Search Results (12,073)

Total flavonoids (TF) from Artemisia argyi, a traditional edible-medicinal Asteraceae herb, were extracted via a food-grade ternary deep eutectic solvent (TDES, Glycerol/Levulinic Acid/Xylitol = 1:1:1 molar ratio, 30% w/w water) under ultrasound assistance. A hybrid response surface methodology–genetic algorithm–artificial neural network (RSM-GA-ANN) model optimized parameters to deliver a maximum TF yield of 107.7 mg/g—1.5–1.8-fold higher than conventional hydroalcoholic extraction. Greenness was quantified by AGREEprep (score = 0.70) and MoGAPI (score = 80/100), confirming the method’s sustainability, with TDES retaining >84% extraction efficiency over three reuse cycles. Molecular dynamics simulations revealed TDES forms a more stable hydrogen bond network with plant cell walls (average H-bond lifetime: 101.279 ps vs. 46.698 ps for 50% ethanol), a finding validated by density functional theory calculations showing TDES establishes 7–9 hydrogen bonds with cellobiose (the cellulose repeating unit), far exceeding ethanol’s 1–2 hydrogen bonds. Purified TF exhibited potent radical-scavenging activity (DPPH IC₅₀: 0.176 mg/mL; ABTS IC₅₀: 0.159 mg/mL) and multipotent enzyme inhibition (α-glucosidase IC₅₀: 55.31 μg/mL; acetylcholinesterase IC₅₀: 0.618 mg/mL; pancreatic lipase IC₅₀: 0.125 mg/mL). TF also suppressed HCT116, A549, and HepG2 proliferation (IC₅₀ ≈ 50 μg/mL) and protected HepG2 cells against H₂O₂-induced oxidative damage. As an in silico probe, the predominant quantified flavonoid eupatilin (3.64 mg/g) docked to xanthine oxidase (−7.78 kcal/mol vs. allopurinol −6.86), offering a structural hypothesis for XO interaction without attributing mixture bioactivity to a single compound. This TDES-based platform offers a scalable, green route to valorize A. argyi for functional food and nutraceutical applications. Full article

The Sanchakou tremolite jade deposit in Qinghai Province represents a significant contact-metasomatic jade resource. Unlike typical contact-metasomatic (D-type) deposits—commonly associated with intermediate-to-acidic intrusions and magnesian carbonate protoliths—the Sanchakou deposit is genetically linked to a relatively SiO₂-poor gabbro intrusion and dolomite. This atypical geological setting raises fundamental questions concerning the sources of ore-forming components and the nature of metasomatic processes involved. To address these questions, this study integrates petrographic observations, whole-rock major- and trace-element geochemistry, and Sr isotopic analyses of tremolite jade, host dolomite wallrocks, gabbro, and their hydrothermally altered counterparts to constrain the origins of Ca, Mg, and Si and to reconstruct the metasomatic evolution of the system. Our results reveal a multi-sourced contribution to ore formation: Ca is derived exclusively from dolomite; >98% of Si originates from an external crustal fluid; and Mg is supplied predominantly (77%) from dolomite, with the remaining 23% sourced from altered gabbro. Strontium isotopic data further confirm the involvement of a gabbro-derived fluid characterized by elevated ⁸⁷Sr/⁸⁶Sr ratios but low Sr concentrations. A well-defined, continuous metasomatic sequence—comprising silicification → diopsidization → tremolitization → nephritization—is clearly documented. The deposit formed in a post-collisional extensional tectonic setting, driven by heat-induced double metasomatism. This study clarifies the provenance and evolutionary pathways of ore-forming materials in this atypical contact-metasomatic system and provides a genetic framework for analogous jade deposits associated with mafic intrusions. Full article

