ACS Publications最新文献

Cells need to migrate through confined spaces during processes such as embryo development and cancer metastasis. However, the fundamental question of how confinement size and surrounding rigidity collectively regulate the migration capability of cells remains unclear. Here, by utilizing maskless photolithography with a digital micromirror device (DMD), a microchannel with precisely controlled width and wall stiffness (similar to those exhibited by natural tissues) is fabricated. We find that increasing the rigidity of the confining wall leads to a more reduced nuclear volume but has no detectable influence on the myosin expression level in the cells. More interestingly, a biphasic trend of the cell speed is observed, with the migration velocity reaching its minimum at an intermediate wall rigidity of ∼10 kPa. A motor-clutch-based pulling race model is then proposed, which suggests that such biphasic dependence is due to the fact that a very soft channel wall will result in small deformation of the nucleus and consequently reduced cell-wall friction, while larger myosin-based crawling force can be triggered by a stiff confining boundary, both leading to a relatively high migration speed. These findings could provide critical insights into novel strategies for controlling the movement of cells and the design of high-performance biological materials.

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.

Cocatalyst engineering is critical for advancing photocatalysis, as it suppresses charge carrier recombination, promotes interfacial electron/hole extraction, and serves as active sites for redox reactions. However, the incompatibility existing between the cocatalyst and host photocatalyst, along with its intrinsic properties of active sites, limits further improvements in the charge separation, surface reaction kinetics, and overall performance. Herein, we introduce palladium hydrides (PdH_x) as an efficient cocatalyst on SrTiO₃ (STO) for photocatalytic overall water splitting, owing to their similar lattice parameters. The constructed PdH_x/STO demonstrates a remarkable 6.4-fold enhancement in hydrogen evolution compared to the Pd/STO control, reaching a rate of 5 mmol·g^–1·h^–1 at a stoichiometric H₂/O₂ ratio of 2:1. Structural characterizations and theoretical analyses prove that the in situ formed PdH_x sites feature the advantages of accelerated electron extraction and modulated hydrogen adsorption energies for hydrogen evolution; femtosecond transient absorption spectroscopy further reveals prolonged charge carrier lifetime and improved charge transfer efficiency.

Controlling the degradation and cell interaction of polymer materials is vital for numerous applications. Transitioning from enzymatic to nonenzymatic hydrolysis offers precise control over degradation processes. In this study, we synthesized high molar mass poly(trimethylene carbonate) (PTMC)–polyphosphonate copolymers to achieve distinctive antifouling and controlled degradation properties. 2-Ethyl-2-oxo-1,3,2-dioxaphospholane (EtPPn) is copolymerized with trimethylene carbonate (TMC) to random P(TMC-co-EtPPn) copolymers through ring-opening copolymerization, utilizing Sn(Oct)₂ as the catalyst. Copolymers with molar masses reaching up to M_n = 218 kg/mol and molar mass dispersities of D̵ < 1.9 are obtained. To maintain hydrophobicity, 10 and 20 mol % of hydrophilic phosphonate units are incorporated into PTMC-copolymers. While copolymers with 10 mol % EtPPn display mechanical properties akin to the homopolymer PTMC, a deviation in elongation at break and yield strength results when 20 mol % EtPPN is incorporated. PTMC–PPE copolymers demonstrate antifouling behavior, i.e., cell repulsion for human mesenchymal stem cells (hMSCs) and inhibited enzymatic degradation by lipase in contrast to PTMC-homopolymers. Conversely, P(TMC-co-EtPPn) undergo abiotic hydrolytic degradation with hydrolysis rates increasing with increasing phosphonate contents. In conclusion, copolymerization with EtPPn enables the switch from enzymatic PTMC degradation to adjustable hydrolytic degradation, offering controlled stabilities of such copolymers in the desired applications.

The sequencing of peptides via N-terminal amino acid removal is a classic reaction termed Edman degradation. This method involves repeated treatment of the N-terminal amino group of a peptide with phenyl isothiocyanate (PITC), followed by treatment with trifluoroacetic acid. Spurred by the need for an alternative non-acid-based chemistry for next-generation protein sequencing technologies, we developed a base-induced N-terminal degradation method. Several N-terminal derivatization reagents carrying supernucleophiles were tested. After rounds of iterative designs, compound DR3, with a N-hydroxysuccinimide as a leaving group and hydrazinecarboxamide as the supernucleophile, demonstrated the highest yield for the peptide derivatization step and the most efficient elimination of the N-terminal amino acid in just 1% of a hydroxide salt. The method successfully removed all 20 amino acids at the N-terminus in high yield. The technique demonstrates compatibility with oligonucleic acids, which differs from Edman degradation due to their inherent sensitivity to acidic environments. To demonstrate the practical application of our approach, we sequenced amino acids sequentially from a peptide, effectively determining the sequence of an unknown peptide. Notably, our methodology was successfully applied to mixtures of peptides derived from protein samples, where a significant fraction of the peptides derivatized with DR3 underwent elimination of their N-terminal amino acid upon addition of base. Overall, although our method does not outperform Edman degradation in efficiency, it serves as a valuable alternative in cases where base-induced cleavage is advantageous, particularly for preserving acid-sensitive functionalities.

