Cationic Organochalcogen with Monomer/Excimer Emissions for Dual-Color Live Cell Imaging and Cell Damage Diagnosis

Dual-Labeled Single Fluorescent Probes for the Simultaneous Two-Color Visualization of Dual Organelles and for Monitoring Cell Autophagy

Dual-labeled single fluorescent probes are powerful tools for studying autophagy on the molecular scale, yet their development has been hampered by design complexity and a lack of valid strategies. Herein, for the first time, we introduce a combinatorial regulation strategy to fabricate dual-labeled probes for studying autophagy by integrating the specific organelle-targeting group and the functional fluorescence switch into a pentacyclic pyrylium scaffold (latent dual-target scaffold). For proof of concept, we prepared a range of dual-labeled probes (TMOs) that display different emission colors in duple organelles. In these probes, TMO1 and TMO2 enabled the simultaneous two-color visualization of the lysosomes and mitochondria. The other probes (TMO3 and TMO4) discriminatively targeted lysosomes/nucleolus and lysosomes/lipid droplets (LDs) with dual-color emission characteristics, respectively. Intriguingly, by simply connecting the endoplasmic reticulum (ER) targeting group to the pentacyclic pyrylium scaffold, we created the first dual-labeled probe TMO5 for simultaneously labeling lysosomes/ER in distinctive fluorescent colors. Subsequently, using the dual-labeled probe TMO2, drug-induced mitophagy was successfully recorded by evaluating the alterations of multiple mitophagy-related parameters, and the mitophagy defects in a cellular model of Parkinson's disease (PD) were also revealed by simultaneous dual-color/dual-organelle imaging. Further, the probe TMO4 can track the movement of lysosomes and LDs in real time and monitor the dynamic process of lipophagy. Therefore, this work not only presents attractive dual-labeled probes to promote the study of organelle interactions during autophagy but also provides a promising combinatorial regulation strategy that may be generalized for designing other dual-labeled probes with multiple organelle combinations.

Recent Advances in Excimer-Based Fluorescence Probes for Biological Applications

The fluorescent probe is a powerful tool for biological sensing and optical imaging, which can directly display analytes at the molecular level. It provides not only direct visualization of biological structures and processes, but also the capability of drug delivery systems regarding the target therapy. Conventional fluorescent probes are mainly based on monomer emission which has two distinguishing shortcomings in practice: small Stokes shifts and short lifetimes. Compared with monomer-based emission, excimer-based fluorescent probes have large Stokes shifts and long lifetimes which benefit biological applications. Recent progress in excimer-based fluorescent sensors (organic small molecules only) for biological applications are highlighted in this review, including materials and mechanisms as well as their representative applications. The progress suggests that excimer-based fluorescent probes have advantages and potential for bioanalytical applications.

Light-Driven Cascade Mitochondria-to-Nucleus Photosensitization in Cancer Cell Ablation

Nuclei and mitochondria are the only cellular organelles containing genes, which are specific targets for efficient cancer therapy. So far, several photosensitizers have been reported for mitochondria targeting, and another few have been reported for nuclei targeting. However, none have been reported for photosensitization in both mitochondria and nucleus, especially in cascade mode, which can significantly reduce the photosensitizers needed for maximal treatment effect. Herein, a light-driven, mitochondria-to-nucleus cascade dual organelle cancer cell ablation strategy is reported. A functionalized iridium complex, named BT-Ir, is designed as a photosensitizer, which targets mitochondria first for photosensitization and subsequently is translocated to a cell nucleus for continuous photodynamic cancer cell ablation. This strategy opens new opportunities for efficient photodynamic therapy.