The physiological and functional responses of maize seedlings imbibed with zinc sulfate, commercial zinc oxide nanoparticles, and nanoparticles synthesized with Moringa oleífera, at 0, 5, 10, 15, 20, and 25 ppm, were evaluated. Vigor percentage, germination, abnormal seedlings, ungerminated seeds, plumule length and radicle length, dry plumule weight, and dry radicle weight were determined. In addition, phenolic concentration, antioxidant activity, and enzymatic activity were determined. ZnO NPs showed the highest %V and %G values (68.23% and 77.34%). ZnSO₄ limited plumule (19.30%) and radicle (23.95%) development as concentrations increased. The highest dry weight of plumule was obtained using ZnO M-NPs (42.99 mg), ZnSO₄ (48.92 mg), and ZnO NPs (51.89 mg) at 5 ppm, compared to the control (38.43 mg). ZnO M-NPs increased the content of free phenolics (9.26%) in the plumule, and ZnO NPs induced the highest accumulation of phenolics in the radicle (17.77%). Both NPs showed higher antioxidant capacity by the FRAP and ABTS methods in relation to control. ZnO M-NPs showed lower CAT activity in the plumule and radicle (1.06 and 1.39 U/g of FW at 5 and 25 ppm, respectively). ZnO NPs showed higher CAT activity in the plumule (3.85 U/g of FW at 5 ppm) and higher Apx activity in the radicle (6.15 U/g of FW at 20 ppm). The physiological and functional responses of maize seedlings depended on both the Zn source and concentration. Full article

In this work, a BiFeO₃/MoS₂ (BM) material was utilized to establish a piezophotocatalytic system under combined visible-light (Vis) illumination and mechanical stirring (MS), which synergistically activated peroxymonosulfate (PMS) toward the oxidation of 4-chlorophenol (4-CP), a representative refractory organic pollutant in water. Under mechanical stirring, the piezoelectric effect in BM generates a polarized electric field that promotes the separation of photogenerated electron–hole pairs, thereby providing more charge carriers for PMS activation and subsequent radical generation. The degradation performance, underlying mechanism, toxicity of degradation products, reusability, and applicability in different water matrices in the BM(1:3)/PMS process were comprehensively evaluated. The results indicated that BM(1:3) exhibited superior performance over other BM ratios (BM(2:1), BM(1:1), and BM(1:2)), achieving 91.6% removal of 4-CP within 30 min at a rotation speed = 1000 rpm, PMS = 2.0 mM, BM(1:3) = 0.5 mg/L, and initial 4-CP = 10 mg/L. Furthermore, water quality parameters exerted notable impacts on 4-CP decomposition. A pH of 4.7 was favorable, and the presence of Cl⁻ enhanced the 4-CP degradation, while HCO₃⁻ and H₂PO₄⁻ suppressed the removal efficiency; SO₄²⁻ and HA showed negligible influence. DFT calculations identified the reactive sites on 4-CP that are prone to attack by various reactive oxygen species (e.g., •O₂⁻, ¹O₂, •OH, and SO₄•⁻), resulting in the transformation of 4-CP through three degradation pathways into smaller organic intermediates, most of which were less toxic than 4-CP. The BM(1:3) catalyst exhibited satisfactory reusability; however, a significant decrease in 4-CP degradation efficiency was observed in the lake water matrix. Overall, the synergy between photocatalysis and the piezoelectric effect in the BM(1:3)/PMS system offers a useful research foundation for the piezophotocatalytic degradation of persistent organic pollutants such as 4-CP. Full article

