Real-time monitoring of dynamic microvesicles (MVs), vesicles associated with living cells, is of great significance in deeply understanding their origin, transport, and function. However, specific labeling MVs poses a challenge due to the lack of unique biomarkers that differentiate them from other cellular compartments. Here, we present a strategy to selectively label MVs by evaluating a series of lipid layer-sensitive cationic indolium-coumarin fluorescent probes (designated as IC-Cn, with n ranging from 1 to 18) that feature varying aliphatic side chains (CnH2n+1). Through in situ cell imaging and analysis, we found that IC-Cn location is highly related to their lipophilicities and the phospholipid layer hydrophobic microenvironments in cellular compartments. In detail, IC-C1 and IC-C2 specifically localize MVs both inside and outside cells. In contrast, IC-C3, IC-C4, and IC-C5 label cellular MVs and mitochondria but with distinct fluorescence lifetimes. Using these probes strategically, we have discovered that, in addition to the biogenesis of MVs from plasma membranes and damaged mitochondria, newly formed MVs can undergo fusion and fission processes. Moreover, mitochondria-derived MVs, beyond being released from parent cells, can fuse with lysosomes to facilitate the removal of dysfunctional mitochondria. The work not only provides new insights into MV physiology but also inspires the design strategies for probes used in specific labeling in cell studies.

Developing highly efficient and robust catalysts based on earth-abundant materials for electrochemical water splitting remains a great challenge. Herein, we report the synthesis of a well-defined hydrogen spillover electrocatalyst, i.e., sulfur vacancy-enriched Co9S8-Ni3S4 hollow heterostructure, via a self-sacrificial template strategy. The introduction of sulfur vacancies greatly decreases the work function of Ni3S4, thereby narrowing the work function difference (Delta phi) with Co9S8. The reduced electron density at their interface facilities the hydrogen species (H*) transfer to trigger hydrogen spillover. Density functional theory (DFT) calculations reveal that H2O molecules preferentially adsorb and dissociate at Co sites of Co9S8 to generate active H* intermediates, which subsequently migrate to Ni sites of Ni3S4 domains for H-2 formation. The hydrogen spillover mechanism is strongly supported by experimental characterizations, including pH-dependent kinetics, in-situ Raman and electrochemical impedance analysis. Benefiting from these synergistic effects, the titled catalyst exhibited excellent electrocatalytic activity for alkaline hydrogen evolution reaction, requiring only 83 mV to achieve 10 mA cm(2), along with remarkable durability, showing no detectable degradation even at 1 A cm(2) for 100 h. This work deepens the fundamental understanding of hydrogen spillover mechanism and offers a practical strategy for developing highly active and durable catalysts for water splitting.

Intracellular viscosity plays an important role in regulating cellular morphology and physiology and is closely related to a host of diseases. Especially, the changes in mitochondrial viscosity will cause some common diseases such as hyperlipidemia, Alzheimer's disease and cancer. In this work, we report the design of a red-emissive molecular rotor for the detection of mitochondrial viscosity in live cells. The probe showed fascinating performance, such as specific targeting to mitochondria, high sensitivity to viscosity, and rapid fluorescence response, especially the dual response mode of fluorescence intensity and fluorescence lifetime. By using this probe, we realized monitoring of the mitochondrial viscosity variations in live cells under different physiological processes. Our study offers an opportunity to discover potential tools for mitochondria-related physiology and pathology investigation. A D-pi-A typed fluorescence lifetime probe for sensitively detecting viscosity has been designed and synthesized. BSOH has been successfully applied to real-time monitoring mitochondrial viscosity in live cells by fluorescence lifetime imaging.

