RSC Advances最新文献

This work presents the utilization of a hydrothermal treatment and a reduction reaction to synthesize a heterogeneous ZnO nanoplate (NPl)/Ag nanoparticle (NP) nanostructure for application in surface-enhanced Raman scattering (SERS). Under hydrothermal conditions, at 180 °C and 20 h, ZnO NPls with a thickness of 40 nm and edgewise size of 200 nm × 350 nm were prepared from precursors containing zinc acetate (CH₃COO)₂Zn and sodium hydroxide (NaOH). Then, Ag NPs with an average diameter of 17 nm were deposited onto the surface of the ZnO NPls by reducing AgNO₃ using trisodium citrate (TSC). The structural, morphological, and compositional behaviors of the prepared heterostructure were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and energy dispersive X-ray spectroscopy (EDS). The optical properties of the as-prepared products were analyzed using Raman, ultraviolet-visible (UV-Vis) absorption and Fourier transform infrared (FTIR) spectroscopies and photoluminescence (PL) technique. Results confirmed the formation of a ZnO NPl/Ag NP heterostructure, with the Ag NPs adhering to the surface of the 2D semiconducting ZnO NPls. The SERS signal from the chemisorbed indigo carmine (IC) molecules on the ZnO/Ag surface was observed at various concentrations between 5 × 10⁻⁹ M and 10⁻⁴ M. The produced SERS substrate demonstrated superior SERS performance in detecting IC, with a low limit of detection (LOD) of 5 × 10⁻⁹ M, a high enhancement factor (EF) of 1.57 × 10⁵, and good uniformity with a relative standard deviation (RSD) of 3.6%. Raman scattering signals from IC adsorbed on this ZnO/Ag heterostructure showed a significant enhancement compared with those of the same molecules adsorbed on a glass substrate. The surface-enhanced Raman scattering of ZnO/Ag was owing to the hotspots at the Ag NPs and effective charge transport among plasmonic Ag NPs, semiconducting ZnO NPls, and the IC molecules. The most captivating aspect of this study is that the molecular structure of IC was compared using computational and experimental methods; in particular, density functional theory (DFT) calculations using the B97 (d,p) basis set were performed to obtain the optimized geometric structure and frontier molecular orbital of IC molecules. This study provides definitive experimental validation underpinning the phenomenon of SERS on metal oxide semiconductor/noble metal hybrids, which can effectively enhance Raman signals owing to the synergistic action of the electromagnetic (EM) and chemical (CM) mechanisms.

Hydrothermal carbonization (HTC) research has mainly focused on primary char production, with limited attention to secondary char, which is formed through polymerization and condensation of dissolved organic compounds in the liquid phase. This research aims to address this gap via an experimental investigation of the impact of stirring on the mass and carbon balance of HTC reaction products, surface functional groups, and surface morphology of secondary char, using fructose as a model compound. A 3D hydrodynamic simulation model was developed for a two-liter HTC stirred reactor. The experimental results indicated that stirring did not significantly influence the pH, mass, carbon balance, and surface functional groups of secondary char produced under the range of experimental conditions (180 °C, 10% biomass to water (B/W) ratio, and a residence time of 0–120 min) studied. Nonetheless, it was observed that a stirring rate of 200 rpm influenced the morphology and shape of the secondary char microspheres, leading to a significant increase in their size i.e., from 1–2 μm in unstirred conditions compared with 70 μm at a stirring rate of 200 rpm. This increase in size was attributed to the aggregation of microspheres into irregular aggregates at stirring rates > 65 rpm and residence times > 1 h. The hydrodynamic model revealed that high turbulence of Re > 10⁴ and velocities > 0.17 m s⁻¹ correlated with regions of secondary char formation, emphasizing their role in particle aggregation. Particle aggregation is significant above a stirring rate of 65 rpm, which corresponds to the onset of turbulent flow in the reactor. Finally, a mechanism is proposed, based on reactor hydrodynamics under stirred conditions, that explains secondary char deposition on the reactor walls and stirrer.