Tetracycline (TC) is a widely used antibiotic that is frequently detected in rivers, lakes and wastewater. Because TC is poorly removed by conventional biological treatment, its residues can harm aquatic organisms and promote the spread of antibiotic resistance; efficient and low-cost technologies for removing TC from water are therefore needed. In this study, copper smelting slag (CSS), an abundant industrial solid waste, was converted into a catalyst composed of Fe₃O₄ particles loaded on mesoporous silica (denoted Fe₃O₄@MS) via an alkali fusion–hydrothermal method. The catalyst was used to activate peroxymonosulfate (PMS), forming the Fe₃O₄@MS/PMS treatment system for the degradation of TC in aqueous solution. The effects of the main operating parameters (catalyst dosage, PMS concentration, initial pH and reaction temperature) on TC degradation were systematically evaluated. Under the optimized conditions (catalyst 0.5 g/L, PMS 1.0 mmol/L, initial pH 6.5, 25 °C), the Fe₃O₄@MS/PMS system removed 98.70% of 50 mg/L TC within 60 min. Radical quenching experiments and electron paramagnetic resonance (EPR) analysis revealed that TC was degraded through both radical pathways (hydroxyl •OH, sulfate SO₄^•− and superoxide O₂^•− radicals) and a non-radical pathway involving singlet oxygen (¹O₂), with •OH being the dominant reactive species. Nine degradation intermediates were identified by liquid chromatography–mass spectrometry (LC-MS), based on which three degradation pathways were proposed. Toxicity estimation indicated that ring-opening and deamination reactions are the key steps for detoxification. In addition, a life cycle assessment (LCA) across five selected impact categories identified the main environmental burdens associated with catalyst production. Overall, this work demonstrates that CSS-derived Fe₃O₄@MS is an efficient, low-cost and sustainable catalyst for PMS-based antibiotic removal from water, offering a circular-economy approach that couples solid-waste valorization with clean water production. Full article

The compact muscle architecture and poor aqueous dispersibility of Sthenoteuthis oualaniensis protein limit its use as a food ingredient. This study developed a gel filtration chromatography (GFC)-guided papain–alcalase sequential hydrolysis strategy using target-window peak area ($A_{\mathrm{target}}$) as a peptide-distribution response. Box–Behnken optimization identified an enzyme dosage of 1110 U/g, a papain/alcalase mass ratio of 3:5, and 8 h hydrolysis, yielding an $A_{\mathrm{target}}$ of 0.0648 ± 0.0012 a.u. O-phthaldialdehyde (OPA)-derived degree of hydrolysis (DH) values were 10.72 ± 0.08%, 35.32 ± 0.12%, and 25.03 ± 0.37% for SPH-Pap, SPH-Alc, and SPH-opt, respectively, showing that the highest $A_{\mathrm{target}}$ did not coincide with the highest DH. The essential-to-total amino acid ratio remained 38.18–39.20%, while lysine and methionine changed modestly. SPH-opt maintained high solubility across a broad pH range and exhibited a peptide profile distinct from those of the single-enzyme hydrolysates. Radical-scavenging capacity was assessed only post-optimization. At 5 mg/mL, SPH-opt showed DPPH and ABTS scavenging rates of 23.75% and 22.84%, respectively; without external standards, these values support only relative within-study comparisons. Overall, $A_{\mathrm{target}}$ and DH provided complementary information on peptide distribution and bond cleavage, and no causal relationship between $A_{\mathrm{target}}$ and radical-scavenging capacity was established. Full article

Fe^II-doped zinc ferrite nanocrystals (Fe^II_xZn_1-xFe^III₂O₄) were prepared via a sol–gel approach in the presence of polyvinyl alcohol as a stabilizer and assessed for their capability to eliminate crystal violet (CV) dye from water-based solutions. The structural and surface characteristics of the prepared materials were examined by XRD, HRTEM, FESEM, ATR–FTIR, XPS, UV–visible spectrophotometer and BET analyses. XRD patterns confirmed the formation of a cubic spinel ferrite structure (Fd-3m), indicating successful incorporation of Fe^II into the ZnFe₂O₄ lattice. ATR–FTIR spectra showed characteristic metal–oxygen vibrations at the tetrahedral and octahedral sites. XPS analysis confirmed the coexistence of Fe^II and Fe^III species, which may promote interfacial charge transfer and redox reactions. HRTEM and FESEM images showed particle agglomeration and grain growth after calcination at 700 °C. Fe^II_0.2Zn_0.8Fe^III₂O₄ exhibited the highest photocatalytic performance, achieving 97.2% degradation of CV under optimized conditions. The effects of contact time, catalyst dosage, initial dye concentration, and pH were systematically studied. The maximum removal efficiency was obtained at pH 10 using 0.075 g catalyst for 20 mg L⁻¹ CV solution within 40 min. Freundlich isotherm models exhibited the strongest correlation (R² = 0.918), pointing to multilayer adsorption occurring across a non-uniform nanoparticle surface. The Dubinin–Radushkevich analysis returned an adsorption energy of 3.01 kJ mol⁻¹, implying that physical forces predominantly control the adsorption mechanism. Kinetic investigations revealed a two-stage CV uptake pathway: fast initial binding at exterior surface sites, succeeded by a slower migration of dye molecules into the internal pores of the adsorbent. Full article

