Fluorescent probes for organelle-targeted bioactive species imaging

Development of “dual-key-and-lock” responsive probes for biosensing and imaging

Recent advances in the development of “dual-key-and-lock” responsive probes for accurate detection of various biomolecules are reviewed.

Simultaneous imaging of lysosomal and mitochondrial viscosity during mitophagy using molecular rotors with dual-color emission

A schematic illustration of rotors to detect mitochondrial and lysosomal viscosity during mitophagy.

A self-delivery DNA nanoprobe for reliable microRNA imaging in live cells by aggregation induced red-shift-emission

A Y-shape and pyrene-modified DNA self-assembly is developed to sensitively and specifically detect microRNA through a pyrene excimer–monomer switch.

A new long-wavelength fluorescent probe for tracking peroxynitrite in live cells and inflammatory sites of zebrafish

Design of a long-wavelength fluorescent probe for tracking peroxynitrite in live cells and inflammatory sites of zebrafish.

Independent bi-reversible reactions and regulable FRET efficiency achieving real-time visualization of Cys metabolizing into SO2

An independent bi-reversible reaction sensor BPC detected cysteine (Cys) and sulfur dioxide (SO₂) based on the regulable FRET efficiency, and achieved real-time process visualization of Cys metabolizing into SO₂ in subcellular organelles and tumors.

BODIPYs revealing lipid droplets as valuable targets for photodynamic theragnosis

Endowing BODIPY PDT agents with the ability to probe lipid droplets is demonstrated to boost their phototoxicity, allowing the efficient use of highly fluorescent dyes (poor ROS sensitizers) as phototoxic agents. Conversely, this fact opens the way to the development of highly bright ROS photosensitizers for performing photodynamic theragnosis (fluorescence bioimaging and photodynamic therapy) from a single simple agent. On the other hand, the noticeable capability of some of the reported dyes to probe lipid droplets in different cell lines under different conditions reveals their use as privileged probes for advancing the study of interesting lipid droplets by fluorescence microscopy.

A cancer cell membrane-camouflaged nanoreactor for enhanced radiotherapy against cancer metastasis

We report a cancer cell membrane-camouflaged nanoreactor based on a GOx decorated TiO₂@MnO₂ core-shell structure for enhanced radiotherapy against cancer metastasis. The nanoreactor could specifically target tumor tissues, catalytically oxidize glucose to generate H₂O₂, and generate abundant ROS under X-ray irradiation.

A general strategy to develop cell membrane fluorescent probes with location- and target-specific fluorogenicities: a case of a Zn2+ probe with cellular selectivity

We reported fluorescent probes to image Zn²⁺ with plasma membrane-specific and Zn²⁺-specific fluorogenicities. The probes contained hydrophobic alkyl chains as membrane-anchored domains and hydrophilic zinc sensor ZTRS, and aggregated to display quenched fluorescence. Cells dissolved the aggregates and the liberated probes were dispersed on the outside of the cell plasma membrane. Aggregates that did not bind to the cell membrane still exhibited aggregation-induced fluorescence quenching after complexing with zinc ions, while probes anchored on the membrane surface exhibited a fluorescence-enhanced response upon recognition of zinc ions.

Carbon nanotubes: An effective platform for biomedical electronics

Cylindrical fullerenes (or carbon nanotubes (CNTs)) have been extensively investigated as potential sensor platforms due to effective and practical manipulation of their physical and chemical properties by functionalization/doping with chemical groups suitable for novel nanocarrier systems. CNTs play a significant role in biomedical applications due to rapid development of synthetic methods, structural integration, surface area-controlled heteroatom doping, and electrical conductivity. This review article comprehensively summarized recent trends in biomedical science and technologies utilizing a promising nanomaterial of CNTs in disease diagnosis and therapeutics, based on their biocompatibility and significance in drug delivery, implants, and bio imaging. Biocompatibility of CNTs is essential for designing effective and practical electronic applications in the biomedical field particularly due to their growing potential in the delivery of anticancer agents. Furthermore, functionalized CNTs have been shown to exhibit advanced electrochemical properties, responsible for functioning of numerous oxidase and dehydrogenase based amperometric biosensors. Finally, faster signal transduction by CNTs allows charge transfer between underlying electrode and redox centres of biomolecules (enzymes).

Multifunctional Nanoscale Metal-Organic Layers for Ratiometric pH and Oxygen Sensing

As a monolayered version of nanoscale metal-organic frameworks (nMOFs), nanoscale metal-organic layers (nMOLs) represent an emerging class of highly tunable two-dimensional materials for hierarchical functionalization and with facile access to analytes. Here we report the design of the first nMOL-based biosensor for ratiometric pH and oxygen sensing in mitochondria. Cationic Hf₁₂-Ru nMOL was solvothermally synthesized by laterally connecting Hf₁₂ secondary building units (SBUs) with oxygen-sensitive Ru(bpy)₃²⁺-derived DBB-Ru ligands (bpy = 2,2'-bipyridine). The Hf₁₂-Ru nMOL was then covalently functionalized with pH-sensitive fluorescein isothiocyanate and pH/oxygen-independent Rhodamine-B isothiocyanate through thiourea linkages to afford Hf₁₂-Ru-F/R as a mitochondria-targeted ratiometric sensor for pH and O₂ in live cells. High-resolution confocal microscope imaging with Hf₁₂-Ru-F/R revealed a positive correlation between pH and local O₂ concentration in mitochondria. Our work shows the potential of nMOL-based ratiometric biosensors in sensing and imaging of biologically important analytes in live cells.

