Unnatural Amino Acids for Biological Spectroscopy and Microscopy.

Due to advances in methods for site-specific incorporation of unnatural amino acids (UAAs) into proteins, a large number of UAAs with tailored chemical and/or physical properties have been developed and used in a wide array of biological applications. In particular, UAAs with specific spectroscopic characteristics can be used as external reporters to produce additional signals, hence increasing the information content obtainable in protein spectroscopic and/or imaging measurements. In this Review, we summarize the progress in the past two decades in the development of such UAAs and their applications in biological spectroscopy and microscopy, with a focus on UAAs that can be used as site-specific vibrational, fluorescence, electron paramagnetic resonance (EPR), or nuclear magnetic resonance (NMR) probes. Wherever applicable, we also discuss future directions.

Atomically precise photothermal nanomachines.

Interfacing molecular machines to inorganic nanoparticles can, in principle, lead to hybrid nanomachines with extended functions. Here we demonstrate a ligand engineering approach to develop atomically precise hybrid nanomachines by interfacing gold nanoclusters with tetraphenylethylene molecular rotors. When gold nanoclusters are irradiated with near-infrared light, the rotation of surface-decorated tetraphenylethylene moieties actively dissipates the absorbed energy to sustain the photothermal nanomachine with an intact structure and steady efficiency. Solid-state nuclear magnetic resonance and femtosecond transient absorption spectroscopy reveal that the photogenerated hot electrons are rapidly cooled down within picoseconds via electron-phonon coupling in the nanomachine. We find that the nanomachine remains structurally and functionally intact in mammalian cells and in vivo. A single dose of near-infrared irradiation can effectively ablate tumours without recurrence in tumour-bearing mice, which shows promise in the development of nanomachine-based theranostics.

Engineering the Co(II)/Co(III) Redox Cycle and Coδ+ Species Shuttle for Nitrate-to-Ammonia Conversion.

Electroreduction of waste nitrate to valuable ammonia offers a green solution for environmental restoration and energy storage. However, the electrochemical self-reconstruction of catalysts remains a huge challenge in terms of maintaining their stability, achieving the desired active sites, and managing metal leaching. Herein, we present an electrical pulse-driven Co surface reconstruction-coupled Coδ+ shuttle strategy for the precise in situ regulation of the Co(II)/Co(III) redox cycle on the Co-based working electrode and guiding the dissolution and redeposition of Co-based particles on the counter electrode. As result, the ammonia synthesis performance and stability are significantly promoted while cathodic hydrogen evolution and anodic ammonia oxidation in a membrane-free configuration are effectively blocked. A high rate of ammonia production of 1.4 ± 0.03 mmol cm-2 h-1 is achieved at -0.8 V in a pulsed system, and the corresponding nitrate-to-ammonia Faraday efficiency is 91.7 ± 1.0%. This work holds promise for the regulation of catalyst reactivity and selectivity by engineering in situ controllable structural and chemical transformations.

Visit to visit transition in TXNIP gene methylation and the risk of type 2 diabetes mellitus: a nested case-control study.

Our study aimed to investigate the association between the transition of the TXNIP gene methylation level and the risk of incident type 2 diabetes mellitus (T2DM). This study included 263 incident cases of T2DM and 263 matched non-T2DM participants. According to the methylation levels of five loci (CpG1-5; chr1:145441102-145442001) on the TXNIP gene, the participants were classified into four transition groups: maintained low, low to high, high to low, and maintained high methylation levels. Compared with individuals whose methylation level of CpG2-5 at the TXNIP gene was maintained low, individuals with maintained high methylation levels showed a 61-87% reduction in T2DM risk (66% for CpG2 [OR: 0.34, 95% CI: 0.14, 0.80]; 77% for CpG3 [OR: 0.23, 95% CI: 0.07, 0.78]; 87% for CpG4 [OR: 0.13, 95% CI: 0.03, 0.56]; and 61% for CpG5 [OR: 0.39, 95% CI: 0.16, 0.92]). Maintained high methylation levels of four loci of the TXNIP gene are associated with a reduction of T2DM incident risk in the current study. Our study suggests that preserving hypermethylation levels of the TXNIP gene may hold promise as a potential preventive measure against the onset of T2DM.

