Structural Engineering of Hierarchical Aerogels Hybrid Networks for Efficient Thermal Comfort Management and Versatile Protection.

In recent years, growing concerns regarding energy efficiency and heat mitigation, along with the critical goal of carbon neutrality, have drawn human attention to the zero-energy-consumption cooling technique. Passive daytime radiative cooling (PDRC) can be an invaluable tool for combating climate change by dispersing ambient heat directly into outer space instead of just transferring it across the surface. Although significant progress has been made in cooling mechanisms, materials design, and application exploration, PDRC faces challenges regarding functionality, durability, and commercialization. Herein, a silica nanofiber aerogels (SNAs) functionalized poly(vinylidene fluoride-co-hexafluoropropene) (P(VDF-HFP)) membrane (SFP membrane), inspired by constructional engineering is constructed. As-prepared membranes with flexible network structure combined hierarchical structure design and practicability principal. As the host material for thermal comfort management (TCM) and versatile protection, the SFP membrane features a large surface area, porous structure, and a robust skeleton that can render excellent mechanical properties. Importantly, the SFP membrane can keep exceptional solar reflectivity (0.95) and strong mid-infrared emittance (0.98) drop the temperature to 12.5 °C below ambient and 96 W m-2 cooling power under typical solar intensities over 910 W m-2 . This work provides a promising avenue for high performance aerogel membranes that can be created for use in a wide variety of applications.

Sculpting Electrochemically Growing or Grown Microarchitectures.

Microarchitectures with complex interior structures are important for many applications. However, engineering complex interior structures within microarchitectures are challenging. This article reports the introduction of electrochemical sculpting processes to carve the microarchitectures during or after their electrochemical growing process to design the interior structure of the microarchitectures. The electrochemical growing and sculpting process tangle together under the constant voltage electrodeposition mode with their strength depending on the ion concentration gradient and the voltage value. The unique thawing process of the frozen electrolyte is used to create the desired sharp ion concentration gradient, and has the potential to control the strength of the sculpting and the growing processes. How to completely decouple the growing and the sculpting process is further studied to gain more accurate control over the interior structures of the microarchitectures. It is revealed that the sculpting process can be exclusively applied onto the electrochemically grown microarchitectures simply by reversing the electric field without triggering any growing processes. Microarchitectures with complex interior structures, including micropyramids with a single cavity exclusively at the outward or every apex to multi-walled hollow pyramids with designable wall numbers and inter-wall distances are prepared as examples.

Latticed-Confined Conversion Chemistry of Battery Electrode.

The electrochemical conversion reaction, usually featured by multiple redox processes and high specific capacity, holds great promise in developing high-energy rechargeable battery technologies. However, the complete structural change accompanied by spontaneous atomic migration and volume variation during the charge/discharge cycle leads to electrode disintegration and performance degradation, therefore severely restricting the application of conventional conversion-type electrodes. Herein, latticed-confined conversion chemistry is proposed, where the "intercalation-like" redox behavior is realized on the electrode with a "conversion-like" high capacity. By delicately formulating the high-entropy compounds, the pristine crystal structure can be preserved by the inert lattice framework, thus enabling an ultra-high initial Coulombic efficiency of 92.5% and a long cycling lifespan over a thousand cycles after the quasistatic charge-discharge cycle. This lattice-confined conversion chemistry unfolds a ubiquitous insight into the localized redox reaction and sheds light on developing high-performance electrodes toward next-generation high-energy rechargeable batteries.

Deciphering Single-Bacterium Adhesion Behavior Modulated by Extracellular Electron Transfer.

For bacterial adhesion and biofilm formation, a thorough understanding of the mechanism and effective modulating is lacking due to the complex extracellular electron transfer (EET) at bacteria-surface interfaces. Here, we explore the adhesion behavior of a model electroactive bacteria under various metabolic conditions by an integrated electrochemical single-cell force microscopy system. A nonlinear model between bacterial adhesion force and electric field intensity is established, which provides a theoretical foundation for precise tuning of bacterial adhesion strength by the surface potential and the direction and flux of electron flow. In particular, based on quantitative analyses with equivalent charge distribution modeling and wormlike chain numerical simulations, it is demonstrated that the chain conformation and unfolding events of outer membrane appendages are dominantly impacted by the dynamic bacterial EET processes. This reveals how the anisotropy of bacterial conductive structure can translate into the desired adhesion behavior in different scenarios.