The rising threat of multidrug-resistant tuberculosis, caused by Mycobacterium tuberculosis, underscores the urgent need for new therapeutic solutions to tackle the challenge of antibiotic resistance. The current study utilized an innovative 3R infection model featuring the amoeba Dictyostelium discoideum infected with Mycobacterium marinum, serving as stand-ins for macrophages and M. tuberculosis, respectively. This high-throughput phenotypic assay allowed for the evaluation of more specific anti-infective activities that may be less prone to resistance mechanisms. To discover novel anti-infective compounds, a diverse collection of 1600 plant NEs from the Pierre Fabre Library was screened using the latter assay. Concurrently, these NEs underwent untargeted UHPLC-HRMS/MS analysis. The biological screening flagged the NE from Stauntonia brunoniana as one of the anti-infective hit NEs. High-resolution HPLC micro-fractionation coupled with bioactivity profiling was employed to highlight the natural products driving this bioactivity. Stilbenes were eventually identified as the primary active compounds in the bioactive fractions. A knowledge graph was then used to leverage the heterogeneous data integrated into it to make a rational selection of stilbene-rich NEs. Using both CANOPUS chemical classes and Jaccard similarity indices to compare features within the metabolome of the 1600 plant NEs collection, 14 NEs rich in stilbenes were retrieved. Among those, the roots of Gnetum edule were flagged as possessing broader chemo-diversity in their stilbene content, along with the corresponding NE also being a strict anti-infective. Eventually, a total of 11 stilbene oligomers were isolated from G. edule and fully characterized by NMR with their absolute stereochemistry established through electronic circular dichroism. Six of these compounds are new since they possess a stereochemistry which was never described in the literature to the best of our knowledge. All of them were assessed for their anti-infective activity and (−)-gnetuhainin M was reported as having the highest anti-infective activity with an IC₅₀ of 22.22 μM.

Oak (Quercus spp.) acorns are used in animal feed and in the treatment of specific diseases due to their nutritional value and high content of bioactive compounds. The aim of the present work is to investigate and compare polyphenolic compounds and the antioxidant activity of Quercus ilex and Quercus robur acorn extracts. This is performed using the matrix solid-phase dispersion (MSPD) extraction process, in an environmentally friendly way with different generally recognised as safe (GRAS) solvents. The GRAS solvents considered were an alcohol, a ketone, an ester and a glycol. Total polyphenolic content (TPC) and antioxidant activity (DPPH and ABTS scavenging test) were determined spectrophotometrically. The different antioxidant data obtained by two approaches are discussed. All Quercus robur extracts show better results than Quercus ilex in both total polyphenolic content and antioxidant activity, the highest results being obtained with ethyl lactate, 76 mgGAE g⁻¹ DW and 2636 μmolTE g⁻¹ DW, respectively. These results demonstrate the correlation between total polyphenolic content and antioxidant activity, and that free radical scavenging is concentration dependent. Individual quantification of the polyphenols was performed by liquid chromatography-tandem mass spectrometry (LC-MS/MS), with the major compounds being gallic acid, ellagic acid, catechin, quercetin and gallotannins in all extracts. MSPD, for the first time applied to acorns, has proven to be a good alternative to conventional processes for obtaining antioxidant extracts rich in bioactive compounds.