New Insight into the Structural Nature of Diphenylalanine Nanotube through Comparison with Amyloid Assemblies.

Diphenylalanine (FF) nanotubes are a star material in the field of peptide self-assembly and have demonstrated numerous intriguing applications. Due to its resemblance to amyloid assembly, the FF nanotube is widely regarded as a simplified mimic of amyloids. Yet, whether FF nanotube truly possesses amyloid structure remains an open question. To better understand the structural nature of FF nanotube, we herein performed a comparative structural investigation between FF nanotube and typical amyloid systems by Aß1-40, Aß1-42, Aß16-22, Aß13-23, α-synuclein, and lysozyme using Fourier transform infrared spectroscopy. Through this comparative investigation, we obtained clear evidence to support that the FF nanotube does not possess a ß-sheet structure, a key structural characteristic of amyloid assembly, thus revealing the non-amyloid structural nature of the FF nanotube. At last, in light of our new finding, we further discussed the unique self-assembly behaviors of FF during nanotube formation and the implications of our work for FF nanotube related applications.

O2-Independent H2O2 Production via Water-Polymer Contact Electrification.

Hydrogen peroxide (H2O2), as a critical green chemical, has received immense attention in energy and environmental fields. The ability to produce H2O2 in earth-abundant water without relying on low solubility oxygen would be a sustainable and potentially economic process, applicable even to anaerobic microenvironments, such as groundwater treatment. However, the direct water to H2O2 process is currently hindered by low selectivity and low production rates. Herein, we report that poly(tetrafluoroethylene) (PTFE), a commonly used inert polymer, can act as an efficient triboelectric catalyst for H2O2 generation. For example, a high H2O2 production rate of 24.8 mmol gcat-1 h-1 at a dosage of 0.01 g/L PTFE was achieved under the condition of pure water, ambient atmosphere, and no sacrificial agents, which exceeds the performance of state-of-the-art aqueous H2O2 powder catalysts. Electron spin resonance and isotope experiments provide strong evidence that water-PTFE tribocatalysis can directly oxidize water to produce H2O2 under both anaerobic and aerobic conditions, albeit with different synthetic pathways. This study demonstrates a potential strategy for green and effective tribocatalytic H2O2 production that may be particularly useful toward environmental applications.

Unravelling the non-classical nucleation mechanism of an amyloid nanosheet through atomic force microscopy and an infrared probe technique.

Understanding the amyloid nucleation mechanism is fundamentally important for the development of diagnostics and therapeutics of amyloid-related diseases and for the design and application of amyloid-based materials. To this end, we here explore the use of atomic force microscopy (AFM) and a side-chain-based infrared (IR) probe technique to investigate the amyloid nanosheet formation mechanism of an Aß16-22 variant, KLVFXAK, where X is p-cyanophenylalanine with its side-chain cyano group being an infrared probe. Using AFM, we reveal that the formation of KLVFXAK amyloid nanosheets follows a two-step non-classical nucleation mechanism. The first step is the rapid formation of a metastable fibrillar intermediate and the second step is slow transformation to the final nanosheet. Using the side-chain-based IR probe technique, we obtain spectroscopic evidence for the proposed nucleation mechanism of the amyloid nanosheet as well as the structural details for the intermediate and amyloid nanosheet. By using the structural constraints set by the two techniques, we propose the structural models for both the fibrillar intermediate and the amyloid nanosheet. In addition, we further investigated the amyloid nanosheet formation mechanism of a similar Aß16-22 variant, KLVFXAE, and showed the impact of mutation on the amyloid nucleation mechanism. Our work also provides a nice example of how to use the combined approach of AFM and a side-chain-based IR probe technique to unravel the complex nucleation mechanism of amyloid formation.

Dose-response associations of triglyceride to high-density lipoprotein cholesterol ratio and triglyceride-glucose index with arterial stiffness risk.

