Mingguang Ren

A fast responsive two-photon fluorescent probe for imaging H2O2 in lysosomes with a large turn-on fluorescence signal

Hydrogen peroxide (H2O2) plays a crucial role in many biological processes in the human body. As our understanding of the complexity of physiological H2O2 in lysosome, investigative tools are required to make sense of this interconnectivity. Toward this goal, we have developed a new example of a fast responsive and lysosome-targeted two-photon H2O2 fluorescent probe (Lyso-HP) with a large turn-on fluorescence signal (80-fold fluorescence enhancement). The addition of H2O2 to Lyso-HP results a dramatic fluorescence enhancement around 550 nm. The probe could image exogenous and endogenous H2O2 in living cells and the probe was located in lysosomes with high colocalization coefficient (0.96) compared with LysoTracker. The large fluorescence enhancement of the two-photon probe Lyso-HP renders it attractive for imaging H2O2 in living tissues with deep tissue penetration. Significantly, the probe is feasible for fluorescently monitoring H2O2 level changes in lysosomes and suitable for fluorescence imaging of H2O2 in living tissues with deep penetration by using two-photon microscopy.

A dual-emission fluorescence-enhanced probe for imaging copper(II) ions in lysosomes

We have developed the first example of a fluorescence-enhanced and lysosome-targeted Cu2+ probe (Lys-Cu) with unique dual-channel emissions. The newly synthesized fluorescent probe Lys-Cu, which contains two recognition sites with different sensing mechanisms for Cu2+, displays fluorescence-enhanced dual-channel emissions with fluorescence response to Cu2+ in the lysosome pH environment. Fluorescence imaging shows that Lys-Cu is membrane-permeable and suitable for visualization of Cu2+ in lysosomes of living cells by dual-channel imaging.

A lysosome-targeted and ratiometric fluorescent probe for imaging exogenous and endogenous hypochlorous acid in living cells

Hypochorous acid plays important roles in numerous physiological and pathological processes. At the cell organelle level, an abnormal concentration of hypochorous acid in the lysosomes causes redox imbalance and the loss of function of the lysosomes. Herein, the first small molecule based, lysosomal-targeted ratiometric fluorescent HOCl probe (Lyso-HA) was synthesized through a rational design. The new probe was highly selective toward HOCl over other reactive oxygen species and exhibits a large variation (up to 97-fold) in its fluorescence ratio (I585/I450), with good signal resolution. The probe Lyso-HA is membrane-permeable and is suitable for ratiometric visualization of exogenous and endogenous HOCl at lysosomes in living cells.

Single Fluorescent Probe for Dual-Imaging Viscosity and H2O2 in Mitochondria with Different Fluorescence Signals in Living Cells

Mitochondria, as essential and interesting organelles within the eukaryotic cells, play key roles in a variety of pathologies, and its abnormalities are closely associated with Alzheimers disease (AD) and other diseases. Studies have shown that the abnormal of viscosity and concentration of hydrogen peroxide in mitochondria were all associated with AD. Accordingly, the detection of viscosity and hydrogen peroxide in mitochondria has attracted great attention. However, it remains a great challenge to explore a single probe, which can dual-detect the viscosity and H2O2 in mitochondria. Herein, in two ways to prevent the twisted internal charge transfer (TICT) process, we designed and sythesized the first dual-detection fluorescent probe Mito-VH that can visualize viscosity and H2O2 in mitochondria with different fluorescence signals in living cells.

A fast-response two-photon fluorescent probe for the detection of Cys over GSH/Hcy with a large turn-on signal and its application in living tissues

Cysteine (Cys), a small-molecule aminothiol, plays important roles in various physiological processes in connection with various diseases, such as skin lesions, edema, hair depigmentation and liver damage. We developed a novel two-photon fluorescent probe for sensing Cys in presence of GSH and Hcy in vivo. The two-photon fluorescent probe exhibited favorable properties, including fast response (about 20 min), good selectivity, and low cytotoxicity. Furthermore, it was successfully applied for imaging Cys in living cells and tissues.

Mitochondria and lysosome-targetable fluorescent probes for HOCl: recent advances and perspectives

Hypochlorous acid (HOCl), as one of the reactive oxygen species (ROS), plays an important role in the destruction of pathogens in the immune system. However, abnormal concentration of biogenic HOCl can also damage host tissues, and it has been shown to be associated with many diseases. Accordingly, detection of HOCl at the subcellular level is important for understanding inflammation and cellular apoptosis. Toward this end, in the past few years, a wide variety of fluorescent HOCl probes have been engineered and applied for imaging of HOCl in subcellular organelles. In this review, we highlight the representative cases of the fluorescent HOCl probes with mitochondria and lysosome-targetable ability. The discussion includes their design strategies, sensing mechanisms, and applications in bio-imaging of HOCl in mitochondria and lysosomes.

A fluorescent probe for ratiometric imaging of exogenous and intracellular formed hypochlorous acid in lysosomes

We have developed a new lysosome-targeting ratiometric fluorescent probe (FL-HA) for specific determination of HOCl in living cells. The developed probe exhibits accurate lysosome-targeting ability, good signal resolution, and high selectivity. Moreover, fluorescence imaging shows that FL-HA could be used as a probe for ratiometric visualization of exogenous and endogenous HOCl in lysosomes with a high colocalization coefficient compared with a commercial lysosomal location dye.

2-benzothiazoleacetonitrile based two-photon fluorescent probe for hydrazine and its bio-imaging and environmental applications

A novel turn-on two-photon fluorescent probe NS-N2H4 was developed with the 2-benzothiazoleacetonitrile as a new recognition site for the detection of hydrazine (N2H4). The two-photon probe exhibited favorable properties including high selectivity, low cytotoxicity and almost 16-fold fluorescence enhancement in the presence of N2H4 in solution. The probe could be used to image hydrazine in the living cells. Notably, we also used the two-photon fluorescent probe to image hydrazine in the tissue imaging for the first time. Furthermore, by the way of probe-loaded TLC plate, we further monitored vapor of hydrazine. Therefore, the novel two-photon probe is expected to be employed to detect N2H4 in biosamples and environmental pollution and the new recognition site will be widely applied to construct fluorescent probes for the detection of N2H4.

A targetable fluorescent probe for imaging exogenous and intracellularly formed nitroxyl in mitochondria in living cells

Nitroxyl plays crucial roles in many biological pathways and can serve as a potent therapeutic agent for the treatment of heart failure. Recent studies suggest that HNO may be produced in mitochondria and the HNO formed might have functional consequences for mitochondrial activity. However, in order to study the function of HNO in mitochondria, a suitable research method is needed. Herein, through rational design, we synthesized a new mitochondria-targeted fluorescent nitroxyl probe (Mito-HNO). The developed probe was highly selective toward HNO over other reactive nitrogen species and reducing species. In addition, the probe Mito-HNO was rapidly responsive and suitable for visualization of HNO in mitochondria in living cells. The probe is expected to be employed in further revealing the biological function of HNO in subcellular mitochondria.

An ESIPT based fluorescent probe for imaging hydrogen sulfide with a large turn-on fluorescence signal

Through an intramolecular nucleophilic substitution reaction and ESIPT mechanism, we designed and synthesized a fluorescent hydrogen sulfide probe with a large turn on fluorescence signal (400-fold). The new probe exhibits high selectivity, good membrane-permeability and is suitable for the visualization of exogenous and endogenous hydrogen sulfide in living cells.