Search Results (414)

Lignin-derived carbon dots (CDs) are promising sustainable fluorescent nanomaterials for environmental sensing, yet precise regulation of their emission behavior and ion-recognition selectivity remains challenging. Herein, a solvent-free precursor–structure–engineering strategy was developed to prepare lignin-derived CDs with tunable photoluminescence and selective metal-ion sensing. Industrial alkali lignin, lysine, and oxalic acid were used as the carbon source, nitrogen source, and carbonization promoter, respectively, while cysteine, histidine, and p-phenylenediamine were introduced as functional precursors. The resulting C-CDs, H-CDs, and P-CDs showed distinct optical and sensing properties. H-CDs exhibited the highest photoluminescence quantum yield of 50.98%, attributed to enhanced graphitic nitrogen formation and electronic conjugation. P-CDs displayed a red-shifted emission at approximately 573 nm due to extended π-conjugated domains. Moreover, C-CDs, H-CDs, and P-CDs showed preferential fluorescence responses toward Fe³⁺, Cu²⁺, and Ag⁺, with detection limits of 0.26, 0.05, and 0.11 μM, respectively. The quenching behavior was inconsistent with a dominant dynamic collisional process and was instead associated primarily with metal–surface interactions. This work clarifies the precursor–structure–property relationship and provides a sustainable route for designing lignin-derived fluorescent probes. Full article

Covalent organic frameworks (COFs) show great potential in environmental remediation, yet the aquatic safety of TpPa (Tp = 1,3,5-triformylphloroglucinol, Pa = p-phenylenediamine), a typical COF, remains unclear. This study employed zebrafish (Danio rerio) to evaluate the environmental toxicity of TpPa and elucidate molecular mechanisms. Zebrafish embryos were exposed to 0–50 mg/L TpPa for 120 h, and developmental toxicity, oxidative stress, and physiological and molecular responses were investigated. Results demonstrated that TpPa exposure exerted concentration- and time-dependent effects. Mortality and malformation rates increased significantly from 5 mg/L, accompanied by reduced body length. The hatching rate showed a biphasic pattern, increasing with concentration at 48 h and decreasing with concentration at 120 h. Spontaneous movement was elevated at 50 mg/L, while heart rate increased dose-dependently starting from 5 mg/L at 48 h and from 1 mg/L at 72 h. Mechanistically, TpPa induced oxidative stress via reactive oxygen species accumulation and impaired the activities of both superoxide dismutase and catalase. These effects activated the p53-mediated apoptotic pathway, reduced the Bcl2/Bax ratio, and disrupted the GH/IGF growth axis and neuromotor regulatory pathways, ultimately causing developmental abnormalities. These findings provide critical data for the environmental safety assessment of TpPa, with direct relevance to establishing health monitoring protocols for COF-exposed aquaculture species. Full article

This work reports the design and validation of a reusable platinum (Pt) electrode platform (ST-E) for green electrochemical analysis. The device integrates Pt working and counter electrodes with an external Ag/AgCl reference and is engineered for repeated regeneration and refunctionalization. Surface renewal by alumina polishing followed by electrochemical activation in 0.5 M H₂SO₄ restores a clean, reproducible Pt surface, as confirmed by diffusion-controlled, reversible ferricyanide voltammetry over 5–150 mV s⁻¹ with near-Nernstian peak separation and i_pa/ipc ≈ 1. Platform versatility is demonstrated in two applications. First, ST-E is functionalized with PFOA-selective molecularly imprinted nanoparticles on an APTES layer, enabling trace determination of perfluorooctanoic acid (1–5 pg mL⁻¹), with a detection limit of 0.50 pg mL⁻¹ and sensitivity of 3.16 μA (pg mL⁻¹)⁻¹. Responses correlate with an equivalently modified commercial screen-printed electrode (r = 0.990, p < 0.005), with Bland–Altman analysis confirming concordance. Second, after regeneration, electropolymerization of o-phenylenediamine yields an insulating poly(o-phenylenediamine) film that attenuates redox currents and increases ΔE_p, illustrating compatibility with diverse surface chemistries. Green metrics (AGREE, AGREEprep ≈ 0.80; BAGI = 75.0) highlight reduced waste and solvent use versus single-use transducers and compatibility with portable potentiostats, supporting circular electrochemical sensing. Full article

