ACS Omega最新文献

Erythroxylum coca, commonly known as “coca” is a plant native to the South American Andes, recognized for its high alkaloid content and potential medical and nutritional applications. This study aimed to characterize the chemical, nutritional, and cytotoxic properties of two E. coca morphotypes (Palo and Caimo) cultivated by Colombian indigenous communities, with the goal of promoting legal uses and economic opportunities in the region. Comprehensive analyses included the evaluation of sugars, organic acids, total polyphenols, flavonoids, antioxidant capacity, volatile compounds, and cytotoxic activity. Chemical analysis revealed that E. coca leaves contain over 50% dietary fiber, while stems surpass 76%, primarily consisting of insoluble fiber. Significant amounts of sucrose, glucose, and fructose were detected, with succinic acid identified as the predominant organic acid. Cytotoxicity evaluation demonstrated that while both morphotypes are safe for consumption, they also exhibit cytotoxic activity against L929 murine fibroblast cell line. Volatile compound analysis highlighted the presence of hexadecanoic and octadecanoic acids, alongside characteristic alkaloids such as cocaine and benzoylecgonine. These findings underscore the nutritional, chemical, and cytotoxic potential of E. coca as a sustainable crop. Its cultivation and research can serve as a valuable resource for indigenous communities, contributing to the development of local economies and fostering its legal and beneficial applications.

Hydrogels have emerged as a versatile class of materials with broad applications in biomedical engineering, drug delivery, and tissue engineering. Understanding their intricate structures and morphologies is crucial for tailoring their properties to meet specific biomedical needs. It has been clearly established that the composition and microarchitecture of the materials play a critical role in essential cellular mechanisms such as mechanosensing, adhesion, and remodeling. This question is essential in tissue engineering, where precisely characterizing the microarchitecture of the materials used to model the cell microenvironment is a critical step to ensure the reproducibility and relevance of reconstructed tissues. In this study, we present a comprehensive comparison of four advanced electron microscopy techniques, namely, scanning electron microscopy, cryo-scanning electron microscopy, environmental scanning electron microscopy, and transmission electron microscopy, to observe the hydrogel microarchitecture, including a comparison of the sample preparation methods for each technique. Each technique’s specific advantages and limitations are discussed in detail, highlighting their unique capabilities in characterizing the hydrogel structures. We illustrate this study with two semisynthetic hydrogels, such as gelatin methacrylate and hyaluronic acid methacrylate. Moreover, we delve into the critical sample preparation steps necessary for each method, emphasizing the need to preserve the hydrogel’s native state while obtaining high-resolution images. This comparative analysis aims to select the most suitable electron microscopy technique for their hydrogel studies, fostering deeper insights into the design and development of advanced biomaterials for tissue engineering applications.

Heavy metal pollutants, such as Cu²⁺, pose significant environmental and health risks due to their toxicity and persistence in water systems. Simultaneously, the increasing accumulation of waste poly(ethylene terephthalate) (PET) bottles represents a growing environmental challenge, contributing to plastic pollution. This study addresses both issues by converting waste PET bottles into porous activated carbon (APC) via pyrolysis, creating an efficient and sustainable adsorbent for Cu²⁺ removal from aqueous solutions. The APC materials were thoroughly characterized by SEM, BET, and XPS analyses, revealing a highly porous structure and abundant oxygen-containing functional groups, which enhance Cu²⁺ adsorption. The adsorption process was determined to be spontaneous, with a low activation energy of 7.47 kJ/mol, indicating a favorable and energy-efficient adsorption mechanism. Among the APC samples, APC-800 exhibited the best performance, achieving a Cu²⁺ removal efficiency of 99.30% and a maximum adsorption capacity of 5.85 mg/g. Recyclability tests confirmed the material’s durability, maintaining over 96% efficiency during the first three cycles, with a slight decline in later cycles. This study demonstrates a dual environmental benefit: mitigating plastic waste by repurposing PET bottles and providing an effective solution for heavy metal pollution, aligning with circular economy principles, and promoting sustainability in environmental management.

