Abstract Nature effectively employs the light-induced transfer of a proton for rapid interconversion between different electronic states of a molecule and uses tautomerism as a functional design principle in biological systems. Twenty-five years ago, the theoretical design concept of proton cranes was introduced to describe molecules capable of transferring protons at a long-range upon photoexcitation, by analogy with the functioning of a mechanical crane. Unlike conventional materials whose function relies on proton transfer events, the proton cranes operate with atomic level precision, enabling the controlled delivery of a proton between predefined sites within a molecule. Shortly after, the theoretical concept was extended to reversibly operating proton delivery systems, placing the proton cranes in the field of molecular machines and light-responsive switches. In 2024, the first clean switching in proton cranes was theoretically predicted and experimentally demonstrated, opening a highway to a broad range of real-world applications of these intriguing systems. Here, we provide an outlook of the current state of the art and progress in the field and formulate guidelines for further development of efficient proton cranes.
Abstract N-Heterocyclic imines (NHIs) represent a promising class of sorbents for electrochemically mediated carbon capture (EMCC) due to their ability to bind CO2 in the neutral state and operate reversibly at redox potentials more positive than that of oxygen. In this study, the effect of electrolyte composition on the thermochemical and electrochemical behavior of NHI-based systems is examined. Using reaction calorimetry and Raman and NMR spectroscopy, we demonstrate that Lewis acid cations stabilize the NHI–CO2 adduct through charged interactions, and the solvent and anion donor number tune this stabilization by modulating the effective cation Lewis acidity. As a result, electrolyte salts can substantially increase the magnitude of the NHI–CO2 reaction enthalpy, leading to higher CO2 loading on NHI at low CO2 partial pressure (10–3 atm) and faster capture kinetics. The impacts of the electrolyte selection on NHI redox behavior as well as oxygen reduction were also investigated. The findings indicate that electrolyte design must balance the strength of cation–NHI–CO2 stabilization, NHI redox activity, and the redox potential separation from oxygen reduction. By providing a mechanistic framework for how individual electrolyte components govern important process parameters, this work offers insights for optimizing electrolyte environments to achieve high-efficiency and reversible EMCC.
Abstract Organic cations and radicals are promising building components for organic optoelectronics, spintronics and quantum information processing. Realizing their full potential requires strategies to enhance their stability and precisely control their solid-state organization. Herein, we describe a modular synthetic strategy via photoelectrocyclization in the presence of tetracyanoethylene (TCNE) to access a series of closed-shell phenalenyl-derived cations featuring an oxonium-embedded benzo[b]perylene (OBP+) π-skeleton. The resulting OBP+ cations can be reversibly reduced to generate neutral open-shell phenalenyl-derived radicals. Noteworthily, we discovered a single crystal of OBP3·TCNE• that readily formed from the reaction mixture, displaying one-dimensional (1D) π-stacked arrays of alternating closed-shell OBP3+ cation and open-shell TCNE•– radical anion. This solid-state arrangement stabilizes otherwise reactive TCNE•– species, preserving its open-shell character even after one month of ambient exposure. OBP3·TCNE• is a rare example of purely organic paramagnetic salt and has been systematically investigated using integrated spectroscopic, magnetic, and computational analyses, together with preliminary photoconductivity measurements (ϕΣμ = 1.4 × 10–5 cm2 V–1 s–1). Overall, this work heralds a versatile photochemical route to redox-switchable cationic π-scaffolds and persistent open-shell crystalline organic materials.