A new benzimidazole–6β-acetoxyvouacapane (4aS,5R,6aS,7R,11aS,11bR)-9-(1-benzyl-1H-benzo[d]imidazol-2-yl)-4,4,7,11b-tetramethyl-1,2,3,4,4a,5,6,6a,7,11,11a,11b-dodecahydrophenanthro[3,2-b]furan-5-yl acetate was synthesized through the semisynthetic functionalization of the natural product 6β-acetoxyvouacapane. The target compound was obtained via a liquid-assisted mechanochemical condensation of aldehyde 6β-acetoxyvouacapane with N-benzyl-o-phenylenediamine, followed by cyclization and oxidative aromatization under mild reaction conditions. The structure of the new compound was established by FT-IR, 1D and 2D NMR spectroscopy (COSY, HSQC, and HMBC), and high-resolution mass spectrometry (HRMS). Full article

Efficient adsorbents and nanozyme-like materials are of growing importance in environmental technologies. Here, we report a simple and potentially scalable approach for the immobilization of biochars onto nonwoven acrylic textiles, yielding composite materials with good retention of immobilized biochar during aqueous treatment and combined adsorption and peroxidase-like activities. The structure of native and biochar-modified textiles was characterized by scanning electron microscopy and small-angle X-ray scattering, confirming the presence of biochar particles on fiber surfaces and within the inter-fiber space, as well as nanoscale structural changes induced by biochar incorporation. Textile-bound biochars exhibited peroxidase-like activity toward N,N-diethyl-p-phenylenediamine in the presence of hydrogen peroxide and enabled effective decolorization of methylene blue. Adsorption alone resulted in 61% dye removal after 240 min, while the combined adsorption-catalytic process achieved 74% decolorization. Modification of the textile-bound biochar with copper ions further enhanced the peroxidase-like activity, increasing dye removal to 85% under identical conditions. The optional incorporation of a magnetic iron wire allows facile magnetic handling of the composite. Owing to its low cost, simplicity of preparation, and dual functionality, the textile-bound biochar composite represents a promising proof-of-concept platform that may warrant further development for dye removal and related environmental applications. Full article

Organic cathode materials (OCMs) are widely regarded as promising candidates for sustainable rechargeable batteries; however, their practical application is hindered by insufficient electrochemical performance and a lack of scalable synthesis methods. Building on our previous study of poly(o-phenylenediamine) (PoPDA), we herein present a single-precursor, solid-phase synthesis of poly(o-phenylenediamine) sulfide derivatives (PoPDAS). Using o-phenylenediamine sulfide (oPDAS) as the sole precursor, thermal treatment at 300–350 °C triggers H₂SO₄ and its decomposition products to simultaneously drive oxidative polymerization forming a conjugated PoPDA backbone, and in situ sulfurization introducing polysulfide (–S_n–) linkages. The dual redox activity of C=N bonds in phenazine repeating units and S–S bonds in –S_n– linkages enables a high theoretical capacity, while the robust polymer matrix effectively confines soluble sulfur species during cycling. To optimize the trade-off between reversible capacity and long-term stability, a secondary sulfurization step has been implemented. Among fourteen samples prepared via varied synthetic routes and conditions, PoPDAS-B-350-0.5 with a moderate sulfur content of 27 wt% exhibits the best performance, delivering a reversible capacity of 358 mAh g⁻¹ and 88% capacity retention after 800 cycles. Electrochemical analysis and ex situ characterization confirm the redox mechanism involving both C=N and S–S groups, and reveal the excellent cycling stability attributed to the robust polymer backbone that confines dissociated sulfur species. These results highlight the potential of integrating multiple redox-active moieties into a polymer architecture via a scalable solid-phase synthesis to afford practical OCMs. Full article

Accurate discrimination of multiple heavy metal ions is essential for environmental monitoring. This study developed a simple fluorescent sensing array utilizing carbon dots derived from black plum peels (PCDs) for the precise identification of metal ions in environmental waters. Three structurally distinct PCDs were hydrothermally synthesized using phenylenediamine isomers as nitrogen dopants, exhibiting distinct fluorescence response patterns to target ions. Pattern recognition was performed using linear discriminant analysis (LDA) and hierarchical clustering analysis (HCA). The optimized system (pH 5–7) achieved high discrimination accuracy for eight metal ions (Sn²⁺, Ag⁺, Hg²⁺, Fe³⁺, Cr³⁺, Pb²⁺, Sb³⁺, and Cu²⁺) at 5–400 μM concentrations. The array effectively identified the binary and ternary mixtures of Hg²⁺/Cu²⁺/Cr³⁺ and successfully detected target ions in river water samples. This cost-effective and scalable approach demonstrates strong potential for applications in water quality monitoring and food safety. Full article

