Janus dendrimersomes coassembled from fluorinated, hydrogenated, and hybrid Janus dendrimers as models for cell fusion and fission

From Frank-Kasper, Quasicrystals, and Biological Membrane Mimics to Reprogramming In Vivo the Living Factory to Target the Delivery of mRNA with One-Component Amphiphilic Janus Dendrimers

This Perspective is dedicated to the 25th Anniversary of Biomacromolecules. It provides a personal view on the developing field of the polymer and biology interface over the 25 years since the journal was launched by the American Chemical Society (ACS). This Perspective is meant to bridge an article published in the first issue of the journal and recent bioinspired developments in the laboratory of the corresponding author. The discovery of supramolecular spherical helices self-organizing into Frank-Kasper and quasicrystals as models of icosahedral viruses, as well as of columnar helical assemblies that mimic rodlike viruses by supramolecular dendrimers, is briefly presented. The transplant of these assemblies from supramolecular dendrimers to block copolymers, giant surfactants, and other self-organized soft matter follows. Amphiphilic self-assembling Janus dendrimers and glycodendrimers as mimics of biological membranes and their glycans are discussed. New concepts derived from them that evolved in the in vivo targeted delivery of mRNA with the simplest one-component synthetic vector systems are introduced. Some synthetic methodologies employed during the synthesis and self-assembly are explained. Unraveling bioinspired applications of novel materials concludes this brief 25th Anniversary Perspective of Biomacromolecules.

Chemical Information Processing by a Responsive Chemical System

Nature has an extraordinary capacity to precisely regulate the chemical reactivity in a highly complex mixture of molecules that is present in the cell. External stimuli lead to transient up- and downregulation of chemical reactions and provide a means for a cell to process information arriving from the environment. The development of synthetic chemical systems with life-like properties requires strategies that allow likewise control over chemical reactivity in a complex environment. Here, we show a synthetic system that mimics the initial steps that take place when a natural signal transduction pathway is activated. Monophosphate nucleosides act as chemical triggers for the self-assembly of nanoreactors that upregulate chemical reactions between reagents present at low micromolar concentrations. Different nucleotides template different assemblies and hence activate different pathways, thus establishing a distinct connection between input and output molecules. Trigger-induced upregulation of chemical reactivity occurs for only a limited amount of time because the chemical triggers are gradually removed from the system by enzymes. It is shown that the same system transiently produces different output molecules depending on the chemical input that is provided.

Designing Peptide-Based Nanoinhibitors of Programmed Cell Death Ligand 1 (PD-L1) for Enhanced Chemo-immunotherapy

The combination of immune checkpoint blockade (ICB) and chemotherapy has shown significant potential in the clinical treatment of various cancers. However, circulating regeneration of PD-L1 within tumor cells greatly limits the efficiency of chemo-immunotherapy and consequent patient response rates. Herein, we report the synthesis of a nanoparticle-based PD-L1 inhibitor (FRS) with a rational design for effective endogenous PD-L1 suppression. The nanoinhibitor is achieved through self-assembly of fluoroalkylated competitive peptides that target PD-L1 palmitoylation. The FRS nanoparticles provide efficient protection and delivery of functional peptides to the cytoplasm of tumors, showing greater inhibition of PD-L1 than nonfluorinated peptidic inhibitors. Moreover, we demonstrate that FRS synergizes with chemotherapeutic doxorubicin (DOX) to boost the antitumor activities via simultaneous reduction of PD-L1 abundance and induction of immunogenic cell death in murine colon tumor models. The nano strategy of PD-L1 regulation present in this study is expected to advance the development of ICB inhibitors and overcome the limitations of conventional ICB-assisted chemo-immunotherapy.

Targeted and Equally Distributed Delivery of mRNA to Organs with Pentaerythritol-Based One-Component Ionizable Amphiphilic Janus Dendrimers

Delivery of nucleic acids with viral and synthetic vectors has pioneered genetic nanomedicine. Four-component lipid nanoparticles (LNPs) consisting of ionizable lipids, phospholipids, cholesterol, and PEG-conjugated lipids, assembled by microfluidic or T-tube, are the benchmark synthetic vector for delivery of mRNA. One-component multifunctional sequence-defined ionizable amphiphilic Janus dendrimer (IAJD) delivery systems for mRNA were developed by us to complement LNPs. IAJDs consist of multifunctional hydrophilic low-generation dendrons or minidendrons conjugated to hydrophobic dendrons. They were inspired by amphiphilic Janus dendrimers and glycodendrimers. IAJDs coassemble with mRNA into predictable-size vesicles, named dendrimersome nanoparticles (DNPs), by simple injection in acetate buffer, rather than by the complex technology required by LNPs. Assembly of DNPs by simple injection together with sequence design in the hydrophilic and hydrophobic modules of IAJDs endowed rapid screening to access discovery. Molecular design principles for targeted delivery were elaborated when the branching points of IAJDs were constructed from symmetrically and nonsymmetrically substituted plant phenolic acids interconnected by pentaerythritol (PE). Here, we report the first library containing simplified IAJDs constructed in only three steps from symmetrically trialkylated PE in the hydrophobic domain and four different piperazine-based ionizable amines in the hydrophilic part. Rapid coassembly with mRNA and in vivo screening led to the discovery of the two most active IAJDs targeting the spleen, liver, and lymph nodes, one predominantly to the spleen and liver and six delivering equally to the spleen, liver, lung, and lymph nodes. These IAJDs represent the simplest synthetic vectors and the first viral or synthetic system delivering equally to multiple organs.

