The accumulation of micro- and nano-plastics (MNPs) in terrestrial ecosystems poses an emerging threat to soil health and plant development. This study examined the effects of fluorescent polystyrene MNPs (0.1-100µm; 0.01-1gL-1) with heterogeneous sizes and shapes on soil properties, microbial activity, and the morpho-physiological traits of Arabidopsis thaliana. In parallel, we assessed whether biochar (20% v/v) could mitigate MNPs-induced alterations. MNPs contamination decreased the soil cation exchange capacity and modified micronutrient availability without affecting pH, whereas biochar significantly increased pH, carbon, and nutrient content. In control soils, higher MNPs concentrations delayed germination and reduced shoot biomass and rosette area, while biochar-amended soils maintained stable or enhanced plant growth and root development across all contamination levels. MNPs exposure induced oxidative stress in roots, with increased hydrogen peroxide and superoxide radical accumulation, but did not upregulate the expression of three root peroxidase genes. Biochar improved microbial biomass and basal respiration, although its combination with MNPs resulted in complex and enzyme-specific responses. Overall, biochar ameliorated several adverse effects of MNPs contamination by enhancing soil fertility and plant performance, suggesting its potential as a sustainable soil amendment to mitigate plastic pollution in terrestrial environments.

Herein we report on a kinetic study of Cu-based catalysts employed in the ARGET-ATRP of the methacrylic derivative of eugenol, namely eugenyl methacrylate (EuMA). Polymerizations were carried out in solution in presence of catalytic systems formed in situ by CuBr2 and nitrogen-ligands such as BiPy, PMDETA, HMTETA and Me6TREN. The formation of insoluble polymers, due to secondary reactions responsible of cross-linking, was observed with CuBr2/BiPy and CuBr2/HMTETA systems; Me6TREN- and PMDETA-based catalyst proved, instead, to be capable of generating linear polymers. For the latter, first order kinetics occurred for monomer conversion up to ca 50 %, whilst higher conversion led to deviations from the linear trend. This suggested the direct involvement of the allyl group in the termination reactions, which was convincedly demonstrated by comparing kinetic results for EuMA and the corresponding di-hydrogenated monomer (DEuMA). At EuMA conversion above 50 %, the side reactions lead to inactivation of the PMDETA-based catalytic system via reducing agent consumption rather than to the formation of insoluble/crosslinked polymers. Electronic structure calculations provided the energy profile for all possible side reactions. Among these, the radical chain transfer to the allyl group through hydrogen abstraction, as well as the attack of the propagating methacrylic radical to the allyl group, contributed to rationalizing the experimental behavior of the three copper-catalyst systems employed in this work. This study demonstrates that modulating the kinetic of polymerization by properly selecting ligands and reaction temperatures represents a useful strategy towards the reduction of undesired secondary reactions of molecules with sensitive functional groups such as bio-derived phenols; moreover, such preserved functional groups would serve as possible post-functionalization sites (i.e. epoxidation) allowing for the preparation of new materials with tailored properties.

Microplastic (MP) pollution is an emerging concern in ruminant production, as animals are exposed to MPs through air, water, and feeds. Ruminants play a key role in MP transmission to humans via animal products and contribute to MP return to agricultural soil through excreta. Identifying effective strategies to mitigate MP pollution in the ruminant sector is crucial. A promising yet understudied approach involves the potential ability of rumen microbiota to degrade MPs. This study investigated the in vitro ruminal degradation of three widely distributed MPs—low-density polyethylene (LDPE), polyethylene terephthalate (PET), and polyamide (PA)—over 24, 48, and 72 h. PET MP exhibited the highest degradation rates (24 h: 0.50 ± 0.070%; 48 h: 0.73 ± 0.057%; and 72 h: 0.96 ± 0.082%), followed by LDPE MP (24 h: 0.03 ± 0.020%; 48 h: 0.25 ± 0.053%; and 72 h: 0.56 ± 0.066%) and PA MP (24 h: 0.10 ± 0.045%; 48 h: 0.02 ± 0.015%; and 72 h: 0.14 ± 0.067%). These findings suggest that the ruminal environment could serve as a promising tool for LDPE, PET, and PA MPs degradation. Further research is needed to elucidate the mechanisms involved, potentially enhancing ruminants’ natural capacity to degrade MPs.