CRISPR/Cas9-edited triple-fusion reporter gene imaging of dynamics and function of transplanted human urinary-induced pluripotent stem cell-derived cardiomyocytes.

PURPOSE: To investigate the post-transplantation behaviour and therapeutic efficacy of human urinary-induced pluripotent stem cell-derived cardiomyocytes (hUiCMs) in infarcted heart. METHODS: We used clustered regularly interspaced short palindromic repeats/CRISPR-associated nuclease 9 (CRISPR/Cas9) technology to integrate a triple-fusion (TF) reporter gene into the AAVS1 locus in human urine-derived hiPSCs (hUiPSCs) to generate TF-hUiPSCs that stably expressed monomeric red fluorescent protein for fluorescence imaging, firefly luciferase for bioluminescence imaging (BLI) and herpes simplex virus thymidine kinase for positron emission tomography (PET) imaging. RESULTS: Transplanted cardiomyocytes derived from TF-hUiPSCs (TF-hUiCMs) engrafted and proliferated in the infarcted heart as monitored by both BLI and PET imaging and significantly improved cardiac function. Under ischaemic conditions, TF-hUiCMs enhanced cardiomyocyte (CM) glucose metabolism and promoted angiogenic activity. CONCLUSION: This study established a CRISPR/Cas9-mediated multimodality reporter gene imaging system that can determine the dynamics and function of TF-hUiCMs in myocardial infarction, which is helpful for investigating the application of stem cell therapy.

Reshaping the Cathodic Catalyst Layer for Anion Exchange Membrane Fuel Cells: From Heterogeneous Catalysis to Homogeneous Catalysis.

In anion exchange membrane fuel cells, catalytic reactions occur at a well-defined three-phase interface, wherein conventional heterogeneous catalyst layer structures exacerbate problems, such as low catalyst utilization and limited mass transfer. We developed a structural engineering strategy to immobilize a molecular catalyst tetrakis(4-methoxyphenyl)porphyrin cobalt(II) (TMPPCo) on the side chains of an ionomer (polyfluorene, PF) to obtain a composite material (PF-TMPPCo), thereby achieving a homogeneous catalysis environment inside ion-flow channels, with greatly improved mass transfer and turnover frequency as a result of 100 % utilization of the catalyst molecules. The unique structure of the homogeneous catalysis system comprising interconnected nanoreactors exhibits advantages of low overpotential and high fuel-cell power density. This strategy of reshaping of the catalyst layer structure may serve as a new platform for applications of many molecular catalysts in fuel cells.

Engineering Energy Level of Metal Center: Ru Single-Atom Site for Efficient and Durable Oxygen Reduction Catalysis.

Emerging as a new frontier in heterogeneous catalysis, single-atom site catalysts (SSCs) have sparked enormous attention and bring about new opportunities to oxygen reduction electrocatalysis. Despite considerable progress achieved recently, most of the reported SSCs suffer from either insufficient activity or unsatisfactory stability, which severely retards their practical application. Here, we demonstrate a novel Ru-SSC with appropriate adsorption free energy of OH* (ΔGOH*) to confer excellent activity and low Fenton reactivity to maintain long-term stability. The as-developed Ru-SSC exhibits encouraging oxygen reduction reaction turnover frequency of 4.99 e- s-1 sites-1, far exceeding the state-of-the-art Fe-SSC counterpart (0.816 e- s-1 sites-1), as a result of Ru energy level regulation via spontaneous OH binding. Furthermore, Ru-SSC exhibits greatly suppressed Fenton reactivity, with restrained generation of reactive oxygen species directly observed, thus endowing the Ru-SSC with much more superior stability (only 17 mV negative shift after 20 000 cycles) than the Fe-SSC counterpart (31 mV). The practical application of Ru-SSC is further validated by its excellent activity and stability in a real fuel cell device.

