliability for real-sample applications. Our work establishes a portable, instrument-free platform for urinary H2O2 determination, with significant potential in clinical diagnostics and environmental monitoring. Full article
(This article belongs to the Section Optical and Photonic Biosensors)
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15 pages, 2504 KiB  
Article
The Effect of the Interaction of Intense Low-Energy Radiation with a Zinc-Oxide-Based Material
by Ihor Virt, Piotr Potera, Nazar Barchuk and Mykola Chekailo
Crystals 2025, 15(8), 685; https://doi.org/10.3390/cryst15080685 - 28 Jul 2025
Viewed by 125
Abstract
Laser annealing of oxide functional thin films makes them compatible with substrates of various types, especially flexible materials. The effects of optical annealing on Ni-doped ZnO thin films were the subject of investigation and analysis in this study. Using pulsed laser deposition, we [...] Read more.
Laser annealing of oxide functional thin films makes them compatible with substrates of various types, especially flexible materials. The effects of optical annealing on Ni-doped ZnO thin films were the subject of investigation and analysis in this study. Using pulsed laser deposition, we deposited polycrystalline ZnNiO films on sapphire and silicon substrates. The deposited film was annealed by laser heating. A continuous CO2 laser was used for this purpose. The uniformly distributed long-wavelength radiation of the CO2 laser can penetrate deeper from the surface of the thin film compared to short-wavelength lasers such as UV and IR lasers. After growth, optical post-annealing processes were applied to improve the conductive properties of the films. The crystallinity and surface morphology of the grown films and annealed films were analyzed using SEM, and their electrical parameters were evaluated using van der Pauw effect measurements. We used electrical conductivity measurements and investigated the photovoltaic properties of the ZnNiO film. After CO2 laser annealing, changes in both the crystalline structure and surface appearance of ZnO were evident. Subsequent to laser annealing, the crystallinity of ZnO showed both change and degradation. High-power CO2 laser annealing changed the structure to a mixed grain size. Surface nanostructuring occurred. This was confirmed by SEM morphological studies. After irradiation, the electrical conductivity of the films increased from 0.06 Sm/cm to 0.31 Sm/cm. The lifetime of non-equilibrium charge carriers decreased from 2.0·10−9 s to 1.2·10−9 s. Full article
(This article belongs to the Section Inorganic Crystalline Materials)
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13 pages, 2146 KiB  
Article
Radical TTM-DMODPA for Ascorbic Acid Non-Catalytic Visual Detection
by Qingmei Zhong, Huixiang Zong, Xiaohui Xie, Xiaomei Rong and Chuan Yan
Chemosensors 2025, 13(8), 277; https://doi.org/10.3390/chemosensors13080277 - 27 Jul 2025
Viewed by 208
Abstract
Ascorbic acid (AA) plays a multidimensional role in human physiological and pathological processes, and the detection of its urinary concentration facilitates the diagnosis of metabolic or kidney diseases. Visual detection exhibits minimal reliance on instrumentation and is suitable for on-site analysis in routine [...] Read more.
Ascorbic acid (AA) plays a multidimensional role in human physiological and pathological processes, and the detection of its urinary concentration facilitates the diagnosis of metabolic or kidney diseases. Visual detection exhibits minimal reliance on instrumentation and is suitable for on-site analysis in routine settings. Current visual colorimetric detection methods typically rely on enzymatic or nanozyme-based catalysis. Organic neutral radicals bearing unpaired electrons represent a class of materials exhibiting intrinsic responsiveness to redox stimuli. The tris (2,4,6-trichlorophenyl) methyl (TTM) radical has attracted widespread attention for its adjustable optical properties and sensitive response to external redox stimuli. We synthesized a novel radical TTM-DMODPA and applied it for non-catalytic colorimetric detection of AA. It not only enables quantitative AA measurement via UV-vis spectroscopy (linear range: 1.25–75 μmol/L, LOD: 0.288 μmol/L) but also facilitates instrument-free visual detection using smartphone cameras (linear range: 0–65 μmol/L, LOD: 1.46 μmol/L). This method demonstrated satisfactory performance in the measurement of AA in actual urine samples. Recovery rates ranged from 97.8% to 104.1%. Consequently, this work provides a portable and effective method for assessing AA levels in actual urine samples. Full article
(This article belongs to the Section (Bio)chemical Sensing)
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13 pages, 3429 KiB  
Article
Membrane Fouling Control and Treatment Performance Using Coagulation–Tubular Ceramic Membrane with Concentrate Recycling
by Yawei Xie, Yichen Fang, Dashan Chen, Jiahang Wei, Chengyue Fan, Xiwang Zhu and Hongyuan Liu
Membranes 2025, 15(8), 225; https://doi.org/10.3390/membranes15080225 - 27 Jul 2025
Viewed by 193
Abstract
A comparative study was conducted to investigate membrane fouling control and treatment performance using natural surface water as the feed source. The evaluated processes included: (1) direct filtration–tubular ceramic membrane (DF-TCM, control); (2) coagulation–tubular ceramic membrane (C-TCM); and (3) coagulation–tubular ceramic membrane with [...] Read more.
