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24 pages, 6698 KB

Open AccessArticle

Green Synthesis of Silver Nanoparticles from Melissa officinalis Flower: Evaluation of Antimicrobial, Antioxidant, and Photocatalytic Activity

by Emre Erden Kopar

Molecules 2026, 31(18), 3300; https://doi.org/10.3390/molecules31183300 - 17 Sep 2026

Viewed by 183

Abstract

Silver nanoparticles (AgNPs) synthesized via green approaches have attracted considerable attention because of their eco-friendly production and versatile biological and photocatalytic properties. In this study, Melissa officinalis flower extract was employed as a natural reducing, capping, and stabilizing agent for the green synthesis [...] Read more.

Silver nanoparticles (AgNPs) synthesized via green approaches have attracted considerable attention because of their eco-friendly production and versatile biological and photocatalytic properties. In this study, Melissa officinalis flower extract was employed as a natural reducing, capping, and stabilizing agent for the green synthesis of AgNPs. HPLC-DAD analysis revealed that the flower extract exhibited a diverse phytochemical profile, including phenolic acids and flavonoids, which may contribute to the reduction of Ag⁺ ions and the stabilization of the synthesized AgNPs. The synthesized nanoparticles were characterized using UV–Vis spectroscopy, ATR-FTIR, SEM, DLS, zeta potential analysis, and XRD. The AgNPs exhibited predominantly spherical to hemispherical morphology with an average particle size of 40 nm and a characteristic surface plasmon resonance peak at 414 nm. DLS analysis revealed a particle size of 111.2 nm and a Z-average hydrodynamic diameter of 296.0 nm, while the zeta potential of −73.2 mV suggested high colloidal stability. XRD analysis confirmed the formation of a face-centered cubic (fcc) crystalline structure. The synthesized AgNPs exhibited photocatalytic activity, achieving degradation efficiencies of 93.6 ± 0.3% for methylene blue and 44.8 ± 0.6% for Coomassie Brilliant Blue R-250 after 180 min. In addition, the nanoparticles exhibited considerable antioxidant activity in the DPPH assay and antimicrobial activity against Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, and Candida albicans. Overall, the findings indicate that AgNPs synthesized from M. officinalis flowers via the green synthesis method exhibited photocatalytic, antioxidant, and antimicrobial activities under the experimental conditions studied. These findings suggest that the synthesized AgNPs could be considered a potential material, particularly for dye removal and antimicrobial applications. Full article

(This article belongs to the Special Issue 30th Anniversary of Molecules—Recent Advances in Green Chemistry)

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19 pages, 1496 KB

Open AccessArticle

Solvent-Dependent GC–MS Fingerprinting of Lipophilic Constituents in Syzygium polyanthum Leaves: A Baseline Study for Future Greener Extraction Optimization

by Frangky Jessy Paat and Sanriomi Sintaro

Molecules 2026, 31(11), 1932; https://doi.org/10.3390/molecules31111932 - 3 Jun 2026

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Abstract

Syzygium polyanthum (Wight) Walp., commonly known as Indonesian bay leaf or Daun salam, is widely used as a culinary and traditional botanical resource. However, region-specific information on its lipophilic constituents remains limited, and the sustainability implications of solvent-dependent phytochemical profiling are rarely [...] Read more.