Recent Progress of Rational Modified Nanocarriers for Cytosolic Protein Delivery

Therapeutic proteins garnered significant attention in the field of disease treatment. In comparison to small molecule drugs, protein therapies offer distinct advantages, including high potency, specificity, low toxicity, and reduced carcinogenicity, even at minimal concentrations. However, the full potential of protein therapy is limited by inherent challenges such as large molecular size, delicate tertiary structure, and poor membrane penetration, resulting in inefficient intracellular delivery into target cells. To address these challenges and enhance the clinical applications of protein therapies, various protein-loaded nanocarriers with tailored modifications were developed, including liposomes, exosomes, polymeric nanoparticles, and nanomotors. Despite these advancements, many of these strategies encounter significant issues such as entrapment within endosomes, leading to low therapeutic efficiency. In this review, we extensively discussed diverse strategies for the rational design of nanocarriers, aiming to overcome these limitations. Additionally, we presented a forward-looking viewpoint on the innovative generation of delivery systems specifically tailored for protein-based therapies. Our intention was to offer theoretical and technical support for the development and enhancement of nanocarriers capable of facilitating cytosolic protein delivery.

Screening Libraries to Discover Molecular Design Principles for the Targeted Delivery of mRNA with One-Component Ionizable Amphiphilic Janus Dendrimers Derived from Plant Phenolic Acids

Viral and synthetic vectors to deliver nucleic acids were key to the rapid development of extraordinarily efficient COVID-19 vaccines. The four-component lipid nanoparticles (LNPs), containing phospholipids, PEG-conjugated lipids, cholesterol, and ionizable lipids, co-assembled with mRNA via a microfluidic technology, are the leading nonviral delivery vector used by BioNTech/Pfizer and Moderna to access COVID-19 mRNA vaccines. LNPs exhibit a statistical distribution of their four components when delivering mRNA. Here, we report a methodology that involves screening libraries to discover the molecular design principles required to realize organ-targeted mRNA delivery and mediate activity with a one-component ionizable multifunctional amphiphilic Janus dendrimer (IAJD) derived from plant phenolic acids. IAJDs co-assemble with mRNA into monodisperse dendrimersome nanoparticles (DNPs) with predictable dimensions, via the simple injection of their ethanol solution in a buffer. The precise location of the functional groups in one-component IAJDs demonstrated that the targeted organs, including the liver, spleen, lymph nodes, and lung, are selected based on the hydrophilic region, while activity is associated with the hydrophobic domain of IAJDs. These principles, and a mechanistic hypothesis to explain activity, simplify the synthesis of IAJDs, the assembly of DNPs, handling, and storage of vaccines, and reduce price, despite employing renewable plant starting materials. Using simple molecular design principles will lead to increased accessibility to a large diversity of mRNA-based vaccines and nanotherapeutics.

CuC(O) Interfaces Deliver Remarkable Selectivity and Stability for CO2 Reduction to C2+ Products at Industrial Current Density of 500 mA cm-2

The electrocatalytic CO₂ reduction reaction (CO₂ RR) is an attractive technology for CO₂ valorization and high-density electrical energy storage. Achieving a high selectivity to C₂₊ products, especially ethylene, during CO₂ RR at high current densities (>500 mA cm^-2 ) is a prized goal of current research, though remains technically very challenging. Herein, it is demonstrated that the surface and interfacial structures of Cu catalysts, and the solid-gas-liquid interfaces on gas-diffusion electrode (GDE) in CO₂ reduction flow cells can be modulated to allow efficient CO₂ RR to C₂₊ products. This approach uses the in situ electrochemical reduction of a CuO nanosheet/graphene oxide dots (CuOC(O)) hybrid. Owing to abundant CuOC interfaces in the CuOC(O) hybrid, the CuO nanosheets are topologically and selectively transformed into metallic Cu nanosheets exposing Cu(100) facets, Cu(110) facets, Cu[n(100) × (110)] step sites, and Cu⁺ /Cu⁰ interfaces during the electroreduction step, the faradaic efficiencie (FE) to C₂₊ hydrocarbons was reached as high as 77.4% (FE_ethylene  ≈ 60%) at 500 mA cm^-2 . In situ infrared spectroscopy and DFT simulations demonstrate that abundant Cu⁺ species and Cu⁰ /Cu⁺ interfaces in the reduced CuOC(O) catalyst improve the adsorption and surface coverage of *CO on the Cu catalyst, thus facilitating CC coupling reactions.

Facilitated Photocatalytic CO2 Reduction in Aerobic Environment on a Copper-Porphyrin Metal-Organic Framework

Herein, we fabricated a π-π stacking hybrid photocatalyst by combining two two-dimensional (2D) materials: g-C₃ N₄ and a Cu-porphyrin metal-organic framework (MOF). After an aerobic photocatalytic pretreatment, this hybrid catalyst exhibited an unprecedented ability to photocatalytically reduce CO₂ to CO and CH₄ under the typical level (20 %) of O₂ in the air. Intriguingly, the presence of O₂ did not suppress CO₂ reduction; instead, a fivefold increase compared with that in the absence of O₂ was observed. Structural analysis indicated that during aerobic pretreatment, the Cu node in the 2D-MOF moiety was hydroxylated by the hydroxyl generated from the reduction of O₂ . Then the formed hydroxylated Cu node maintained its structure during aerobic CO₂ reduction, whereas it underwent structural alteration and was reductively devitalized in the absence of O₂ . Theoretical calculations further demonstrated that CO₂ reduction, instead of O₂ reduction, occurred preferentially on the hydroxylated Cu node.