The joining of Y6 has effectively promoted the power conversion efficiency (PCE) of organic solar cells, and the impact of its end-group modification on the PCE is significant. Here, eight different groups are introduced to modify the end-group of Y6, forming eight acceptors named V1, V2, V3, V4, V5, V6, V7, and R. The excited states, light absorption properties, and intermolecular electron transfer are discussed by the density functional theory. The density of state, average local ionization energy, Hirshfeld population, ionization potential, electron affinity, and electron mobility are also calculated. Results show that V7 obtains the largest red-shift in the UV–visible absorption spectra (787.55 nm). V7 and V5 have better electronic coupling while exhibiting the leading electron mobility (0.9577 and 0.4383 cm² V^–1 s^–1). Acceptors with rigid skeletons, good planarity, minimal steric hindrance, and locally uniform ALIE distributions have the potential to achieve higher electron mobility. These results indicate that precise end-group engineering can effectively regulate the electron mobility of acceptors, thereby increasing the PCE.

The broad application of laccase mimics is notably constrained by their costly and intricate synthesis routes. For example, researchers often use peptides to coordinate with copper ions to mimic the active sites of laccases, thereby constructing laccase mimics. However, these synthetic methods are quite complex, such as requiring high temperatures, the use of organic solvents, long durations, and cumbersome procedures. In this study, we introduce a straightforward yet highly active, robust, and versatile laccase mimic known as HH-Cu, which was synthesized through a simple precipitation reaction by combining the dipeptide HH with Cu²⁺ ions in phosphate-buffered saline (PBS). By adjusting the ratio of HH to copper ions, we were able to produce the most effective organic–inorganic hybrid nanoparticles, namely, HH-Cu, which outperforms the HH-Cu nanoflowers. HH-Cu demonstrates extraordinary catalytic efficiency, with a 4.7-fold higher maximum velocity (v_max) and a lower Michaelis constant (K_m) compared to natural laccase. This nanozyme is also remarkably resilient under harsh conditions such as extreme pH levels, high temperatures, and high salinity, and it shows excellent storage stability and reusability. We successfully applied this nanozyme for the degradation and quantitative detection of various phenolic pollutants and epinephrine. HH-Cu demonstrates a markedly superior sensitivity for detecting epinephrine than laccase and offers a comparable limit of detection and a broader linear range compared to other laccase mimics. This research should lay the groundwork for ongoing efforts in the development of organic–inorganic hybrid nanozymes and provide an effective method for the simple and efficient synthesis of laccase mimics.

In this article, we discuss a simple method to prepare core–shell Ag@TiO₂ nanoparticles (NPs) with an optimized shell thickness to engineer plasmonic photocatalysts and surface-enhanced Raman scattering (SERS) substrates. Variation in the shell (TiO₂) thickness was analyzed by an acid-etching method, and the deterioration of the shell was traced by monitoring the extinction spectra of both colloidal and solid-supported Ag@TiO₂ NPs. Attainment of the optimum shell thickness was confirmed by noticing the simultaneous appearance of the LSPR absorption band (at 450 nm) of core silver nanostructures (d = ∼10 nm) and the scattering signature of the shell (TiO₂) in the extinction spectrum of Ag@TiO₂ NPs. This study showed that the optimum thickness of TiO₂ is ∼2 nm, which allowed LSPR excitation by visible light. The observed blue shift of the LSPR peak, compared to the unetched Ag@TiO₂ NPs, with etching time indicated the size reduction of the NPs. Ag@TiO₂ with the optimum thickness exhibited a reaction rate five times faster than that of unetched Ag@TiO₂ under visible light irradiation. Ag@TiO₂ NPs exhibited higher photocatalytic activity under visible light irradiation than under UV light. Furthermore, Ag@TiO₂ NPs with the optimized thickness exhibited significantly higher SERS activity than the unetched Ag@TiO₂ NPs. The elevated photocatalytic and SERS activities exhibited by engineered Ag@TiO₂ NPs reveal the effectiveness of the etching process in creating a plasmonic effect in core(plasmonic)–shell (semiconductor) nanostructures.