Syzygium polyanthum (Wight) Walp., commonly known as Indonesian bay leaf or Daun salam, is widely used as a culinary and traditional botanical resource. However, region-specific information on its lipophilic constituents remains limited, and the sustainability implications of solvent-dependent phytochemical profiling are rarely addressed. This study characterized the GC–MS-detectable volatile lipophilic constituents of a selected nonpolar fraction of S. polyanthum leaves collected from Paniki Bawah, Mapanget District, Manado, Indonesia, using GC–MS, while evaluating solvent-related limitations for future greener extraction strategies. Dried leaf powder was macerated with 96% ethanol, followed by liquid–liquid partitioning with n-hexane and ethyl acetate. The n-hexane fraction was separated by silica gel column chromatography, and a TLC-selected fraction was analyzed by GC–MS. Compound annotation was supported by NIST 17 library matching, retention-index comparison using a C8–C40 n-alkane series, diagnostic ion evaluation, solvent blank analysis, and triplicate injections. Ethanolic extraction of 900 g dried powder yielded 87.0 g crude extract (9.67%). The n-hexane, ethyl acetate, and aqueous fractions yielded 5.98%, 21.15%, and 72.87%, respectively. GC–MS analysis tentatively annotated 11 compounds representing 94.44% of the total normalized peak area. The major constituents were palmitic acid, phytol, squalene, and neophytadiene. All annotations showed match scores of 90–98%, ΔRI values of 4–8 units, and RSD values of 1.86–3.27%. Although ethanol use, sunlight drying, solvent recovery, and recirculating chiller-assisted evaporation partially aligned with green chemistry principles, the use of n-hexane and chloroform means that the workflow should not be described as fully green. This study provides a baseline GC–MS fingerprint to support future greener extraction optimization. Full article

(This article belongs to the Special Issue 30th Anniversary of Molecules—Recent Advances in Green Chemistry)

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23 pages, 9860 KB

Open AccessArticle

GIS-Based Temporal and Spatial Analysis of Industrial Wastewater Pollution in the Konya Municipal Sewer System

by Süheyla Tongur and Sefa Çetin

Molecules 2026, 31(10), 1738; https://doi.org/10.3390/molecules31101738 - 19 May 2026

Viewed by 459

Abstract

Wastewater containing high pollutant loads is discharged into the municipal sewerage system by industrial facilities operating within the industrial zones of Konya, Türkiye. Although regulations mandate that wastewater be treated to comply with specified discharge standards, some facilities lack pretreatment systems due to [...] Read more.

Wastewater containing high pollutant loads is discharged into the municipal sewerage system by industrial facilities operating within the industrial zones of Konya, Türkiye. Although regulations mandate that wastewater be treated to comply with specified discharge standards, some facilities lack pretreatment systems due to high capital and operational costs, while existing systems experience operational deficiencies. As a consequence, operational disruptions and increased environmental risks occur within the municipal sewerage system. Periodic sampling and inspection activities conducted by municipal authorities are becoming increasingly challenging for effective monitoring and evaluation as the number of facilities increases. In this study, a Geographic Information System (GIS)-based approach was developed to enhance monitoring effectiveness, and industrial wastewater quality data were analyzed using ArcGIS Pro 2.9 software (Esri, Redlands, CA, USA) to generate spatial pollution distribution maps. Samples were collected from five industrial facilities and four sewer junction points located in the Hacıyusufmescit, Emirgazi, and Fetih neighborhoods, where odor problems are frequently reported, during the 2022–2023 period. It was determined that COD (24,960 mg/L), BOD (2970 mg/L), and oil and grease (254 mg/L) concentrations significantly exceeded the regulatory discharge limits, particularly during the summer season. The results demonstrate that GIS-based monitoring systems constitute an effective tool for the early detection of pollution and odor-related problems at the urban scale, for the systematic management of control processes, and for the facilitation of evidence-based decision-making. Full article

(This article belongs to the Special Issue 30th Anniversary of Molecules—Recent Advances in Green Chemistry)

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17 pages, 3057 KB

Open AccessArticle

Identification and Characterization of a Polyethylene-Degrading Fungus Aspergillus sydowii Isolated from Soils of Waste Disposal Sites

by Qingyue Wang, Linlu Wang, Xiaoyu Chen, Aozhuo Wang and Youxi Zhao

Molecules 2026, 31(10), 1557; https://doi.org/10.3390/molecules31101557 - 7 May 2026

Viewed by 758

Abstract

Petrochemical-based plastics are widely used due to their convenience and low cost, with polyethylene (PE) being the most produced globally. However, the lack of efficient and sustainable treatment methods for conventional plastic wastes has led to severe environmental pollution. A new fungus strain [...] Read more.