A biotinylated ruthenium(ii) photosensitizer for tumor-targeted two-photon photodynamic therapy

Platinum-resistant cancer cells are sensitive to changes in the levels of reactive oxidative species (ROS). Herein, we design a biotin-modified Ru(ii) complex as a photosensitizer (denoted as Ru-Biotin). Ru-Biotin can selectively target cancer cells and produce vast amounts of singlet oxygen under two-photon excitation at 820 nm leading to cell apoptosis. Ru-Biotin is therefore an excellent candidate to overcome platinum resistance via two-photon photodynamic therapy.

RNA imaging in living mice enabled by an in vivo hybridization chain reaction circuit with a tripartite DNA probe

RNA imaging in living animals helps decipher biology and creates new theranostics for disease treatment. Due to their low delivery efficiency and high background, however, fluorescence probes for in situ RNA imaging in living mice have not been reported. We develop a new cell-targeting fluorescent probe that enables RNA imaging in living mice via an in vivo hybridization chain reaction (HCR). The minimalistic Y-shaped design of the tripartite DNA probe improves its performance in live animal studies and serves as a modular scaffold for three DNA motifs for cell-targeting and the HCR circuit. The tripartite DNA probe allows facile synthesis with a high yield and demonstrates ultrasensitive RNA detection in vitro. The probe also exhibits selective and efficient internalization into folate (FA) receptor-overexpressed cells via a caveolar-mediated endocytosis mechanism and produces fluorescence signals dynamically correlated with intracellular target expressions. Furthermore, the probe exhibits specific delivery into tumor cells and allows high-contrast imaging of miR-21 in living mice. The tripartite DNA design may open the door for intracellular RNA imaging in living animals using DNA-minimal structures and its design strategy can help future development of DNA-based multi-functional molecular probes.

A mitochondria-targeting dinuclear Ir-Ru complex as a synergistic photoactivated chemotherapy and photodynamic therapy agent against cisplatin-resistant tumour cells

A mitochondria-targeting hetero-binuclear Ir(iii)-Ru(ii) complex was developed as a photoactivated chemotherapy (PACT) and photodynamic therapy (PDT) bifunctional agent to achieve a synergistic effective therapeutic outcome for the therapy of cisplatin-resistant tumour cells.

A Novel ESIPT Phthalimide-Based Fluorescent Probe for Quantitative Detection of H2O2

Hydrogen peroxide (H₂O₂) is a majority reactive oxygen species (ROS) and acts as an essential role in pathological and physiological processes. Therefore, the development of quantitative detection of methods for H₂O₂ is necessary. Here, we constructed of a novel simple fluorescence probe for detection of H₂O₂ based on the excited-state intramolecular proton transfer process. The probe utilized a phthalimide derivative as the fluorophore and selected phenylboronic acid as the recognition site for H₂O₂. In response to H₂O₂, the probe exhibited 63-fold fluorescence intensity enhancement, a low detection limit (8.4 × 10^-8 M), and large Stokes shift (111 nm). In addition, the probe displayed high selectivity for H₂O₂ over other ROS. Moreover, the probe was successfully employed for imaging of H₂O₂ in living cells.

Tetraphenylene-Coated Near-Infrared Benzoselenodiazole Dye: AIE Behavior, Mechanochromism, and Bioimaging

A D-π-A-π-D type of tetraphenylene-coating benzoselenodiazole fluorescence dye with near-infrared emission has been designed and constructed. This dye shows an obvious aggregation-induced-emission behavior. In the solid state, it exhibits a reversible mechanochromism with the changes of near-infrared emission. Furthermore, this dye can be used to track the lysosomes of living cells and images in vivo.

Introduction of the α-ketoamide structure: en route to develop hydrogen peroxide responsive prodrugs

New light on H₂O₂-activated prodrugs: the first α-ketoamide based prodrug opens up new alternatives for designing non-boron based H₂O₂-responsive promoieties.

Leveraging the elevated levels of hydrogen peroxide (H₂O₂) in cancer, inflammatory diseases and cardiovascular disorders, H₂O₂-activated promoieties have been widely used in drugs and biomaterials design. However, the overwhelming majority of the promoieties only share the common structure of a H₂O₂-responsive arylboronic acid/ester moiety with low diversity. We report here an unprecedented strategy to construct novel H₂O₂-responsive prodrugs based on an α-ketoamide structure. As a proof of concept, we designed and synthesized a panel of α-ketoamide based nitrogen mustard prodrugs, among which KAM-2 showed potent growth inhibitory activity and high selectivity toward cancer cells. The H₂O₂-trigged decomposition of KAM-2 was validated, and the DNA damaging and apoptosis promoting activity attributed to the released nitrogen mustard were demonstrated. Our work unveils α-ketoamide as a new scaffold for prodrug design and may quickly inspire future developments.

A straightforward synthesis of phenyl boronic acid (PBA) containing BODIPY dyes: new functional and modular fluorescent tools for the tethering of the glycan domain of antibodies

We report here on the efficient and straightforward synthesis of a series of modular and functional PBA-BODIPY dyes 1–4. They are an outstanding example of the efficient merge of the versatility of the 3,5-dichloro-BODIPY derivatives and the receptor-like ability of the PBA moiety. The potential bioanalytical applicability of these tools was assessed by measuring the binding to glycan chains of antibodies by a Quartz Crystal Microbalance (QCM).

PBA-BODIPY dyes as functional and modular fluorescent probes for the tethering of the glycan domain of mAbs.

Positive charge-dependent cell targeted staining and DNA detection

Fluorescence probes containing pyridinium compounds and different negative ions with the applications of specific tracing of different cell organelles and DNA detection!

Ultrafast labeling and high-fidelity imaging of mitochondria in cancer cells using an aggregation-enhanced emission fluorescent probe

An aggregation-enhanced emission probe was developed for ultrafast labeling and high-fidelity imaging of mitochondria in cancer cells with a high signal-to-noise ratio.