Abstract Direct air capture (DAC) is a promising strategy for mitigating atmospheric CO2 accumulation, yet sorbent evaluation remains dominated by equilibrium uptake under static conditions that fail to capture kinetic, humid, and process-level constraints relevant to real operation. Here we establish a dynamic evaluation framework that replaces equilibrium-centric metrics with a unified platform integrating high-precision gravimetric measurements, ppm-level CO2 nondispersion infrared detection, and capacitive humidity sensing, enabling direct quantification of adsorption kinetics, H2O/CO2 coadsorption, breakthrough behavior, and regeneration energy under low CO2 concentration and dry/humid conditions. Using TAEA@MIL-101(Cr) as a benchmark system, we introduce a sonication-assisted impregnation strategy that enables coordinated amine anchoring with preserved porosity and strong CO2 chemisorption. The optimized material exhibits a high equilibrium CO2 of 3.12 mmol g–1 (13.8 wt %) at 298 K, a dynamic breakthrough capacity of 12.4 wt % under dry conditions, and a retained capacity of 9.7 wt % at 50% relative humidity. Complete regeneration is achieved at 50 °C, enabling low-energy temperature-swing operation. This work establishes a generalizable dynamic benchmarking framework for DAC sorbents and positions TAEA@MIL-101(Cr) as a reference platform bridging molecular design, kinetic performance, and process-level energy requirements to complement conventional equilibrium evaluation.
Abstract Phase propagation and phase separation in biomolecular condensates have emerged as key concepts for understanding the nonequilibrium evolution of functional assemblies, yet achieving analogous processes in soft molecular aggregates remains challenging. Here, we directly visualize phase propagation between coexisting J-type coupled and excimer-emitting domains within individual crystalline fibrils of a chiral perylenediimide dimer (RCy-PDI2) using fluorescence lifetime imaging microscopy (FLIM). FLIM analysis revealed heterogeneous distribution of short (τblue ≈ 1.5 ns) and long (τgreen ≈ 8 ns) fluorescence lifetime components in a single aggregate fibril. Time-dependent FLIM measurements facilitated the understanding of phase propagation and shrinkage-induced fibril fracture in the aggregate fibrils. Steady-state and chiroptical measurements of (RCy-PDI2) aggregate fibrils indicated the presence of J-type aggregate formation and excimer emission. Three-dimensional electron diffraction (3D ED) reveals a toluene-intercalated structure enforcing a V-shaped geometry (interplanar angle: 26.3°), enabling strong Coulombic coupling (Jc = -55 to -73 meV) consistent with J-type interactions. Toluene diffusion and detrapping drive structural relaxation, converting J-type domains into excimer-emitting regions within the same fibril, establishing a direct structural basis for excitonic state selection. This work correlates excitonic heterogeneity with phase propagation, expanding our understanding of the role of solvent diffusion and molecular stacking in the development of functional supramolecular materials.
Abstract The implementation of green chemistry principles in catalysis is essential for sustainable production of specialty chemicals, where selectivity and efficiency are paramount. Unspecific peroxygenases (UPOs) have emerged as promising biocatalysts for enantioselective C–H oxyfunctionalization reactions, using hydrogen peroxide (H2O2) as the sole oxidant. However, the instability of UPOs toward H2O2 and the nonsustainable production of this reagent remain key challenges. Herein, we report the design of a hybrid chemo-enzymatic heterogeneous catalyst integrating an Au–Pd-based material with the PaDa-I UPO mutant, using an “enzyme-in-a-cage” immobilization strategy. This bifunctional system enables controlled in situ H2O2 generation directly from H2 and O2, coupled with the enantioselective hydroxylation of ethylbenzene in a single reactor. The catalyst exhibits high activity, excellent enantioselectivity (ee = 97.7%), and stability without enzyme leaching. This approach offers a robust and sustainable platform for one-pot chemo-enzymatic cascade reactions in chemical synthesis.
Patrick Shih cofounded Totality Biosciences to make human milk oligosaccharides for more-nutritious baby formula.