Petrochemical-based plastics are widely used due to their convenience and low cost, with polyethylene (PE) being the most produced globally. However, the lack of efficient and sustainable treatment methods for conventional plastic wastes has led to severe environmental pollution. A new fungus strain capable of degrading PE was isolated from soil samples collected at a waste disposal site in Henan province and identified as Aspergillus sydowii W144. After 30 days of incubation under solid-state culture conditions, the strain demonstrated significant oxidative depolymerization of low-density polyethylene (LDPE). FTIR results revealed a substantial increase in the carbonyl index of the LDPE film, while differential scanning calorimetry (DSC) analysis detected an enhanced crystallinity in the LDPE film. Notably, distinct pitting and erosion marks were observed on the surface of LDPE film using scanning electron microscopy (SEM). Quantitative analysis showed a weight loss rate of 6.39% and a reduction in Weight-Average Molecular Weight (Mw) by 50.93%. Among currently identified PE-degrading strains polyethylene, A. sydowii W144 exhibits particularly outstanding depolymerization efficiency, especially on untreated PE. Based on the whole-genome data of A. sydowii W144, a preliminary model of the putative polyethylene degradation pathway in A. sydowii W144 was constructed through homology-based sequence analysis and by referencing previously reported polyethylene degradation pathways. Laccase/multicopper oxidase plays a key role in the initial oxidation of PE. Heterologous expression of the candidate gene laccase4 in Pichia pastoris yielded an active enzyme (~56 kDa) with a laccase activity of 460 U/L, confirming its functionality. This study provides a novel microbial resource and potential enzymatic tools for PE biodegradation. The strain exhibits a promising application in complex ecosystems for PE pollution. IMPORTANCE: The polyethylene-degrading strain A. sydowii W144 isolated in this study exhibits highly efficient depolymerization capabilities, particularly under solid-state culture conditions. Genomic sequencing analysis enabled the construction of a potential polyethylene (PE) degradation pathway and facilitated the identification of key laccase and multicopper oxidase genes involved in this process. The isolation of this novel strain enriches the microbial resources available for PE waste treatment and offers new insights into the mechanisms of plastic biodegradation. Full article

(This article belongs to the Special Issue 30th Anniversary of Molecules—Recent Advances in Green Chemistry)

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18 pages, 2772 KB

Open AccessArticle

Enhanced Interfacial Plasma Degradation of Per- and Polyfluoroalkyl Substances (PFAS) via Ultrasonically Generated Microdroplets

by Ao Chen, Haoyu Yuan, Zhengtong Qiu and Chaonan Mu

Molecules 2026, 31(7), 1157; https://doi.org/10.3390/molecules31071157 - 31 Mar 2026

Viewed by 1114

Abstract

The exceptional stability of C-F bonds renders PFAS highly persistent in aqueous environments, posing significant challenges for conventional treatment technologies. While plasma-based technologies show promise, their efficiency is often limited by poor gas–liquid mass transfer in bulk liquid. Here, an in-house constructed ultrasonic [...] Read more.

The exceptional stability of C-F bonds renders PFAS highly persistent in aqueous environments, posing significant challenges for conventional treatment technologies. While plasma-based technologies show promise, their efficiency is often limited by poor gas–liquid mass transfer in bulk liquid. Here, an in-house constructed ultrasonic atomization–dielectric barrier discharge (UEN-DBD) system was developed to promote PFAS degradation under non-thermal plasma conditions. Ultrasonic atomization generated microdroplets, which promoted PFAS enrichment at the surface of microdroplets and facilitate interactions with plasma-generated reactive species. Using perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS) as model compounds, degradation behavior was evaluated over an initial concentration range of 0.01–1.0 ppm. At 0.01 ppm, degradation efficiencies of 96.06% for PFOA and 94.86% for PFOS were achieved within 5 min. Electron paramagnetic resonance (EPR) spectroscopy confirmed the formation of oxidative radicals (·OH) and suggested a mixed redox environment involving reactive species, potentially including superoxide (O₂·⁻) or hydrated electrons (e_aq⁻), in the discharge-treated system. High-resolution mass spectrometry results are consistent with a stepwise chain-shortening pathway dominated by successive –CF₂– scission, while fluoride-release measurements provided supporting evidence for partial defluorination. These findings advance the understanding of plasma-assisted PFAS degradation at the gas–liquid interface and provide a basis for the further development of plasma-assisted PFAS treatment strategies. Full article