Next-generation wastewater treatment and recycling rely on membrane-based processes, but they face a trade-off among permeability, selectivity, and fouling resistance. In the present study, thin-film nanocomposite (TFN) membranes were fabricated by incorporating a ternary TiO₂-SiO₂-biochar nanofiller into a polysulfone (PSf) support using nonsolvent-induced phase separation, after which m-phenylenediamine and trimesoyl chloride were used via interfacial polymerization to produce a selective polyamide layer. The membrane compositions were M1 (22 wt.% PSf), M2 (22 wt.% PSf/0.5 wt.% TiO₂/0.5 wt.% SiO₂/0.5 wt.% biochar), and M3 (polyamide-coated M2). FTIR, XRD, SEM, contact-angle, porosity, and mechanical analyses supported successful membrane formation and changes in morphology, wettability, and structural strength after nanofiller incorporation and TFC coating. The addition of a nanofiller increased the hydrophilicity of the membranes by decreasing the water contact angle from 98.6 ± 0.8° for pristine PSf to 35.6 ± 1.5° for the nanocomposite membrane. Consequently, the pure-water permeability increased from 21 to 37 L m⁻² h⁻¹ bar⁻¹. After polyamide layer formation, the optimized TFN membrane maintained a contact angle of 55.4 ± 3.8° and achieved a high Congo red rejection of 98% with permeate flux of 7–9 L m⁻² h⁻¹ bar⁻¹. The membrane also showed good antifouling performance, with flux recovery ratios exceeding 90%. For heavy-metal-containing solutions, the optimized membrane showed apparent removal efficiencies of 78–98% for multivalent heavy metals (Pb²⁺, Hg²⁺, Cd²⁺, Mn²⁺, Zn²⁺, Cu²⁺, Ni²⁺, Fe³⁺, As³⁺, and Cr⁶⁺). Static adsorption tests showed the order M2 > M3 > M1, confirming that exposed TiO₂-SiO₂-biochar sites contribute to pollutant uptake, while the superior filtration performance of M3 is attributed to the combined effect of the polyamide selective layer and adsorption-assisted interactions. Overall, the TiO₂-SiO₂-biochar-based TFN membrane provides a promising platform for dye removal and preliminary heavy-metal attenuation from contaminated water. Full article

This study investigated rubber additives and relevant transformation products (RARTPs) in surface waters of Kaifeng, a city linking the Yellow River and Huaihe River basins. Seven of fifteen target analytes were detected in >10% of samples. The hydrolysis product 4-hydroxydiphenylamine (4OH) showed the highest detection frequency (70%), followed by 1,2-Dihydro-2,2,4-trimethylquinoline (TMQ, 57%) and N-(1,3-Dimethylbutyl)-N′-phenyl-p-phenylenediamine (6PPD, 27%). TMQ had the highest average concentration (6.16 ± 4.17 ng·L⁻¹). Urban rivers (14.20 ± 4.72 ng·L⁻¹) were contamination hotspots, driven by management practices (e.g., dredging of urban lakes). Although detected at lower levels (0.09 ± 0.21 ng·L⁻¹), 6PPD-quinone (6PPD-Q) was associated with elevated risk (risk quotient, RQ ≥ 1) at 19% of sites. The chronic daily intake assessment showed that drinking water ingestion contributed 66.7% of total exposure in daily use, whereas dermal absorption dominated during swimming. Children, especially girls, were the most vulnerable subgroup. Although estimated chronic daily intakes (CDIs) from surface water accounted for only a negligible proportion of the daily urinary excretion of p-phenylenediamine antioxidants (PPDs) reported in a Chinese population, the ecological risk of 6PPD-Q warrants continued attention. These findings highlight the need for improved management of water bodies receiving urban runoff and aquaculture inputs, and further health risk assessment of RARTPs. Full article

