Toward Ultra‐High‐Quality‐Factor Wireless Masing Magnetic Resonance SensingAdelabu, Isaiah; Nantogma, Shiraz; Fleischer, Simon; Abdulmojeed, Mustapha; Maissin, Henri; Schmidt, Andreas B.; Lehmkuhl, Soeren; Rosen, Matthew S.; Appelt, Stephan; Theis, Thomas; Qian, Chunqi; Chekmenev, Eduard Y.
doi: 10.1002/anie.202406551pmid: 38822492
It has recently been shown that a bolus of hyperpolarized nuclear spins can yield stimulated emission signals similar in nature to maser signals, potentially enabling new ways of sensing hyperpolarized contrast media, including most notably [1‐13C]pyruvate that is under evaluation in over 50 clinical trials for metabolic imaging of cancer. The stimulated NMR signal emissions lasting for minutes do not require radio‐frequency excitation, offering unprecedented advantages compared to conventional MR sensing. However, creating nuclear spin maser emission is challenging in practice due to stringent fundamental requirements, making practical in vivo applications hardly possible using conventional passive MR detectors. Here, we demonstrate the utility of a wireless NMR maser detector, the quality factor of which was enhanced 22‐fold (to 1,670) via parametric pumping. This active‐feedback technique breaks the intrinsic fundamental limit of NMR detector circuit quality factor. We show the use of parametric pumping to reduce the threshold requirement for inducing nuclear spin masing at 300 MHz resonance frequency in a preclinical MRI scanner. Indeed, stimulated emission from hyperpolarized protons was obtained under highly unfavorable conditions of low magnetic field homogeneity (T2* of 3 ms). Greater gains of the quality factor of the MR detector (up to 1 million) were also demonstrated.
Common Biosynthesis of Non‐Canonical C16 Terpenes through a Fragmentation‐Recombination MechanismXu, Houchao; Goldfuss, Bernd; Dickschat, Jeroen S.
doi: 10.1002/anie.202408809pmid: 38924286
The biosynthesis of six recently reported non‐canonical C16 sesquiterpenoids named after ancient Greek philosophers, archimedene, aristotelene, eratosthenene, pythagorene, α‐democritene and anaximandrene, was investigated through density functional theory (DFT) calculations and isotopic labeling experiments. The results revealed for all compounds except archimedene a unique fragmentation‐recombination mechanism as previously demonstrated for sodorifen biosynthesis, in addition to a remarkable “dancing” mechanism for anaximandrene biosynthesis.
A NIR‐Light‐Activated and Lysosomal‐Targeted Pt(II) Metallacycle for Highly Potent Evoking of Immunogenic Cell Death that Potentiates Cancer Immunotherapy of Deep‐Seated TumorsLi, Chonglu; Tu, Le; Xu, Yuling; Li, Meiqin; Du, Jiaxing; Stang, Peter J.; Sun, Yan; Sun, Yao
doi: 10.1002/anie.202406392pmid: 38775364
Though platinum (Pt)‐based complexes have been recently exploited as immunogenic cell death (ICD) inducers for activating immunotherapy, the effective activation of sufficient immune responses with minimal side effects in deep‐seated tumors remains a formidable challenge. Herein, we propose the first example of a near‐infrared (NIR) light‐activated and lysosomal targeted Pt(II) metallacycle (1) as a supramolecular ICD inducer. 1 synergistically potentiates immunomodulatory response in deep‐seated tumors via multiple‐regulated approaches, involving NIR light excitation, boosted reactive oxygen species (ROS) generation, good selectivity between normal and tumor cells, and enhanced tumor penetration/retention capabilities. Specifically, 1 has excellent depth‐activated ROS production (~7 mm), accompanied by strong anti‐diffusion and anti‐ROS quenching ability. In vitro experiments demonstrate that 1 exhibits significant cellular uptake and ROS generation in tumor cells as well as respective multicellular tumor spheroids. Based on these advantages, 1 induces a more efficient ICD in an ultralow dose (i.e., 5 μM) compared with the clinical ICD inducer‐oxaliplatin (300 μM). In vivo, vaccination experiments further demonstrate that 1 serves as a potent ICD inducer through eliciting CD8+/CD4+ T cell response and Foxp3+ T cell depletion with negligible adverse effects. This study pioneers a promising avenue for safe and effective metal‐based ICD agents in immunotherapy.