(This article belongs to the Special Issue 30th Anniversary of Molecules—Recent Advances in Green Chemistry)

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15 pages, 985 KB

Open AccessArticle

Predicting Solubility Enhancement of Trans-Resveratrol and Hesperetin in Binary Solvent Mixtures Using New Hansen Parameters

by Iván Montenegro, Ángeles Domínguez, Begoña González and Elena Gómez

Molecules 2026, 31(7), 1117; https://doi.org/10.3390/molecules31071117 - 28 Mar 2026

Cited by 1 | Viewed by 664

Abstract

The solubility values of polyphenolic compounds in different extraction solvents are crucial for their recovery from natural matrices. Hansen solubility parameters (HSPs) stand out as a predictive tool for evaluating solute-solvent affinity and thus rational solvent selection for extraction processes. In this study, [...] Read more.

The solubility values of polyphenolic compounds in different extraction solvents are crucial for their recovery from natural matrices. Hansen solubility parameters (HSPs) stand out as a predictive tool for evaluating solute-solvent affinity and thus rational solvent selection for extraction processes. In this study, HSPs of trans-resveratrol and hesperetin were calculated using a semi-empirical method to assess the capability to predict the solubility behavior of both polyphenols in organic binary solvent mixtures. Experimental solubility of both polyphenols was determined in up to 21 monosolvents at 298.15 K and 0.1 MPa and used to classify them to iteratively calculate HSPs. Calculated HSPs were compared and discussed with literature values in terms of molecular interactions, demonstrating a fair agreement. Solubility of trans-resveratrol and hesperetin was then determined in methanol + MEK, ethanol + MEK, methanol + MiBK, ethanol + MiBK, and methanol + ethanol binary solvent mixtures. trans-Resveratrol achieved higher mole fraction solubility than hesperetin in all binary mixtures across the whole molar fraction range except in methanol + MiBK. Both compounds exhibited enhanced solubility in all alcohols + ketone binary mixtures, attributed to synergistic solvent effects. HSP analysis revealed a minimum Hansen distance between solute and solvent mixtures at compositions corresponding to the solubility maximum in synergistic systems. Additionally, calculated HSPs proved to effectively estimate the concentration at which this phenomenon occurs in all tested systems, reaching a robust correlation between maximum solubility and minimum Hansen distance. Overall, insights from this study underscore the effectiveness of experimentally derived HSPs in predicting the solubility behavior of polyphenols and seek to provide valuable guidance on solvent selection strategies for the recovery of bioactive compounds. Full article

(This article belongs to the Special Issue 30th Anniversary of Molecules—Recent Advances in Green Chemistry)

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20 pages, 1391 KB

Open AccessArticle

Leachability and Chemical Profiles of Per- and Polyfluoroalkyl Substances in Electronic Waste Components: Targeted and Non-Targeted Analysis

by Joshua O. Ocheje, Yelena Katsenovich, Berrin Tansel, Craig P. Dufresne and Natalia Quinete

Molecules 2026, 31(3), 445; https://doi.org/10.3390/molecules31030445 - 27 Jan 2026

Viewed by 1783

Abstract

Electronic waste (e-waste) is a growing solid waste stream with largely undisclosed and poorly characterized fluorinated constituents. We evaluated per- and polyfluoroalkyl substances (PFAS) leachability from four e-waste components (phone screens, phone plastics, capacitors, and Lithium-ion batteries) using a 30-day deionized water leaching [...] Read more.

