A near-infrared emissive Al3+ sensing platform for specific detection in solution, cells and probing DNase activity

An NIR-Fluorophore-Based Theranostic for Selective Initiation of Tumor Pyroptosis-Induced Immunotherapy

Pyroptosis is an inflammatory form of programmed cell death that can effectively eliminate malignant cells and boost anticancer immunity. However, most of the current pyroptosis inducers lack cell selectivity, which may cause severe side effects for cancer therapy. In this work, for the first time, the authors discovered that the commonly used near-infrared (NIR) fluorogenic hemicyanine (CyNH₂ ) induces pyrolysis to kill cancer cells and boost antitumor immunity. Cancer cells overexpressing the NAD(P)H: quinone oxidoreductase isozyme 1 (NQO1)-responsive theranostic (NCyNH₂ ) are designed for selective cell pyroptosis and are nonfluorescent with low toxicity before activation. In the presence of NQO1, the fluorescence of CyNH₂ is restored and can selectively initiate pyroptosis of cancer cells and further lead to systemic antitumor immunity activation for solid tumor therapy. Thus, this fluorogenic NIR dye may represent a novel theranostic agent for the selective initiation of tumor pyroptosis.

Cu2+-selective NIR fluorescence sensor based on heptamethine cyanine in aqueous media and its application

A near-infrared (NIR) colorimetric fluorescence sensor, Cy7C3, based on heptamethine cyanine dye was synthesized for determining the presence of Cu²⁺ ions. The sensor showed highly sensitive fluorescence quenching toward Cu²⁺ ions in acetonitrile/buffer solution at physiological pH with long emission wavelength of 718 nm. Cy7C3 also provided an excellent selectivity to Cu²⁺ ions over other competing metal ions, with a low detection limit of 9 ppb, which was lower than the maximum concentration of Cu²⁺ ions in drinking water of U.S. EPA. Cy7C3 could achieve naked-eye detection of Cu²⁺ ions via the color change from blue to colorless, which allowed determination of Cu²⁺ ions in hydroponic fertilizers. Additionally, the sensor was developed to detect Cu²⁺ ions in HepG2 cancer cells via fluorescence imaging.

Theoretical Design of Near-Infrared Al3+ Fluorescent Probes Based on Salicylaldehyde Acylhydrazone Schiff Base Derivatives

The aim of this paper is to design near-infrared (NIR) Al³⁺ fluorescent probes based on a Schiff base to extend their applications in biological systems. By combining benzo[h]quinoline unit and salicylaldehyde acylhydrazone, we designed two new Schiff base derivatives. According to theoretical simulations on previous experimental Al³⁺ probes, we obtained the appropriate theoretical approaches to describe the properties of these fluorescent probes. By employing such approaches on our newly designed molecules, it is found that the new molecules have high selectivity toward Al³⁺ and that their corresponding Al³⁺ complexes can emit NIR fluorescence. As a result, they are expected to be potential NIR Al³⁺ fluorescent probes.

Pyrene-phenylglycinol linked reversible ratiometric fluorescent chemosensor for the detection of aluminium in nanomolar range and its bio-imaging

Pyrene-phenylglycinol tangled ratiometric sensor (R)-1 was developed for the detection of Al³⁺ ion over other metal ions. Ratiometric behaviour of (R)-1 for Al³⁺ ion explained through monomer emission and excimer quenching leads to avoiding the π-π interactions of bis-pyrene rings. Pull-push to push-pull binding mechanism is successfully explained by DFT and sensing of Al³⁺-ions demonstrated in living cells. The LOD of (R)-1 for Al³⁺ downs to nanomolar concentrations which is lower than the allowed concentration of drinking water set by the (World Health Organization) WHO.

A novel OFF-ON-OFF fluorescence probe based on coumarin for Al3+ and F- detection and bioimaging in living cells

A novel fluorescence probe L2 based on coumarin has been designed and synthesized. The probe L2 can be used for relay recognition of metal ions Al³⁺ and anion F^- in the aqueous HEPES buffer (0.05 M, pH = 7.4), and build a OFF-ON-OFF detection system. The probe showed high selectivity and sensitivity to target ions in the process of relay recognition, and the corresponding detection limit could be as low as 0.014 μM (Al³⁺) and 0.03 μM (F^-). Besides, the geometry optimizations of probe L2 and [L2 + Al³⁺] complex were carried out using the Gaussian 16 program based on DFT, and the identification mechanism of the probe was also discussed by the mass spectrometry and theoretical calculations. Moreover, the probe has also been successfully applied to detection of target ions in living cells.

Exploring the potential of a urea derivative: an AIE-luminogen and its interaction with human serum albumin in aqueous medium

A simple AIE active urea molecule (L1) can selectively interact with HSAviaturn-on fluorescence response in aqueous medium.

A review of mechanisms for fluorescent ‘‘turn-on’’ probes to detect Al3+ ions

The adverse effect of Al³⁺ ions on human health as well as the environment makes it desirable to develop sensitive and specific techniques for the detection of Al³⁺ ions.

Long-wavelength analyte-sensitive luminescent probes and optical (bio)sensors

Long-wavelength luminescent probes and sensors become increasingly popular. They offer the advantage of lower levels of autofluorescence in most biological probes. Due to high penetration depth and low scattering of red and NIR light such probes potentially enable in vivo measurements in tissues and some of them have already reached a high level of reliability required for such applications. This review focuses on the recent progress in development and application of long-wavelength analyte-sensitive probes which can operate both reversibly and irreversibly. Photophysical properties, sensing mechanisms, advantages and limitations of individual probes are discussed.