Precise Control of Metal Active Sites of Metal-Organic Framework Nanozymes for Achieving Excellent Enzyme-Like Activity and Efficient Pancreatitis Therapy.

Acute pancreatitis (AP) is a potentially life-threatening inflammatory disease that can lead to the development of systemic inflammatory response syndrome and its progression to severe acute pancreatitis. Hence, there is an urgent need for the rational design of highly efficient antioxidants to treat AP. Herein, an optimized Cu-based metal-organic framework (MOF) nanozyme with exceptional antioxidant activity is introduced, designed to effectively alleviate AP, by engineering the metal coordination centers in MN2Cl2 (M = Co, Ni, Cu). Specifically, the Cu MOF, which benefits from a Cu active center similar to that of natural superoxide dismutase (SOD), exhibited at least four times higher SOD-like activity than the Ni/Co MOF. Theoretical analyses further demonstrate that the CuN2Cl2 site not only has a moderate adsorption effect on the substrate molecule •OOH but also reduces the dissociation energy of the product H2 O2 . Additionally, the Cu MOF nanozyme possesses the excellent catalase-like activity and •OH removal ability. Consequently, the Cu MOF with broad-spectrum antioxidant activity can efficiently scavenge reactive oxygen species to alleviate arginine-induced AP. More importantly, it can also mitigate apoptosis and necrosis of acinar cells by activating the PINK1/PARK2-mediated mitophagy pathway. This study highlights the distinctive functions of tunable MOF nanozymes and their potential bio-applications.

Aqueous Binders Compatible with Ionic Liquid Electrolyte for High-Performance Aluminum-Ion Batteries.

The incompatibility of poly(vinylidene difluoride) (PVDF) with acidic ionic liquid electrolytes and the use of toxic and high-cost N-methyl pyrrolidone (NMP) solvents hinder the wide application of aluminum-ion batteries (AIBs). In this work, sodium alginate (Na-Alg) is developed as an aqueous binder for the fabrication of graphite positive electrodes in AIBs. The compatibility of various binders with the ionic liquid electrolyte is evaluated, and interaction between various binders and graphite particles before and after cycling is compared and discussed. The results demonstrate that the well compatibility of Na-Alg in ionic liquids and its reasonable distribution on the graphite surface facilitate fast charge transfer and ion diffusion, reduce electrode polarization, and thus contributing to significantly improved cycling stability and rate capability of AIBs. This work provides a new insight into the development of low-cost, eco-friendly, and high-performance binders for AIBs.

Short-Range Charge Transfer in DNA Base Triplets: Real-Time Tracking of Coherent Fluctuation Electron Transfer.

The short-range charge transfer of DNA base triplets has wide application prospects in bioelectronic devices for identifying DNA bases and clinical diagnostics, and the key to its development is to understand the mechanisms of short-range electron dynamics. However, tracing how electrons are transferred during the short-range charge transfer of DNA base triplets remains a great challenge. Here, by means of ab initio molecular dynamics and Ehrenfest dynamics, the nuclear-electron interaction in the thymine-adenine-thymine (TAT) charge transfer process is successfully simulated. The results show that the electron transfer of TAT has an oscillating phenomenon with a period of 10 fs. The charge density difference proves that the charge transfer proportion is as high as 59.817% at 50 fs. The peak position of the hydrogen bond fluctuates regularly between -0.040 and -0.056. The time-dependent Marcus-Levich-Jortner theory proves that the vibrational coupling between nucleus and electron induces coherent electron transfer in TAT. This work provides a real-time demonstration of the short-range coherent electron transfer of DNA base triplets and establishes a theoretical basis for the design and development of novel biological probe molecules.

Fluorescence emission mechanism for the π-conjugated zwitterion 2,4-Bisimidazolylphenol base on ESIPT: A TDDFT theoretical reconsideration.

Molecules with zwitterionic characteristics exhibit significant potential for utilization in nonlinear optics, optoelectronics, and organic lasers owing to their large dipole moments. Recently, the synthesized compound 2,4-bis (4,5-diphenyl-1H-imidazol-2-yl) phenol (2,4-bImP) by Sakai et al. has been noticed for its unique photochromic properties in solvents [J. Phys. Chem. A, 125 (2021), 4784-4792]. The observed fluorescence in chloroform was attributed to the keto tautomer. Based on the excited state intramolecular proton transfer, the photochromism of 2,4-bImP in chloroform was interpreted as zwitterion production. However, the zwitterion with a specific electronic structure can be in resonance with the conventional neutral structure. The impact of the resonance contribution from the zwitterion and the conventional neutral structure on fluorescence attribution was not taken into account in the previous studies. In this investigation, the ESIPT mechanism of the 2,4-bImP in chloroform has been explored using both the density functional theory and the time-dependent density functional theory. The optimized geometric configuration parameters illustrate the molecular resonant properties. The calculated fluorescence spectra on the basis of the optimization results further corroborate that the fluorescence peaks after proton transfer originates from the resonance of the zwitterionic and the neutral configuration. The zwitterionic nature of the molecule was demonstrated by electrostatic potential and atomic dipole modified Hesfeld atomic charge (ADCH) analysis. Furthermore, the characterization of potential energy curves and IR spectrum further verified the resonance of both the zwitterionic and neutral structures. The results reveal that the 2,4-bImP molecule generates the neutral o-quinoid structure and the zwitterionic structure resonance phenomenon following ESIPT. The aforementioned resonance structure offers novel insights into the ascription of fluorescence. These discoveries establish the theoretical foundation for the exploration and development of zwitterions.