Electronic waste (e-waste) is a growing solid waste stream with largely undisclosed and poorly characterized fluorinated constituents. We evaluated per- and polyfluoroalkyl substances (PFAS) leachability from four e-waste components (phone screens, phone plastics, capacitors, and Lithium-ion batteries) using a 30-day deionized water leaching test. PFAS were extracted by solid-phase extraction using weak anion exchange (WAX) cartridges and analyzed with a liquid chromatography triple-quadrupole mass spectrometer. In addition, the PFAS chemical profiles of e-waste components were characterized by non-targeted analysis. Leachable sums of detected PFAS (∑PFAS) were highest in phone screens (1739–1932 ng·kg⁻¹) and phone plastics (1575–2197 ng·kg⁻¹) and an order of magnitude lower in Lithium-ion batteries (148–158 ng·kg⁻¹) and capacitors (147–243 ng·kg⁻¹). Short-chain perfluoroalkyl acids (PFAAs) (e.g., PFBA, PFHxA) and legacy acids (e.g., PFOA, PFNA) were more prevalent in phone screens/plastics, whereas capacitors and batteries showed mixed sulfonate/carboxylate patterns (PFOS, PFHxS, and 6:2 FTS). Although capacitors and Lithium-ion batteries contained essential PFAS with high hazard potential at trace levels, phone screens and phone plastics pose a greater risk per mass due to higher ∑PFAS levels and larger volumes. Non-targeted analysis using Orbitrap Astral revealed CF₂/CF₂O homologous trends (confidence levels 2–3) with corroborating targeted findings. These findings highlight the need for PFAS-free alternatives, the disclosure of fluorinated additives, and stronger end-of-life management strategies to prevent PFAS releases from e-waste. Full article

(This article belongs to the Special Issue 30th Anniversary of Molecules—Recent Advances in Green Chemistry)

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17 pages, 1299 KB

Open AccessArticle

Design of a Recyclable Photoresponsive Adsorbent via Green Synthesis of Ag Nanoparticles in Porous Aromatic Frameworks for Low-Energy Desulfurization

by Tiantian Li, Xiaowen Li, Hao Wu and Qunyu Chen

Molecules 2026, 31(2), 248; https://doi.org/10.3390/molecules31020248 - 12 Jan 2026

Cited by 1 | Viewed by 599

Abstract

Based on the pressing need to develop efficient desulfurization technologies for fuel oils, this study presents a novel photoresponsive adsorbent for the removal of refractory thiophenic sulfides. Conventional hydrodesulfurization exhibits limited efficiency for such compounds, while adsorption–desorption processes often suffer from high energy [...] Read more.

Based on the pressing need to develop efficient desulfurization technologies for fuel oils, this study presents a novel photoresponsive adsorbent for the removal of refractory thiophenic sulfides. Conventional hydrodesulfurization exhibits limited efficiency for such compounds, while adsorption–desorption processes often suffer from high energy consumption during regeneration. Inspired by natural stimuli-responsive systems, we designed a photothermal adsorbent by incorporating silver nanoparticles (Ag NPs) into a porous aromatic framework (PAF) via a green photoreduction method. The resulting materials, denoted as Ag(0)PBPAF-n (n = 1, 2, 3), were thoroughly characterized to confirm successful synthesis and structural integrity. The introduced Ag NPs serve as adsorption sites, enhancing uptake capacity through weak interactions with sulfur atoms in thiophenic molecules. More significantly, under light irradiation, the localized surface plasmon resonance (LSPR) of Ag NPs enables efficient photothermal conversion, triggering rapid desorption without conventional heating. Adsorption–desorption tests demonstrated that up to 48% of adsorbed thiophenic sulfur could be released upon illumination. Fixed-bed experiments further verified that light can effectively stimulate regeneration and improve energy efficiency. This work offers a promising strategy for designing recyclable adsorbents with low-energy regeneration driven by clean solar energy. Full article

(This article belongs to the Special Issue 30th Anniversary of Molecules—Recent Advances in Green Chemistry)

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Review

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31 pages, 8477 KB

Open AccessReview

Plastic-Degrading Microorganisms: Biodegradation Pathways and Habitat Origins

by Martyna Jowita Żarska, Marcin Damian Jasiak, Patryk Mierzejewski, Klaudiusz Tomczyk, Jakub Małecki, Roksana Gudz, Aneta Krystyna Urbanek, Katarzyna Ewa Kosiorowska and Julia Alicja Dybka

Molecules 2026, 31(10), 1638; https://doi.org/10.3390/molecules31101638 - 13 May 2026

Viewed by 2757

Abstract

Microbial biodegradation represents a promising approach to addressing global plastic pollution, yet the metabolic pathways and environmental origins of polymer-degrading microorganisms remain incompletely characterized. This review synthesizes current knowledge on biodegradation mechanisms across major polymer classes and identifies key environmental reservoirs harboring native [...] Read more.

