Chemical & Biomedical Imaging最新文献

Metal ions play crucial roles in biological processes, and their dysregulation can lead to various diseases. Understanding the distribution of these metal ions provides deeper insight into their roles in both health and disease. DNAzymes offer a general approach for detecting nearly any metal ion within cells and in vivo with high sensitivity and selectivity, including different oxidation states of the same metal ion. This Review summarizes recent developments in signal transduction strategies for DNAzyme-based sensing and imaging of metal ions in living cells and in vivo. We examine various signal transduction strategies to convert metal ion binding by DNAzymes into measurable signals. These strategies include fluorescence imaging using small molecules, nanostructures and nanoparticles, motors and machines, and other fluorescent materials as well as bioluminescence imaging. We then provide recent examples of applying these DNAzyme-based fluorescence or bioluminescence imaging methods to understand metal ion dynamics and their roles in diseases in living cells and in vivo. Finally, we discuss future directions for advancing intracellular and in vivo metal ion imaging using DNAzymes.

Cardiovascular diseases are the leading cause of death around the globe. In recent years, a crucial role of the immune system has been acknowledged in cardiac disease progression, opening the door for immunomodulatory therapies. To this ongoing change of paradigm, positron emission tomography (PET) imaging of the immune system has become a remarkable tool to reveal immune cell trafficking and monitor disease progression and treatment response. Currently, PET imaging of the immune system in cardiovascular disease mainly focuses on the innate immune system such as macrophages, while the immune cells of the adaptive immune system including B and T cells are less studied. This can be ascribed to the lack of radiotracers specifically binding to B and T cell biomarkers compatible with PET imaging within the cardiovascular system. In this review, we summarize current knowledge about the role of the adaptive immune system (e.g., B and T cells) in major cardiovascular diseases and introduce key biomarkers for specific targeting of these immune cells and their subpopulations. Finally, we present available radiotracers for these biomarkers and propose a pathway for developing probes or optimizing those already used in other fields (e.g., oncology) to make them compatible with the cardiovascular system.

Drug-induced hepatotoxicity is a long-standing concern of modern medicine. The production of peroxynitrite (ONOO^-) is proposed as an early sign of the progression of drug-induced hepatotoxicity. However, conventional blood tests fail to offer a real-time unambiguous visualization of such hepatotoxicity in vivo. ONOO^- probes that are currently reported are mainly located in the visible or the first near-infrared (NIR-I) window, which have limited in vivo biosensing application due to the autofluorescence and photon scattering. Here, we report an ONOO^- responsive cyanine dye, IR-1061 J-aggregate (J _IR-1061), which exhibits a red shift over 500 nm, with an absorption peak at 1580 nm in the NIR-IIb region. By conjugating J _IR‑1061 with rare earth nanoparticles (RENPs) that have NIR-IIb emission at 1550 nm, a dual-mode imaging probe RENPs-J _IR‑1061 is developed. RENPs-J _IR‑1061 shows a fast and sensitive response to ONOO^-, with activatable NIR-IIb fluorescence and a change in the photoacoustic signals, which is successfully applied for real-time monitoring of hepatotoxicity in vivo.

Aqueous batteries have received a great deal of attention for grid-scale energy storage applications but suffer from low-capacity retention and utilization. A lack of understanding of chemomechanical instabilities and charge storage mechanisms in cathodes limits the development of advanced aqueous batteries. To shed light on these instabilities, operando techniques are necessary to probe the complex interplay between electrochemistry and mechanics during cycling. Here, we report an operando technique to probe electrochemical strains in cathodes in aqueous electrolytes during battery cycling via optical imaging and digital image correlation. Operando mechanical measurements indicate that the cathode undergoes positive strain generation during discharge and negative generation during charge. Strain derivatives reveal a close correlation between electrochemical and mechanical behaviors, highlighting the connection between electrochemistry and mechanics. This operando imaging technique is broadly applicable and paves the way for a deeper understanding of deformation mechanisms in aqueous, multivalent ion battery materials.

Variations in droplet wettability affect localized corrosion during scanning electrochemical cell microscopy (SECCM) on stainless steel. The droplet dynamics are influenced by stainless-steel microstructural features and surface conditions-such as surface roughness, inclusions, and the addition of an oil layer. As opposed to previous work on aluminum alloys, droplet spreading is promoted by oil immersion, which leads to an increase in the cathodic currents. Rougher surfaces hinder droplet spreading, largely due to the droplet pinning effect, and exhibit higher pitting corrosion incidences compared to smoother surfaces. Moreover, the presence of inclusions intensifies pitting initiation and constrains the landing area (droplet size). We report that while the landing area does not affect the number of metastable pits, small landing areas lead to a high probability of stable pitting.