Although the Pacific oyster (Crassostrea gigas) is a premium marine protein source, its neuroprotective peptidome remains largely uncharacterized. This study established an integrated in silico and in vitro pipeline to discover acetylcholinesterase (AChE)-targeting peptides with cellular AChE-regulating and neuroprotective peptides from simulated gastrointestinal digests of oyster. Peptidomic profiling identified 18,292 sequences, which were filtered down to seven candidates predicted to have favorable blood–brain barrier (BBB) permeability and to be non-toxic and non-allergenic (VPYPR, VPVHF, HHTF, PVHF, GPKPW, HWF, and KYW) via multi-step virtual screening. In cellular assays, simulated H₂O₂ injury (500 μM) reduced PC12 cell viability to 47.53 ± 4.53%. Compared with the model group, pretreatment with the three most potent candidates—HHTF, VPYPR, and VPVHF (200 μM)—significantly rescued injured cells, restoring cell viability to 88.31 ± 7.83%, 85.12 ± 3.35%, and 82.00 ± 3.47%, respectively (p < 0.05). These peptides effectively fortified cellular antioxidant defenses by increasing glutathione (GSH) levels to 24.24, 30.11, and 26.83 nmol/mg protein (from 20.22 nmol/mg protein in the model group) and superoxide dismutase (SOD) activity to 151.41, 153.97, and 151.96 U/mg protein (from 119.33 U/mg protein), while suppressing malondialdehyde (MDA) accumulation to 0.088, 0.064, and 0.086 nmol/mg protein (from 0.193 nmol/mg protein). Crucially, the peptides alleviated cholinergic dysfunction by normalizing the H₂O₂-induced elevation of intracellular AChE activity (11.39 nmol/min/mg protein) down to 7.02, 6.22, and 7.14 nmol/min/mg protein, respectively. Specifically, VPYPR (200 μM) restored AChE activity to a level (6.22 nmol/min/mg protein) that was not significantly different from that in the normal control group (p > 0.05). Molecular dynamics (MD) simulations (100 ns) and molecular mechanics Poisson–Boltzmann surface area (MM-PBSA) calculations identified VPYPR as the leading candidate with a remarkably low binding free energy of −49.74 ± 3.58 kcal/mol. This study demonstrates that oyster gastrointestinal digests are valuable reservoirs of multi-target neuroprotective ingredients and provides an efficient strategy for marine bioactive peptide discovery. Full article