In the context of sustainable development, the utilization of semiconductor materials for the degradation of dyes, antibiotics, heavy metals, and pesticides in wastewater under visible light has emerged as a focal point of contemporary research. In this investigation, a WO₃@TiO₂ composite was synthesized via a solvothermal method, with the composite exhibiting a molar ratio of 5% WO₃ to TiO₂ precursors demonstrating optimal photocatalytic degradation performance. This material achieved complete degradation of 20 mg per L Rhodamine B (RhB) dye and tetracycline (TC) antibiotic within 30 min. Furthermore, the effects of initial pollutant concentration and solution pH on catalytic efficacy were systematically explored. The findings revealed that at RhB concentrations below 40 mg L⁻¹, the degradation proceeded at an accelerated rate, with a rate constant exceeding 0.128 min⁻¹. The catalyst exhibited robust performance across a broad pH range, attaining peak degradation efficiency at pH ≈ 3. The exceptional photocatalytic prowess of the WO₃@TiO₂ composite is predominantly attributable to its distinctive hollow microstructure, the intimate interfacial synergy between WO₃ and TiO₂, and the efficient separation of photogenerated electrons and holes facilitated by the type-II heterojunction architecture.

In this study, we developed a biosensor using a gold screen-printed electrode (Au-SPE) functionalized with mercaptoundecanoic acid (MUA) and an antibody for detecting the vascular-endothelial cadherin (CD144) as a endothelial biomarker protein on extracellular vesicles (EVs) isolated from saliva. The MUA functionalization provides a stable platform for immobilizing the CD144 antibody, ensuring the detection of the target protein. This biosensor combines Au-SPE technology with an immunoassay, offering a rapid, sensitive, and non-invasive method for detection of CD144 carried by EVs. Characterization of saliva-derived EVs using transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA) confirmed their morphology and size, which fell within the expected range of 80–180 nm. NTA indicated a lower concentration of particles in saliva-EVs than in serum-EVs (controls), highlighting the need for sensitive detection of EV cargos in this type of EV. Immunodetection confirmed the presence of CD144 in both saliva and serum-derived EVs, with higher concentrations in serum. Functionalization of Au-SPEs with MUA and CD144 antibodies was confirmed by significant resistance changes, and atomic force microscopy (AFM) was used to verify the preservation of EV morphology and their capturing post-immune adsorption. A calibration curve demonstrated the high sensitivity of the biosensor prototype for detecting CD144-positive EVs, with a limit of detection (LOD) of 0.111 ng mL⁻¹ and a limit of quantification (LOQ) of 0.37 ng mL⁻¹, requiring only 3 μL of EV-sample. This biosensor shows potential as a novel method for detecting and studying endothelial biomarkers associated with cardiovascular disease in EVs isolated from saliva, a capability not currently available with existing tools. Furthermore, it provides a key platform for expanding research to other biomarkers and diseases by monitoring protein cargos in the EVs, enhancing its utility across diverse clinical applications.

In this study, we fabricated Nd-based PL composites by embedding Nd compounds in a transparent resin and investigated the relationship between the size of Nd-based particles and PL properties. Nd(III)-based photoluminescent composite films were fabricated using neodymium nitrate hexahydrate and transparent urethane resin. The resulting Nd-based composite film was pale blue in color. The composite films exhibited near-infrared PL properties with a peak at 1.06 μm (⁴F_3/2 → ⁴I_11/2) by irradiation with UV-visible-near-infrared light using a halogen lamp. In the case of the composite film, further irradiation with UV light (using a Hg lamp) for 2 h or less resulted in the film showing strong PL at 1.06 μm under halogen lamp irradiation. Upon UV irradiation for more than 2 h, the film turned brown owing to the reaction of urethane with nitric acid derived from the Nd raw material, and the PL intensity became weaker. The Nd₂O₃ nanoparticles in the composite film were measured using transmission electron microscopy, and the particle size ranged from 15.0–35.1 nm. The PL intensity of the composite films was strongest when the size of the Nd-based particles was approximately 20 nm.