Two-dimensional cell culture may be insufficient when it comes to understanding human disease. The redox behavior of complex, three-dimensional tissue is critical to understanding disease genesis and propagation. Unfortunately, few measurement tools are available for such three-dimensional models to yield quantitative insight into how reactive oxygen species (ROS) form over time. Here, we demonstrate an imaging platform for the real-time visualization of H₂O₂ formation for mammalian spheroids made of noncancerous human embryonic kidney cells (HEK-293) and metastatic breast cancer cells (MCF-7 and MDA-MB-231). We take advantage of the luminol and H₂O₂ electrochemiluminescence reaction on a transparent tin-doped indium oxide electrode. The luminescence of this reaction as a function of [H₂O₂] is linear (R ² = 0.98) with a dynamic range between 0.5 μM to 0.1 mM, and limit of detection of 2.26 ± 0.58 μM. Our method allows for the observation of ROS activity in growing spheroids days in advance of current techniques without the need to sacrifice the sample postanalysis. Finally, we use our procedure to demonstrate how key ROS pathways in cancerous spheroids can be up-regulated and downregulated through the addition of common metabolic drugs, rotenone and carbonyl cyanide-p-trifluoromethoxyphenylhydrazone. Our results suggest that the Warburg Effect can be studied for single mammalian cancerous spheroids, and the use of metabolic drugs allows one to implicate specific metabolic pathways in ROS formation. We expect this diagnostic tool to have wide applications in understanding the real-time propagation of human disease in a system more closely related to human tissue.

The pressing challenges of the energy crisis and environmental problems necessitate the pursuit of efficient and sustainable energy conversion technologies, wherein catalytic processes play a vital role in addressing these issues. Single-molecule fluorescence microscopy (SMFM) offers a transformative approach to understanding various catalytic reactions by enabling real-time visualization of molecular adsorption, diffusion, and transformation on catalytic surfaces. The unprecedented insights into the spatial distribution of active sites, catalytic heterogeneity, and the dynamics of key intermediates result in single- or subparticle level structure-property relations, thereby offering insightful perspectives for catalyst design and mechanistic understanding of energy-related catalytic processes. In this review, we provide an overview of the recent progress in using SMFM for investigating energy-related catalytic reactions. The advancement in SMFM imaging techniques for investigating nonfluorescent chemical processes is also highlighted. Finally, we conclude the review by commenting on the current challenges and prospects in advancing SMFM in energy research. We hope that the capable SMFM imaging techniques and insights will promote the development and realistic application of various energy-related catalytic reactions, together with inspiring researchers to explore the power of SMFM in other applications.

Aggregation-induced emission luminogens (AIEgens) have been prosperously developed and applied in the fields of optical imaging and theranostics since its establishment. Nowadays, AIEgens can fulfill nearly all requirements in optical imaging and theranostics with emission spectra ranging from visible to near-infrared wavelengths. Although a variety of AIEgens with varying wavelengths and functionalities have been continuously designed, their performance is heavily dependent on the use of conventional light sources, such as xenon lamps and lasers, which severely hinder further applications due to limited penetration depth and background autofluorescence in biological tissues. To mitigate these limitations and maximize the potential of AIEgens, unconventional excitation sources such as chemical energy, ultrasound, and X-ray offer effective alternatives that circumvent the drawbacks associated with traditional light-based constant excitation. In this Review, we introduce the fundamental principles governing the combination of unconventional excitation sources with AIEgens, highlight recent advancements in using AIEgens excited by these unconventional sources for bioimaging and theranostics, and discuss current challenges and future perspectives aimed at advancing the biomedical applications of AIEgens.

Albumin encapsulation is a powerful strategy for drug delivery, yet its potential has not been fully explored for photodynamic therapy (PDT) agents. Cl-containing near-infrared (NIR) cyanine dyes are intrinsically PDT agents and tend to covalently bind with albumin; however, their PDT efficiency in tumors is largely compromised due to limited accumulation of the complex (size less than 10 nm) to the tumor site. To maximize their PDT effect while retaining sufficient NIR brightness for imaging-guided PDT, we developed a DTT-promoted encapsulation strategy to enhance singlet oxygen release for Cl-containing dyes. By disrupting disulfide bonds in albumin, the protein shell is loosened, increasing size while maintaining singlet oxygen release, partial brightness, and photostability. In vivo experiments reveal the rapid tumor accumulation of IR-6B3@DTT-HSA, enabling flexible treatment timing. This strategy enhances targeted delivery and PDT efficacy, paving the way for broader applications in cancer therapy.