Bioorthogonally activated probes for precise fluorescence imaging.

Over the past two decades, bioorthogonal chemistry has undergone a remarkable development, challenging traditional assumptions in biology and medicine. Recent advancements in the design of probes tailored for bioorthogonal applications have met the increasing demand for precise imaging, facilitating the exploration of complex biological systems. These state-of-the-art probes enable highly sensitive, low background, imaging of biological species and events within live organisms, achieving resolutions comparable to the size of the biomolecule under investigation.

Visible and near-infrared light-induced photoclick reactions.

Photoclick reactions combine the advantages offered by light-driven processes, that is, non-invasive and high spatiotemporal control, with classical click chemistry and have found applications ranging from surface functionalization, polymer conjugation, photocrosslinking, protein labelling and bioimaging. Despite these advances, most photoclick reactions typically require near-ultraviolet (UV) and mid-UV light to proceed. UV light can trigger undesirable responses, including cellular apoptosis, and therefore, visible and near-infrared light-induced photoclick reaction systems are highly desirable.

With or without a co-solvent? highly efficient ultrafast phenanthrenequinone-electron rich alkene (PQ-ERA) photoclick reactions.

The light-induced photocycloaddition of 9,10-phenanthrenequinone (PQ) with electron-rich alkenes (ERA), known as the PQ-ERA reaction, is a highly attractive photoclick reaction characterized by its operational simplicity and high biocompatibility. One essential aspect of photoclick reactions is their high rate, however the limited solubility of PQs often requires the use of a co-solvent. Evaluating the effect of different co-solvents on the PQ-ERA reaction and their influence on the reaction rate, we discovered that sulfur-containing compounds, in particular the frequently used solubilizing co-solvent DMSO, quench the triplet state of the PQ.

Supramolecular Polymerization as a Tool to Reveal the Magnetic Transition Dipole Moment of Heptazines.

Heptazine derivatives have attracted significant interest due to their small S-T gap, which contributes to their unique electronic and optical properties. However, the nature of the lowest excited state remains ambiguous. In the present study, we characterize the lowest optical transition of heptazine by its magnetic transition dipole moment.

Molecular Engineering To Enhance Reactivity and Selectivity in an Ultrafast Photoclick Reaction.

Light-induced 9,10-phenanthrenequinone-electron-rich alkene (PQ-ERA) photocycloadditions are an attractive new type of photoclick reaction, featuring fast conversions and high biocompatibility. However, the tunability of the reaction was hardly investigated up to now. To this end, we explored the influence of substituents on both reaction partners and the reaction rate between the PQs and ERAs.

Hydrazone-based boron difluoride complexes as triplet photosensitizers for singlet oxygen generation.

Due to the highly selective nature of singlet oxygen as an oxidant, it has received considerable interest in various areas of (organic) chemistry. Two green light activated hydrazone-based boron difluoride triplet photosensitizers possessing high quantum yields for O formation are reported. These photostable complexes are promising in applications in synthesis and catalysis.

Fluorescence detection and imaging of intracellular sulphite using a remote light activatable photochromic nanoprobe.

The development of a responsive fluorescent probe for the detection of a particular biomolecule in a specific site at the desired moment is important in the fields of bioanalysis and imaging, molecular biology and biomedical research. In this work, we report the development of a remote-light activatable nanoprobe for the fluorescence detection of sulphite in pure aqueous solution and its imaging applications in living cells. The nanoprobe, Poly-Cm-SP, is fabricated simply by wrapping photochromic molecules (Cm-SP) into a polymer nanoparticle.

Dynamic Control of a Multistate Chiral Supramolecular Polymer in Water.

Natural systems transfer chiral information across multiple length scales through dynamic supramolecular interaction to accomplish various functions. Inspired by nature, many exquisite artificial supramolecular systems have been developed, in which controlling the supramolecular chirality holds the key to completing specific tasks. However, to achieve precise and non-invasive control and modulation of chirality in these systems remains challenging.

Ultrafast Photoclick Reaction for Selective F-Positron Emission Tomography Tracer Synthesis in Flow.

The development of very fast, clean, and selective methods for indirect labeling in PET tracer synthesis is an ongoing challenge. Here we present the development of an ultrafast photoclick method for the synthesis of short-lived F-PET tracers based on the photocycloaddition reaction of 9,10-phenanthrenequinones with electron-rich alkenes. The respective precursors are synthetically easily accessible and can be functionalized with various target groups.

A hydrogen peroxide activatable nanoprobe for light-controlled "double-check" multi-colour fluorescence imaging.

A new probe for precise and accurate bioimaging contributes significantly to advancing biomedical research for early disease diagnosis and treatment monitoring. Through wrapping a photochromic molecule (SP-Np-B) within a polymer nanoparticle, a new light-controlled multicolour fluorescence nanoprobe (Poly-SP-Np-B) is developed for precise fluorescence subcellular bioimaging. Poly-SP-Np-B shows an "OFF-ON" red-emitting fluorescence response upon alternate UV/Vis light irradiation.

An artificial protein-probe hybrid as a responsive probe for ratiometric detection and imaging of hydrogen peroxide in cells.

An artificial protein-probe hybrid, Cm-Np-B@BSA, was prepared via host-guest interactions between hydrogen peroxide (H2O2)-responsive Cm-Np-B molecule and bovine serum albumin (BSA). The Cm-Np-B@BSA probe exhibited high sensitivity and selectivity towards H2O2 under physiological conditions and had excellent biocompatibility, allowing for sensitive ratiometric detection and imaging of endogenous H2O2 in live cells.

Photocontrolled Fluorescence "Double-Check" Bioimaging Enabled by a Glycoprobe-Protein Hybrid.

Despite the rapid development of imaging techniques, precise probe localization and modulation in living cells is still a challenging task. Here we show that the simple hybridization between a photochromic fluorescent glycoprobe and human serum albumin (HSA) enables a unique fluorescence "double-check" mechanism for precisely localizing and manipulating probe molecules in living cells. Docking of a carbohydrate-modified naphthalimide (Naph)-spiropyran (SP) dyad to a hydrophobic pocket of HSA produces the glycoprobe-protein hybrid, causing the protein conformation to fold as determined by small-angle X-ray scattering.

Remote light-controlled intracellular target recognition by photochromic fluorescent glycoprobes.

Development of powerful fluorescence imaging probes and techniques sets the basis for the spatiotemporal tracking of cells at different physiological and pathological stages. While current imaging approaches rely on passive probe-analyte interactions, here we develop photochromic fluorescent glycoprobes capable of remote light-controlled intracellular target recognition. Conjugation between a fluorophore and spiropyran produces the photochromic probe, which is subsequently equipped with a glycoligand "antenna" to actively localize a target cell expressing a selective receptor.

Photochromism and molecular logic gate operation of a water-compatible bis-glycosyl diarylethene.

We report the synthesis of a water-compatible bis-glycosyl diarylethene using click chemistry that undergoes photochromism and functions as a molecular logic gate.