Assembling Complex Macromolecules and Self-Organizations of Biological Relevance with Cu(I)-Catalyzed Azide-Alkyne, Thio-Bromo, and TERMINI Double "Click" Reactions

In 2022, the Nobel Prize in Chemistry was awarded to Bertozzi, Meldal, and Sharpless "for the development of click chemistry and biorthogonal chemistry". Since 2001, when the concept of click chemistry was advanced by Sharpless laboratory, synthetic chemists started to envision click reactions as the preferred choice of synthetic methodology employed to create new functions. This brief perspective will summarize research performed in our laboratories with the classic Cu(I)-catalyzed azide-alkyne click (CuAAC) reaction elaborated by Meldal and Sharpless, with the thio-bromo click (TBC) and with the less-used, irreversible TERminator Multifunctional INItiator (TERMINI) dual click (TBC) reactions, the last two elaborated in our laboratory. These click reactions will be used to assemble, by accelerated modular-orthogonal methodologies, complex macromolecules and self-organizations of biological relevance. Self-assembling amphiphilic Janus dendrimers and Janus glycodendrimers together with their biological membrane mimics known as dendrimersomes and glycodendrimersomes as well as simple methodologies to assemble macromolecules with perfect and complex architecture such as dendrimers from commercial monomers and building blocks will be discussed. This perspective is dedicated to the 75th anniversary of Professor Bogdan C. Simionescu, the son of my (VP) Ph.D. mentor, Professor Cristofor I. Simionescu, who as his father, took both science and science administration in his hands, and dedicated his life to handling them in a tandem way, to their best.

Tuning the C1 /C2 Selectivity of Electrochemical CO2 Reduction on Cu-CeO2 Nanorods by Oxidation State Control

Ceria (CeO₂ ) is one of the most extensively used rare earth oxides. Recently, it has been used as a support material for metal catalysts for electrochemical energy conversion. However, to date, the nature of metal/CeO₂ interfaces and their impact on electrochemical processes remains unclear. Here, a Cu-CeO₂ nanorod electrochemical CO₂ reduction catalyst is presented. Using operando analysis and computational techniques, it is found that, on the application of a reductive electrochemical potential, Cu undergoes an abrupt change in solubility in the ceria matrix converting from less stable randomly dissolved single atomic Cu²⁺ ions to (Cu⁰ ,Cu¹⁺ ) nanoclusters. Unlike single atomic Cu, which produces C₁ products as the main product during electrochemical CO₂ reduction, the coexistence of (Cu⁰ ,Cu¹⁺ ) clusters lowers the energy barrier for C-C coupling and enables the selective production of C₂₊ hydrocarbons. As a result, the coexistence of (Cu⁰ ,Cu¹⁺ ) in the clusters at the Cu-ceria interface results in a C₂₊ partial current density/unit Cu weight 27 times that of a corresponding Cu-carbon catalyst under the same conditions.

Intrinsic Charge Polarization in Bi19 S27 Cl3 Nanorods Promotes Selective CC Coupling Reaction during Photoreduction of CO2 to Ethanol

Obtaining multi-carbon products via CO₂  photoreduction is a major catalytic challenge involving multielectron-mediated CC bond formation. Complex design of multicomponent interfaces that are exploited to achieve this chemical transformation, often leads to untraceable deleterious changes in the interfacial chemical environment affecting CO₂  conversion efficiency and product selectivity. Alternatively, robust metal centers having asymmetric charge distribution can effectuate CC coupling reaction through the stabilization of intermediates, for desired product selectivity. However, generating inherent charge distribution in a single component catalyst is a difficult material design challenge. Here, a novel photocatalyst, Bi₁₉ S₂₇ Cl₃ , is presented which selectively converts CO₂  to a C₂  product, ethanol, in high yield under visible light irradiation. Structural analysis through transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy reveals the presence of charge polarized bismuth centers in Bi₁₉ S₂₇ Cl₃ . The intrinsic electric field induced by charge polarized bismuth centers renders better separation efficiency of photogenerated electron-hole pair. Furthermore, charge polarized centers yield better adsorption of CO* intermediate and accelerate the rate determining CC coupling step through the formation of OCCOH intermediate. Formation of these intermediates is experimentally mapped by in situ Fourier-transform infrared spectroscopy and further confirmed by theoretical calculation.

Surface Water as an Initial Proton Source for the Electrochemical CO Reduction Reaction on Copper Surfaces

We have employed in situ electrochemical shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) and density functional theory (DFT) calculations to study the CO reduction reaction (CORR) on Cu single-crystal surfaces under various conditions. Coadsorbed and structure-/potential-dependent surface species, including *CO, Cu-O_ad , and Cu-OH_ad , were identified using electrochemical spectroscopy and isotope labeling. The relative abundance of *OH follows a "volcano" trend with applied potentials in aqueous solutions, which is yet absent in absolute alcoholic solutions. Combined with DFT calculations, we propose that the surface H₂ O can serve as a strong proton donor for the first protonation step in both the C₁ and C₂ pathways of CORR at various applied potentials in alkaline electrolytes, leaving adsorbed *OH on the surface. This work provides fresh insights into the initial protonation steps and identity of key interfacial intermediates formed during CORR on Cu surfaces.

Fast Screening for Copper-Based Bimetallic Electrocatalysts: Efficient Electrocatalytic Reduction of CO2 to C2+ Products on Magnesium-Modified Copper

Electroreduction of CO₂ (CO₂ RR) into high value-added chemicals is an attractive route to achieve carbon neutrality. However, the development of an efficient catalyst for CO₂ RR is still largely by trial-and-error and is very time-consuming. Herein, we built an electrocatalyst testing platform featuring a home-built automatic flow cell to accelerate the discovery of efficient catalysts. A fast screening of 109 Cu-based bimetallic catalysts in only 55 h identifies Mg combined with Cu as the best electrocatalyst for CO₂ to C₂₊ products. The thus designed Mg-Cu catalyst achieves a Faradaic efficiency (FE) of C₂₊ products up to 80 % with a current density of 1.0 A cm^-2 at -0.77 V versus reversible hydrogen electrode (RHE). Systematic experiments with in situ spectroelectrochemistry analyses show that Mg²⁺ species stabilize Cu⁺ sites during CO₂ RR and promote the CO₂ activation, thus enhancing the *CO coverage to promote C-C coupling.