Background/Objectives: Exercise in hypoxic environments induces greater physiological stress than normoxic conditions, potentially limiting exercise performance through reduced skeletal muscle oxygenation and increased metabolic strain. Beetroot juice (BRJ), a dietary source of inorganic nitrate, may enhance nitric oxide (NO) bioavailability and oxygen delivery under hypoxic conditions. This study examined the acute effects of BRJ supplementation on metabolic responses, skeletal muscle oxygenation, and cardiac function during submaximal exercise at a fixed heart rate under normoxic and hypoxic conditions. Methods: Twelve healthy adult males completed four conditions in a randomized, crossover design, with double-blinding applied to the supplementation condition: normoxic condition + placebo (NPLA), normoxic condition + BRJ (NBRJ), hypoxic condition + placebo (HPLA), and hypoxic condition + BRJ (HBRJ). Participants ingested 70 mL of BRJ (400 mg NO₃⁻) or placebo 2.5 h before 30 min of submaximal exercise at 70% HRmax under normoxic (FiO₂ 20.9%) or hypoxic (FiO₂ 14.5%) conditions. A two-way repeated-measures ANOVA was used to test the main effects of environment and treatment and their interaction for each outcome. Results: Hypoxic conditions required a significantly lower mechanical load and induced greater physiological stress. However, a significant environment × treatment interaction was observed for Deoxy_Hb, with HBRJ statistically indistinguishable from normoxic conditions, indicating a clear attenuation of the hypoxia-induced increase in oxygen extraction. In addition, a significant main effect of treatment without a significant interaction was observed for RER, and HBRJ did not differ significantly from NBRJ. Conclusions: BRJ supplementation may help attenuate hypoxia-induced skeletal muscle deoxygenation, as reflected in Deoxy_Hb, potentially via NO-mediated mechanisms; however, as circulating nitrate/nitrite concentrations were not directly measured and interaction effects were not confirmed for most variables, these findings should be regarded as preliminary evidence for the potential use of BRJ as a nutritional strategy in hypoxic exercise settings. Full article

Understanding hydrogeochemical change after coal mine closure is needed to protect groundwater in multi-layer aquifer systems, but predictions that span decades are scarce. Earlier FEFLOW–PHREEQC studies of mine hydrogeochemistry have reduced the subsurface to one aquifer, so they cannot resolve the goaf-to-aquifer transport that governs post-closure risk. This study presents a decadal-scale (10-year) reactive transport simulation for a 9-layer mine system with layer-specific kinetics, a step beyond the single-aquifer simplifications of earlier applications. We modeled groundwater rebound and water–rock interaction at a permanently closed deep coal mine in Xuzhou, China, with a three-dimensional FEFLOW–PHREEQC framework. The four aquifers (Q, 7S, L4, O) each received their own reactive parameters, so the goaf and surrounding units were coupled yet chemically distinct. Pyrite-driven acid mine drainage was set as a non-point source in the mined-out zone, with initial pH 2.1 and pyrite content 0.225 mol/L. pH in the stope rose from 2.1 to 5.6 in 5 years and to 6.6 at year 10, a result of fast neutralization by carbonate-buffered alkaline water. Sulfate and total Fe in the overlying 7S aquifer rose without interruption, and Fe passed the 0.3 mg/L drinking-water limit in every monitored aquifer (0.34 to 14 mg/L). Plumes stayed within the mined area for the first 5 years, then moved down-gradient toward dewatering centers. A sensitivity test found that longitudinal dispersivity and porosity controlled SO4²⁻ transport, while transverse dispersivity had little effect. The 7S aquifer is the most vulnerable receptor of post-closure contamination. The deep Ordovician aquifer stayed stable because carbonate buffering and hydraulic isolation protected it. Because each aquifer carries its own parameters, the framework transfers to other abandoned coalfields and supports long-term groundwater-quality forecasting there. Full article

Historical mining districts are long-term sources of environmental contamination, especially where agriculture and grazing occur near mining areas. This study evaluates mercury (Hg) and other potentially toxic elements (PTEs) in soils from Solana de Peñarrubia, within the Almadén mining district (Spain). Thirty-four soil samples collected using a regular staggered grid were analyzed for total Hg and major oxides and selected trace elements. Spatial patterns were evaluated using Kriging interpolation, hierarchical clustering, PCA, and the geoaccumulation index, after standardizing variables to minimize differences in magnitude among them. Thermal desorption and microscopy were performed on three selected high-Hg samples, with thermal assignments interpreted as operational rather than definitive mineralogical identifications. Hg concentrations ranged from 10 to 994 mg kg⁻¹, with the highest values in the northern sector. The PCA separated cropland soils, associated mainly with lithological variables, from soils with anthropogenic inputs related to Hg, Pb, SO₃, and SiO₂. The geoaccumulation index indicated Hg enrichment, reaching the extremely polluted category at the maximum concentration. Thermal desorption profiles were dominated by fractions within the reference range of α-HgS, accounting for 78.27–87.44% of the estimated relative abundance, while microscopic examination revealed particles consistent with cinnabar in high-Hg samples. The Hg anomaly showed no straightforward relationship with the mapped local lithology and may partly reflect, as a working hypothesis, the possible redistribution of Hg-bearing mineralized materials associated with historical mining or metallurgical activities. Full article