The Ring Opening Metathesis Polymerization (ROMP) of 3-substituted cyclooctene monomers having side chains functionalized with fluorescent coumarin or carbazole units was successfully accomplished using commercial Grubbs' second and third generation catalysts. The resulting polymers were highly regio-(head to tail) and stereo-regular (trans) and showed thermal properties strongly dependent on the structure of their pendant moieties. The photoluminescent behavior of the synthesized polymers was investigated in solution and in the solid state. Interestingly, in the solid state strong excimer emission was observed for the carbazole-containing polymers because of the intra-and intermolecular coupling of pendant carbazole units. Following the chemical hydrogenation of the carbazole-containing polymer backbone, a linear polyethylene derivative was obtained that exhibited the same fluorescence emission behavior as its unsaturated counterpart. A functionalized polycyclooctene was also synthesized by copolymerization of cyclooctene with a low amount of carbazole-containing monomer. Subsequent saturation of the polymer backbone provided the corresponding functionalized polyethylene. Both of these polymers showed fluorescence emission from isolated carbazole units and chemicophysical properties typical of pristine polycyclooctenes and polyethylenes, suggesting that they may have potential applications as fluorescent markers for these materials, as preliminarily confirmed by the preparation of a fluorescent blend of the hydrogenated copolymer (1 wt%) with commercial low-density polyethylene.

Plastic pollution represents a persistent global issue, with catastrophic effects on ecosystems. Due to unique properties, these synthetic materials do not break down into biodegradable compounds when naturally dispersed, but degrade into smaller fragments, known as micro- (MPs) and nanoplastics (NPs), that easily enter the food chain. Among plastics, polypropylene (PP) is one of the most common, whose consumption has dramatically increased in recent years for single-use packaging and surgical masks. In this context, given the widespread detection of PP-MPs and NPs in various biological matrices, investigating their toxicity in living organisms is crucial. For these reasons, this study aims to assess how PP-MPs and NPs affect tissue regeneration following injury, proposing the freshwater leech Hirudo verbana as an established experimental model. Injured leeches were examined at different time points after plastic administration, and analyses were conducted using microscopy, immunofluorescence, and molecular biology techniques. The results demonstrate that plastic exposure induces fibrosis, disrupts tissue reorganization, delays wound repair, and activates the innate immune and oxidative stress responses. In summary, this project provides new insight into the adverse effects of PP particles on living organisms, highlighting for the first time their negative impact on proper tissue regeneration.

Monolithic composite aerogel based on a photocatalytic system, constituted by Fe0 (ZVI) coupled with ZnS (FZ), embedded into syndiotactic polystyrene (sPS) matrix was used, for the first time, in the lindane degradation under UV light. The content of FZ photocatalyst inside the monolithic composite aerogel (FZsPS) composite was 3 wt%. FESEM images of FZsPS indicate that the FZ photocatalyst is well dispersed in the polymer matrix. EDS analyses and temperature-programmed reduction (TPR-H2) measurements revealed an interpenetrated structure of the ZVI and ZnS phases as well the presence of some iron in an oxidized form. Photocatalytic activity data showed that in presence FZsPS aerogel, the almost complete lindane degradation was achieved after only 30 min of UV irradiation time. FZsPS was also effective in the lindane mineralization since a TOC removal of about 94 % was detected after 180 min of treatment time. Remarkably, based on the toxicity evaluation on Artemia fran-ciscana, while the bare FZ photocatalyst showed significant toxicity per se, no toxicity or genotoxicity was found in the water treated with the FZsPS composite system where FZ is immobilized into the sPS aerogel matrix. Therefore the proposed composite photocatalyst can be considered as a model for a strategy to eliminate the environmental impact of catalysts that would otherwise be harmful to water.