Learning the relationship between nanoscale chemical patterning and hydrophobicity

The hydrophobicity of proteins and similar surfaces, which display chemical heterogeneity at the nanoscale, drives countless aqueous interactions and assemblies. However, predicting how surface chemical patterning influences hydrophobicity remains a challenge. Here, we address this challenge by using molecular simulations and machine learning to characterize and model the hydrophobicity of a diverse library of patterned surfaces, spanning a wide range of sizes, shapes, and chemical compositions. We find that simple models, based only on polar content, are inaccurate, whereas complex neural network models are accurate but challenging to interpret. However, by systematically incorporating chemical correlations between surface groups into our models, we are able to construct a series of minimal models of hydrophobicity, which are both accurate and interpretable. Our models highlight that the number of proximal polar groups is a key determinant of hydrophobicity and that polar neighbors enhance hydrophobicity. Although our minimal models are trained on particular patch size and shape, their interpretability enables us to generalize them to rectangular patches of all shapes and sizes. We also demonstrate how our models can be used to predict hot-spot locations with the largest marginal contributions to hydrophobicity and to design chemical patterns that have a fixed polar content but vary widely in their hydrophobicity. Our data-driven models and the principles they furnish for modulating hydrophobicity could facilitate the design of novel materials and engineered proteins with stronger interactions or enhanced solubilities.

Molecularly Distorted Local Structure in Bi2 CuO4 Oxide to Stabilize Lattice Oxygen for Efficient Formate Electrosynthesis

The electrochemical CO₂ reduction reaction (CO₂ RR) provides an economically feasible way for converting green energy into valuable chemical feedstocks and fuels. Great progress has been achieved in the understanding and synthesis of oxidized-based precatalysts; however, their dynamical changes of local structure under operando conditions still hinder their further applications. Here a molecularly distorted Bi₂ CuO₄ precatalyst for efficient CO₂ -to-formate conversion is reported. X-ray absorption fine structure (XAFS) results and theoretical calculations suggest that the distorted structure with molecularly like [CuO₄ ]^6- unit rotation is more conducive to the structural stability of the sample. Operando XAFS and scanning transmission electron microscopy (STEM) results prove that quite a bit of lattice oxygen can remain in the distorted sample after CO₂ RR. Electrochemical measurements of the distorted sample show an excellent activity and selectivity with a high formate partial current density of 194.6 mA cm^-2 at an extremely low overpotential of -400 mV. Further in situ surface-enhanced infrared absorption spectroscopy (SEIRAS) and density functional theory (DFT) calculations illustrate that the retained oxygen can optimize the adsorption of *OCHO intermediate for the enhanced CO₂ RR performance.

Grain Boundary-Derived Cu+ /Cu0 Interfaces in CuO Nanosheets for Low Overpotential Carbon Dioxide Electroreduction to Ethylene

Electrochemical CO₂ reduction reaction can be used to produce value-added hydrocarbon fuels and chemicals by coupling with clean electrical energy. However, highly active, selective, and energy-efficient CO₂ conversion to multicarbon hydrocarbons, such as C₂ H₄ , remains challenging because of the lack of efficient catalysts. Herein, an ultrasonication-assisted electrodeposition strategy to synthesize CuO nanosheets for low-overpotential CO₂ electroreduction to C₂ H₄ is reported. A high C₂ H₄ Faradaic efficiency of 62.5% is achieved over the CuO nanosheets at a small potential of -0.52 V versus a reversible hydrogen electrode, corresponding to a record high half-cell cathodic energy efficiency of 41%. The selectivity toward C₂ H₄ is maintained for over 60 h of continuous operation. The CuO nanosheets are prone to in situ restructuring during CO₂ reduction, forming abundant grain boundaries (GBs). Stable Cu⁺ /Cu⁰ interfaces are derived from the low-coordinated Cu atoms in the reconstructed GB regions and act as highly active sites for CO₂ reduction at low overpotentials. In situ Raman spectroscopic analysis and density functional theory computation reveal that the Cu⁺ /Cu⁰ interfaces offer high *CO surface coverage and lower the activation energy barrier for *CO dimerization, which, in synergy, facilitates CO₂ reduction to C₂ H₄ at low overpotentials.

In Situ Halogen-Ion Leaching Regulates Multiple Sites on Tandem Catalysts for Efficient CO2 Electroreduction to C2+ Products

Tandem catalysts can divide the reaction into distinct steps by local multiple sites and thus are attractive to trigger CO₂ RR to C₂₊ products. However, the evolution of catalysts generally exists during CO₂ RR, thus a closer investigation of the reconstitution, interplay, and active origin of dual components in tandem catalysts is warranted. Here, taking AgI-CuO as a conceptual tandem catalyst, we uncovered the interaction of two phases during the electrochemical reconstruction. Multiple operando techniques unraveled that in situ iodine ions leaching from AgI restrained the entire reduction of CuO to acquire stable active Cu⁰ /Cu⁺ species during the CO₂ RR. This way, the residual iodine species of the Ag matrix accelerated CO generation and iodine-induced Cu⁰ /Cu⁺ promotes C-C coupling. This self-adaptive dual-optimization endowed our catalysts with an excellent C₂₊ Faradaic efficiency of 68.9 %. Material operando changes in this work offer a new approach for manipulating active species towards enhancing C₂₊ products.

