JACS Au最新文献

The lanmodulin (LanM) protein has emerged as an effective means for rare earth element (REE) extraction and separation from complex feedstocks without the use of organic solvents. Whereas the binding of LanM to individual REEs has been well characterized, little is known about the thermodynamics of mixed metal binding complexes (i.e., heterogeneous ion complexes), which limits the ability to accurately predict separation performance for a given metal ion mixture. In this paper, we employ the law of mass action to establish a theory of perfect cooperativity for LanM-REE complexation at the two highest-affinity binding sites. The theory is then used to derive an equation that explains the nonintuitive REE binding behavior of LanM, where separation factors for binary pairs of ions vary widely based on the ratio of ions in the aqueous phase, a phenomenon that is distinct from single-ion-binding chemical chelators. We then experimentally validate this theory and perform the first quantitative characterization of LanM complexation with heterogeneous ion pairs using resin-immobilized LanM. Importantly, the resulting homogeneous and heterogeneous constants enable accurate prediction of the equilibrium state of LanM in the presence of mixtures of up to 10 REEs, confirming that the perfect cooperativity model is an accurate mechanistic description of REE complexation by LanM. We further employ the model to simulate separation performance over a range of homogeneous and heterogeneous binding constants, revealing important insights into how mixed binding differentially impacts REE separations based on the relative positioning of the ion pairs within the lanthanide series. In addition to informing REE separation process optimization, these results provide mathematical and experimental insight into competition dynamics in other ubiquitous and medically relevant, cooperative binding proteins, such as calmodulin.

Degradable polymers are an effective solution for white plastic pollution. Polycaprolactone is a type of degradable plastic with desirable mechanical and biocompatible properties, and its monomer, ε-caprolactone (ε-CL), is often synthesized by Baeyer–Villiger (B–V) oxidation that demands peroxyacids with low safety and low atom-efficiency. Herein, we devised an electrochemical B–V oxidation system simply driven by H₂O₂ for the efficient production of ε-CL. This system involves two steps with the direct oxidation of H₂O₂ into •OOH radicals at the electrode surface and the indirect oxidation of cyclohexanone by the generated reactive oxygen species. The modulation of the interfacial ionic environment by amphipathic sulfonimide anions [e.g., bis(trifluoromethane)sulfonimide (TFSI^–)] is highly critical. It enables the efficient B–V oxidation into ε-caprolactone with ∼100% selectivity and 68.4% yield at a potential of 1.28 V vs RHE, much lower than the potentials applied for electrochemical B–V oxidation systems using water as the O sources. On hydrophilic electrodes with the action of sulfonimide anions, hydrophilic H₂O₂ can be enriched within the double layer for direct oxidation while hydrophobic cyclohexanone can be simultaneously accumulated for rapidly reacting with the reactive oxygen species. This work not only enriches the electrified method of the ancient B–V oxidation by using only H₂O₂ toward monomer production of biodegradable plastics but also emphasizes the critical role of the interfacial ionic environment for electrosynthesis systems that may extend the scope of activity optimization.

It remains challenging to construct C═N bonds due to their facile hydrogenation. Herein, a single Co atom catalyst was discovered to be active for the selective construction of C═N bonds toward the synthesis of imines and N-heterocycles via reductive coupling of nitroarenes with various alcohols, including inert aliphatic ones. DFT calculations and experimental data revealed that the transfer hydrogenation proceeded via the intramolecular hydride transfer and the transfer of H from the α-C_sp3-H bond to the nitro group was the rate-determining step. The single Co atoms served as a bridge to transfer the electrons from the catalyst to the adsorbed alcohol molecules, resulting in the activation of the α-C_sp3-H bond. Unlike metal nanoparticles, the C═N bonds in imine products can be reserved due to the large steric hindrance from substituents on C and N. DFT calculation also confirmed that transfer hydrogenation of the C═N bonds in imines is thermodynamically unfavored with a much higher energy barrier compared with the transfer hydrogenation of the –NO₂ group (1.47 vs 1.15 eV).