Ferroptosis represents a promising strategy to overcome apoptosis-associated drug resistance, yet access to diverse and drug-like ferroptosis-inducing chemical space remains limited. Among potential scaffolds for populating this high-value space, cyanamide-bearing molecules are attractive but synthetically challenging due to the long-standing difficulty of constructing the N-CN bond. Here we disclose a thiocyanate-enabled cascade cyclization that leverages inexpensive, low-toxicity inorganic thiocyanate as an unconventional electrophilic CN surrogate. This transformation proceeds through a cascade sequence involving SCN installation, remote S → N cyano migration, and subsequent intramolecular thiazine annulation under mild, metal-free conditions. The resulting cyanamide 3,4-dihydro-2H-1,4-thiazines exhibited nanomolar ferroptosis-inducing potency; lead compounds 3b and 3c achieved IC50 values of 6.8 nM and 14 nM, respectively; and significantly suppressed tumor growth in a lung cancer PDX model.
Interleukin-2 (IL-2) is a potent mediator of T-cell activation with significant potential for cancer immunotherapy, yet its clinical utility is severely constrained by its narrow therapeutic window. Here we report a chemically masked IL-2 prodrug (Cm-proIL2) that enables tumor-microenvironment-responsive cytokine activation through tumor-associated protease cleavage. Site-specific conjugation of a poly-(ethylene glycol) (PEG) moiety selectively masks peripheral receptor engagement, while PEG removal within the tumor microenvironment restores IL-2 receptor binding and reduces molecular size, thereby enhancing intratumoral lymphocyte penetration and effector T cell functionality. Building on this modular platform, we further engineered a PD-1-targeted nanobody fusion, PD1-Cm-proIL2, to enable the cis delivery of IL-2 activity to PD-1+ tumor-infiltrating T cells. PD1-Cm-proIL2 induces robust antitumor immunity, resulting in complete tumor regression and durable protection upon tumor rechallenge in a murine colorectal cancer model. Together, these findings demonstrate the feasibility of chemically masked, tumor-responsive cytokine activation as a strategy for improving the therapeutic index of IL-2-based immunotherapies.
Protein arginine deiminase-4 (PAD4) catalyzes hydrolysis of arginine to citrulline in proteins that promote widespread cellular changes that can induce innate immunity and promote cancer. Hyperactivity of PAD4 leads to a form of cell death called NETosis, releasing PAD4 to the extracellular space to promote various autoimmune diseases through the generation of anticitrulline protein antibodies (ACPAs). Little is known about the specific citrullinated substrates that lead to autoimmunity, but there is growing evidence that PAD4 is localized to the cell surface in response to inflammation. Here, we characterize the cellular consequences of exogenous PAD4, showing that it induces morphological changes that increase cell migration, a hallmark of cancer. We then devised a robust proteomics approach to identify PAD4 substrates. We identified ∼ 3000 citrullinated peptides from 1300 proteins upon exogenous addition of PAD4 both inside and outside of cells. This extracellular set can be further augmented by targeting PAD4 to cancer cells using a HER2 binding protein conjugate. Finally, we studied how citrullinated cells can induce a humoral response in vivo to produce ACPAs. We believe these studies further our understanding of cellular consequences of extracellular PAD4 and identify new PAD4 substrates that are potential neoepitopes for ACPA generation.
Neutral or basic conditions are commonly required for the selective electrochemical reduction of CO2, leading to the accumulation of carbonate salts and the generation of formate rather than formic acid. A generalizable strategy for obtaining formic acid (not formate) in the electroreduction of CO2 with molecular catalysts is introduced, based on controlling acidity gradients using a dual-electrolyte cell with a proton-exchange membrane. This approach uses anodic water oxidation as the source of protons and electrons for CO2 reduction to formic acid, while mitigating H2 evolution near the cathode and avoiding carbonate formation. Mechanistic studies, including systems modeling, provide insight into the origin of the formic acid selectivity and guide the broader implementation of this strategy in molecular electrocatalysis for CO2 utilization.