Microfluidics-Assisted Synthesis of Hierarchical Cu2 O Nanocrystal as C2 -Selective CO2 Reduction Electrocatalyst

Copper-based catalysts have attracted enormous attention due to their high selectivity for C₂₊ products during the electrochemical reduction of CO₂ (CO₂ RR). In particular, grain boundaries on the catalysts contribute to the generation of various Cu coordination environments, which have been found essential for C-C coupling. However, smooth-surfaced Cu₂ O nanocrystals generally lack the ability for the surface reorganization to form multiple grain boundaries and desired Cu undercoordination sites. Flow chemistry armed with the unparalleled ability to mix reaction mixture can achieve a very high concentration of unstable reaction intermediates, which in turn are used up rapidly to lead to kinetics-driven nanocrystal growth. Herein, the synthesis of a unique hierarchical structure of Cu₂ O with numerous steps (h-Cu₂ O ONS) via flow chemistry-assisted modulation of nanocrystal growth kinetics is reported. The surface of h-Cu₂ O ONS underwent rapid surface reconstruction under CO₂ RR conditions to exhibit multiple heterointerfaces between Cu₂ O and Cu phases, setting the preferable condition to facilitate C-C bond formation. Notably, the h-Cu₂ O ONS obtained the increased C₂ H₄ Faradaic efficiency from 31.9% to 43.5% during electrocatalysis concurrent with the morphological reorganization, showing the role of the stepped surface. Also, the h-Cu₂ O ONS demonstrated a 3.8-fold higher ethylene production rate as compared to the Cu₂ O nanocube.

Tailoring the Surface and Interface Structures of Copper-Based Catalysts for Electrochemical Reduction of CO2 to Ethylene and Ethanol

Electrochemical CO₂ reduction to valuable ethylene and ethanol offers a promising strategy to lower CO₂ emissions while storing renewable electricity. Cu-based catalysts have shown the potential for CO₂ -to-ethylene/ethanol conversion, but still suffer from low activity and selectivity. Herein, the effects of surface and interface structures in Cu-based catalysts for CO₂ -to-ethylene/ethanol production are systematically discussed. Both reactions involve three crucial steps: formation of CO intermediate, CC coupling, and hydrodeoxygenation of C₂ intermediates. For ethylene, the key step is CC coupling, which can be enhanced by tailoring the surface structures of catalyst such as step sites on facets, Cu⁰ /Cu^δ+ species and nanopores, as well as the optimized molecule-catalyst and electrolyte-catalyst interfaces further promoting the higher ethylene production. While the controllable hydrodeoxygenation of C₂ intermediate is important for ethanol, which can be achieved by tuning the stability of oxygenate intermediates through the metallic cluster induced special atomic configuration and bimetallic synergy induced the double active sites on catalyst surface. Additionally, constraining CO coverage by the complex-catalyst interface and stabilizing CO bond by N-doped carbon/Cu interface can also enhance the ethanol selectivity. The structure-performance relationships will provide the guidance for the design of Cu-based catalysts for highly efficient reduction of CO₂ .

Copper Carbonate Hydroxide as Precursor of Interfacial CO in CO2 Electroreduction

Copper electrodes are especially effective in catalysis of C₂ and further multi-carbon products in the CO₂ reduction reaction (CO₂ RR) and therefore of major technological interest. The reasons for the unparalleled Cu performance in CO₂ RR are insufficiently understood. Here, the electrode-electrolyte interface was highlighted as a dynamic physical-chemical system and determinant of catalytic events. Exploiting the intrinsic surface-enhanced Raman effect of previously characterized Cu foam electrodes, operando Raman experiments were used to interrogate structures and molecular interactions at the electrode-electrolyte interface at subcatalytic and catalytic potentials. Formation of a copper carbonate hydroxide (CuCarHyd) was detected, which resembles the mineral malachite. Its carbonate ions could be directly converted to CO at low overpotential. These and further experiments suggested a basic mode of CO₂ /carbonate reduction at Cu electrodes interfaces that contrasted previous mechanistic models: the starting point in carbon reduction was not CO₂ but carbonate ions bound to the metallic Cu electrode in form of CuCarHyd structures. It was hypothesized that Cu oxides residues could enhance CO₂ RR indirectly by supporting formation of CuCarHyd motifs. The presence of CuCarHyd patches at catalytic potentials might result from alkalization in conjunction with local electrical potential gradients, enabling the formation of metastable CuCarHyd motifs over a large range of potentials.

Heterogeneous Synthetic Vesicles toward Artificial Cells: Engineering Structure and Composition of Membranes for Multimodal Functionalities

The desire to develop artificial cells to imitate living cells in synthetic vesicle platforms has continuously increased over the past few decades. In particular, heterogeneous synthetic vesicles made from two or more building blocks have attracted attention for artificial cell applications based on their multifunctional modules with asymmetric structures. In addition to the traditional liposomes or polymersomes, polypeptides and proteins have recently been highlighted as potential building blocks to construct artificial cells owing to their specific biological functionalities. Incorporating one or more functionally folded, globular protein into synthetic vesicles enables more cell-like functions mediated by proteins. This Review highlights the recent research about synthetic vesicles toward artificial cell models, from traditional synthetic vesicles to protein-assembled vesicles with asymmetric structures. We aim to provide fundamental and practical insights into applying knowledge on molecular self-assembly to the bottom-up construction of artificial cell platforms with heterogeneous building blocks.

The Unexpected Importance of the Primary Structure of the Hydrophobic Part of One-Component Ionizable Amphiphilic Janus Dendrimers in Targeted mRNA Delivery Activity

Viral and synthetic vectors for delivery of nucleic acids impacted genetic nanomedicine by aiding the rapid development of the extraordinarily efficient Covid-19 vaccines. Access to targeted delivery of nucleic acids is expected to expand the field of nanomedicine beyond most expectations. Both viral and synthetic vectors have advantages and disadvantages. The major advantage of the synthetic vectors is their unlimited synthetic capability. The four-component lipid nanoparticles (LNPs) are the leading nonviral vector for mRNA used by Pfizer and Moderna in Covid-19 vaccines. Their synthetic capacity inspired us to develop a one-component multifunctional sequence-defined ionizable amphiphilic Janus dendrimer (IAJD) delivery system for mRNA. The first experiments on IAJDs provided, through a rational-library design combined with orthogonal-modular accelerated synthesis and sequence control in their hydrophilic part, some of the most active synthetic vectors for the delivery of mRNA to lung. The second experiments employed a similar strategy, generating, by a less complex hydrophilic structure, a library of IAJDs targeting spleen, liver, and lung. Here, we report preliminary studies designing the hydrophobic region of IAJDs by using dissimilar alkyl lengths and demonstrate the unexpectedly important role of the primary structure of the hydrophobic part of IAJDs by increasing up to 90.2-fold the activity of targeted delivery of mRNA to spleen, lymph nodes, liver, and lung. The principles of the design strategy reported here and in previous publications indicate that IAJDs could have a profound impact on the future of genetic nanomedicine.

