Chemical & Biomedical Imaging最新文献

Extracellular vesicles (EVs) are small, membrane-bound structures released by various cell types into the extracellular environment, which play a crucial role in intercellular communication and the transfer of biomolecules between cells. Given their functional significance, there are intense research interests to use EVs as disease markers and drug carriers. However, EVs characterization is greatly hindered by the small size, the low biomolecule payload, and the high level of heterogeneity. To address these challenges, researchers have adopted sensitive microscopic methods such as single-molecule fluorescence imaging, single-particle dark-field imaging, surface-enhanced Raman scattering, and surface plasmon resonance imaging for single EV analysis. These techniques can detect signals from individual EVs, enabling a detailed study of the heterogeneity. Analysis of EVs cargo has provided insights into the protein/nucleic acid expression and enabled subgroup differentiation. Superresolution mapping has visualized EVs structures, and single EV tracking has offered insights into their release and uptake mechanisms. In this review, we will summarize the recent advances in optical imaging of single EVs, including the biomarkers used for EV labeling, the performance of the reported microscopic methods, and their biological findings. Finally, we will address the limitations of the existing methods and outline prospects for future development in this field.

For specific drug research and development, a drug-screening strategy (DSS) plays an indispensable role in the biomedical field. Unfortunately, traditional strategies are complicated and insufficiently accurate due to the widely used single-target screening method. Herein, a simple dual-target-based drug-screening strategy (dt-DSS) is proposed to screen highly effective drugs by fluorescence imaging. As a proof of concept, we utilized a dual-responsive fluorescence probe to screen drugs for diabetic cardiomyopathy (DCM). We first developed and took advantage of a dual-response probe HDB to detect reactive oxygen species (ROS) and mitophagy levels in cellular starvation and high glucose models. Based on this, HDB was utilized to study the effects of different drugs in the mitophagy process caused by the high-glucose cell model for DCM. Combined with Western blotting assays, we found that Drp-1 inhibitors could fundamentally reduce mitophagy caused by the high-glucose cells model. Compared with commercial single-target antioxidant drugs, the drugs with simultaneous antioxidant capacity and Drp-1 inhibition screened by dt-DSS, such as resveratrol and icariin, could treat DCM better. Therefore, HDB as an effective tool could accurately and quickly screen high-potency drugs for DCM. We believe that this work provides an attractive strategy to explore the pathogenesis of diabetic cardiomyopathy and precisely screen for highly effective drugs.

Cerenkov radiation-induced photodynamic therapy (CR-induced PDT) has shown the potential to overcome the light penetration limitation in conventional PDT. In addition, the tumor-associated antigens (TAAs) produced by PDT can initiate an antitumor immune process but only show a limited immunotherapeutic effect without the use of immunotherapeutic agents. Herein, a CR-induced PDT hydrogel (R837/⁸⁹Zr-HG-PpIX) has been developed by in situ formation of a hyaluronic acid (HA)-based hydrogel integrated with internal light source ⁸⁹Zr, photosensitizer protoporphyrin IX (PpIX), and immune adjuvant imiquimod (R837). The obtained R837/⁸⁹Zr-HG-PpIX hydrogel with long-term tumor retention and low radiation leakage can provide long-lasting photodynamic therapy without phototoxicity in normal tissues. In addition, the loaded R837 improves the immunogenicity of TAAs released after PDT, resulting in considerably enhanced immune responses. At relatively low radioactivity, R837/⁸⁹Zr-HG-PpIX shows significant inhibition in subcutaneous H22 tumor-bearing BALB/c mice and orthotopic VX2 liver tumor-bearing rabbits. Furthermore, the combination of such a CR-induced PDT hydrogel with anti-PD-L1 exhibits the abscopal effect to inhibit the growth of distant tumors. Therefore, the proposed in situ formed CR-induced PDT hydrogel with long-term photodynamic-immunotherapy provides an effective strategy for deep tumor therapy.