Localized Electrochemical Impedance Measurements on Nafion Membranes: Observation and Analysis of Spatially Diverse Proton Transport Using Atomic Force Microscopy.

The distribution of ion conductive channels on the Nafion membrane surface, which determines the formation of the three-phase boundary, plays a very important role in improving the performance of proton-exchange membrane fuel cells. Therefore, understanding the microstructures at the catalyst layer/membrane interfaces of proton-exchange membranes is essential. Although current-sensing atomic force microscopy (AFM) can present some surface conductance data, localized impedance measurement providing more accurate proton-transport information is desirable. To obtain this information, in our study, localized electrochemical impedance spectroscopy was measured automatically with a home-built AFM-electrochemical impedance spectroscopy setup in which AFM was coupled with an impedance tester by a customized procedure. By this method, the localized proton-transport resistance at different humidities was observed in spatially diverse locations, and the value decreased as the membrane became hydrated. Furthermore, the microstructure of the Nafion membrane was numerically reconstructed at different hydration levels to examine the relationship between the membrane microstructural morphology and proton-transport resistance. The results showed that the spatial diversity of proton-transport resistance arose from the variable concentration of hydrophilic groups at the contact location of the AFM tip and the membrane, and from the heterogeneity of dry sulfonic acid groups in the membrane that creates local variation in water content.

Bridging the Surface Charge and Catalytic Activity of a Defective Carbon Electrocatalyst.

Electrocatalysis is dominated by reaction at the solid-liquid-gas interface; surface properties of electrocatalysts determine the electrochemical behavior. The surface charge of active sites on catalysts modulate adsorption and desorption of intermediates. However, there is no direct evidence to bridge surface charge and catalytic activity of active sites. Defects (active sites) were created on a HOPG (highly oriented pyrolytic graphite) surface that broke the intrinsic sp2 -hybridization of graphite by plasma, inducing localization of surface charge onto defective active sites, as shown by scanning ion conductance microscopy (SICM) and Kelvin probe force microscopy (KPFM). An electrochemical test revealed enhanced intrinsic activity by the localized surface charge. DFT calculations confirmed the relationship between surface charge and catalytic activity. This work correlates surface charge and catalytic activity, providing insights into electrocatalytic behavior and guiding the design of advanced electrocatalysts.

Heat treated carbon supported iron(ii)phthalocyanine oxygen reduction catalysts: elucidation of the structure-activity relationship using X-ray absorption spectroscopy.

This paper focuses on studying the influence of the heat treatment on the structure and activity of carbon supported Fe(ii)phthalocyanine (FePc/C) oxygen reduction reaction (ORR) catalysts under alkaline conditions. The FePc macrocycle was deposited onto ketjen black carbon and heated treated for 2 hours under inert atmosphere (Ar) at different temperatures (400, 500, 600, 700, 800, 900 and 1000 °C). The atomic structure of Fe in each sample has been determined by XAS and correlated to the activity and ORR mechanisms determined in electrochemical half cells and in a complete H2/O2 anion exchange membrane fuel cells (AEM-FC). The results show that the samples prepared at 600 and 700 °C have the highest electrochemical catalytic activity for the ORR, consistent with the findings that the FeN4 active sites are thermally stable up to 700 °C, confirmed by both XANES linear combination fittings and EXAFS fittings. Upon annealing at temperatures above 800 °C, the FeN4 structure partially decomposes to small iron nanoparticles. The transition from the FeN4 structure to metallic Fe results in a significant loss in ORR activity and an increase in the production of undesirable HO2- during catalysis.

Single immunization of non-adjuvanted recombinant TTFC-mi3 nanoparticle vaccine elicited a rapid and potent protective immunity against tetanus.