BACKGROUND: The triglyceride to high-density lipoprotein cholesterol (TG/HDL-C) ratio and triglyceride-glucose (TyG) index are novel indexes for insulin resistance (IR). We aimed to evaluate associations of TG/HDL-C and TyG with arterial stiffness risk. METHODS: We enrolled 1979 participants from the Rural Chinese Cohort Study, examining arterial stiffness by brachial-ankle pulse wave velocity (baPWV). Logistic and linear regression models were employed to calculate effect estimates. For meta-analysis, we searched relevant articles from PubMed, Embase and Web of Science up to August 26, 2023. The fixed-effects or random-effects models were used to calculate the pooled estimates. We evaluated dose-response associations using restricted cubic splines. RESULTS: For cross-sectional studies, the adjusted ORs (95%CIs) for arterial stiffness were 1.12 (1.01-1.23) and 1.78 (1.38-2.30) for per 1 unit increment in TG/HDL-C and TyG. In the meta-analysis, the pooled ORs (95% CIs) were 1.26 (1.14-1.39) and 1.57 (1.36-1.82) for per 1 unit increment of TG/HDL-C and TyG. Additionally, both TG/HDL-C and TyG were positively related to PWV, with ß of 0.09 (95% CI 0.04-0.14) and 0.57 (95% CI 0.35-0.78) m/s. We also found linear associations of TG/HDL-C and TyG with arterial stiffness risk. CONCLUSIONS: High TG/HDL-C and TyG were related to increased arterial stiffness risk, indicating TG/HDL-C and TyG may be convincing predictors of arterial stiffness.

Early-stage dynamics of chloride ion-pumping rhodopsin revealed by a femtosecond X-ray laser.

Chloride ion-pumping rhodopsin (ClR) in some marine bacteria utilizes light energy to actively transport Cl- into cells. How the ClR initiates the transport is elusive. Here, we show the dynamics of ion transport observed with time-resolved serial femtosecond (fs) crystallography using the Linac Coherent Light Source. X-ray pulses captured structural changes in ClR upon flash illumination with a 550 nm fs-pumping laser. High-resolution structures for five time points (dark to 100 ps after flashing) reveal complex and coordinated dynamics comprising retinal isomerization, water molecule rearrangement, and conformational changes of various residues. Combining data from time-resolved spectroscopy experiments and molecular dynamics simulations, this study reveals that the chloride ion close to the Schiff base undergoes a dissociation-diffusion process upon light-triggered retinal isomerization.

Obesity and risk of depressive disorder in children and adolescents: A meta-analysis of observational studies.

PURPOSE: This meta-analysis evaluated the relationship between overweight/obesity and depressive disorders in children and adolescents. METHODS: We examined the databases of PubMed, Embase and Web of Science for pertinent observational studies released up until 20 February 2022. The pooled relative risks (RRs) and 95% confidence intervals (CIs) of obesity and overweight with depressive disorder were calculated by means of random-effects models. The Newcastle-Ottawa Quality Assessment Scale and Agency for Healthcare Research and Quality scale were adopted to evaluate the study quality. RESULTS: Finally, for this meta-analysis, we evaluated 22 observational publications covering 175 135 participants (5 cohort study articles, 1 case-control study article and 16 cross-sectional study articles). A significant positive association was found between obesity and the risk of depression (RR 1.32, 95% CI 1.09-1.60, I2 = 79.90%, Pheterogeneity < 0.001) and in the association between obesity and depressive symptoms (RR 1.16, 95% CI: 1.00-1.35, I2 = 25.0%, Pheterogeneity = 0.247). On sensitivity analysis, the pooled RRs remained robust. Subgroup analysis indicated that obese children and teenagers in western countries were more prone to depression. CONCLUSION: Evidence from this meta-analysis, based on observational studies, supported the idea that obese children and adolescents are more likely to experience depression and depressive symptoms.

Giant Out-of-Plane Exciton Emission Enhancement in Two-Dimensional Indium Selenide via a Plasmonic Nanocavity.