Molecular imaging was developed from basic molecular recognition. It can visualize not only the expression levels of specific molecules in a living system but also specific biological processes, thus providing guidance for early detection and treatment of diseases. As a noninvasive method, imaging agents are one of the foundations of high spatial resolution imaging, and their sensitivity and specificity can be improved by coupling targeting ligands to imaging probes. Among the various targeting ligands (antibodies, aptamers, etc.), targeting peptides are widely used in various modalities of molecular imaging due to their high affinities toward the molecular target and their excellent physicochemical properties. In this review, we summarize the design concepts and methods of targeting peptides in molecular imaging, introduce the combination of targeting peptides and imaging probes in different imaging modalities (e.g., fluorescence imaging, radionuclide imaging), and provide examples of their applications in bioimaging. Finally, the challenges and strategies for clinical translation and practical application of targeting peptide-based imaging reagents are briefly discussed.

An uncontrolled immune response leads to many diseases; therefore, monitoring inflammation is crucial for the diagnosis of subsequent diseases, drug screening, and targeted therapy. Since the inflammatory response mainly occurs in macrophages, there is a need to develop more inflammatory probes with macrophage-targeting ability. Herein, we designed a macrophage-targeted and hydrogen-peroxide-activated fluorescent probe BOH-HCy-Man for real-time imaging of inflammation in vivo and a control probe BOH-HCy without the macrophage-targeting part. The larger rate constant toward H₂O₂ led to the higher sensitivity of BOH-HCy-Man (19.1-fold) than BOH-HCy (10.2-fold) in vitro. With the help of its macrophage-targeting ability, BOH-HCy-Man possessed an additional 1.6-fold fluorescent enhancement in inflamed RAW 264.7 cells or 1.3-fold fluorescent enhancement in vivo than BOH-HCy. We expected that BOH-HCy-Man will be a powerful tool for early diagnosis of inflammation related diseases.

Lipid rafts (LRs) are relatively well-ordered functional microdomains in cell membranes and play an irreplaceable role in physiological processes as a transduction platform for multiple signaling pathways. Due to their small size and high spatiotemporal dynamics, it is difficult to perform lipid raft-localized biomolecule imaging on the surface of living cells. Here, we report a DNA nanotechnology-based platform for reversible manipulation and localized analysis of lipid rafts, which consists of two modules: “patching and coding probe pair” and “fishing probe”. The probe pair is generated by modifying two different sets of connectable DNA structures on a lipid raft-specific protein. After recognizing lipid rafts, the two probes in close proximity are linked by a DNA ligase reaction to form a lipid raft identity (LR-ID) code. The LR-ID strand patches and stabilizes the lipid raft structure. Interestingly, the raft patches formed can be depatched by restriction endonucleases, providing the first reversible manipulation of the lipid raft structure in living cells. We also designed a “fishing probe” with a DNA hairpin structure using an aptamer that can specifically bind to the target. The probe can cascade the reaction to two input signals “LR-ID” and “target protein” to generate an “off–on” fluorescence switch, allowing imaging and dynamic monitoring of target proteins localized in lipid rafts. By encoding arbitrary targets (in the case of glycans) in lipid rafts, we have created a universal lipid raft-localized imaging platform. This work provides an integrated analytical and manipulative platform to reveal lipid rafts and associated signaling pathways at the molecular level.