The stereoselective polymerization of conjugated dienes promoted by using transition metal complexes has attracted much interest in both industrial and academic environments for the relevance of polydienes as synthetic rubbers and for the challenging reaction mechanisms. Among the different transition metal complexes, those based on group IV have been demonstrated to be versatile and efficient catalysts. Titanium complexes are generally more active than zirconium complexes. A rare exception to this trend is represented by a series of Zr(IV) complexes supported by (anilidomethyl)pyridine ligands that, after activation by using Al(iBu2H)/MAO, were found to be highly active affording exclusively cis-1,4-polybutadiene. To rationalize this unexpected trend and to obtain more insights into the parameters that control the reactivity of group IV complexes, a theoretical investigation of the entire polymerization mechanism, employing density functional methods, was undertaken. In the framework of the widely accepted polymerization scheme, the different intermediates featuring h4 (both cis and trans) coordination of the monomer and h1 or h3 (syn or anti)allyl coordination of the growing chain were scrutinized. Subsequently, the effects of the metal center on the free-energy profiles of the elementary steps involved in the reaction were examined. The results presented herein aim to achieve a better knowledge of the influence of the metal on the polymerization rates and on the stereoselectivity of the reaction.

Plastic pollution is a global problem affecting the environment and, consequently, people’s well-being. Careful and timely end-of-life plastic recycling is certainly a way, albeit a partial one, to remedy the problem. The immediate identification and selection of the different types of plastic materials in the recycling process certainly facilitate its recovery and reuse, allowing the damage caused by plastic emission into the environment to be limited. Recently, new technologies for automatic sorting of plastics based upon fluorescent tagging have been considered. This article reports the synthesis and characterization of fluorescent copolymers of poly(methyl methacrylate) (PMMA) that could be potentially used as fluorescent markers of commercial PMMA. Poly(methylmetacrylate-co-2-(9-carbazolyl)ethyl methacrylate) (P(MMA-co-CEMA)) and poly(methylmetacrylate-co-7-methacryloyloxycoumarin) (P(MMA-co-MAOC)) samples containing a small number of fluorescent units (<4%) were synthesized by free-radical polymerization. All copolymer samples show chemico-physical properties like those of pure PMMA and produce fluorescence emission under 290 nm wavelength excitation. P(MMA-co-CEMA)s and P(MMA-co-MAOC)s were also tested as fluorescent dyes for PMMA identification. The experimental results demonstrate that PMMA/P(MMA-co-CEMA) and PMMA/P(MMA-co-MAOC) blends prepared using 1% by weight of fluorescent copolymer show a homogeneous morphology completely similar to pure PMMA and are still optically active.

Two series of random copolymers containing at the same time two fluorescent groups, carbazole and coumarin, linked to a poly(norbornene dicarboximide) backbone have been prepared by controlled ring-opening metathesis polymerization (ROMP), promoted by Grubbs' third generation catalyst (G3). The relative amount of the two functionalities was systematically varied along the copolymer chain, and the high degree of structural control observed allowed also for the preparation of a block copolymer with an equimolar content of fluorophore groups. In comparison to the related homopolymers, all the random copolymers exhibited in solution typical photoluminescence due to the carbazole or coumarin moiety, together with fluorescence arising from the energy transfer from the donor carbazole groups to the acceptor coumarin groups. This energy transfer seems to occur through intramolecular interactions, as it is not observed in the block copolymer and in the 50/50 homopolymer blend. On the other hand, in the solid state also the energy transfer from carbazole to coumarin through interchain interactions can take place. Of note, moving from solution to solid state fluorescence analysis, a blue shift of the band related to the energy transfer phenomenon is observed. This finding could be related to a combined effect of energy and electron transfer from donor to acceptor.