Atomically Dispersed Heteronuclear Dual-Atom Catalysts: A New Rising Star in Atomic Catalysis

Atomic catalysts (AC) are gaining extensive research interest as the most active new frontier in heterogeneous catalysis due to their unique electronic structures and maximum atom-utilization efficiencies. Among all the atom catalysts, atomically dispersed heteronuclear dual-atom catalysts (HDACs), which are featured with asymmetric active sites, have recently opened new pathways in the field of advancing atomic catalysis. In this review, the up-to-date investigations on heteronuclear dual-atom catalysts together with the last advances on their theoretical predictions and experimental constructions are summarized. Furthermore, the current experimental synthetic strategies and accessible characterization techniques for these kinds of atomic catalysts, are also discussed. Finally, the crucial challenges in both theoretical and experimental aspects, as well as the future prospects of HDACs for energy-related applications are provided. It is believed that this review will inspire the rational design and synthesis of the new generation of highly effective HDACs.

Adaptive Synthesis of Functional Amphiphilic Dendrons as a Novel Approach to Artificial Supramolecular Objects

Supramolecular structures, such as micelles, liposomes, polymerosomes or dendrimerosomes, are widely studied and used as drug delivery systems. The behavior of amphiphilic building blocks strongly depends on their spatial distribution and shape of polar and nonpolar component. This report is focused on the development of new versatile synthetic protocols for amphiphilic carbosilane dendrons (amp-CS-DDNs) capable of self-assembly to regular micelles and other supramolecular objects. The presented strategy enables the fine modification of amphiphilic structure in several ways and also enables the facile connection of a desired functionality. DLS experiments demonstrated correlations between structural parameters of amp-CS-DDNs and the size of formed nanoparticles. For detailed information about the organization and spatial distribution of amp-CS-DDNs assemblies, computer simulation models were studied by using molecular dynamics in explicit water.

Synergistic Effect of Cu2 O Mesh Pattern on High-Facet Cu Surface for Selective CO2 Electroreduction to Ethanol

Although the electroconversion of carbon dioxide (CO₂ ) into ethanol is considered to be one of the most promising ways of using CO₂ , the ethanol selectivity is less than 50% because of difficulties in designing an optimal catalyst that arise from the complicated pathways for the electroreduction of CO₂ to ethanol. Several approaches including the fabrication of oxide-derived structures, atomic surface control, and the Cu⁺ /Cu interfaces have been primarily used to produce ethanol from CO₂ . Here, a combined structure with Cu⁺ and high-facets as electrocatalysts is constructed by creating high-facets of wrinkled Cu surrounded by Cu₂ O mesh patterns. Using chemical vapor deposition graphene growth procedures, the insufficiently grown graphene is used as an oxidation-masking material, and the high-facet wrinkled Cu is simultaneously generated during the graphene growth synthesis. The resulting electrocatalyst shows an ethanol selectivity of 43% at -0.8 V versus reversible hydrogen electrode, which is one of the highest ethanol selectivity values reported thus far. This is attributed to the role of Cu⁺ in enhancing CO binding strength, and the high-facets, which favor C-C coupling and the ethanol pathway. This method for generating the combined structure can be widely applicable not only for electrochemical catalysts but also in various fields.

Spontaneous Formation and Fusion of Raspberry Vesicle Self-Assembled from Star Block Terpolymers in Aqueous Solution

The spontaneous formation and fusion of raspberry vesicles was studied using the dissipative particle dynamics (DPD) method. The vesicles were formed through the self-assembly of amphiphilic E₁₂O₆F₂ star terpolymers in selective solvent. E and F blocks are solvophobic and the O block is solvophilic. The shortest F block plays a major role in the formation of raspberry vesicles. Distinct vesicle formation mechanisms were observed at different polymer concentrations. At higher concentrations, vesicles form via the bending and closure of an oblate F-bump-E bilayer. At lower concentrations, the formation pathway contains: the initial formation of a vesicle with a core, the combination of such vesicles into cylindrical micelles, and the bending of the cylindrical micelles to form a hollow vesicle. In addition, raspberry vesicle fusion is regulated by F bumps through the continuous coalescence of them from apposed vesicle membranes. The contact area bends, followed by the formation of a fusion pore and a tilted inner layer. As the pore sealed, the hemifusion structure appears, which further restructures to form a vesicle. Our results provide guidance on understanding the dynamic processes of complex vesicles and biological membrane fusion.

Molecular Cleavage of Metal-Organic Frameworks and Application to Energy Storage and Conversion

The physicochemical properties of metal-organic frameworks (MOFs) significantly depend on composition, topology, and porosity, which can be tuned via synthesis. In addition to a classic direct synthesis, postsynthesis modulations of MOFs, including ion exchange, installation, and destruction, can significantly expand the application. Because of a limitation of the qualitative hard and soft acids and bases (HSAB) theory, posttreatment permits regulation of MOF structure by cleaving chemical bonds at the molecular level. Here, methods of coordination bond scission to tailor the structure are critically appraised and the application to energy storage and conversion is assessed. MOF structures synthesized by molecular-level coordination bond cleavage are described and the corresponding MOFs for electrocatalysis and renewable battery applications are evaluated. Significant emphasis is placed on various coordination bond cleavage to tune properties, including chemical groups, electronic structures, and morphologies. The review concludes with a critical perspective on practical application, together with challenges and future outlook for this emerging field.