As one of the major causes of antimicrobial resistance, beta-lactamase develops rapidly among bacteria. Detection of beta-lactamase in an efficient and low-cost point-of-care testing (POCT) way is urgently needed. However, due to the volatile environmental factors, the quantitative measurement of current POCT is often inaccurate. Herein, we demonstrate an artificial intelligence (AI)-assisted mobile health system that consists of a paper-based beta-lactamase fluorogenic probe analytical device and a smartphone-based AI cloud. An ultrafast broad-spectrum fluorogenic probe (B1) that could respond to beta-lactamase within 20 s was first synthesized, and the detection limit was determined to be 0.13 nmol/L. Meanwhile, a three-dimensional microfluidic paper-based analytical device was fabricated for integration of B1. Also, a smartphone-based AI cloud was developed to correct errors automatically and output results intelligently. This smart system could calibrate the temperature and pH in the beta-lactamase level detection in complex samples and mice infected with various bacteria, which shows the problem-solving ability in interdisciplinary research, and demonstrates potential clinical benefits.

Integrating imaging and therapeutic capabilities into a single entity can offer enhanced diagnostic accuracy and treatment efficacy in clinically effective formulations. Due to the diversity of chemical structures and/or limited solubility of inhibitors or fluorophores, it is essential to employ a robust delivery carrier that can facilitate drug absorption and distribution during its circulation in the blood. This study explores the potential of hollow gadolinium oxide (Gd2O3) nanocarriers in imaging and drug delivery applications. The citric acid (CA)-capped hollow gadolinium oxide nanocarriers were synthesized via urea-assisted precipitation and hydrothermal methods using carbon spheres as sacrificial templates. The resulting nanosized hollow spheres displayed a spherical morphology and demonstrated relaxation rates in the longitudinal and transverse directions, as indicated by their r 1 and r(2) values of 1.8 and 5.3 s(-1) mM(-1), respectively. To mimic the physiological conditions, the hollow gadolinium oxide spheres were loaded separately with antibiotic sparfloxacin and the azo dye Congo red at neutral pH (7.4) and body temperature (37 degrees C). The CR-loaded nanospheres exhibited a time-dependent internalization behavior with HeLa cells, suggesting their imaging potential for intracellular drug delivery. Furthermore, the SP-loaded nanospheres demonstrated antimicrobial activity against both Gram-positive and Gram-negative bacteria, demonstrating their therapeutic potential against bacterial infections. To mitigate the risk of leaching of Gd3+ ions and their inherent toxicity, a CA coating was applied to hollow gadolinium oxide surface which resulted in outstanding cell viability of the surface functionalized nanocarriers. In addition, the CA coating offered additional support for the increased encapsulation and continuous release of drug molecules until 1 week (168 h). The characterization data provide evidence for the potential of CA-capped hollow gadolinium oxide spheres as positive MR contrast agents and their applicability as safe and controlled drug carriers.

Temperature homeostasis is critical for cells to perform their physiological functions. Among the diverse methods for temperature detection, fluorescent temperature probes stand out as a proven and effective tool, especially for monitoring temperature in cells and suborganelles, with a specific emphasis on mitochondria. The utilization of these probes provides a new opportunity to enhance our understanding of the mechanisms and interconnections underlying various physiological activities related to temperature homeostasis. However, the complexity and variability of cells and suborganelles necessitate fluorescent temperature probes with high resolution and sensitivity. To meet the demanding requirements for intracellular/subcellular temperature detection, several strategies have been developed, offering a range of options to address this challenge. This review examines four fundamental temperature-response strategies employed by small molecule and polymer probes, including intramolecular rotation, polarity sensitivity, Forster resonance energy transfer, and structural changes. The primary emphasis was placed on elucidating molecular design and biological applications specific to each type of probe. Furthermore, this review provides an insightful discussion on factors that may affect fluorescent thermometry, providing valuable perspectives for future development in the field. Finally, the review concludes by presenting cutting-edge response strategies and research insights for mitigating biases in temperature sensing. In this review, we primarily summarized four temperature-response strategies. Then, we further analyzed the chemical modifications and biological applications of the probes. Finally, we have provided a prospective on the future development of probes.