Glycolipids are essential for myelin integrity, but their extensive isomeric complexity, where isomers like galactosylceramide (GalCer) and glucosylceramide (GlcCer) have unique functions, has hindered our ability to map their metabolism in the brain. Existing mass spectrometry methods fail to resolve this complexity. We fundamentally overcome this barrier with a powerful new isomer-resolved mass spectrometry imaging workflow. By coupling ion mobility and mass spectrometry imaging with targeted enzymatic pretreatment, our method provides direct visualization of distinct de novo metabolic pathways for GalCer and GlcCer in situ. When applied to rat brains across the lifespan (2, 6, and 12 months), this technology revealed a previously unrecognized age-related decline that selectively affected the GalCer pathway, while the isomeric GlcCer pathway remained comparatively stable. We confirmed these metabolic alterations colocalize with myelin-associated proteins specifically in oligodendrocyte-rich regions, providing a functional link to altered oligodendrocyte-related lipid metabolism. This integrated approach provides a new paradigm for dissecting isomer-specific glycolipid metabolism, offering insight into lipid alterations in brain aging and opening new avenues for biomarker discovery in neurodegeneration.
Elemental mass spectrometry imaging (MSI) of biomolecules via metal-conjugated antibodies enables highly multiplexed, in situ quantitative analyses. However, the detection of low abundance analytes by elemental MSI and the spatial resolution of the images obtained are inhibited by detector sensitivity. To overcome this constraint, we introduce FRACTAL-MSI, a signal amplification method that adapts FluoRescent signal Amplification via Cyclic staining of TArget moLecules (FRACTAL) for multimodal laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and immunofluorescence (IF) imaging by alternating fluorescent- and lanthanide-tagged secondary antibodies on the same histological section. Using NeuN as a model neuronal marker, we demonstrate 23-80× amplification of IF and LA-ICP-MS signals in fresh-frozen murine brain, FFPE tissue, and SH-SY5Y cells. Two image fusion methods that did not require machine learning were then developed that exploited true probe colocalization to generate quantitative elemental images at IF resolution. The enhanced sensitivity permitted super-resolution reconstruction of LA-ICP-MS data to obtain subcellular images with a 250 nm resolution, or greater than that of the 40× IF obtained via image fusion. We also demonstrated selective target amplification within a 4-plex elemental panel. Together, FRACTAL-MSI provides a practical, broadly accessible strategy to improve detection, and therefore the resolution, of low-abundance biomolecules.
Abstract Engineering physiologically relevant cardiac substrates requires precise control over both electrical and mechanical cues to guide cardiomyocyte functions and features. In this work, we report a biomolecular-based approach toward spatially controllable photostimulation of cardiac behavior via digital light processing of conductive interfaces on a range of substrate stiffnesses. The symmetric peptide-quaterthiophene-peptide units are designed to form conductive patterns atop biopolymeric hydrogels, allowing for microscale spatial control of photoconductive pathways that can influence cardiomyocyte alignment and intercellular communication in a light-activated manner. Substrate stiffness was modulated through adjusting material composition across a physiologically relevant range to reflect healthy and fibrotic cardiac tissue conditions. The ability to tailor the geometry of conductive pathways across a range of biomaterial interfaces and stiffnesses enables systematic assessment of how electrical signals from patterned optoelectronic peptides regulate cardiomyocyte behavior. Neonatal rat ventricular myocytes (NRVMs) cultured on π-conjugated peptide-based substrates exhibited enhanced alignment, synchronous contractility, and altered calcium flux dynamics compared to nonconductive substrates. Furthermore, the optoelectronic cardiac biomaterial-based scaffolds were shown to possess biological photostimulation capabilities, specifically enabling light-induced localized stimulation of excitable cells for high-resolution stimulation without the need for external electrodes or genetic modifications necessary for optogenetic approaches. Photostimulated NRVMs interfaced with optoelectronic peptide structures were shown to be more confined to the printed conductive patterns, with more cell localization and structural remodeling with respect to the patterns than in non-photostimulated conditions. The peptide-based platform presented here provides a potential approach to control mechanical and optoelectronic cues using microscale patterns in vitro, while opening avenues for advanced cardiac disease modeling, drug development, and the development of complex bioelectronic cardiac interfaces.