The conventional inactivated tetanus toxin plays an instrumental role in preventing tetanus. Nevertheless, the challenges associated with its production process, the potential for adverse reactions, and reduced effectiveness in vulnerable populations such as neonates and the elderly rise the need for a novel tetanus toxin vaccine. Recombinant subunit vaccine offer a viable solution, and the tetanus toxin fragment C (TTFC) is emerging as a promising candidate. In this study, through spontaneous isopeptide bond formation we conjugated the recombinant TTFC to self-assembled mi3 nanoparticle, which derived from an optimized KDPG aldolase, and generated the TTFC-mi3 protein nanoparticle vaccine. We found that TTFC-mi3 is stable, uniform spherical nanoparticles. Comparing with the free TTFC alone, TTFC-mi3 enhances the uptake and subsequent activation of dendric cells (DCs). In addition, a single dose of adjuvant-free TTFC-mi3 elicited a more rapid and potent protective immunity in mice. Moreover, TTFC-mi3 is of favorable safety in vitro and in vivo. Our findings indicate that TTFC-mi3 is a rapid-response, non-aluminum-adjuvanted vaccine against tetanus.

Accelerating Oxygen Electrocatalysis Kinetics on Metal-Organic Frameworks via Bond Length Optimization.

Metal-organic frameworks (MOFs) have been developed as an ideal platform for exploration of the relationship between intrinsic structure and catalytic activity, but the limited catalytic activity and stability has hampered their practical use in water splitting. Herein, we develop a bond length adjustment strategy for optimizing naphthalene-based MOFs that synthesized by acid etching Co-naphthalenedicarboxylic acid-based MOFs (donated as AE-CoNDA) to serve as efficient catalyst for water splitting. AE-CoNDA exhibits a low overpotential of 260 mV to reach 10 mA cm-2 and a small Tafel slope of 62 mV dec-1 with excellent stability over 100 h. After integrated AE-CoNDA onto BiVO4, photocurrent density of 4.3 mA cm-2 is achieved at 1.23 V. Experimental investigations demonstrate that the stretched Co-O bond length was found to optimize the orbitals hybridization of Co 3d and O 2p, which accounts for the fast kinetics and high activity. Theoretical calculations reveal that the stretched Co-O bond length strengthens the adsorption of oxygen-contained intermediates at the Co active sites for highly efficient water splitting.

A Mitochondria-Targeted NIR-II AIEgen Induced Pyroptosis for Enhanced Tumor Immunotherapy.

Cancer immunotherapy is a favorable strategy for facilitating anti-tumor immunity, but it shows limited benefits in clinical practice owing to the immunosuppressive tumor microenvironment. Pyroptosis shows great immunostimulatory effect on tumor, whereas the lack of pyroptotic inducer with imaging property has restricted its progress in tumor theranostics. Herein, a mitochondria-targeted aggregation-induced emission (AIE) luminogen (TPA-2TIN) with NIR-II emission is designed for highly efficient induction of tumor cell pyroptosis. The fabricated TPA-2TIN nanoparticles can be efficiently taken up by tumor cells and selectively accumulated in tumor for a long term observed by NIR-II fluorescence imaging. More importantly, the TPA-2TIN nanoparticles can effectively stimulate immune responses both in vitro and in vivo mediated by the mitochondrial dysfunctions and the subsequent activation of the pyroptotic pathway. Ultimately, the reversal of the immunosuppressive tumor microenvironment significantly enhances the immune checkpoint therapy. This study paves a new avenue for adjuvant immunotherapy of cancer.

Radiolabeled AIE Probes as Dual-modality Imaging Agents for PET/NIR-II Fluorescence-Guided Photothermal Therapy.

Breast cancer has become a huge burden with continued rise of incidence and death rate worldwide. Various methods for diagnosis and therapy of breast cancer have met the challenges of lack of complete information about the tumor location and limited therapy efficacy. Although aggregation-induced emission luminogens (AIEgens) have shown great promise for various cancer treatment applications, they may be incompetent for deep-seated tumor diagnosis due to the limited penetration depth. Herein, we designed and prepared a radiolabeled AIEgen-based organic photothermal agent for bimodal PET/fluorescence imaging-guided breast tumor photothermal therapy. The prepared multifunctional nanoparticles (68 Ga-TPA-TTINC NPs) with NIR-II fluorescence, gamma irradiation and photothermal conversion property could be efficiently taken up by tumor cells and induce reactive oxygen species burst in vitro, further boosting the photothermal treatment of tumor in vivo. More importantly, the nanoprobe could target and clearly visualize 4T1 tumor xenografts through PET and NIR-II fluorescence imaging with high tumor/muscle ratio up to 4.8, which provides a promising tool and solution for breast tumor theranostics.