Biomolecular condensation involving proteins and nucleic acids has been recognized to play crucial roles in genome organization and transcriptional regulation. However, the biophysical mechanisms underlying the droplet fusion dynamics and microstructure evolution during the early stage of liquid–liquid phase separation (LLPS) remain elusive. In this work, we study the phase separation of linker histone H1, which is among the most abundant chromatin proteins, in the presence of single-stranded DNA (ssDNA) capable of forming a G-quadruplex by using molecular simulations and experimental characterization. We found that droplet fusion is a rather stochastic and kinetically controlled process. Productive fusion events are triggered by the formation of ssDNA-mediated electrostatic bridges within the droplet contacting zone. The droplet microstructure is size-dependent and evolves driven by maximizing the number of electrostatic contacts. We also showed that the folding of ssDNA to the G-quadruplex promotes LLPS by increasing the multivalency and strength of protein–DNA interactions. These findings provide deep mechanistic insights into the growth dynamics of biomolecular droplets and highlight the key role of kinetic control during the early stage of ssDNA–protein condensation.

The elucidation of aggregation rules for short peptides (e.g., tetrapeptides and pentapeptides) is crucial for the precise manipulation of aggregation. In this study, we derive comprehensive aggregation rules for tetrapeptides and pentapeptides across the entire sequence space based on the aggregation propensity values predicted by a transformer-based deep learning model. Our analysis focuses on three quantitative aspects. First, we investigate the type and positional effects of amino acids on aggregation, considering both the first- and second-order contributions. By identifying specific amino acids and amino acid pairs that promote or attenuate aggregation, we gain insights into the underlying aggregation mechanisms. Second, we explore the transferability of aggregation propensities between tetrapeptides and pentapeptides, aiming to explore the possibility of enhancing or mitigating aggregation by concatenating or removing specific amino acids at the termini. Finally, we evaluate the aggregation morphologies of over 20,000 tetrapeptides, regarding the morphology distribution and type and positional contributions of each amino acid. This work extends the existing aggregation rules from tripeptide sequences to millions of tetrapeptide and pentapeptide sequences, offering experimentalists an explicit roadmap for fine-tuning the aggregation behavior of short peptides for diverse applications, including hydrogels, emulsions, or pharmaceuticals.

The chemiluminescent light-emission pathway of phenoxy-1,2-dioxetane luminophores is increasingly attracting the scientific community’s attention. Dioxetane probes that undergo rapid, flash-type chemiexcitation demonstrate higher detection sensitivity than those with a slower, glow-type chemiexcitation rate. This is primarily because the rapid flash-type produces a greater number of photons within a given time. Herein, we discovered that dioxetanes fused to 7-norbornyl and homocubanyl units present accelerated chemiexcitation rates supported by DFT computational simulations. Specifically, the 7-norbornyl and homocubanyl spirofused dioxetanes exhibited a chemiexcitation rate 14.2-fold and 230-fold faster than that of spiro-adamantyl dioxetane, respectively. A turn-ON dioxetane probe for the detection of the enzyme β-galactosidase, containing the 7-norbornyl spirofused unit, exhibited an S/N value of 415 at a low enzyme concentration. This probe demonstrated an increase in detection sensitivity toward β-galactosidase expressing bacteria E. coli with a limit-of-detection value that is 12.8-fold more sensitive than that obtained by the adamantyl counterpart. Interestingly, the computed activation free energies of the homocubanyl and 7-norbornyl units were correlated with their CC_sC spiro-angle to corroborate the measured chemiexcitation rates.

Photolysis of a platinum(II) azide complex in the presence of styrenes enables C═C double bond cleavage upon dissociative olefin imination to aldimido (Pt^II–N═CHPh) and formimido (Pt^II–N═CH₂) complexes as the main products. Spectroscopic and quantum chemical examinations support a mechanism that commences with the decay of the metallonitrene photoproduct (Pt^II–N) via bimolecular coupling and nitrogen loss as N₂. The resulting platinum(I) complex initiates a radical chain mechanism via a dinuclear radical-bridged species (Pt^II–CH₂CHPhN^•–Pt^II) as a direct precursor to C–C scission. The preference for the Pt^I mediated route over styrene aziridination is attributed to the distinct nucleophilicity of the triplet metallonitrene.

