Chemical & Biomedical Imaging最新文献

Understanding heterogeneous electrochemical reactions in the positive electrode of the Li-ion battery is essential for improving battery capacity and fast charging capabilities. Observing these reactions under operando conditions is essential to clarify the relationship between microstructure and chemical heterogeneity during the electrochemical processes. While X-ray nanoimaging is a valuable tool for operando measurements, mitigating X-ray radiation damage poses a significant challenge that requires optimized measurement protocols. In this study, we conducted a comprehensive analysis of the microstructure and chemical state distribution from the electrode to the particle scale using full-field transmission X-ray microscopy combined with X-ray absorption fine-structure spectroscopy (TXM-XAFS). We developed a dedicated operando cell to explore the relationship between microstructure, chemical state during the operando stepped charging process conditions. To mitigate X-ray-induced damage, the beam irradiation time has been optimized, and a coarse-to-fine approach combining quick 2-dimensional TXM-XAFS scans and 3-dimensional computed tomography-TXM-XAFS measurement has been adopted to reduce the overall dose while maintaining multidimensional and high-resolution information acquisition. Our results indicated that the distribution of charge varied among particles within the electrode and was significantly influenced by the proximity to the separator. By employing data clustering with the Gaussian mixture model, we identified factors of inactive domains that impede charge reaction. This analytical approach aids in understanding the factors contributing to reaction stagnation within a complex Li-ion battery, despite the challenges posed by X-ray radiation damage.

Unfolded proteins, as critical biomarkers in cancer, hold significant potential for tumor-specific imaging. However, the content of unfolded proteins within distinct subcellular organelles varies markedly and reflects divergent physiological implications. Currently, few fluorescent probes enable precise quantification and imaging of mitochondrial unfolded proteins. Herein, we report a fluorescent probe, MAP, for accurate imaging of mitochondrial unfolded proteins. MAP incorporates a triphenylphosphonium group that specifically targets mitochondria, with cellular uptake efficiency proportional to mitochondrial membrane potential. Within mitochondria, the maleimide moiety of MAP covalently reacts with thiol groups on unfolded proteins, restricting molecular rotation and suppressing intramolecular charge transfer (ICT), thereby triggering a significant fluorescence enhancement. Owing to the hyperpolarized mitochondrial membrane potential and abundant mitochondrial unfolded proteins in SKOV3 cells, MAP with superior biocompatibility achieves tumor-specific imaging with a high signal-to-noise ratio (9.5), enabling precise intraoperative navigation for ovarian cancer resection. This molecular design strategy provides a foundational framework for developing organelle-specific unfolded protein probes and advancing image-guided surgical applications.

The integration of vibrational probes with instrumental technologies heralds a broad and transformative future for biomedical imaging and chemical biology.

Near-infrared (NIR) fluorescence imaging of tumor caspase-3 activity can be applied for real-time monitoring of the therapeutic effect of an anticancer drug in vivo. Aggregation-induced emission luminogens (AIEgens) are highly sensitive, unique fluorophores, but there is no NIR AIEgen reported for the above purpose. Herein, we rationally developed an activatable NIR AIEgen, Ac-Asp-Glu-Val-Asp-Pra-QMT (Ac-DEVD-Pra-QMT), to sensitively image caspase-3 activity in apoptotic 4T1 cells and tumor. After being internalized by cisplatin-induced apoptotic tumor cells, Ac-DEVD-Pra-QMT is subjected to caspase-3 cleavage to yield hydrophobic Pra-QMT, which spontaneously aggregates into nanoparticles to turn "On" the NIR fluorescence. Experimental results show that Ac-DEVD-Pra-QMT renders 14.9-fold and 2.7-fold higher NIR fluorescent intensities compared to those of the control groups in vitro and in vivo, respectively. We expect that Ac-DEVD-Pra-QMT could serve as a valuable tool for the early tracking of chemotherapeutic effects in the near future.

Bioluminescence is routinely used to track cellular and molecular features in vivo. This technique relies upon the enzymatic oxidation of a small molecule to produce a photon of light. However, most bioluminescent probes exhibit suboptimal tissue penetrance, limiting applications in some preclinical models. We aimed to develop red-shifted tools for more sensitive, deep tissue imaging. Toward this end, we were inspired by the cell-compatible and red-emitting chromophore present in common fluorescent proteins (FPs). We synthesized two firefly luciferin analogues (FPLucs) based on the fluorescent motif. The probes produced >650 nm light, with peak emission values of 701 and 699 nm, making them amenable for tissue imaging. We further identified more optimal luciferases for processing FPLucs, using a combination of Rosetta-guided design and screening. When incubated with the analogues, the engineered luciferases exhibited improved light outputs compared to native firefly luciferase. The designer luciferase-luciferin pairs could also be readily detected in tissue mimics. Continued development of these and other fluorophore-inspired luciferins will expand applications of bioluminescence imaging.