177 Lu Radiolabelled AIE Dots for Multimodal Imaging Guided Photothermal/Radiopharmaceutical Tumor Therapy.

Aggregation-induced emission luminogens (AIEgens) in the second near-infrared region (NIR-II,1000-1700 nm) have shown tremendous potential as theragnostic probe for tumor multimodal diagnostic imaging and combined treatment owing to their programmable optical, structural and functional properties. Herein, we presented a radionuclide 177 Lu-labeled AIEgen, 177 Lu-2TT-oC6B dots, for NIR-II fluorescence and SPECT/CT imaging-guided tumor photothermal and radiopharmaceutical therapy. Intriguingly, 177 Lu-2TT-oC6B self-assembled into 10 nm dots, exhibited high NIR-II fluorescence quantum yield (QY, 1.34 %) and unprecedented photothermal conversion efficiency (PCE, 70.3 %) in vitro, furtherly performed extremely long blood circulation (T1/2 =52.4 h), persistent tumor accumulation and retention in tumor (NIR-II SNR=5.56; SPECT SNR=36.59) via intravenous administration in vivo. Furthermore, upon NIR light activation and 177 Lu irradiation, 177 Lu-2TT-oC6B demonstrated great application potential in synergistic photothermal/radiopharmaceutical tumor therapy.

Contracted Fe-N5-C11 Sites in Single-Atom Catalysts Boosting Catalytic Performance for Oxygen Reduction Reaction.

Promoting the catalyst performance for oxygen reduction reaction (ORR) in energy conversion devices through controlled manipulation of the structure of catalytic active sites has been a major challenge. In this work, we prepared Fe-N-C single-atom catalysts (SACs) with Fe-N5 active sites and found that the catalytic activity of the catalyst with shrinkable Fe-N5-C11 sites for ORR was significantly improved compared with the catalyst bearing normal Fe-N5-C12 sites. The catalyst C@PVI-(TPC)Fe-800, prepared by pyrolyzing an axial-imidazole-coordinated iron corrole precursor, exhibited positive shifted half-wave potential (E1/2 = 0.89 V vs RHE) and higher peak power density (Pmax = 129 mW/cm2) than the iron porphyrin-derived counterpart C@PVI-(TPP)Fe-800 (E1/2 = 0.81 V, Pmax = 110 mW/cm2) in 0.1 M KOH electrolyte and Zn-air batteries, respectively. X-ray absorption spectroscopy (XAS) analysis of C@PVI-(TPC)Fe-800 revealed a contracted Fe-N5-C11 structure with iron in a higher oxidation state than the porphyrin-derived Fe-N5-C12 counterpart. Density functional theory (DFT) calculations demonstrated that C@PVI-(TPC)Fe-800 possesses a higher HOMO energy level than C@PVI-(TPP)Fe-800, which can increase its electron-donating ability and thus help achieve enhanced O2 adsorption as well as O-O bond activation. This work provides a new approach to tune the active site structure of SACs with unique contracted Fe-N5-C11 sites that remarkably promote the catalyst performance, suggesting significant implications for catalyst design in energy conversion devices.

Dramatically enhanced cleavage of the C-C bond using an electrocatalytically coupled reaction.