Ellagic acid (EA) is a potent antioxidant that reduces oxidative stress and promotes differentiation. By lowering the harmful levels of reactive oxygen species (ROS), EA fosters an environment conducive to the osteoblastic differentiation (OB) of stem cells. In addition, it promotes autophagy and mitophagy, which are vital for promoting differentiation. Effective autophagic activity recycles damaged organelles and proteins, meeting the energy required during differentiation and shielding from apoptosis. However, molecular mechanisms underlying the osteogenic differentiation of mesenchymal stem cells remain inadequately explored. Therefore, the current study aims to define the regulatory role of EA during the OB of dental pulp-derived stem cells (DPSC) and to study how autophagy and mitophagy are being modulated during this differentiation process. Herein, we showed that the expression level of osteoblast-specific markers, autophagy, and mitophagy-associated markers was significantly elevated during EA-mediated OB differentiation of DPSC. Moreover, we found that the EA induced the osteoblastic-specific markers through canonical BMP2 pathway molecules, reduced ROS in both basal and activated states, and induced autophagy and mitophagy molecules along with enhanced mitochondrial functions. Cell cycle analysis revealed that the G1 phase was arrested via phosphorylation of γ-H2AX, ATM, and CHK2 proteins. Furthermore, in silico analysis revealed that EA strongly binds with osteonectin, a crucial noncollagen protein involved in bone remodeling, and confirmed by Western blot analysis. These results support that EA could be a promising natural compound for bone repair and regeneration applications.

Bone wear caused by injury or deterioration due to age leads to the use of autologous and allogeneic implants that are sometimes rejected by the body. Currently, work is being carried out on the development of composites that induce bone repair. In this study, composites with montmorillonite clay (MMT), hydroxyapatite (HAp), and gelatin were prepared. Initially, various ratios of HAp/MMT composites (1:1, 2:1, and 1:2) were examined, and the 2:1 ratio provided a better biological response. Finally, the HAp/MMT/Gel ternary mixtures were prepared using different percentages of gelatin: 10, 50, and 90% and maintaining the 2:1 HAp/MMT ratio. All materials were assayed in a biomineralization proof using simulated biological fluids. In the HAp/MMT/Gel diffraction pattern, the peaks associated with MMT and HAp are preserved at 20 and 32° in 2θ, respectively; the addition of gelatin promotes structural changes. Biocompatibility studies show that there are no morphological changes in the platelets since it does not exceed 5 μm of pseudopodia, which suggests that there is no rejection of the material. On the other hand, the biomineralization study, followed by SEM and FTIR characterization, showed the generation of apatite and demonstrated its potential application in bone tissue regeneration.

UV-curable resins with a low dielectric constant can be processed or patterned to form required shapes, making them highly applicable to special fields. Unlike conventional photoresists limited by the polarization effect due to highly polar bonds, an all-hydrocarbon-type low-dielectric photoresist was designed and synthesized with excellent performance. Based on previous works, the film-forming resin poly 1-(4-vinylphenyl)-2-(4-benzocyclobutenyl)ethylene-styrene (P-DVB-St) was prepared by introducing styrene (St) into the 1-(4-vinylphenyl)-2-(4-benzocyclobutenyl)ethene (DVB) backbone via anionic polymerization, and the photoresist properties were improved by adjusting the cross-linking density of the polymer. The introduction of styrene improved the mechanical properties while maintaining the photolithographic patterning properties of the photoresist. Since the resin has a dual UV/thermal-cured structure, it has better thermal stability (T_5% = 401 °C), lower dielectric constant (2.62 at 10 MHz) and dielectric loss (1.7 × 10^–3), and better photolithographic patterning (the graphic resolution is 5 μm).

Metal–organic frameworks (MOFs) are promising precursors for creating metal–nitrogen–carbon (M–N–C) electrocatalysts with high performance, though maintaining their structure during pyrolysis is challenging. This study examines the transformation of a Zn-based MOF into an M–N–C electrocatalyst, focusing on the preservation of the carbon framework and the prevention of Zn aggregation during pyrolysis. A highly porous Zn–N–C electrocatalyst derived from Zn-TAL MOF (where TAL stands for the TalTech-UniTartu Alliance Laboratory) was synthesized via optimized pyrolysis, yielding notable electrocatalytic activity toward oxygen reduction reaction (ORR). Scanning electron microscopy (SEM) and X-ray diffraction spectroscopy (XRD) analyses confirmed that the carbon framework preserved its integrity and remained free of Zn metal aggregates, even at elevated temperatures. Rotating disc electrode (RDE) tests in an alkaline solution showed that the optimized Zn–N–C electrocatalyst demonstrated ORR activity on par with commercial Pt/C electrocatalysts. In an anion-exchange membrane fuel cell (AEMFC), the Zn–N–C material pyrolyzed at 1000 °C exhibited a peak power density of 553 mW cm^–2 at 60 °C. This work demonstrates that Zn-TAL MOF is an excellent precursor for forming hollow Zn–N–C structures, making it a promising high-performance Pt-free electrocatalyst for fuel cells.