Brachytherapy is an established treatment modality that has been globally utilized for the therapy of malignant solid tumors. However, classic therapeutic sealed sources used in brachytherapy must be surgically implanted directly into the tumor site and removed after the requisite period of treatment. In order to avoid the trauma involved in the surgical procedures and prevent undesirable radioactive distribution at the cancerous site, well-dispersed radiolabeled nanomaterials are now being explored for brachytherapy applications. This emerging field has been coined “nanoscale brachytherapy”. Despite present-day advancements, an ongoing challenge is obtaining an advanced, functional nanomaterial that concurrently incorporates features of high radiolabeling yield, short labeling time, good radiolabeling stability, and long tumor retention time without leakage of radioactivity to the nontargeted organs. Further, attachment of suitable targeting ligands to the nanoplatforms would widen the nanoscale brachytherapy approach to tumors expressing various phenotypes. Molecular imaging using radiolabeled nanoplatforms enables noninvasive visualization of cellular functions and biological processes in vivo. In vivo imaging also aids in visualizing the localization and retention of the radiolabeled nanoplatforms at the tumor site for the requisite time period to render safe and effective therapy. Herein, we review the advancements over the last several years in the synthesis and use of functionalized radiolabeled nanoplatforms as a noninvasive substitute to standard brachytherapy sources. The limitations of present-day brachytherapy sealed sources are analyzed, while highlighting the advantages of using radiolabeled nanoparticles (NPs) for this purpose. The recent progress in the development of different radiolabeling methods, delivery techniques and nanoparticle internalization mechanisms are discussed. The preclinical studies performed to date are summarized with an emphasis on the current challenges toward the future translation of nanoscale brachytherapy in routine clinical practices.

Vomocytosis is a process that occurs when internalized fungal pathogens escape from phagocytes without compromising the viability of the pathogen and the host cell. Manual quantification of time-lapse microscopy videos is currently used as the standard to study pathogen behavior and vomocytosis incidence. However, human-driven quantification of vomocytosis (and the closely related phenomenon, exocytosis) is incredibly burdensome, especially when a large volume of cells and interactions needs to be analyzed. In this study, we designed a MATLAB algorithm that measures the extent of colocalization between the phagocyte and fungal cell (Cryptococcus neoformans; CN) and rapidly reports the occurrence of vomocytosis in a high throughput manner. Our code processes multichannel, time-lapse microscopy videos of cocultured CN and immune cells that have each been fluorescently stained with unique dyes and provides quantitative readouts of the spatiotemporally dynamic process that is vomocytosis. This study also explored metrics, such as the rate of change of pathogen colocalization with the host cell, that could potentially be used to predict vomocytosis occurrence based on the quantitative data collected. Ultimately, the algorithm quantifies vomocytosis events and reduces the time for video analysis from over 1 h to just 10 min, a reduction in labor of 83%, while simultaneously minimizing human error. This tool significantly minimizes the vomocytosis analysis pipeline, accelerates our ability to elucidate unstudied aspects of this phenomenon, and expedites our ability to characterize CN strains for the study of their epidemiology and virulence.

With the flourishing development of precision medicine, theranostics, generally recognized as the integration of diagnosis and treatment, has emerged as a prominent trend in clinical research. However, theranostics primarily emphasizes the end result of integration, without providing sufficient details on how precise diagnosis and synergetic individualized treatment could be achieved and what clinical challenges could be effectively addressed in clinical practice. Molecular probe technology provides a robust method to bridge the gap between theory and practice. Through meticulous design of the chemical structure, imaging labels or drugs were conjugated to tumor-targeting peptides, antibodies, or inducers to form molecular probes, which allow a seamless switch between targeted intervention and targeted imaging with consistency in time, space, and biodistribution. Thus, this review proposes a concept called “molecular eye”, which refers to a comprehensive system for precise diagnosis and treatment of major clinical diseases based on molecular probe technology. This medical system emphasizes the chemical basis of probe development and optimization, which can provide precise actionable information for clinical decision making, allow molecular-targeted therapy, expand the indications of old therapy, and accelerate the regulatory approval of molecular drugs. “Molecular eye” resembles the piercing eye of the Monkey King, which can detect previously “invisible” diseases and facilitate disease diagnosis, treatment, real-time evaluation, and pathology research, guiding drug development. The emergence of the “molecular eyes” will provide opportunities and challenges in the fields of clinical practice and medical research and propel the progression of contemporary medicine toward precision medicine.