Luteolin and its derivative glycosides (cynaroside, orientin and isoorientin) are compounds with a flavonoid structure of plant origin. There are different studies in the literature on the antioxidant capacities of the structures and their inhibition effects on some enzymes. In this study, the antioxidant capacities of each structure were determined comparatively, and their inhibitory effects against enzymes associated with different diseases such as acetylcholinesterase, butyrylcholinesterase, α-glycosidase and α-amylase were evaluated by comparative investigation in vitro and in silico. Antioxidant capacities were determined for each structure by iron ions (Fe³⁺), cupric ions (Cu²⁺), Fe³⁺−Triphenyltetrazolium chloride (TPTZ) reduction methods and 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), N,N-dimethyl-p-phenylenediamine (DMPD) radical scavenging methods. According to the results obtained, it was determined that the antioxidant capacities of the structures were close to or better than butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), trolox, α tocopherol and ascorbic acid, which are used as standard antioxidants. The results of the study, which was conducted to determine the inhibition effects of the structures on the determined enzymes, were found to coincide experimentally and theoretically. According to the inhibition results, the best inhibitors were found as orientin (IC₅₀: 27.729 nM) for the human carbonic anhydrase I (hCA I), cynaroside (IC₅₀: 18.24 nM) for the human carbonic anhydrase I (hCA II), isoorientin (IC₅₀: 1.93 nM) for the acetylcholinesterase (AChE), and cynaroside (IC₅₀: 6.41 and 7.15 nM) for the butyrylcholinesterase (BChE) and α-glycosidase enzymes. Additionally, absorption, distribution, metabolism, and excretion (ADME) profiles and toxicity assessments of the structures were determined in a virtual environment. Full article

Template removal represents a critical yet often underexplored step in the fabrication of electropolymerized molecularly imprinted polymers (e-MIPs), directly influencing cavity integrity, selectivity, and sensor performance. In this review, we provide a comprehensive analysis of the most commonly employed template removal strategies, including immersion-based methods and electrochemical cleaning, with a particular focus on systems based on polypyrrole (PPy) and poly(o-phenylenediamine) (PoPD). We examine how template removal conditions, such as solvent composition, pH, and applied potential, affect polymer structure, doping state, swelling behavior, and electrochemical properties. Special attention is given to mechanistic aspects such as protonation/deprotonation, overoxidation, and polymer–template interactions, which govern both remotion efficiency and potential degradation pathways. By comparing PPy and PoPD systems, we highlight how intrinsic polymer properties dictate the suitability of specific removal strategies. Additionally, we discuss emerging approaches, including multi-step template removal protocols and the incorporation of conductive nanomaterials to mitigate performance loss. This work aims to provide a mechanistic perspective on how template removal conditions affect polymer structure, electrochemical properties, and the overall performance of e-MIP-based sensors. Full article

Three kinds of nitrogen-doped carbon quantum dots (N-CQDs) were successfully fabricated through a one-pot hydrothermal reaction at 180 °C for 12 h. L-lactic acid served as the carbon precursor, while three phenylenediamine isomers (o-phenylenediamine, m-phenylenediamine, p-phenylenediamine) were employed as nitrogen dopants, yielding samples denoted as OPD-LA, MPD-LA, and PPD-LA. All as-prepared N-CQDs presented uniformly dispersed spherical nanostructures, with average particle sizes of 8.2 nm (OPD-LA), 9.3 nm (MPD-LA), and 10.5 nm (PPD-LA). Abundant surface functional groups, including hydroxyl, carboxyl, amino, and amide moieties, endowed these N-CQDs with outstanding water solubility and tailorable fluorescence emission. The maximum emission wavelengths were centered at 550 nm, 505 nm, and 450 nm for OPD-LA, MPD-LA, and PPD-LA, respectively, exhibiting excitation-independent emission positions yet excitation-dependent intensity. MPD-LA delivered the highest fluorescence quantum yield of 9.59%, and the incorporation of lactic acid significantly elevated the quantum yield of all samples. The N-CQDs maintain high fluorescence intensity and favorable stability within the pH range of 4–11, possessing outstanding salt resistance and stable storage performance for six months. Their fluorescence was effectively quenched upon exposure to Fe³⁺, with a linear detection range of 10–100 μM and a low limit of detection (LOD) of 1.49 μM. These lactic acid-derived N-CQDs hold great promise as functional fluorescent probes for Fe³⁺ sensing applications. Full article