A comparative study was conducted to investigate membrane fouling control and treatment performance using natural surface water as the feed source. The evaluated processes included: (1) direct filtration–tubular ceramic membrane (DF-TCM, control); (2) coagulation–tubular ceramic membrane (C-TCM); and (3) coagulation–tubular ceramic membrane with concentrate recycling (C-TCM-CR). Experimental results demonstrated that under constant flux operation at 75 L/(m2·h) for 8 h, the C-TCM-CR process reduced the transmembrane pressure (TMP) increase by 83% and 35% compared to DF-TCM and C-TCM, respectively. Floc size distribution analysis and cake layer characterization revealed that the C-TCM-CR process enhanced coagulation efficiency and formed high-porosity cake layers on membrane surfaces, thereby mitigating fouling development. Notably, the coagulation-assisted processes demonstrated improved organic matter removal, with 13%, 10%, and 10% enhancement in CODMn, UV254, and medium molecular weight organics (2000–10,000 Da) removal compared to DF-TCM, along with a moderate enhancement in fluorescent substances removal efficiency. All three processes achieved over 99% turbidity removal efficiency, as the ceramic membranes demonstrate excellent filtration performance. Full article
(This article belongs to the Section Membrane Applications for Water Treatment)
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16 pages, 2045 KiB  
Article
The Antimicrobial Activity of Silver Nanoparticles Biosynthesized Using Cymbopogon citratus Against Multidrug-Resistant Bacteria Isolated from an Intensive Care Unit
by Bianca Picinin Gusso, Aline Rosa Almeida, Michael Ramos Nunes, Daniela Becker, Dachamir Hotza, Cleonice Gonçalves da Rosa, Vanessa Valgas dos Santos and Bruna Fernanda da Silva
Pharmaceuticals 2025, 18(8), 1120; https://doi.org/10.3390/ph18081120 - 27 Jul 2025
Viewed by 277
Abstract
Objective: This study aimed to evaluate the in vitro efficacy of silver nanoparticles (AgNPs) synthesized by bioreduction using lemongrass (Cymbopogon citratus) essential oil against multidrug-resistant (MDR) bacteria isolated from an Intensive Care Unit (ICU). Methods: The essential oil was extracted and [...] Read more.
Objective: This study aimed to evaluate the in vitro efficacy of silver nanoparticles (AgNPs) synthesized by bioreduction using lemongrass (Cymbopogon citratus) essential oil against multidrug-resistant (MDR) bacteria isolated from an Intensive Care Unit (ICU). Methods: The essential oil was extracted and characterized by gas chromatography–mass spectrometry (GC-MS). Antioxidant activity was assessed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay, the 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assay, and total phenolic content. AgNPs (3 mM and 6 mM silver nitrate) were characterized by UV-Vis spectroscopy, dynamic light scattering (DLS), zeta potential, transmission electron microscopy (TEM), and Fourier-transform infrared (FTIR) spectroscopy. Bacterial isolates were obtained from ICU surfaces and personal protective equipment (PPE). Results: The essential oil presented citral A, citral B, and β-myrcene as major components (97.5% of identified compounds). AgNPs at 3 mM showed smaller size (87 nm), lower Polydispersity Index (0.14), and higher colloidal stability (−23 mV). The 6 mM formulation (147 nm; PDI 0.91; −10 mV) was more effective against a strain of Enterococcus spp. resistant to all antibiotics tested. FTIR analysis indicated the presence of O–H, C=O, and C–O groups involved in nanoparticle stabilization. Discussion: The higher antimicrobial efficacy of the 6 mM formulation was attributed to the greater availability of active AgNPs. Conclusions: The green synthesis of AgNPs using C. citratus essential oil proved effective against MDR bacteria and represents a sustainable and promising alternative for microbiological control in healthcare environments. Full article
(This article belongs to the Special Issue Therapeutic Potential of Silver Nanoparticles (AgNPs), 2nd Edition)
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12 pages, 3396 KiB  
Article
The Influence of Precursor pH on the Synthesis and Morphology of AuNPs Synthesized Using Green Tea Leaf Extract
by Oksana Velgosova, Zuzana Mikulková and Maksym Lisnichuk
Crystals 2025, 15(8), 682; https://doi.org/10.3390/cryst15080682 - 26 Jul 2025
Viewed by 169
Abstract
This study investigates the effect of precursor pH (1.3, 2, 4, 6, 8, and 10) on the synthesis of gold nanoparticles (AuNPs) via a green synthesis approach using an aqueous extract of green tea (Camellia sinensis) leaves. The formation of AuNPs [...] Read more.
