Precision targeted ruthenium(ii) luminophores; highly effective probes for cell imaging by stimulated emission depletion (STED) microscopy

Multimodal Super-resolution Optical Microscopy Using a Transition-Metal-Based Probe Provides Unprecedented Capabilities for Imaging Both Nuclear Chromatin and Mitochondria

Detailed studies on the live cell uptake properties of a dinuclear membrane-permeable Ru^II cell probe show that, at low concentrations, the complex localizes and images mitochondria. At concentrations above ∼20 μM, the complex images nuclear DNA. Because the complex is extremely photostable, has a large Stokes shift, and displays intrinsic subcellular targeting, its compatibility with super-resolution techniques was investigated. It was found to be very well suited to image mitochondria and nuclear chromatin in two color, 2C-SIM, and STED and 3D-STED, both in fixed and live cells. In particular, due to its vastly improved photostability compared to that of conventional SR probes, it can provide images of nuclear DNA at unprecedented resolution.

Dual-targeted peptide-conjugated multifunctional fluorescent probe with AIEgen for efficient nucleus-specific imaging and long-term tracing of cancer cells

Precisely targeted transportation of a long-term tracing regent to a nucleus with low toxicity is one of the most challenging concerns in revealing cancer cell behaviors. Here, we report a dual-targeted peptide-conjugated multifunctional fluorescent probe (cNGR-CPP-NLS-RGD-PyTPE, TCNTP) with aggregation-induced emission (AIE) characteristic, for efficient nucleus-specific imaging and long-term and low-toxicity tracing of cancer cells. TCNTP mainly consists of two components: one is a functionalized combinatorial peptide (TCNT) containing two targeted peptides (cNGR and RGD), a cell-penetrating peptide (CPP) and a nuclear localization signal (NLS), which can specifically bind to a cell surface and effectively enter into the nucleus; the other one is an AIE-active tetraphenylethene derivative (PyTPE, a typical AIEgen) as fluorescence imaging reagent. In the presence of aminopeptidase N (CD13) and integrin αvβ3, TCNTP can specifically bind to both of them using cNGR and RGD, respectively, lighting up its yellow fluorescence. Because it contains CPP, TCNTP can be effectively integrated into the cytoplasm, and then be delivered into the nucleus with the help of NLS. TCNTP exhibited strong fluorescence in the nucleus of CD13 and integrin αvβ3 overexpression cells due to the specific targeting ability, efficient transport capacity and AIE characteristic in a more crowded space. Furthermore, TCNTP can be applied for long-term tracing in living cells, scarcely affecting normal cells with negligible toxicity in more than ten passages.

Turning on the red phosphorescence of a [Ru(tpy)(bpy)(Cl)]Cl complex by amide substitution: self-aggregation, toxicity, and cellular localization of an emissive ruthenium-based amphiphile

Dodecylamide functionalization of [Ru(tpy)(bpy)Cl]Cl led to an emissive, self-assembling, and cytotoxic complex targeting membranes.

Protein-based fluorescent nanoparticles for super-resolution STED imaging of live cells

Protein-based fluorescent nanoparticles with excellent biocompatibility, good colloidal stability and photostability have been synthesized as attractive markers for STED nanoscopy in biological imaging.

Development of nanoparticles for super-resolution imaging (sriNPs) can greatly enrich the toolbox of robust optical probes for biological studies. Moreover, sriNPs enable us to monitor the behavior of engineered nanomaterials in complex biological environments with high spatial resolution, which is important for advancing our understanding of nano–bio interactions. Up to now, reports on sriNPs have been scarce. In this work, we report a facile strategy to prepare protein-based fluorescent NPs that can be utilized as probes in super-resolution microscopy. The method is simple and straightforward, and easily extendible to other types of fluorophores. By using Atto647N–transferrin NPs as an example, we have achieved a roughly four-fold resolution improvement by using STED nanoscopy. These protein-based sriNPs possess excellent biocompatibility, good colloidal stability and photostability, making them attractive candidates for biological studies. Moreover, STED nanoscopy enables the precise imaging of NP structures in living cells, and revealed the co-existence of multiple NPs within one endosomal vesicle.

Luminescent ruthenium polypyridyl complexes with extended ‘dppz’ like ligands as DNA targeting binders and cellular agents

DNA-binding and phototoxicity of Ru(ii) complexes with ligands derived from pyrazinodipyridophenazine and either phen or TAP as ancillary ligands are reported.