Recent advances in the development of small molecules targeting RNA G-quadruplexes for drug discovery

Extensive evidence indicates that RNA G-quadruplexes have associated with some important cellular events. Investigation of RNA G-quadruplexes is thus vital to revealing their biofunctions. Several small molecules have been developed to target RNA G-quadruplexes to date. Some of the small molecules showed significantly light-up fluorescence signals upon binding to RNA G-quadruplexes, while some of them regulated the biofunctions of RNA G-quadruplexes. In this mini-review, the small molecules divided into four kinds are expounded which focused mainly on their structural features and biological activities. Moreover, we raised the current challenges and promising prospects. This mini-review might contribute to exploiting more sophisticated small molecules targeting RNA G-quadruplexes with high specificity based on the reported chemical structural features.

A CHA-based DNA stochastic walker that traverses on cell membranes

DNA walkers, imitating protein motors, are a class of nucleic acid nanodevice that can move along a precisely defined "track". With a promising future in materials and biotechnology, DNA walkers have gained extensive attention among researchers. Here, we introduce a catalytic hairpin assembly (CHA)-based DNA walker on cell membranes. We designed hairpin strand (H1) modified cells as tracks. Driven by DNA strand exchange, catalytic strands move on cell membranes and other hairpin strands (H2) in the solution are loaded on cells. Additionally, we also introduce a CHA-based DNA motor and use the motor for cell membrane target sensing.

An insight into the electro-chemical properties of halogen (F, Cl and Br) doped BP and BN nanocages as anodes in metal-ion batteries

Here, electro-chemical properties of BN and BP nanocages as anodes in metal-ion batteries are examined. The effect of halogens adoption of BN and BP-NCs on electro-chemical properties of M-IBs are investigated. Results showed that the BP nanocages as anode electrode in M-IBs has higher efficiency than BN nanocages and the K-IB has higher cell voltage than N-IBs. Results indicated that the halogens adoption of BN and BP-NCs are improved the cell voltage of M-IBs. Results proved that the F-doped M-IBs have higher cell voltage than M-IBs. Finally, F-B17P18 as anodes in K-IB is proposed as suitable electrodes.

Multifunctional N-P-doped carbon dots for regulation of apoptosis and autophagy in B16F10 melanoma cancer cells and in vitro imaging applications

Rationale: The present study reports the multifunctional anticancer activity against B16F10 melanoma cancer cells and the bioimaging ability of fluorescent nitrogen-phosphorous-doped carbon dots (NPCDs). Methods: The NPCDs were synthesized using a single-step, thermal treatment and were characterized by TEM, XPS, fluorescence and UV-Vis spectroscopy, and FTIR analysis. The anticancer efficacy of NPCDs was confirmed by using cell viability assay, morphological evaluation, fluorescent live-dead cell assay, mitochondrial potential assay, ROS production, RT-PCR, western-blot analysis, siRNA transfection, and cellular bioimaging ability. Results: The NPCDs inhibited the proliferation of B16F10 melanoma cancer cells after 24 h of treatment and induced apoptosis, as confirmed by the presence of fragmented nuclei, reduced mitochondrial membrane potential, and elevated levels of reactive oxygen species. The NPCDs treatment further elevated the levels of pro-apoptotic factors and down-regulated the level of Bcl2 (B-cell lymphoma 2) that weakened the mitochondrial membrane, and activated proteases such as caspases. Treatment with NPCDs also resulted in dose-dependent cell cycle arrest, as indicated by reduced cyclin-dependent kinase (CDK)-2, -4, and -6 protein levels and an enhanced level of p21. More importantly, the NPCDs induced the activation of autophagy by upregulating the protein expression levels of LC3-II and ATG-5 (autophagy-related-5) and by downregulating p62 level, validated by knockdown of ATG-5. Additionally, owing to their excellent luminescence property, these NPCDs were also applicable in cellular bioimaging, as evidenced by the microscopic fluorescence imaging of B16F10 melanoma cells. Conclusion: Based on these findings, we conclude that our newly synthesized NPCDs induced cell cycle arrest, autophagy, and apoptosis in B16F10 melanoma cells and presented good cellular bioimaging capability.