Unexpected high selectivity for acetate formation from CO2 reduction with copper based 2D hybrid catalysts at ultralow potentials

Copper-based catalysts are efficient for CO₂ reduction affording commodity chemicals. However, Cu(i) active species are easily reduced to Cu(0) during the CO₂RR, leading to a rapid decay of catalytic performance. Herein, we report a hybrid-catalyst that firmly anchors 2D-Cu metallic dots on F-doped Cu_xO nanoplates (Cu_xOF), synthesized by electrochemical-transformation under the same conditions as the targeted CO₂RR. The as-prepared Cu/Cu_xOF hybrid showed unusual catalytic activity towards the CO₂RR for CH₃COO⁻ generation, with a high FE of 27% at extremely low potentials. The combined experimental and theoretical results show that nanoscale hybridization engenders an effective s,p-d coupling in Cu/Cu_xOF, raising the d-band center of Cu and thus enhancing electroactivity and selectivity for the acetate formation. This work highlights the use of electronic interactions to bias a hybrid catalyst towards a particular pathway, which is critical for tuning the activity and selectivity of copper-based catalysts for the CO₂RR.

A two-dimensional (2D) copper hybrid catalyst (Cu/Cu_xOF) composed of metallic Cu well dispersed on 2D F-doped Cu_xO nanoplates (Cu_xOF) is reported, which shows high catalytic activity toward the CO₂RR for acetate generation.

Recent Advances in Catalyst Structure and Composition Engineering Strategies for Regulating CO2 Electrochemical Reduction

Electrochemical CO₂ reduction has been recognized as a promising solution in tackling energy- and environment-related challenges of human society. In the past few years, the rapid development of advanced electrocatalysts has significantly improved the efficiency of this reaction and accelerated the practical applications of this technology. Herein, representative catalyst structures and composition engineering strategies in regulating the CO₂ reduction selectivity and activity toward various products including carbon monoxide, formate, methane, methanol, ethylene, and ethanol are summarized. An overview of in situ/operando characterizations and advanced computational modeling in deepening the understanding of the reaction mechanisms and accelerating catalyst design are also provided. To conclude, future challenges and opportunities in this research field are discussed.

Direct Evidence of Subsurface Oxygen Formation in Oxide-Derived Cu by X-ray Photoelectron Spectroscopy

Subsurface oxygen has been proposed to be crucial in oxide‐derived copper (OD‐Cu) electrocatalysts for enhancing the binding of CO intermediates during CO₂ reduction reaction (CO₂RR). However, the presence of such oxygen species under reductive conditions still remains debated. In this work, the existence of subsurface oxygen is validated by grazing incident hard X‐ray photoelectron spectroscopy, where OD‐Cu was prepared by reduction of Cu oxide with H₂ without exposing to air. The results suggest two types of subsurface oxygen embedded between the fully reduced metallic surface and the Cu₂O buried beneath: (i) oxygen staying at lattice defects and/or vacancies in the surface‐most region and (ii) interstitial oxygen intercalated in metal structure. This study adds convincing support to the presence of subsurface oxygen in OD‐Cu, which previously has been suggested to play an important role to mitigate the σ‐repulsion of Cu for CO intermediates in CO₂RR.

Targeted Delivery of mRNA with One-Component Ionizable Amphiphilic Janus Dendrimers

Targeted and efficient delivery of nucleic acids with viral and synthetic vectors is the key step of genetic nanomedicine. The four-component lipid nanoparticle synthetic delivery systems consisting of ionizable lipids, phospholipids, cholesterol, and a PEG-conjugated lipid, assembled by microfluidic or T-tube technology, have been extraordinarily successful for delivery of mRNA to provide Covid-19 vaccines. Recently, we reported a one-component multifunctional sequence-defined ionizable amphiphilic Janus dendrimer (IAJD) synthetic delivery system for mRNA relying on amphiphilic Janus dendrimers and glycodendrimers developed in our laboratory. Amphiphilic Janus dendrimers consist of functional hydrophilic dendrons conjugated to hydrophobic dendrons. Co-assembly of IAJDs with mRNA into dendrimersome nanoparticles (DNPs) occurs by simple injection in acetate buffer, rather than by microfluidic devices, and provides a very efficient system for delivery of mRNA to lung. Here we report the replacement of most of the hydrophilic fragment of the dendron from IAJDs, maintaining only its ionizable amine, while changing its interconnecting group to the hydrophobic dendron from amide to ester. The resulting IAJDs demonstrated that protonated ionizable amines play dual roles of hydrophilic fragment and binding ligand for mRNA, changing delivery from lung to spleen and/or liver. Replacing the interconnecting ester with the amide switched the delivery back to lung. Delivery predominantly to liver is favored by pairs of odd and even alkyl groups in the hydrophobic dendron. This simple structural change transformed the targeted delivery of mRNA mediated with IAJDs, from lung to liver and spleen, and expands the utility of DNPs from therapeutics to vaccines.