A novel series of quinoxaline derivatives was designed and synthesized to target VEGFR-2, a receptor critical in cancer progression, with a focus on favorable pharmacophoric features. Among these derivatives, compound 11d emerged as a promising candidate, exhibiting potent cytotoxicity against MDA-MB-231 and MCF-7 cancer cell lines, with IC₅₀ values of 21.68 μM and 35.81 μM, respectively, while displaying significantly reduced toxicity in normal cell lines WI-38 and WISH (IC₅₀ values of 82.46 μM and 75.27 μM). Compared to standard treatments doxorubicin and sorafenib, compound 11d demonstrated a favorable therapeutic window. Inhibition assays showed that 11d inhibits VEGFR-2 with an IC₅₀ of 62.26 nM ± 2.77, comparable to sorafenib. Mechanistically, treatment with 11d upregulated pro-apoptotic markers BAX, caspase-8, and caspase-9, while downregulating the anti-apoptotic marker Bcl-2, resulting in a significant BAX/Bcl-2 ratio increase (16.11). A wound healing assay confirmed 11d's anti-migratory effects, limiting wound closure in MDA-MB-231 cells to 27.51% compared to untreated cells. Additionally, flow cytometry revealed that 11d induced both early (46.43%) and late apoptosis (31.49%) in MDA-MB-231 cells, alongside G1 phase cell cycle arrest, reducing S and G2/M phase progression. Molecular docking and dynamics simulations over 200 ns demonstrated stable binding of compound 11d to VEGFR-2, with docking scores superior and comparable to sorafenib. Density Functional Theory (DFT) calculations underscored 11d's stability and reactivity, while in silico ADMET analysis predicted a favorable safety profile over sorafenib, particularly with respect to carcinogenic and chronic toxicity risks. These findings indicate that quinoxaline derivative 11d holds potential as a selective and effective VEGFR-2 inhibitor with promising antitumor and anti-metastatic properties, warranting further investigation.

Color vision deficiency, or color blindness, is an ocular condition in which individuals have difficulty distinguishing between certain colors. While there is currently no cure for this condition, various wearables can be used to improve the color perception of those affected. The most common wearables used are color-filtering glasses and lenses, which filter out the problematic wavelengths. The most prevalent form of color vision deficiency is red-green color blindness. In this study, gold nanoparticles were in situ reduced onto contact lens material, forming plasmonic contact lenses targeted for red-green color blindness management. The absorption of the plasmonic particles, which peaked at around 533 nm, filtered out specific wavelengths to significantly enhance the color perception of both deuteranopia and protanopia. The study also presented an approach of imaging through the plasmonic lenses, followed by color blindness vision simulation to replicate a colorblind individual's vision. When combined with the Ishihara test, this approach proved to effectively improve color perception with the use of plasmonic contact lenses. The study presents a facile method for creating stable, hydrophilic plasmonic contact lenses to manage color blindness. It also offers a unique way to simulate the impact of color filtering on the vision of individuals with color blindness.

Hyaluronic acid-coated capecitabine-loaded nanomicelles (HA-CAP-M) are synthesized to overcome the challenges associated with capecitabine (CAP) conventional delivery such as low permeability and systemic toxicity. Nanomicelles containing saponin, glycerol, and vitamin-E TPGS formulation of capecitabine were further encapsulated with hyaluronic acid (HA) for CD44 receptor-mediated targeting. Optimization of the formulation was carried out using a Box–Behnken design resulting in 17.8 nm particle size, 89.3% entrapment efficiency and a biphasic drug release profile. Characterization studies validated stability, spherical structure, and desirable encapsulation characteristics of the nanomicelles. Lowered critical micelle concentration (CMC) and acceptable drug release kinetics revealed improved thermodynamic stability and controlled drug release, as predicted by the Hixson–Crowell model. HA-CAP-M showed much higher permeability and cytotoxicity than the free CAP, with an IC₅₀ of 2.964 μg mL⁻¹ in in vitro experiments. AO/PI staining also demonstrated dose-dependent apoptosis in MCF-7 breast cancer cells and validated the highly effective active targeting of HA. In addition, the formulation demonstrated good stability during storage and dilution conditions, confirming its stability as a drug delivery platform. In conclusion, HA-functionalized nanomicelles provide a biocompatible and efficient system for the targeted breast cancer therapy, enhancing the therapeutic efficacy of capecitabine.