Function Switch of a Fungal Sesterterpene Synthase through Molecular Dynamics Simulation Assisted Alteration of an Aromatic Residue Cluster in the Active Pocket of PfNSZhang, Weiyan; Wang, Xinye; Zhu, Guoliang; Zhu, Bin; Peng, Kaitong; Hsiang, Tom; Zhang, Lixin; Liu, Xueting
doi: 10.1002/anie.202406246pmid: 38934471
Terpene synthases (TPSs) play pivotal roles in generating diverse terpenoids through complex cyclization pathways. Protein engineering of TPSs offers a crucial approach to expanding terpene diversity. However, significant potential remains untapped due to limited understanding of the structure‐function relationships of TPSs. In this investigation, using a joint approach of molecular dynamics simulations‐assisted engineering and site‐directed mutagenesis, we manipulated the aromatic residue cluster (ARC) of a bifunctional terpene synthase (BFTPS), Pestalotiopsis fici nigtetraene synthase (PfNS). This led to the discovery of previously unreported catalytic functions yielding different cyclization patterns of sesterterpenes. Specifically, a quadruple variant (F89A/Y113F/W193L/T194W) completely altered PfNS′s function, converting it from producing the bicyclic sesterterpene nigtetraene to the tricyclic ophiobolin F. Additionally, analysis of catalytic profiles by double, triple, and quadruple variants demonstrated that the ARC functions as a switch, unprecedently redirecting the production of 5/11 bicyclic (Type B) sesterterpenes to 5/15 bicyclic (Type A) ones. Molecular dynamics simulations and theozyme calculations further elucidated that, in addition to cation‐π interactions, C−H⋅⋅⋅π interactions also play a key role in the cyclization patterns. This study offers a feasible strategy in protein engineering of TPSs for various industrial applications.
Inducing Immunogenic Cancer Cell Death through Oxygen‐Economized Photodynamic Therapy with Nitric Oxide‐Releasing PhotosensitizersXu, Feijie; Wang, Meijun; Dotse, Eunice; Chow, Kwan T.; Lo, Pui‐Chi
doi: 10.1002/anie.202404561pmid: 38887983
Photodynamic therapy (PDT) utilizes reactive oxygen species (ROS) for eradication of cancer cells. Its effectiveness is governed by the oxygen content, which is scarce in the hypoxic tumor microenvironment. We report herein two zinc(II) phthalocyanines substituted with two or four nitric oxide (NO)‐releasing moieties, namely ZnPc‐2NO and ZnPc‐4NO, which can suppress the mitochondrial respiration, thereby sparing more intracellular oxygen for PDT. Using HT29 human colorectal adenocarcinoma cells and A549 human lung carcinoma cells, we have demonstrated that both conjugates release NO upon interaction with the intracellular glutathione, which can reduce the cellular oxygen consumption rate and adenosine triphosphate generation and alter the mitochondrial membrane potential. They can also relieve the hypoxic status of cancer cells and decrease the expression of hypoxia‐inducible factor protein HIF‐1α. Upon light irradiation, both conjugates can generate ROS and induce cytotoxicity even under a hypoxic condition, overcoming the oxygen‐dependent nature of PDT. Interestingly, the photodynamic action of ZnPc‐2NO elicits the release of damage‐associated molecular patterns, inducing the maturation of dendritic cells and triggering an antitumor immune response. The immunogenic cell death caused by this oxygen‐economized PDT has been demonstrated through a series of in vitro and in vivo experiments.
Accelerating the Discovery of Oxygen Reduction Electrocatalysts: High‐Throughput Screening of Element Combinations in Pt‐Based High‐Entropy AlloysPan, Yiyang; Shan, Xiangyi; Cai, Furong; Gao, Han; Xu, Jianan; Zhou, Min
doi: 10.1002/anie.202407116pmid: 38934207
The vast number of element combinations and the explosive growth of composition space pose significant challenges to the development of high‐entropy alloys (HEAs). Here, we propose a procedural research method aimed at accelerating the discovery of efficient electrocatalysts for oxygen reduction reaction (ORR) based on Pt‐based quinary HEAs. The method begins with an element library provided by a large language model (LLM), combined with microscale precursor printing and pulse high‐temperature synthesis techniques to prepare multi‐element combination HEA array in one step. Through high‐throughput measurement using scanning electrochemical cell microscopy (SECCM), precise identification of highly active HEA element combinations and exploration of composition space for a specific combination are achieved. Advantageous element combinations are further validated in practical electrocatalytic evaluations. The contributions of individual element sites and the synergistic effects among elements of such HEAs in enhancing reaction activity are elucidated via density functional theory (DFT) calculations. This method integrates high‐throughput experiments, practical catalyst validation, and DFT calculations, providing a new pathway for accelerating the discovery of efficient multi‐element materials in the field of energy catalysis.