Recent Advances in Interface Engineering for Electrocatalytic CO2 Reduction Reaction

Electrocatalytic CO₂ reduction reaction (CO₂RR) can store and transform the intermittent renewable energy in the form of chemical energy for industrial production of chemicals and fuels, which can dramatically reduce CO₂ emission and contribute to carbon-neutral cycle. Efficient electrocatalytic reduction of chemically inert CO₂ is challenging from thermodynamic and kinetic points of view. Therefore, low-cost, highly efficient, and readily available electrocatalysts have been the focus for promoting the conversion of CO₂. Very recently, interface engineering has been considered as a highly effective strategy to modulate the electrocatalytic performance through electronic and/or structural modulation, regulations of electron/proton/mass/intermediates, and the control of local reactant concentration, thereby achieving desirable reaction pathway, inhibiting competing hydrogen generation, breaking binding-energy scaling relations of intermediates, and promoting CO₂ mass transfer. In this review, we aim to provide a comprehensive overview of current developments in interface engineering for CO₂RR from both a theoretical and experimental standpoint, involving interfaces between metal and metal, metal and metal oxide, metal and nonmetal, metal oxide and metal oxide, organic molecules and inorganic materials, electrode and electrolyte, molecular catalysts and electrode, etc. Finally, the opportunities and challenges of interface engineering for CO₂RR are proposed.

Highly Ethylene-Selective Electrocatalytic CO2 Reduction Enabled by Isolated Cu-S Motifs in Metal-Organic Framework Based Precatalysts

Copper-based materials are efficient electrocatalysts for the conversion of CO₂ to C₂₊ products, and most these materials are reconstructed in situ to regenerate active species. It is a challenge to precisely design precatalysts to obtain active sites for the CO₂ reduction reaction (CO₂ RR). Herein, we develop a strategy based on local sulfur doping of a Cu-based metal-organic framework precatalyst, in which the stable Cu-S motif is dispersed in the framework of HKUST-1 (S-HKUST-1). The precatalyst exhibits a high ethylene selectivity in an H-type cell with a maximum faradaic efficiency (FE) of 60.0 %, and delivers a current density of 400 mA cm^-2 with an ethylene FE up to 57.2 % in a flow cell. Operando X-ray absorption results demonstrate that Cu^δ+ species stabilized by the Cu-S motif exist in S-HKUST-1 during CO₂ RR. Density functional theory calculations indicate the partially oxidized Cu^δ+ at the Cu/Cu_x S_y interface is favorable for coupling of the *CO intermediate due to the modest distance between coupling sites and optimized adsorption energy.

Subsurface-Carbon-Induced Local Charge of Copper for an On-Surface Displacement Reaction

Transition-metal carbides have sparked unprecedented enthusiasm as high-performance catalysts in recent years. Still, the catalytic properties of copper carbide remain unexplored. By introducing subsurface carbon to Cu(111), a displacement reaction of a proton in a carboxyl acid group with a single Cu atom is demonstrated at the atomic scale and room temperature. Its occurrence is attributed to the C-doping-induced local charge of surface Cu atoms (up to +0.30 e/atom), which accelerates the rate of on-surface deprotonation via reduction of the corresponding energy barrier, thus enabling the instant displacement of a proton with a Cu atom when the molecules adsorb on the surface. This well-defined and robust Cu^δ+ surface based on subsurface-carbon doping offers a novel catalytic platform for on-surface synthesis.

In Situ Characterization for Boosting Electrocatalytic Carbon Dioxide Reduction

The electrocatalytic reduction of carbon dioxide into organic fuels and feedstocks is a fascinating method to implement the sustainable carbon cycle. Thus, a rational design of advanced electrocatalysts and a deep understanding of reaction mechanisms are crucial for the complex reactions of carbon dioxide reduction with multiple electron transfer. In situ and operando techniques with real-time monitoring are important to obtain deep insight into the electrocatalytic reaction to reveal the dynamic evolution of electrocatalysts' structure and composition under experimental conditions. In this paper, the reaction pathways for the CO₂ reduction reaction (CO₂ RR) in the generation of various products (e.g., C₁ and C₂ ) via the proposed mechanisms are introduced. Moreover, recent advances in the development and applications of in situ and operando characterization techniques, from the basic working principles and in situ cell structure to detailed applications are discussed. Suggestions and future directions of in situ/operando analysis are also addressed.

Catalyst Design for Electrochemical Reduction of CO2 to Multicarbon Products

Electrochemical reduction of CO₂ (CO₂ RR), driven by renewable energy (such as wind and solar energy), is an effective route toward carbon neutralization. The multicarbon (C₂₊ ) products from CO₂ RR are highly desirable, since they are important fuels, chemicals, and industrial raw materials. However, selective reduction of CO₂ to C₂₊ products is especially challenging, due to low selectivity, poor yield, and high overpotential. Since the performance of CO₂ RR is closely related to the structure and composition of catalysts, which alter the binding energy of intermediates generated in CO₂ RR, it is necessary to study these effects systematically to achieve possible design strategies. Herein, design strategies toward catalysts for CO₂ conversion to C₂₊ products are discussed on the basis of the adjustment of the structure and composition of catalysts, such as morphology control, defect engineering, bimetal, and surface modification. Meanwhile the reaction mechanisms and structure evolution of catalysts during CO₂ RR are focused on in particular. Finally, challenges and perspectives are proposed for further improvement of CO₂ RR technologies.

Identifying Structure-Selectivity Correlations in the Electrochemical Reduction of CO2 : A Comparison of Well-Ordered Atomically Clean and Chemically Etched Copper Single-Crystal Surfaces

The identification of the active sites for the electrochemical reduction of CO2 (CO2 RR) to specific chemical products is elusive, owing in part to insufficient data gathered on clean and atomically well-ordered electrode surfaces. Here, ultrahigh vacuum based preparation methods and surface science characterization techniques are used with gas chromatography to demonstrate that subtle changes in the preparation of well-oriented Cu(100) and Cu(111) single-crystal surfaces drastically affect their CO2 RR selectivity. Copper single crystals with clean, flat, and atomically ordered surfaces are predicted to yield hydrocarbons; however, these were found experimentally to favor the production of H2 . Only when roughness and defects are introduced, for example by electrochemical etching or a plasma treatment, are significant amounts of hydrocarbons generated. These results show that structural and morphological effects are the key factors determining the catalytic selectivity of CO2 RR.