Zirconium-based metal organic frameworks (Zr-MOFs) are of great potential in catalysis due to their robustness, stability, and catalytic activity toward a broad range of reactions. Although their structure and activity could be optimized via multiple approaches, the influence of different metal-oxo cluster nuclearities has been scarcely investigated. In this work, we report on the reactivity of the dodecanuclear Zr-MOF hcp UiO-66, which features a [Zr₁₂O₂₂] cluster node instead of the ubiquitous [Zr₆O₈] found in the literature, toward the hydrolysis of peptide bonds under physiological pH conditions. This challenging reaction is of great importance in the fields of biochemistry and proteomics, where MOFs offer great potential as selective and tunable heterogeneous artificial enzymes. Using the dipeptide glycylglycine as a model substrate, we demonstrated that the Zr₁₂-based hcp UiO-66 accelerates peptide bond hydrolysis 10,000-fold with respect to the uncatalyzed reaction. Although the rate of glycylglycine hydrolysis by Zr₁₂-based UiO-66 is initially faster than that of Zr₆-based UiO-66, the dodecanuclear MOF yields an overall slower reaction by taking a longer time to afford the same reaction yield. Based on extended X-ray absorption fine structure and in situ infrared studies combined with molecular modeling, the slower conversion is caused by the strong affinity of the Zr₁₂ cluster for the product glycine. The understanding gained on the interactions of MOFs with biomolecules contributes to the development of MOF nanozymes for bioinspired applications and suggests that further optimization of the structure is needed to harvest the emerging greater reactivity of Zr₁₂ clusters.

Alzheimer’s disease (AD), the most prevalent neurodegenerative disorder among older adults, significantly impairs behavioral and cognitive functions, posing a severe threat to patients’ health and quality of life. The Tricetin (TRN), a natural flavonoid found in wheat, pomegranate, and eucalyptus honey, has demonstrated anti-inflammatory, antitumor, and neuroprotective properties. However, its role in the context of AD has not been previously explored. This study investigated the antineuroinflammatory and autophagic protective effects of TRN in lipopolysaccharide (LPS)-induced BV2 cells and _D-galactose/sodium nitrite/aluminum chloride (_D-gal/NaNO₂/AlCl₃)-induced AD mice. The RNA sequencing examined the underlying mechanisms by which TRN ameliorates AD-related pathologies. Our research findings revealed that TRN significantly improved memory and mobility in AD mice, reduced Aβ deposition, and inhibited Tau protein phosphorylation. Furthermore, TRN regulated enzyme activities and reduced pathological markers associated with AD. Moreover, it modulated inflammatory mediators, inhibited the nuclear translocation of NF-κB in LPS-induced BV2 cells, and exerted anti-inflammatory and autophagic protective effects via the PI3K/Akt/mTOR signaling pathway. In conclusion, TRN demonstrated robust neuroprotective effects in vitro and in vivo AD models by regulating the PI3K/Akt/mTOR signaling pathway. These findings highlight its potential as a promising therapeutic agent for treating AD.

Deformability has been recognized as a prime important characteristic influencing cellular uptake. But little is known about whether it controls cell–nanoparticle interfaces driven out of equilibrium. Here, we report on soft elastic active nanoparticles whose deformability due to the rigidity regulates the nonequilibrium interaction and dynamics in their endocytosis process. Simulations demonstrate a definitely nonmonotonic feature for the dependence of uptake efficiency on nanoparticle rigidity, in striking contrast to their passive counterpart. There exists a minimum activity for certain cellular uptake, which turns to a larger rigidity for a more vertical orientation of the nanoparticle. We analyze these results by developing analytical theories that reveal the physical origin of various energetic contributions and dissipations governed by the dynamic interplay between nanoparticle deformability and activity. Altogether, the present findings provide new insights into the nonequilibrium physics at cellular interfaces and might be of immediate interest to designing soft systems for the desired biomedical applications.

Polymer incorporation has been proven effective to enhance the mechanical strength of MXene fibers via interfacial cross-linking, yet the simultaneous improvement in electrochemical performance, particularly output capacitance and high rate capability, remains a challenge, and the major obstacle is identified as the sluggish ion diffusion kinetics. Herein, interlayer manipulation in Ti₃C₂T_X fiber is proposed, and the roles of substitutional groups in celluloses are examined. The addition of cellulose can obviously improve the spinnability of MXene dope and effectively bridge the adjacent Ti₃C₂T_X nanosheets via hydrogen bonds. Moreover, hydroxyethyl cellulose with a suitable group size and moderate adsorption ability is preferred for diminishing the steric effect and facilitating rapid proton transport. Simultaneous improvements in capacitance (1531 F cm^–3 at 2 A cm^–3) and strength (∼76 MPa) are achieved for the optimized M-HEC-1.0% fiber together with a superior high rate capability retaining 89.2% at 15 A cm^–3.

Due to the slow conversion kinetics of polysulfides, the practical application of lithium–sulfur batteries faces significant challenges. Transition metal tellurides exhibit good catalytic activity and are expected to help mitigate the shuttle effect in lithium–sulfur batteries. Vacancies, as a form of defect, can further enhance the conductivity and catalytic activity of the catalysts. However, most vacancy creation is achieved by the action of strong reducing agents (such as H₂, NaBH₄, hydrazine, etc.). Here, we utilized the similarity in lattice parameters between NiTe and NiTe₂ to adjust the extent of lattice contraction in NiTe₂ by controlling the Te powder content, ultimately obtaining a Te-vacancy-rich NiTe_x-NC catalyst under mild conditions. The unsaturated coordination between Ni and Te provides abundant active sites for the chemical adsorption and catalytic conversion of polysulfides, thus allowing NiTe_x-NC to significantly lower the reaction energy barrier of polysulfides and effectively inhibit the shuttle effect. The results show that NiTe_x-NC can achieve a specific capacity of 589.4 mAh g^–1 at a rate of 7 C, and after 1000 cycles at 2 C, the capacity decay per cycle is only 0.0278%. Even under complex conditions (with a sulfur loading of 7.5 mg cm^–2 and a liquid sulfur ratio of 10 μL mg^–1), it still maintains good cycling stability.