Lysosome- and plasma membrane-accumulative and tumor-targetable polythiophene nanoparticles for enhanced sonodynamic therapy.

Sonodynamic therapy (SDT) has emerged as a promising treatment approach of solid tumors given its deep tissue penetration, non-invasiveness, few side effects, and negligible drug resistance. Herein, we report the first polythiophene derivative-based sonosensitizer (PT2) containing a quaternary ammonium salt and dodecyl chains with better ultrasound stability than that of traditional sonosensitizers, such as Rose Bengal and chlorin e6. PT2 was encapsulated by folic acid-containing polyethylene glycol. The obtained nanoparticles (PDPF NPs) exhibited excellent biocompatibility, cancer cell-targeting capacity, and accumulated mainly in the lysosomes and plasma membranes of cells. These NPs could generate singlet oxygen and superoxide anions simultaneously under ultrasound irradiation. In vitro and in vivo experimental results demonstrated that PDPF NPs could induce cancer-cell death through apoptosis and necrosis, inhibit DNA replication, and ultimately achieve tumor depletion upon US irradiation. These findings revealed that polythiophene could serve as an efficacious sonosensitizer for enhanced US treatment of deep-seated tumors.

General Strategy for Specific Fluorescence Imaging of Homocysteine in Living Cells and In Vivo.

The aberrantly changed level of homocysteine (Hcy) triggers a variety of pathological symptoms and subsequently Hcy-related diseases. Direct and selective visualization of Hcy in biological systems is pivotal to understanding the pathological functions of Hcy at the molecular level. Herein, a general strategy was developed for the specific fluorescence imaging of Hcy through the combination of dual-binding sites and the introduction of a nitro group at the 6-position of the 7-diethylaminocoumarin fluorophore. Also, a series of novel fluorescent probes were exploited for monitoring Hcy with excellent selectivity, high sensitivity, and far-red/near-infrared fluorescence emission. Furthermore, fluorescence imaging of endogenous Hcy dynamics in living cells and in vivo was achieved, providing direct and solid evidence for the increasement of endogenous Hcy in type 2 diabetes mellitus and Alzheimer's disease. This research will greatly advance the development and understanding of the molecular nexus between the Hcy metabolism cascade and the root causes of diseases related to Hcy.

A novel AIE fluorescent probe for the monitoring of aluminum ions in living cells and zebrafish.

A novel fluorescent probe BTD with aggregation induced emission (AIE) characteristics for the monitoring of Al3+ was developed. This fluorescent probe could be used to detect Al3+ in aqueous solution under mild conditions, along with high sensitivity and high selectivity. The detection limit of the probe BTD for Al3+ is as low as 3.25 nM, which is below the WHO recommendation concentration (7.41 µM) for drinking water. Furthermore, this probe was successfully applied to the sensing of Al3+ in living cells and zebrafish.

Direct Quantification and Visualization of Homocysteine, Cysteine, and Glutathione in Alzheimer's and Parkinson's Disease Model Tissues.

Alzheimer's disease (AD) and Parkinson's disease (PD) are chronic neurodegenerative diseases with high morbidity and mortality. Homocysteine (Hcy), cysteine (Cys), and glutathione (GSH) are closely related to AD and PD. However, the dynamics of Hcy, Cys, and GSH in the brain tissues and the potential pathogenesis between Cys/Hcy/GSH with AD and PD remain unclear. Herein, a novel fluorescent probe 1 with multiple binding sites was rationally designed and exploited for the direct quantification of serum total Hcy and Cys along with superior optical properties. Importantly, differentiation and simultaneity fluorescence imaging of Cys, Hcy, and GSH dynamics were achieved in living cells, tissues, and mouse models of AD and PD with this probe, providing direct evidences for the relationship between Hcy/Cys/GSH and AD/PD for the first time. In addition, pathogenesis studies demonstrated that elevated Hcy and Cys levels are closely related to imbalanced redox homeostasis, increased amyloid aggregates, and nerve cell cytotoxicity. These findings will greatly promote the understanding of the functions of Hcy/Cys/GSH in Alzheimer's and Parkinson's diseases, demonstrating clinical promise for the early diagnosis and prevention of AD and PD.

A novel red emission fluorescent probe for monitoring carbon monoxide in living cells and zebrafish.

Carbon monoxide (CO), a gaseous signal molecule, plays a crucial role in biological systems. With the aim of unraveling its biological functions, a novel fluorescent probe for sensing CO was rationally designed and synthesized based on a coumarin derivative fluorophore merging tetrahydroquinoxaline unit and five-membered pyrrolidine. This fluorescent probe demonstrated a large Stokes shift (Δλ = 132 nm), high quantum yield, red emission, high sensitivity and selectivity for CO with remarkable fluorescence turn-on. And the detection limit for CORM-3 is as low as 31.2 nM with the linear range of 0-30 µM. More importantly, this novel probe has been successfully applied to the fluorescence imaging of CO in HepG2 cells and zebrafish, providing a useful approach for the further understanding of the physiological and pathological roles of CO in living systems.

Turn-on fluorescent probe for sensing exogenous and endogenous hypochlorous acid in living cells, zebrafishes and mice.