Out-of-plane (OP) exciton-based emitters in two-dimensional semiconductor materials are attractive candidates for novel photonic applications, such as radially polarized sources, integrated photonic chips, and quantum communications. However, their low quantum efficiency resulting from forbidden transitions limits their practicality. In this work, we achieve a giant enhancement of up to 34000 for OP exciton emission in indium selenide (InSe) via a designed Ag nanocube-over-Au film plasmonic nanocavity. The large photoluminescence enhancement factor (PLEF) is attributed to the induced OP local electric field (Ez) within the nanocavity, which facilitates effective OP exciton-plasmon interaction and subsequent tremendous enhancement. Moreover, the nanoantenna effect resulting from the effective interaction improves the directivity of spontaneous radiation. Our results not only reveal an effective photoluminescence enhancement approach for OP excitons but also present an avenue for designing on-chip photonic devices with an OP dipole orientation.

Electrostatic Field in Contact-Electro-Catalysis Driven C-F Bond Cleavage of Perfluoroalkyl Substances.

Perfluoroalkyl substances (PFASs) are persistent and toxic to human health. It is demanding for high-efficient and green technologies to remove PFASs from water. In this study, a novel PFAS treatment technology was developed, utilizing polytetrafluoroethylene (PTFE) particles (1-5 µm) as the catalyst and a low frequency ultrasound (US, 40 kHz, 0.3 W/cm2) for activation. Remarkably, this system can induce near-complete defluorination for different structured PFASs. The underlying mechanism relies on contact electrification between PTFE and water, which induces cumulative electrons on PTFE surface, and creates a high surface voltage (tens of volts). Such high surface voltage can generate abundant reactive oxygen species (ROS, i.e., O2⋅-, HO⋅, etc.) and a strong interfacial electrostatic field (IEF of 109~1010 V/m). Consequently, the strong IEF significantly activates PFAS molecules and reduces the energy barrier of O2⋅- nucleophilic reaction. Simultaneously, the co-existence of surface electrons (PTFE*(e-)) and HO⋅ enables synergetic reduction and oxidation of PFAS and its intermediates, leading to enhanced and thorough defluorination. The US/PTFE method shows compelling advantages of low energy consumption, zero chemical input, and few harmful intermediates. It offers a new and promising solution for effectively treating the PFAS-contaminated drinking water.

Nonfullerene Acceptor Featuring Unique Self-Regulation Effect for Organic Solar Cells with 19 % Efficiency.

The blend nanomorphology of electron-donor (D) and -acceptor (A) materials is of vital importance to achieving highly efficient organic solar cells. Exogenous additives especially aromatic additives are always needed to further optimize the nanomorphology of blend films, which is hardly compatible with industrial manufacture. Herein, we proposed a unique approach to meticulously modulate the aggregation behavior of NFAs in both crystal and thin film nanomorphology via self-regulation effect. Nonfullerene acceptor Z9 was designed and synthesized by tethering phenyl groups on the inner side chains of the Y6 backbone. Compared with Y6, the tethered phenyl groups participated in the molecular aggregation via the π-π stacking of phenyl-phenyl and phenyl-2-(5,6-difluoro-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (IC-2F) groups, which induced 3D charge transport with phenyl-mediated super-exchange electron coupling. Moreover, ordered molecular packing with suitable phase separation was observed in Z9-based blend films. High power conversion efficiencies (PCEs) of 19.0 % (certified PCE of 18.6 %) for Z9-based devices were achieved without additives, indicating the great potential of the self-regulation strategy in NFA design.

Photocatalytic CO2 Reduction by Near-Infrared-Light (1200 nm) Irradiation and a Ruthenium-Intercalated NiAl-Layered Double Hydroxide.