The transition to green and sustainable catalysts necessitates efficient and safe preparation techniques using abundant and renewable resources. Many metal nanoparticles (NPs) are excellent catalysts but suffer from poor colloidal stability. NP immobilization or fabrication of metal nanostructures on solid supports can avoid issues with NP aggregation and facilitate the reuse of catalysts, but it may result in a decrease in the catalytic performance of the NPs. Here, we show that well-defined colloidal silver, gold, and platinum NPs can be self-assembled in bacterial nanocellulose (BC) membranes, yielding BC-NP nanocomposites that are highly catalytically active using the reduction of 4-nitrophenol (4-NP) as a model reaction. The large effective surface area of BC enables the assembly of large quantities of NPs, resulting in materials with excellent catalytic performance. To address the mass transport limitations of reactants through the 3D nanofibrillar BC network, the membranes were dissociated using sonication to produce dispersed nanocellulose fibrils. This process dramatically reduced the time required for the adsorption of the NPs from days to minutes. Moreover, the catalytic performance of the nanofibril-supported NPs was drastically improved. A turnover frequency above 21,000 h(-1) was demonstrated, which is more than one order of magnitude higher than that for previously reported soft substrate-supported AuNP-based catalytic materials. The ease of fabrication, abundance, and low environmental footprint of the support material, along with reusability, stability, and unprecedented catalytic performance, make BC-NP nanocomposites a compelling option for green and sustainable catalysis.

Mitophagy has a critical role in maintaining cellular homeostasis through acidic lysosomes engulfing excess or impaired mitochondria, thereby pH fluctuation is one of the most significant indicators for tracking mitophagy. Then such precise pH tracking demands the fluorogenic probe that has tailored contemporaneous features, including mitochondrial-specificity, excellent biocompatibility, wide pH-sensitive range of 8.0-4.0, and especially quantitative ability. However, available molecular probes cannot simultaneously meet all the requirements since it is extremely difficult to integrate multiple functionalities into a single molecule. To fully address this issue, we herein integrate two fluorogenic pH sensitive units, a mitochondria-specific block, cell-penetrating facilitator, and biocompatible segments into an elegant silica nano scaffold, which greatly ensures the applicability for real-time tracking of pH fluctuations in mitophagy. Most significantly, at a single wavelength excitation, the integrated pH-sensitive units have spectra-distinguishable fluorescence towards alkaline and acidic pH in a broad range that covers mitochondrial and lysosomal pH, thus enabling a ratiometric analysis of pH variations during the whole mitophagy. This work also provides constructive insights into the fabrication of advanced fluorescent nanoprobes for diverse biomedical applications.

Cerium oxide nanoparticles with integrated gadolinium have been proved to be useful as contrast agents in magnetic resonance imaging. Of question is their performance in dual-energy computed tomography. The aims of this work are to determine (1) the relation between the computed tomography number and the concentration of the I, Gd or Ce contrast agent and (2) under what conditions it is possible to resolve the type of contrast agent. Hounsfield values of iodoacetic acid, gadolinium acetate and cerium acetate dissolved in water at molar concentrations of 10, 50 and 100 mM were measured in a water phantom using the Siemens SOMATOM Definition Force scanner; gadolinium- and cerium acetate were used as substitutes for the gadolinium-integrated cerium oxide nanoparticles. The relation between the molar concentration of the I, Gd or Ce contrast agent and the Hounsfield value was linear. Concentrations had to be sufficiently high to resolve the contrast agents.

We report the formation of silicide by annealing of a SiOx surface, with low coverage of Eu doped Gd2O3 nanoparticles. The annealing temperature required for removal of native oxide from the Si substrate decreases with close to 200 degrees C in presence of the nanoparticles. X-ray photoemission electron microscopy, low-energy electron microscopy and mirror electron microscopy are used to monitor the silicide formation and SiOx removal. Fragmentation of the nanoparticles is observed, and the SiOx layer is gradually removed. Eu migrates to clean Si areas during the annealing process, while Gd is found in areas where oxide is still present. This annealing process is clearly facilitated in the presence of rare-earth based nanoparticles, where nanoparticles are suggested to function as reaction sites to catalyze the oxygen removal and simultaneously form Eu based silicide. Reduction of the annealing temperature of SiOx substrates is also observed in presence of pure Eu3+ and Gd3+ ions. Simultaneous oxygen removal and EuSi formation enable this new rare-earth catalyzed annealing and silicide formation to find applications both within optoelectronics and processing microelectronic industry.