The increasingly intense consumption of plastics and, above all, their improper disposal in the environment are causing serious environmental concerns. Great efforts have been made for the development of new methods aimed at facilitating and speeding up the identification and sorting of different materials in the plastic recycling process. In this field, new strategies based on fluorescent tagging have been developed. This work concerns the synthesis and characterization of new fluorescent copolymers of polyethylene (PE) and polystyrene (PS), which are among the most produced and consumed plastic materials. The synthesized copolymers are potentially suitable for use as fluorescent markers of PE and PS. Ethylene-co-N-pentenyl carbazole (P(E-co-PK)) and styrene-co-4-(N-carbazolyl)methyl styrene (P(S-co-SK)) copolymers were prepared by Ziegler–Natta and free radical polymerization, respectively. If excited at 300 nm, both P(E-co-PK)s and P(S-co-SK)s give fluorescence emissions resulting in them being optically active. Moreover, due to the low amount of fluorescent units, they show chemico-physical properties such as those of their corresponding homopolymers (PE and PS). P(E-co-PK)s and P(S-co-SK)s have been also tested as fluorescent markers of PE and PS. The experimental results demonstrate that from PE/P(E-co-PK) and PS/P(S-co-SK) blends prepared using only 1% by weight of fluorescent copolymer, distinguishable fluorescent emissions can be still detected.

Supercritical antisolvent precipitation was used to obtain ZnO (undoped) and Fe-doped ZnO photocatalysts at different Fe/Zn molar ratio percentages (0.57, 0.75 and 0.84 mol%). Wide-angle X-ray diffraction showed the hexagonal wurtzite as the main crystalline phase of the cauliflower-like nanoparticle aggregations (observed from Field Emission Scanning Electron Microscopy) with a mean diameter of 54.5 nm for the pure ZnO nano -particles and a higher mean diameter (in the range 109.1-121.5 nm) for Fe-doped ZnO nanoparticles. XRF confirmed the approximate Fe/Zn ratios (0.55, 0.77, 0.82 mol%). The band gap energy, derived from UV -Vis diffuse reflectance measurements decreased upon Fe doping with values ranging from 3.22 (ZnO) to 2.83 eV (0.57 mol% Fe). The photocatalytic activity results showed that the undoped ZnO photocatalyst completely removes color from an aqueous solution containing Acid Orange 7 dye (AO7) after 30 min of UV light irradiation. Whereas Fe-doped ZnO photocatalyst with 0.75 mol% Fe content (0.75Fe) exhibited the highest discoloration efficiency (52 %) and total organic carbon (TOC) removal efficiency (similar to 36 %) of AO7 after 180 min under visible light. Moreover, the main reactive oxygen species involved in the AO7 degradation were assessed with the optimized photocatalyst (0.75Fe) in presence of scavenger molecules. The experimental results revealed that positive holes and superoxide are responsible for target dye degradation under visible light.

In this work, two compounds belonging to the BODIPY family, and previously investigated for their photosensitizing properties, have been bound to the amino-pendant groups of three random copolymers, with different amounts of methyl methacrylate (MMA) and 2-(dimethylamino)ethyl methacrylate (DMAEMA) in the backbone. The P(MMA-ran-DMAEMA) copolymers have inherently bactericidal activity, due to the amino groups of DMAEMA and to the quaternized nitrogens bounded to BODIPY. Systems consisting of filter paper discs coated with copolymers conjugated to BODIPY were tested on two model microorganisms, Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). On solid medium, irradiation with green light induced an antimicrobial effect, visible as a clear inhibition area around the coated disks. The system based on the copolymer with 43% DMAEMA and circa 0.70 wt/wt% of BODIPY was the most efficient in both bacterial species, and a selectivity for the Gram-positive model was observed, independently of the conjugated BODIPY. A residual antimicrobial activity was also observed after dark incubation, attributed to the inherently bactericidal properties of copolymers.

