Clathrin meets caveolae: fuse or not?

Fluorescent Polymer Dot-Based Multicolor Stimulated Emission Depletion Nanoscopy with a Single Laser Beam Pair for Cellular Tracking

Stimulated emission depletion (STED) nanoscopy provides subdiffraction resolution while preserving the benefits of fluorescence confocal microscopy in live-cell imaging. However, there are several challenges for multicolor STED nanoscopy, including sophisticated microscopy architectures, fast photobleaching, and cross talk of fluorescent probes. Here, we introduce two types of nanoscale fluorescent semiconducting polymer dots (Pdots) with different emission wavelengths: CNPPV (poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-(1-cyanovinylene-1,4-phenylene)]) Pdots and PDFDP (poly[{9,9-dihexyl-2,7-bis(1-cyanovinylene)fluorene}-alt-co-{2,5-bis (N,N'-diphenylamino)-1,4-phenylene}]) Pdots, for dual-color STED bioimaging and cellular tracking. Besides bright fluorescence, strong photostability, and easy bioconjugation, these Pdots have large Stokes shifts, which make it possible to share both excitation and depletion beams, thus requiring only a single pair of laser beams for the dual-color STED imaging. Long-term tracking of cellular organelles by the Pdots has been achieved in living cells, and the dynamic interaction of endosomes derived from clathrin-mediated and caveolae-mediated endocytic pathways has been monitored for the first time to propose their interaction models. These results demonstrate the promise of Pdots as excellent probes for live-cell multicolor STED nanoscopy.

Single-molecule imaging and tracking of molecular dynamics in living cells

Unlike the ensemble-averaging measurements, the single-molecule imaging and tracking (SMIT) in living cells provides the real-time quantitative information about the locations, kinetics, dynamics and interactions of individual molecules in their native environments with high spatiotemporal resolution and minimal perturbation. The past decade has witnessed a transforming development in the methods of SMIT with living cells, including fluorescent probes, labeling strategies, fluorescence microscopy, and detection and tracking algorithms. In this review, we will discuss these aspects with a particular focus on their recent advancements. We will then describe representative single-molecule studies to illustrate how the single-molecule approaches can be applied to monitor biomolecular interaction/reaction dynamics, and extract the molecular mechanistic information for different cellular systems.

Hybrid bicelles as a pH-sensitive nanocarrier for hydrophobic drug delivery

Stabilized disc-like hybrid bicelles provide pH-sensitive release, preferable cellular uptake, tumor accumulation and therapeutic effect in vitro and in vivo.