Nitrogen (N) sources affect forage production, soil N dynamics, and greenhouse gas (GHG) emissions. This study evaluated short-term effects of contrasting N sources on forage responses, soil health indicators, and GHG emissions in a cool-season oat (Avena sativa L.) and annual ryegrass (Lolium multiflorum L.) system. Treatments were T1 (grass only), T2 (grass + N), T3 (grass + legume), T4 (grass + poultry litter), and T5 (grass + cattle dung). Crude protein was greater in T3 than in T4 (18% versus 13%; p = 0.02). In May, T3 had the greatest microbial C:N ratio (60.6) and soil inorganic N (45.5 mg N kg⁻¹; p < 0.01). Potentially mineralizable N was greater in T3 than in T1, T2 and T4 (3.96 versus ≤ 2.71 mg NH₄-N kg⁻¹ day⁻¹; p < 0.01). Mean daily CH₄ fluxes were greater (p < 0.01) under T5 (1106 g CH₄-C ha⁻¹ day⁻¹) than under T1 and T3 (≤−3.59 g CH₄-C ha⁻¹ day⁻¹). Mean daily CO₂ fluxes were lower in T3 and T4 than in T1, T2, and T5. There were no effects on N₂O emissions. Legume integration enhanced short-term N cycling and forage nutritive value, without N₂O emissions, over a 60-day experiment. Full article

Citrus × aurantium ‘Daidai’ (Citrus aurantium L. var. amara Engl.) is a sour orange cultivar whose dried flower buds are listed in the Chinese national catalogue of substances that serve both as food and as medicine, whereas the dried flower buds of the ordinary species C. × aurantium L. lack this dual recognition. Although the essential oil and hydrosol of these buds have been investigated, the still-bottom water remaining after hydrodistillation is routinely discarded and its chemical composition remains largely unexplored. In this study, we compared the chemical profiles of still-bottom water obtained from the dried flower buds of C. aurantium L. var. amara Engl. (CAVAF) and C. × aurantium L. (CALF) after two pretreatments (simple soaking vs. ultrasonic-microwave synergistic treatment) and evaluated the chemical antioxidant activities of both the hydrosol and the still-bottom water. HPLC-Q-TOF-HRMS identified 215 compounds across the four water samples. The major constituents were neohesperidin (13.18–39.66%), blumeatin (9.78–10.25%), narirutin (13.46–18.01%), and α-D-(6-O-Sinapoyl)-glucopyranosyl(1→22)-β-D-(3-O-sinapoyl)-fructofuranose (7.46–8.57%). Relative to CALF, the CAVAF samples contained a large number of annotated compounds and higher relative amounts of several flavonoids and limonoids (up to nine-fold) in the still-bottom water. Higher relative abundances of the principal flavonoid glycosides were observed after ultrasonic-microwave pretreatment compared with soaking. The hydrosol of both varieties showed only modest radical scavenging activity and weak reducing power. In contrast, the still-bottom water exhibited clear DPPH, ABTS, and hydroxyl radical scavenging, with half-maximal inhibitory concentrations ranging from 0.1901 to 4.873 mg/mL, although reducing power remained limited. These findings suggest that botanical variety and pretreatment method may influence both the metabolite profile and the in vitro radical scavenging behavior of the distillation by-products. The results supply chemical compositional support for the food-medicine homology status of CAVAF and indicate that still-bottom water is a recoverable source of potential polar antioxidants that is currently under-utilized. Full article