Hydrophilic actinide masking agents are believed to be efficient alternatives to circumvent the extensive hazardous organic solvents/diluents typically employed in the liquid–liquid extraction for nuclear waste management. However, the practical application of hydrophilic ligands faces significant challenges in both synthetic/purification procedures and, more importantly, the acid resistance of the ligands themselves. Herein, we have demonstrated the combination of phenanthroline diimide framework with a biomotif of histidine flanking parts could achieve efficient separation of trivalent lanthanides/actinides (also actinides/actinides) under high acidity of over 1 M HNO₃. This approach leverages the soft–hard coordination properties of N, O-hybrid ligands, as well as the energetically favored imides for metal coordination and the multiple protonation of histidine. These factors collectively contribute to the synthesis of an easily accessible, highly water-soluble, superior selective, and acid-resistant Am(III) masking agent. Thus, we have shown in this paper, by proper combination of synthetic N, O-hybrid ligand with amino acid, trivalent lanthanide and actinide separation could be efficiently fulfilled in a more sustainable manner.

Perovskite solar cells (PSCs) are recognized as one of the most promising next-generation photovoltaics, primarily due to their exceptional power conversion efficiency, ease of processing, and cost-effectiveness. Despite these advantages, challenges remain in achieving high-quality films and ensuring the long-term stability of PSCs, which hinder their widespread commercialization. Polymers, characterized by multifunctional groups, superior thermal stability, flexible long chains, and cross-linking capabilities, offer significant potential to enhance the performance and reliability of PSCs. This review comprehensively presents the multifaceted roles that polymers play in PSCs. Through carefully controlling interactions between polymers and perovskites, crucial aspects such as film crystallization kinetics, carrier transport process, ion migration issues, and mechanical properties under bending can be effectively regulated to maximize the device performance. Furthermore, the hydrophobic properties and strong chelated cross-linking networks of polymers significantly enhance the stability of PSCs under various environmental conditions while effectively mitigating lead leakage, thereby addressing environmental concerns and long-term durability. Moreover, this Perspective identifies potential pathways for further advancing polymer-based strategies in PSC applications.

This Perspective elucidates the transformative impacts of advanced nanotechnology and dynamic energy systems on the polymer chain reaction (PCR), a cornerstone technique in biomedical research and diagnostic applications. Since its invention, the optimization of PCR─specifically its efficiency, specificity, cycling rate, and detection sensitivity─has been a focal point of scientific exploration. Our analysis spans the modulation of PCR from both material and energetic perspectives, emphasizing the intricate interplay between PCR components and externally added entities such as molecules, nanoparticles (NPs), and optical microcavities. We begin with a foundational overview of PCR, detailing the basic principles of PCR modulation through molecular additives to highlight material-level interactions. Then, we delve into how NPs, with their diverse material and surface properties, influence PCR through interface interactions and hydrothermal conduction, drawing parallels to molecular behaviors. Additionally, this Perspective ventures into the energetic regulation of PCR, examining the roles of electromagnetic radiation and optical resonators. We underscore the advanced capabilities of optical technologies in PCR regulation, characterized by their ultrafast, residue-free, and noninvasive nature, alongside label-free detection methods. Notably, optical resonators present a pioneering approach to control PCR processes even in the absence of light, targeting the often-overlooked water component in PCR. By integrating discussions on photocaging and vibrational strong coupling, this review presents innovative methods for the precise regulation of PCR processes, envisioning a new era of PCR technology that enhances both research and clinical diagnostics. The synergy between nanotechnological enhancements and energy dynamics not only enriches our understanding of PCR but also opens new avenues for developing rapid, accurate, and efficient PCR systems. We hope that this Perspective will inspire further innovations in PCR technology and guide the development of next-generation clinical detection instruments.