This paper describes a generalized approach for the selective electrocatalytic C-C bond splitting in aliphatic alcohols at low temperature in aqueous state, with ethanol as an example. We show that selective C-C bond cleavage, leading to carbon dioxide, is possible in high pH aqueous media at low overpotentials. This improved selectivity and activity is achieved using a solution-born co-catalyst based on Pb(IV) acetate, which controls the mode of the ethanol adsorption so as to facilitate direct activation of the C-C bond. The simultaneously formed under-potentially deposited (UPD) Pb and surface lead hydroxide change the functionality of the catalyst surface for efficient promotion of CO oxidation. The resulting catalyst retains an unprecedented ability to sustain the full oxidation reaction pathway on an extended time scale of hours as opposed to minutes without addition of Pb(IV) acetate.

Unusual Electron Donor-Acceptor Sequenced NIR AIEgen for Highly Efficient Mitochondria-Targeted Cancer Cell Photodynamic Therapy.

Photodynamic therapy (PDT) is recognized to be a promising strategy for anticancer treatment. Considering the progressive application of PDT in clinical trials, highly efficient and photostable photosensitizers (PSs) are in strong demand. Aggregation-induced emission (AIE) based PSs are promising phototheranostic materials for tumor imaging and PDT due to their high fluorescence efficiency and photostability. Herein, a mitochondria-targeted PS, TPA-2TCP with AIE characteristics is developed by adopting an acceptor-π-donor-π-acceptor (A-π-D-π-A) structure. The untypical sequence of the electron donors and electron acceptors endows the derived AIE PS with evident redshift of the absorption and emission, and efficient generation of reactive oxygen species. With the positively charged pyridinium groups, nanoparticulated AIE PS (TPA-2TCP NPs) exhibits high cell binding efficiency towards 4T1 breast cancer cells, leading to the massive cell death via the apoptotic pathway under white light irradiation, demonstrating its potential application in cancer imaging and PDT.

Recent Advances in Microfluidic Devices for the Radiosynthesis of PET-imaging Probes.

In order to accommodate the growing demand for positron emission tomography (PET), it will be necessary to create innovative radiochemical and engineering technologies to optimize the manufacture and development of PET probes. Microfluidic devices allow radiosynthesis to be performed in microscale amounts, significantly impacting PET tracer production. Compared to traditional methods, microfluidic devices can produce PET tracers in a shorter time, higher yields, with lower reagent consumption, higher molar activity, and faster purification. This review examines microfluidic devices from an engineering perspective. Recently developed microfluidic radiosynthesis devices are classified into three categories according to their reaction volume: continuous-flow, batch-flow, and droplet-based microreactors. The principles of device architecture, radiosynthesis process, and the relative strengths and limitations of each category are emphasized by citing typical examples. Finally, the possible future applications of this technology are outlined. A flexible, miniature, fully automated radiochemical microfluidic platform will offer more straightforward and cheaper molecular imaging procedures and the potential for precision medicine that could allow operators to create customized tracers for individual patient doses.

Highly Efficient Radiosynthesis and Biological Evaluation of [18 F]Safinamide, a Radiolabelled Anti-Parkinsonian Drug for Positron Emission Tomography Imaging.

As an add-on drug approved for Parkinson's disease treatment, safinamide has multiple functions, such as selective and reversible monoamine oxidase-B inhibition, voltage-sensitive sodium/potassium channel blockage, and glutamate release inhibition. Meanwhile, safinamide shows tremendous therapeutic potential in the context of other central nervous system diseases (e. g. ischaemic stroke, amyotrophic lateral sclerosis, depression, etc.). In this work, [18 F]safinamide, which is safinamide labelled by the positron-emitting radionuclide [18 F]fluorine, was synthesized automatically based on iodonium ylide precursors with high radiochemical yield and high molar activity. Density functional theory was applied to calculate the Gibbs free energy change during iodonium ylide-mediated fluorination and to interpret the effect of tetraethylammonium (TEA+ ) as the counter cation in these reactions to improve the nucleophilicity of [18 F/19 F]fluoride. In addition, positron emission tomography studies on Sprague Dawley rats were carried out to determine the imaging characteristics, pharmacokinetics, and metabolism of the [18 F]safinamide radiotracer. The results displayed the complete biodistribution of the radiotracer, especially in rat brains, and revealed that [18 F]safinamide has moderate brain uptake, rapid and reversible binding kinetics, and good stability.