The increasing use of electric vehicles has led to a growing demand for rare-earth elements, particularly neodymium (Nd), which is a critical component of Nd–Fe–B permanent magnets used in traction motors. End-of-life electric vehicle motors are therefore considered promising secondary resources for Nd recovery. In this study, a pyrometallurgical process using non-ferrous smelting slag as a flux was proposed for recovering Nd from Nd–Fe–B magnets contained in waste electric vehicle motors. Steel and magnet fractions obtained from a dismantled motor were melted at approximately 1600 °C under an air atmosphere, and Fe₂O₃ was added as an oxidizing agent to promote the selective oxidation of Nd. The oxidized Nd was subsequently partitioned into the slag phase as Nd₂O₃ through metal–slag separation. The effects of the slag flux addition ratio, Fe₂O₃ content, slag flux type, and crucible material on Nd recovery behavior were systematically investigated. Increasing the fayalite-based slag flux addition enhanced Nd transfer into the slag phase, and the highest Nd recovery of approximately 80% was obtained at a slag flux addition ratio of 30 wt%. The addition of 2 wt% Fe₂O₃ was found to be suitable for promoting stable Nd oxidation and efficient slag–metal separation. The non-ferrous smelting slag exhibited chemical and phase characteristics comparable to those of synthetic fayalite slag flux, resulting in similar Nd recovery performance. In addition, the crucible material significantly affected the process stability and Nd recovery behavior. Although a carbon crucible showed relatively high Nd recovery, severe slag foaming and crucible erosion occurred during melting. In contrast, alumina and MgO crucibles provided stable process conditions with comparable Nd recovery behavior, whereas zirconia crucibles caused relatively higher Nd loss. These results demonstrate that non-ferrous smelting slag can be effectively used as a flux for the pyrometallurgical recovery of Nd from end-of-life electric vehicle motors, offering a potential route for sustainable rare-earth recycling. Full article

Photodynamic therapy (PDT) exploits photoactivated materials that generate reactive oxygen species (ROS) to induce selective cancer cell death. Nitrogen-doped carbon dots (N-CDs) have emerged as promising photosensitizers owing to their favorable optical properties, while hybridization with titanium dioxide (TiO₂) may further enhance photoinduced ROS generation through improved charge separation. Here, we synthesized a series of N-CD/TiO₂ hybrid composites with varying TiO₂ content using a hydrothermal approach and systematically investigated the relationship between their physicochemical characteristics and biological activity. The hybrid materials were characterized by Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, dynamic light scattering, and UV–visible spectroscopy. Among the formulations investigated, the composite containing 90% N-CDs and 10% TiO₂ (N-CDs10T) exhibited the smallest hydrodynamic diameter, a relatively narrow particle size distribution, favorable optical properties, and the strongest irradiation-dependent biological responses. Biological activity was evaluated in A549 lung adenocarcinoma and Kelly neuroblastoma cells. Under dark conditions, all formulations displayed relatively low intrinsic cytotoxicity. Following irradiation with 365 nm UVA light, however, N-CDs10T induced a marked increase in intracellular ROS production, activation of antioxidant response element (ARE)-dependent signaling, disruption of cell-cycle progression, apoptosis-associated cell death, and inhibition of cell proliferation and migration. Kelly cells exhibited greater sensitivity than A549 cells, with IC₅₀ values decreasing from 0.98 mg/mL under dark conditions to 0.52 mg/mL following irradiation. Collectively, these findings demonstrate that N-CD/TiO₂ hybrid composites function as photoresponsive materials that enhance ROS-mediated cytotoxicity upon light activation. Beyond demonstrating phototoxicity, this study systematically links hybrid composition with oxidative stress signaling and multiple cellular responses, providing a comprehensive biological evaluation of N-CD/TiO₂ hybrid materials. While additional studies are required to identify the predominant ROS, evaluate selectivity in non-malignant cells, and optimize activation at clinically relevant wavelengths, the present work establishes a proof of concept for the development of N-CD/TiO₂ hybrid composites for photodynamic applications. Full article