Hypochlorous acid (HOCl), belonging to biologically significant reactive oxygen species (ROS), plays crucial roles in many biological and pathological processes. It is of great value to explore fluorescent probes for the image of hypochlorous acid in various biological environments. We herein reported a novel fluorescent probe HN-ClO for monitoring HOCl with moderate water-solubility, good photostability, high fluorescence quantum yield and large Stokes shift. This probe exhibited excellent selectivity and high sensitivity to sense HOCl. Furthermore, probe HN-ClO was successfully applied to monitor endogenous and exogenous HOCl in living cells, zebrafishes and mice, and possessed the potential to further explore the physiological and pathological roles of hypochlorous acid in biological systems.

A novel fluorescent probe with dual-sites for simultaneously monitoring metabolisms of cysteine in living cells and zebrafishes.

Understanding cellular metabolism holds immense potential for developing new drugs that regulate metabolic pathways. Two gas signal molecules, SO2 and H2S, are the main metabolites from cysteine (Cys) via oxidation and desulfurization pathways, respectively. However, a few fluorescent probes for real-time monitor of the metabolic pathways of cysteine have been reported. To understand metabolic alterations of cysteine, we have rationally designed and prepared a dual-signal fluorescent probe HN, which could differentiate SO2 and H2S through two different fluorescence channels simultaneously, along with similar reaction kinetics and both "off-on" fluorescence responses. Probe HN exhibits the potential to monitor the metabolism pathways of cysteine, and the distinguishment of cancer cells from normal cells could be realized. This methodology will promote further understanding of the physiological and pathological roles of cysteine.

A novel fluorescent probe for detection of Glutathione dynamics during ROS-induced redox imbalance.

Monitoring cellular GSH dynamics is of great value to understand its complex biological functions and related diseases. It still remains challenging to understand the mechanism of GSH dynamics in complex intracellular environment. Herein, a novel fluorescent probe featured with chlorinated coumarin-TCF was exploited for sensing of GSH with high selectivity and high sensitivity. Large fluorescence enhancement at 471 nm was observed upon addition of GSH with large emission distance (Δλem = 219 nm). This novel probe was successfully applied to monitor endogenous and exogenous GSH dynamics without interference of other thiols via fluorescence imaging. More importantly, using this probe, low dose reactive oxygen species induced GSH increasement through nuclear factor (erythroid-derived 2)-like 2 (Nrf2) signal pathway in BEL-7402 cells was observed. This novel fluorescent probe has the potential for quantitative monitoring of cellular GSH, which will promote further understanding of its physiological and pathological roles in biological systems.

A novel fluorescent probe for selective imaging of cellular cysteine with large Stokes shift and high quantum yield.

A new strategy endowing probe with large Stokes shift, high quantum yield and red emission was developed by incorporating tetrahydroquinoxaline unit and five-membered pyrrolidine ring on fluorophore. As demonstrated, a novel probe was rationally designed and synthesized for sensitive monitor of cellular cysteine (Cys) and endogenous aminoacylase with large Stokes shift and high quantum yield.

Simultaneous Visualization of Endogenous Homocysteine, Cysteine, Glutathione, and their Transformation through Different Fluorescence Channels.

Studying numerous biologically important species simultaneously is crucial to understanding cellular functions and the root causes of related diseases. Direct visualization of endogenous biothiols in biological systems is of great value to understanding their biological roles. Herein, a novel multi-signal fluorescent probe was rationally designed and exploited for the simultaneous sensing of homocysteine (Hcy), cysteine (Cys), and glutathione (GSH) using different emission channels. This probe was successfully applied to the simultaneous discrimination between and visualization of endogenous Hcy, Cys, GSH, and their transformation in living cells.

A dual-emission and mitochondria-targeted fluorescent probe for rapid detection of SO2 derivatives and its imaging in living cells.

A novel mitochondria-targeted fluorescent probe for sensing SO2 derivatives was constructed by integrating phenanthroimidazole and cyanine moieties. Excited by different channels, this probe exhibited unique dual-channel fluorescence-enhanced emissions and colorimetric response to HSO3- quickly (less than 20 s). The sensing process was confirmed to undergo nucleophilic addition of HSO3- to C˭C double bond in the probe Mito-PTB via NMR and HRMS analyses. Furthermore, fluorescence co-localization studies demonstrated that the probe Mito-PTB was a mitochondria-targetable fluorescent probe for SO2 derivatives with good cell membrane permeability. Thus, probe Mito-PTB has the potential applications to explore the role played by SO2 derivatives in biology.

A Multi-signal Fluorescent Probe with Multiple Binding Sites for Simultaneous Sensing of Cysteine, Homocysteine, and Glutathione.

A novel fluorescent probe was developed by integrating chlorinated coumarin and benzothiazolylacetonitrile and exploited for simultaneous detection of cysteine (Cys), homocysteine (Hcy), and glutathione (GSH). Featuring four binding sites and different reaction mechanisms for different biothiols, this probe exhibited rapid fluorescence turn-on for distinguishing Cys, Hcy, and GSH with 108-, 128-, 30-fold fluorescence increases at 457, 559, 529 nm, respectively, across different excitation wavelengths. Furthermore, the probe was successfully applied to the fluorescence imaging of endogenous Cys and GSH and exogenous Cys, Hcy, and GSH in living cells.