Plastics are a heterogeneous class of synthetic compounds that, due to their unique characteristics find numerous applications both in industrial and civil fields. However, despite the great advantages that these materials brought in everyday life, the plastic wastes resulting from their massive use represent one of the main environmental problems at the global level. Once released, plastics persist for a long time and are subjected both to biotic and abiotic processes leading to the formation of small particles, known as micro and to nanoplastics, that interact with organisms, accumulating inside tissues and risking to enter in the trophic chain. Among the different types of plastic, polypropylene (PP) is one of the diffused, widely exploited in food and textile industries for disposable packaging and to produce surgical masks. Owing to the huge distribution and the resultant abundant presence of PP waste products, it results necessary investigate the possible toxicity on living organisms. For these reasons, here we analyzed the effects of PP micro and nanoplastics dispersed in freshwater, using the medicinal leech Hirudo verbana as invertebrate model. To better follow the plastics fate, fluorescent particles, labeled with a fluorophore, have been used. Animals were examined at various timings after plastics exposure and results were analyzed by means of microscopy, immunofluorescent and molecular biology analyses. After assessing the entrance of PP fragments into leech tissues, the activation of the innate immune response was evaluated. The results show that the presence of micro and nanoplastics induces an initial physical protection that consists in the secretion of mucus, followed by an increase of blood vessels and the recruitment of immune cells, in particular macrophages. Moreover, macrophages were directly involved in both phagocytic and encapsulation processes, as demonstrated by acid phosphatase (ACP) histoenzymatic and Thioflavin-T assays, expressing specific pro-inflammatory factors, such as HvRNASET2 and HmAIF-1, as demonstrated by immunolocalization and qPCR experiments. Finally, the expression levels of genes related to oxidative stress-induced enzymes have been investigated, in order to evaluate the possible increase in reactive oxygen species (ROS), due to the entry into the leech tissues of PP micro and nanoplastics. This work allows deepening the current knowledge of the possible harmful effects on human health deriving from micro and nanoplastics dispersion, leading new insight about freshwater ecosystems that often represent the first environments interested in plastic pollution.

This article describes data related to the research paper entitled "ROMP of norbornene and oxanorbornene derivatives with pendant fluorophore carbazole and coumarin groups" [1]. Six novel norbornene and oxanorbornene dicarboximides derivatives functionalized with carbazole or coumarin moieties, are synthesized and investigated in the preparation of fluorescent polymers by Ring-Opening Metathesis Polymerization (ROMP). Herein, we report on the characterization of all these compounds by 1D and 2D Nuclear Magnetic Resonance (NMR), UV-Visible and fluorescence spectroscopy. The characterization data include information obtained from H-1, C-13, Homonuclear Correlation Spectroscopy (H-1-H-1 COSY) and Heteronuclear Single Quantum Coherence (H-1-C-13 HSQC). The absorbence and fluorescence spectra for all these compounds are given. This work provides useful characterization data for the design of new norbornene and oxanorbornene-based monomers with fluorescent carbazole and coumarin groups, which can be employed for the synthesis of functional materials via ROMP. (C) 2022 The Authors. Published by Elsevier Inc.

Zinc and magnesium complexes of N-heterocyclic carbene (NHC)-phenoxy-imine ligands derived from chiral (S, S)-trans-1,2-diaminocyclohexane have been synthetized. Either monomeric or dimeric species have been ob-tained depending on the reaction conditions. All complexes were tested as catalysts for the ring opening poly-merization (ROP) of lactide showing moderate activity and control degree. MALDI-ToF-MS spectra of PLA highlighted that magnesium complex promoted the formation of cyclic PLA, whereas zinc analogous and its monomeric species gave linear PLA, suggesting that different polymerization mechanisms occur depending on the metal center. Moreover, according to MALDI-ToF-MS spectra, in the absence of additional initiators, poly-mers arising from zinc catalysts would bear the NHC-phenoxy-imine hybrid ligand as terminal unit. Computa-tional studies were performed in order to shed light on catalyst behaviors and on the mechanisms involved in the ROP of lactide. Free energy profiles of the initiation step suggest that microstructural differences lie in the ligand role. Indeed, in the absence of additional initiators, the ligand participates to the initiation involving its NHC moiety when wrapped around magnesium and its phenoxy-imine moiety when bound to zinc.