Near-infrared light-driven photocatalytic CO2 reduction (NIR-CO2PR) holds tremendous promise for the production of valuable commodity chemicals and fuels. However, designing photocatalysts capable of reducing CO2 with low energy NIR photons remains challenging. Herein, a novel NIR-driven photocatalyst comprising an anionic Ru complex intercalated between NiAl-layered double hydroxide nanosheets (NiAl-Ru-LDH) is shown to deliver efficient CO2 photoreduction (0.887 µmol h-1) with CO selectivity of 84.81% under 1200 nm illumination and excellent stability over 50 testing cycles. This remarkable performance results from the intercalated Ru complex lowering the LDH band gap (0.98 eV) via a compression-related charge redistribution phenomenon. Furthermore, transient absorption spectroscopy data verified light-induced electron transfer from the Ru complex towards the LDH sheets, increasing the availability of electrons to drive CO2PR. The presence of hydroxyl defects in the LDH sheets promotes the adsorption of CO2 molecules and lowers the energy barriers for NIR-CO2PR to CO. To our knowledge, this is one of the first reports of NIR-CO2PR at wavelengths up to 1200 nm in LDH-based photocatalyst systems.

Precise Methylation Yields Acceptor with Hydrogen-Bonding Network for High-Efficiency and Thermally Stable Polymer Solar Cells.

Utilizing intermolecular hydrogen-bonding interactions stands for an effective approach in advancing the efficiency and stability of small-molecule acceptors (SMAs) for polymer solar cells. Herein, we synthesized three SMAs (Qo1, Qo2, and Qo3) using indeno[1,2-b]quinoxalin-11-one (Qox) as the electron-deficient group, with the incorporation of a methylation strategy. Through crystallographic analysis, it is observed that two Qox-based methylated acceptors (Qo2 and Qo3) exhibit multiple hydrogen bond-assisted 3D network transport structures, in contrast to the 2D transport structure observed in gem-dichlorinated counterpart (Qo4). Notably, Qo2 exhibits multiple and stronger hydrogen-bonding interactions compared with Qo3. Consequently, PM6 : Qo2 device realizes the highest power conversion efficiency (PCE) of 18.4 %, surpassing the efficiencies of devices based on Qo1 (15.8 %), Qo3 (16.7 %), and Qo4 (2.4 %). This remarkable PCE in PM6 : Qo2 device can be primarily ascribed to the enhanced donor-acceptor miscibility, more favorable medium structure, and more efficient charge transfer and collection behavior. Moreover, the PM6 : Qo2 device demonstrates exceptional thermal stability, retaining 82.8 % of its initial PCE after undergoing annealing at 65 °C for 250 hours. Our research showcases that precise methylation, particularly targeting the formation of intermolecular hydrogen-bonding interactions to tune crystal packing patterns, represents a promising strategy in the molecular design of efficient and stable SMAs.

Designing A-D-A Type Fused-Ring Electron Acceptors with a Bulky 3D Substituent at the Central Donor Core to Minimize Non-Radiative Losses and Enhance Organic Solar Cell Efficiency.

Designing and synthesizing narrow bandgap acceptors that exhibit high photoluminescence quantum yield (PLQY) and strong crystallinity is a highly effective, yet challenging, approach to reducing non-radiative energy losses (∆Enr) and boosting the performance of organic solar cells (OSCs). We have successfully designed and synthesized an A-D-A type fused-ring electron acceptor, named DM-F, which features a planar molecular backbone adorned with bulky three-dimensional camphane side groups at its central core. These bulky substituents effectively hinder the formation of H-aggregates of the acceptors, promoting the formation of more J-aggregates and notably elevating the PLQY of the acceptor in the film. As anticipated, DM-F showcases pronounced near-infrared absorption coupled with impressive crystallinity. Organic solar cells (OSCs) leveraging DM-F exhibit a high EQEEL value and remarkably low ∆Enr of 0.137 eV-currently the most minimal reported value for OSCs. Moreover, the power conversion efficiency (PCE) of binary and ternary OSCs utilizing DM-F has reached 16.16% and 20.09%, respectively, marking a new apex in reported efficiency within the OSCs field. In conclusion, our study reveals that designing narrow bandgap acceptors with high PLQY is an effective way to reduce ∆Enr and improve the PCE of OSCs.

Nickel(II) Phototheranostics: A Case Study in Photoactivated H2O2-Enhanced Immunotherapy.