Microbial biodegradation represents a promising approach to addressing global plastic pollution, yet the metabolic pathways and environmental origins of polymer-degrading microorganisms remain incompletely characterized. This review synthesizes current knowledge on biodegradation mechanisms across major polymer classes and identifies key environmental reservoirs harboring native plastic-degrading microbiota. Biodegradation pathways differ fundamentally according to polymer chemistry. Polyesters such as PET undergo hydrolytic cleavage by PETases and MHETases, releasing terephthalic acid and ethylene glycol for assimilation via the β-ketoadipate pathway and the TCA cycle. Biodegradable polyesters (PLA, PBAT, PHAs, PCL) are similarly hydrolyzed by cutinases, lipases, and depolymerases. In contrast, polyolefins (PE, PP) and polystyrene lack hydrolyzable bonds and require oxidative attack by laccases, peroxidases, and alkane monooxygenases, followed by β-oxidation to acetyl-CoA. Three principal environmental reservoirs supply plastic-degrading microorganisms: contaminated ecosystems including landfills and the plastisphere; soil microbiota contributing ligninolytic fungi and actinomycetes; and compost environments yielding thermostable enzymes such as leaf-branch compost cutinase. Across all environments, microbial consortia demonstrate superior degradation efficiency compared to single-species cultures, reflecting the enzymatic complexity required for complete polymer mineralization. Understanding these pathways and their environmental origins provides a foundation for biological plastic waste management strategies. Full article

(This article belongs to the Special Issue 30th Anniversary of Molecules—Recent Advances in Green Chemistry)

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45 pages, 4533 KB

Open AccessReview

Nanoparticle-Catalysed Microwave-Driven MCRs for Sustainable Heterocycle Synthesis

by Venkatesan Kasi, Malgorzata Jeleń, Xiao-Hui Chu, Parasuraman Karthikeyan, Beata Morak Młodawska and Lai-Hock Tey

Molecules 2026, 31(6), 1031; https://doi.org/10.3390/molecules31061031 - 19 Mar 2026

Cited by 10 | Viewed by 1361

Abstract

Nanoparticle-catalysed microwave-aided multicomponent reactions (MCRs) have been demonstrated to be competent and environmentally benign tools for the quick synthesis of a wide spectrum of fused heterocyclic systems. The distinctive physicochemical properties of nanoparticles, including a substantial surface area, readily modifiable surface functionality, and [...] Read more.

Nanoparticle-catalysed microwave-aided multicomponent reactions (MCRs) have been demonstrated to be competent and environmentally benign tools for the quick synthesis of a wide spectrum of fused heterocyclic systems. The distinctive physicochemical properties of nanoparticles, including a substantial surface area, readily modifiable surface functionality, and heightened catalytic activities, when coupled with microwave irradiation, have enabled a marked improvement in reaction rates, product yields, and selectivity compared to conventional heating methods. This review highlights recent advancements in microwave-assisted MCRs facilitated by diverse nanomaterials, such as magnetic nanocatalysts, metal and metal oxide nanoparticles, mesoporous silica systems, and nanohybrids. It emphasises catalyst design, catalytic efficacy, scope, recyclability, and alignment with green chemistry principles in both solvent-free and aqueous environments, as well as the utilisation of recyclable catalysts. In summary, microwave-assisted multi-component reactions catalysed by nanoparticles are ecofriendly and versatile methods for the sustainable synthesis of such fused heterocycles containing bioactive pyridine, pyrazole, phenazine, pyrimidine, pyran, imidazole, and relevant pyridine derivatives, possessing potential in medicinal and material chemistry. Full article

(This article belongs to the Special Issue 30th Anniversary of Molecules—Recent Advances in Green Chemistry)

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