Abstract A central challenge across modern chemistry, biology, materials science, and origins-of-life research is obtaining a balance between harnessing beneficial photoreactions and minimizing detrimental photodamage. Here, we have discovered an aggregation-induced photoprotection pathway provided by nonconjugated small molecules. Although conventionally classified as UV-transparent due to the lack of chromophores, these molecules are found to form supramolecular assemblies at elevated concentrations and develop emergent UV-absorbing properties, likely via slip-stacked J-aggregation, as confirmed by multiple spectroscopic characterizations. Density functional theory calculations further elucidated the mechanism of the observed concentration-dependent absorption. A predictive structure–property relationship has been proposed. Regulated by concentration, this effect can smartly allow necessary photoreactions while shielding critical biomolecules from excessive UV radiation. It also suggests that self-photoprotection of the aggregatable molecules could have enabled their prebiotic survival and enduring presence under harsh UV conditions. Furthermore, these findings prompted us to develop a convenient and noninvasive photoprotection strategy for contemporary plastic materials using inexpensive and environmentally friendly small agents.
Abstract Clostridium difficile (C. difficile), a Gram-positive bacterium responsible for life-threatening diarrhea, causes approximately 12 800 deaths annually in the United States, yet no licensed vaccine is currently available. PS-III, a cell-surface glycan composed of 6,6′-phosphodiester-linked di-N-acetylglucosamine (di-GlcNAc) repeats, has been identified as a promising vaccine antigen because of its potent immunogenicity. However, the lack of efficient synthetic method limited the availability of structurally defined PS-III antigens, hampering systematic immunological analysis. Herein, we report a solid-phase synthesis strategy employing Merrifield resin that enables efficient assembly of PS-III oligosaccharides up to a tridecasaccharide─the largest well-defined structure synthesized up to date. Three CRM197-conjugated vaccines bearing precisely defined glycotopes ranging from pentasaccharide to tridecasaccharide were constructed and evaluated in both in vitro and in vivo immunization studies. Glycan microarray profiling of sera from immunized mice revealed glycotope length-dependent IgG/IgM responses, with the nonasaccharide (1d-CRM197) and tridecasaccharide conjugate (1f-CRM197) eliciting the strongest binding. In a murine challenge model, most glycoconjugate vaccines conferred superior protection against C. difficile compared with inactivated whole cell bacteria vaccine. Notably, 1f-CRM197 induced a nearly complete bacterial killing in the opsonophagocytic assay. Collectively, we have established an efficient solid-phase synthesis for well-defined C. difficile PS-III glycans. The resulting CRM197-conjugate vaccines with short-to-long glycans showed potent activity in opsonophagocytic and murine models, paving the way for preclinical development of C. difficile glycoconjugate vaccines.
Ligand dimerization represents a powerful strategy to enhance avidity, potency, and selectivity. Leveraging the natural-product molecular glue rocaglamide (RocA), we identified BisRoc, a dimeric rocaglate ligand that potently and durably suppresses translation and exhibits greater specificity across a cancer cell line panel than the monomeric RocA. CRISPRi screening revealed that BisRoc activity is influenced by cellular context, including IFITM-mediated uptake, ABC-type efflux transporters, and the translation initiation factor eIF4A2. Mechanistic studies showed that the paralogs eIF4A1 and eIF4A2 are differentially sensitive to BisRoc-induced dimerization. Owing to the presence of multiple binding sites on RNAs, BisRoc-bridged eIF4A-RNA motifs assemble into higher-order complexes that promote stress-granule formation more efficiently than monomeric RocA. Given the widespread multivalency of RNA-RBP interactions, this ligand dimerization strategy may be extended to modulate the higher-order assembly of other RNA-binding proteins.