N-doped TiO2 (N-TiO2) and N-doped ZnO (N-ZnO) were synthesized utilizing ammonia as a dopant source. The chemico-physical characteristics of synthesized samples were studied by Raman spectroscopy, X-ray diffraction, SEM analysis, N2 adsorption–desorption at −196 °C, and diffuse reflectance spectroscopy. Compared to undoped samples, the introduction of nitrogen in the semiconductor lattice resulted in a shift of band-gap energy to a lower value: 3.0 eV for N-ZnO and 2.35 eV for N-TiO2. The photocatalysts were tested for the degradation of Eriochrome Black T (EBT), which was selected as a model azo dye. Both N-doped semiconductors evidenced an improvement in photocatalytic activity under visible light irradiation (62% and 20% EBT discoloration for N-TiO2 and N-ZnO, respectively) in comparison with the undoped samples, which were inactive in the presence of visible light. Different behavior was observed under UV irradiation. Whereas N-TiO2 was more photoactive than commercial undoped TiO2, the introduction of nitrogen in ZnO wurtzite resulted in a drastic reduction in photocatalytic activity, with only 45% EBT discoloration compared to total color removal obtained with the commercial ZnO sample, suggesting intrinsic limitations for doping of this class of semiconductors.

The last decades have witnessed a rapid growth of applications of N-heterocyclic carbenes (NHCs) in different chemistry fields. Due to their unique steric and electronic properties, NHCs have become a powerful tool in coordination chemistry, allowing the preparation of stable metal-ligand frameworks with both main group metals and transition metals. An overview on the use of five membered monodentate C2-symmetric N-heterocyclic carbenes (NHCs) as ligands for transition-metal complexes and their most relevant applications in asymmetric catalysis is offered.

A series of new (oxa)norbornene dicarboximide monomers, decorated with carbazole and coumarin as pendant fluorophore groups, were synthesized and characterized. Their behaviour in ring-opening metathesis polymerization (ROMP) was explored in the presence of commercial Grubbs' third generation catalyst G3 and cis-selective catalyst GZ. Norbornene dicarboximide (NDI) monomers were successfully polymerized by both the catalysts, while oxanorbornene dicarboximide (ONDI) analogues showed scarce reactivity toward polymerization promoted by GZ. The nature of the spacer (ethylene or p-xylene) between the NDI unit and the chromophore seems to not affect the outcome of the polymerization. Moving from G3 to GZ, it was possible to synthetize NDI-based polymers with cis-olefin content increasing from 47 to 89%, depending on the nature of the pendant fluorophore group. The obtained polymers showed photoluminescence in solution and solid state owing to the carbazole or coumarin fragment, regardless of the nature of the spacer and cis-olefin amount. Interestingly, a significant excimer emission due to the overlap of carbazole groups was observed for a carbazole-functionalized polymer film, as a result of the combined effect of two factors, the stiffness of the spacer (p-xylene) linking the NDI moiety to the fluorophore and the high stereoregularity degree (83% cis) of the main chain.

Fluorescent polypropylenes for the detection of PP-derived microplastic pollutants in organic tissues.

Poly-L-lactic acid (PLLA) aerogel-based scaffolds were obtained from physical PLLA gels containing cyclopentanone (CPO) or methyl benzoate (BzOMe) molecules. An innovative single step method of solvent extraction, using supercritical CO2, was used to achieve cylindrical monolithic aerogels. The pore distribution and size, analyzed by SEM microscopy, were found to be related to the crystalline forms present in the physical nodes that hold the gels together, the stable α’-form and the metastable co-crystalline ε-form, detected in the PLLA/BzOMe and PLLA/CPO aerogels, respectively. A higher mechanical compressive strength was found for the PLLA/CPO aerogels, which exhibit a more homogenous porosity. In vitro biocompatibility tests also indicated that monolithic PLLA/CPO aerogels exhibited greater cell viability than PLLA/BzOMe aerogels. An improved biocompatibility of PLLA/CPO monolithic aerogels was finally observed by coating the surface of the aerogels with polydopamine (PDA) obtained by the in situ polymerization of dopamine (DA). The synergistic effect of biodegradable polyester (PLLA) and the biomimetic interface (PDA) makes this new 3D porous scaffold, with porosity and mechanical properties that are tunable based on the solvent used in the preparation process, attractive for tissue engineering applications.