This study investigates the effect of precursor pH (1.3, 2, 4, 6, 8, and 10) on the synthesis of gold nanoparticles (AuNPs) via a green synthesis approach using an aqueous extract of green tea (Camellia sinensis) leaves. The formation of AuNPs was monitored using UV-vis spectrophotometry and confirmed using transmission electron microscopy (TEM). The results confirmed that the morphology and size of the AuNPs are strongly dependent on the pH of the reaction medium. Based on spectral features, the color of the colloids, and TEM analysis, the synthesized samples were classified into three groups. The first (pH 8 and 10) contained predominantly spherical nanoparticles with an average diameter of ~18 nm, the second (pH 1.3 and 2) contained different shaped nanoparticles (20–250 nm in diameter), and the third (pH 4 and 6) contained flower-like nanostructures with a mean diameter of ~60 nm. UV-vis analysis revealed good stability of all AuNP colloids, except at pH 1.3, where a significant decrease in absorbance intensity over time was observed. These findings confirm that tuning the precursor pH allows for controlled manipulation of nanoparticle morphology and stability in green synthesis systems. Full article
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18 pages, 4008 KiB  
Article
Carboxymethyl Chitosan Cinnamaldehyde Coated SilverNanocomposites for Antifungal Seed Priming in Wheat: A Dual-Action Approach Toward Sustainable Crop Protection
by María Mondéjar-López, María Paz García-Simarro, Lourdes Gómez-Gómez, Oussama Ahrazem and Enrique Niza
Polymers 2025, 17(15), 2031; https://doi.org/10.3390/polym17152031 - 25 Jul 2025
Viewed by 201
Abstract
Biogenic silver nanoparticles (AgNPs) were synthesized via a green chemistry strategy using wheat extract and subsequently functionalized with a carboxymethyl chitosan–cinnamaldehyde (CMC=CIN) conjugate through covalent imine bonding. The resulting nanohybrid (AgNP–CMC=CIN) was extensively characterized to confirm successful biofunctionalization: UV–Vis spectroscopy revealed characteristic cinnamaldehyde [...] Read more.
Biogenic silver nanoparticles (AgNPs) were synthesized via a green chemistry strategy using wheat extract and subsequently functionalized with a carboxymethyl chitosan–cinnamaldehyde (CMC=CIN) conjugate through covalent imine bonding. The resulting nanohybrid (AgNP–CMC=CIN) was extensively characterized to confirm successful biofunctionalization: UV–Vis spectroscopy revealed characteristic cinnamaldehyde absorption peaks; ATR-FTIR spectra confirmed polymer–terpene bonding; and TEM analysis evidenced uniform nanoparticle morphology. Dynamic light scattering (DLS) measurements indicated an increase in hydrodynamic size upon coating (from 59.46 ± 12.63 nm to 110.17 ± 4.74 nm), while maintaining low polydispersity (PDI: 0.29 to 0.27) and stable surface charge (zeta potential ~ −30 mV), suggesting colloidal stability and homogeneous polymer encapsulation. Antifungal activity was evaluated against Fusarium oxysporum, Penicillium citrinum, Aspergillus niger, and Aspergillus brasiliensis. The minimum inhibitory concentration (MIC) against F. oxysporum was significantly reduced to 83 μg/mL with AgNP–CMC=CIN, compared to 708 μg/mL for uncoated AgNPs, and was comparable to the reference fungicide tebuconazole (52 μg/mL). Seed priming with AgNP–CMC=CIN led to improved germination (85%) and markedly reduced fungal colonization, while maintaining a favorable phytotoxicity profile. These findings highlight the potential of polysaccharide-terpene-functionalized biogenic AgNPs as a sustainable alternative to conventional fungicides, supporting their application in precision agriculture and integrated crop protection strategies. Full article
(This article belongs to the Special Issue Polymer Materials for Environmental Applications)
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