For agricultural films, spectral matching, UV protection, and environmental durability are essential for efficient crop production. A self-cleaning silane-crosslinked red/blue dual-emission carbon dot/polyvinyl alcohol composite film (KH/RB-CQDs/PVA) was fabricated via a covalent anchoring strategy. RB-CQDs were synthesized by a two-step hydrothermal method using o-phenylenediamine: initial blue-emitting carbon cores formed, then phosphoric acid-assisted secondary treatment covalently bridged residual precursor-derived red fluorophores onto cores through pyrophosphate bonds, as evidenced by TEM, XPS, ³¹P NMR, HPLC-MS and DFT. This rigid bridging suppressed excessive core growth and energy transfer while spatially separating dual emission, endowing excellent photostability (>95% fluorescence retention after 50 min UV and 30 d storage). Subsequently, KH-560 was employed to construct a robust covalent crosslinked network anchoring RB-CQDs in PVA and forming rough Si-O-Si surface structures, confirmed by SEM and XPS. The resulting film exhibited 16.16% quantum yield, 291% tensile strength enhancement, 95% UV shielding, and <1% contaminant residue. Chlorophyll fluorescence kinetics, gas-exchange analyses, and photosynthetic response curves demonstrated that KH/RB-CQDs/PVA increased the potato net photosynthetic rate by 55.46% and tuber yield by 76% through synergistic optimization of photosystem II electron transport and RuBisCO-mediated carbon assimilation. This work provides a molecular design principle for high-performance intelligent agricultural films. Full article

Forward osmosis (FO) membranes have garnered widespread research interest in water treatment, yet their permeability–selectivity trade-off, internal concentration polarization, and membrane fouling remain critical challenges. Herein, a chitooligosaccharide/polydopamine (COS/PDA) co-deposition strategy was proposed to modify polyethersulfone (PES) substrates for constructing high-performance thin-film composite (TFC) FO membranes. COS suppressed excessive PDA aggregation, reduced substrate roughness, and improved substrate hydrophilicity. This substrate modification regulated interfacial polymerization by increasing the adsorption capacity for m-phenylenediamine (MPD) while slowing its diffusion rate, thereby forming thinner, smoother, and more densely crosslinked polyamide (PA) layers. The optimized C₄P₁-TFC membrane delivered water fluxes of 42.2 and 23.5 L m⁻² h⁻¹ in pressure-retarded osmosis (PRO) and FO modes, respectively, representing 43.1% and 40.2% improvements over the pristine membrane. Its specific salt flux decreased to 0.07 and 0.15 g L⁻¹ in the two modes, respectively, suggesting enhanced selectivity. Meanwhile, the C₄P₁-TFC membrane showed antibacterial rates of 85.7% against Escherichia coli and 86.9% against Staphylococcus aureus, together with improved antifouling performance against bovine serum albumin and lysozyme. This work presents a simple and effective co-deposition approach for simultaneously improving the separation, antibacterial, and antifouling performance of TFC FO membranes, showing promising potential for practical applications. Full article

Ascorbic acid (AA) or vitamin C is an important biomolecule that plays a crucial role in biological and physiological systems. Deficiency and/or excess of AA in the body can lead to severe diseases such as scurvy and gastrointestinal complications. Therefore, it is crucial to monitor the levels of AA in the body and supplements. Polyvinylpyrrolidone nickel oxide nanoparticles (PVP-NiONPs) are prepared and evaluated for their potential as nanozymes with peroxidase-like activity. o-Phenylenediamine (OPD) was used as a chromogen in the presence of hydrogen peroxide. The oxidized OPD was produced by ROS from PVP-NiONPs and H₂O₂. This was monitored using UV-vis spectra and by colour changes using the naked eye. AA reduced the oxidized OPD during its sensing. The UV-vis signal was linear for AA concentrations ranging from 40 µM to 400 μM. The limit of detection (LOD) for AA was calculated to be 0.11 μM using 3σ and the limit of quantification (LOQ) was 0.36 μM using 10σ indicating a very high sensitivity. The colorimetric sensor showed good reproducibility and a recovery rate between 92.3% and 102.6%, indicating high accuracy and reliability. The findings of this work confirmed that PVP-NiONPs possess enzyme-like activity and are a promising alternative for the quantitative, on-site detection of ascorbic acid. Full article