ESIPT mechanism of triple emission with hydroxy-oxadiazole compound in DMSO: A theoretical reconsideration.

The compound in solvents with triple fluorescence feature of excited state intramolecular proton transfer (ESIPT) has a broad prospect in fluorescent probes, dye sensors and molecular synthesis of photosensitive dyes. An ESIPT molecule hydroxy-bis-2,5-disubstituted-1,3,4-oxadiazoles (compound 1a) emits two fluorescence peaks in dichloromethane (DCM) and three fluorescence peaks in dimethyl sulfoxide (DMSO). [Dyes and Pigments 197 (2022) 109927]. Two longer peaks were attributed to enol and keto emission in both solvents and the shortest third peak in DMSO was just attributed simply. However, there is a significant difference in proton affinity between DCM and DMSO solvents which has influence on the position of emission peaks. Therefore, the correctness of this conclusion needs to be further verified. In this research, density functional theory and time-dependent density functional theory method are used to explore ESIPT process. Optimized structures indicate ESIPT occurs through molecular bridge assisted by DMSO. The calculated fluorescence spectra demonstrate two peaks indeed originated from enol and keto in DCM, while interestingly three peaks are originated from enol, keto and intermediate in DMSO. Infrared spectrum, electrostatic potential and potential energy curves further prove existence of three structures. We reveal the mechanisms that compound 1a molecule occurs ESIPT in DCM solvent and undergoes an ESIPT through assisted by DMSO molecular bridge. Additionally, three fluorescence peaks in DMSO are reattributed. Our work is expected to provide an insight for understanding intra- and intermolecular interactions and synthesis of efficient organic lighting-emitting molecule.

Reconsideration of the ESIPT off mechanism for fluorescent probe MNC in aqueous solution.

Fluorescent probes with excited state intramolecular proton transfer (ESIPT) properties play a significant role in the research of life science and material science. Guo et al. designed 3-hydroxy-2-(6-Methoxynaphthalen-2-yl)-4H-chromen-4-one (MNC) as a control to achieve the dual-color fluorescence imaging of lipid droplets and endoplasmic reticulum (ER). They deemed that the ESIPT process would be turned off in ER with high water content [J. Am. Chem. Soc. 2021, 143, 3169-3179]. However, contrary to the conventional ESIPT off case, the enol* state fluorescence intensity that should have been enhanced was severely quenched in water. Here, combined with ultrafast spectrum, steady-state fluorescence spectrum and potential energy surface, the mechanism of ESIPT process of MNC turned off in water is revised. Furthermore, the formation of aggregated states in water is responsible for the quenching of MNC fluorescence. This work is expected to provide broader ideas for the design of hydrophobic fluorescent probes.

Altered brain function in patients with acrophobia: A voxel-wise degree centrality analysis.

AIM: To explore the local spontaneous neural activity and whole-brain functional connectivity patterns in the resting brain of acrophobia patients. METHODS: 50 patients with acrophobia and 47 healthy controls were selected for this study. All participants underwent resting-state MRI scans after enrollment. The imaging data were then analyzed using a voxel-based degree centrality (DC) method, and seed-based functional connectivity (FC) correlation analysis was used to explore the correlation between abnormal functional connectivity and clinical symptom scales in acrophobia. The severity of symptoms was evaluated using self-report and behavioral measures. RESULTS: Compared to controls, acrophobia patients showed higher DC in the right cuneus and left middle occipital gyrus and significantly lower DC in the right cerebellum and left orbitofrontal cortex (p < 0.01, GRF corrected). Additionally, there were negative correlations between the acrophobia questionnaire avoidance (AQ- Avoidance) scores and right cerebellum-left perirhinal cortex FC (r = -0.317, p = 0.025) and between scores of the 7-item generalized anxiety disorder scale and left middle occipital gyrus-right cuneus FC (r = -0.379, p = 0.007). In the acrophobia group, there was a positive correlation between behavioral avoidance scale and right cerebellum-right cuneus FC (r = 0.377, p = 0.007). CONCLUSIONS: The findings indicated that there are local abnormalities in spontaneous neural activity and functional connectivity in the visual cortex, cerebellum, and orbitofrontal cortex in patients with acrophobia.