Phototheranostics have emerged as a promising subset of cancer theranostics owing to their potential to provide precise photoinduced diagnoses and therapeutic outcomes. However, the design of phototheranostics remains challenging due to the nature of tumors and their microenvironment, including limitations to the oxygen supply, high rates of recurrence and metastasis, and the immunosuppressive state of cancer cells. Here we report a dual-functional oxygen-independent phototheranostic agent, Ni-2, rationally designed to provide a near-infrared (NIR) photoactivated thermal- and hydroxyl radical (•OH)-enhanced photoimmunotherapeutic anticancer response. Under 880 nm laser irradiation, Ni-2 exhibited high photostability and excellent photoacoustic and photothermal effects with a photothermal conversion efficacy of 58.0%, as well as novel photoredox features that allowed the catalytic conversion of H2O2 to •OH upon photooxidation of Ni(II) to Ni(III). As a multifunctional photoagent, Ni-2 was found not only to inhibit tumor growth in a CT26 tumor-bearing mouse model but also to activate an immune response via a combination of photothermal- and H2O2-induced effects. When combined with an antiprogrammed death-ligand 1 (aPD-L1), Ni-2 treatment allowed for the suppression of distant tumor growth and cancer metastasis. Collectively, the present results provide support for the proposition that Ni-2 or its analogues could emerge as useful tools for photoimmunotherapy. They also highlight the potential of appropriately designed 3d transition metal complexes as "all- in-one" phototheranostics.

Synergistic Promotion of the Photocatalytic Preparation of Hydrogen Peroxide (H2 O2 ) from Oxygen by Benzoxazine and Si─O─Ti Bond.

Hydrogen peroxide (H2 O2 ) is considered one of the most important chemical products and has a promising future in photocatalytic preparation, which is green, pollution-free, and hardly consumes any non-renewable energy. This study involves the preparation of benzoxazine with Si─O bonds via the Mannich reaction, followed by co-hydrolysis to produce photocatalysts containing benzoxazine with Si─O─Ti bonds. In this study, a benzoxazine photocatalyst with Si─O─Ti bonds is synthesized and characterized using fourier transform infrared spectroscopy, nuclear magnetic resonance, and X-ray photoelectron spectroscopy. The size and elemental distribution of the nanoparticles are confirmed by transmission electron microscopy and scanning electron microscopy. The photocatalytic synthesis of H2 O2 is tested using the titanium salt detection method, and the rate is found to be 7.28 µmol h-1 . Additionally, the catalyst exhibits good hydrolysis resistance and could be reused multiple times. The use of benzoxazine with Si─O─Ti bonds presents a promising experimental and theoretical foundation for the industrial production of H2 O2 through photocatalytic synthesis.

Complex-valued matrix-vector multiplication system for a large-scale optical FFT.

Recent advancements in optical convolutional neural networks (CNNs) and radar signal processing systems have brought an increasing need for the adoption of optical fast Fourier transform (OFFT). Presently, the fast Fourier transform (FFT) is executed using electronic means within prevailing architectures. However, this electronic approach faces limitations in terms of both speed and power consumption. Concurrently, existing OFFT systems struggle to balance the demands of large-scale processing and high precision simultaneously. In response, we introduce a novel, to the best of our knowledge, solution: a complex-valued matrix-vector system harnessed through wavelength selective switches (WSSs) for the realization of a 24-input optical FFT, achieving a high-accuracy level of 5.4 bits. This study capitalizes on the abundant wavelength resources available to present a feasible solution for an optical FFT system with a large N.

Harnessing the power of a photoinitiated thiol-ene "click" reaction for the efficient synthesis of S-lipidated collagen model peptide amphiphiles.

A photoinitiated thiol-ene "click" reaction was used to synthesize S-lipidated collagen model peptide amphiphiles. Use of 2-iminothiolane provided an epimerization-free thiol handle required for thiol-ene based incorporation of lipid moieties onto collagen-based peptide sequences. This approach not only led to improvements in the triple helical characteristics of the resulting collagen model peptides but also increased the aqueous solubility of the peptide amphiphiles. As a result, this methodology holds significant potential for the design and advancement of functional peptide amphiphiles, offering enhanced capabilities across a wide range of applications.