Fangfang Meng

A novel near-infrared fluorescent platform with good photostability and the application for a reaction-based Cu2+ probe in living cells

Most of the near-infrared (NIR) fluorescent copper ion probes are coordination-based, and the fluorescence enhancement is between 10 and 20 folds. Herein, a novel NIR fluorescent dye named CSCN with excellent photostability and a reaction-based Cu(2+) NIR probe named CSCN-Cu were reported. CSCN exhibited good photostability toward photo irradiation. CSCN-Cu showed lower background fluorescent interference and over 40-fold fluorescence enhancement in NIR region, it also exhibited good selectivity toward Cu(2+) in Hepes solution. Biotic experiments demonstrated that CSCN-Cu possessed low toxicity and successfully imaged Cu(2+) in living cells under the conditions performed.

Single fluorescent probe for reversibly detecting copper ions and cysteine in a pure water system

The selective detection of copper ions and cysteine has been very challenging, especially in pure water system. In this work, we have engineered a novel fluorescent probe PI, which remarkably can reversibly detect copper ions (Cu2+) and cysteine (Cys) in a pure water system. In addition, the time dependent fluorescence intensity changes of the probe PI revealed that the probe showed higher fluorescence intensity within 2 s in the presence of Cu2+ and Cys than in the presence of Cu2+. Furthermore, we demonstrated that this probe could effectively detect Cu2+ and Cys in living cells. The present study provided a unique strategy in which a single fluorescent probe detected multiple targets.

A dual-site two-photon fluorescent probe for visualizing mitochondrial aminothiols in living cells and mouse liver tissues

Thiol-containing amino acids (RSH) play a key role in maintaining the redox environment. In this work, we developed a novel dual-site two-photon (TP) fluorescent RSH probe (CA-TPP) for imaging mitochondrial RSH in living cells and mouse liver tissues. This probe exhibited rapid response and high TP photostability towards mitochondrial RSH. In particular, probe CA-TPP was capable of using TP fluorescence to track mitochondrial RSH over a long period.

A mitochondria-targetable fluorescent probe with a large Stokes shift for detecting hydrogen peroxide in aqueous solution and living cells

Fluorescent probes with large Stokes shifts play a key role in maintaining the accuracy of biological imaging and minimizing the self-quenching effect. In this work, we have developed a novel fluorescent probe CAI, which possessed a large Stokes shift in various solutions. We found that CAI was capable of detecting hydrogen peroxide (H2O2) in aqueous solution. Furthermore, probe CAI can sense exogenous and endogenous H2O2 in the mitochondria of living RAW 264.7 cells. In addition, probe CAI exhibited ideal properties such as excellent photostability, high sensitivity and selectivity. This fluorescent dye with a large Stokes shift was expected to have a more broad range of applications for developing various fluorescent probes with large Stokes shifts.

Ratiometric fluorescent probe with AIE property for monitoring endogenous hydrogen peroxide in macrophages and cancer cells

Hydrogen peroxide (H2O2) plays a key role in the progression of human illnesses, such as autoimmune and auto-inflammatory diseases, infectious diseases, diabetes, and cancer, etc. In this work, we have discribed a novel probe, TPE-TLE, which remarkably displayed AIE property and ratiometric fluorescence emission profiles in the presence of H2O2. This ratiometric fluorescent probe with AIE property exhibits outstanding features such as the well-resolved emission peaks, high sensitivity, high selectivity, low cytotoxicity, and good cell-membrane permeability. These excellent attributes enable us to demonstrate the ratiometric imaging of endogenously produced H2O2 in macrophages and cancer cells based on the novel ratiometric probe with AIE property for the first time. By comparing two kinds of cells, it is firstly found that cancer cells should contain much more endogenous H2O2 than macrophages. We expect that TPE-TLE will be useful fluorescent platform for the development of a variety of ratiometric fluorescent probes with AIE property to achieve unique biological applications.

A photostable fluorescent probe for rapid monitoring and tracking of a trans-membrane process and mitochondrial fission and fusion dynamics

Rapid monitoring and tracking of a trans membrane process and mitochondrial fission and fusion dynamics play critical roles in judging the occurrence and development of disease, and can give insights for studying apoptosis and cell degeneration. However, the existing probes are not capable of rapid monitoring and tracking the above dynamics process. To solve this problem, we develop a unique functional mitochondria probe containing long alkyl chains, 3,5-bis((E)-2-(pyridin-4-yl)vinyl)-1H-indole monoiodide (MT-PVIM), which is capable of rapid real-time imaging and tracking mitochondrial fission and fusion dynamics. In addition, compared with a commercially available mitochondrial probe MTR, the MT-PVIM probe has excellent specificity to mitochondria with outstanding tolerance of micro-environmental changes, thus representing a potential candidate as a tracking agent for apoptosis studies. The good performance of our proposed approach demonstrates that this strategy might open up new opportunities for the development of rapid image mitochondria-targetable molecular tools for bioanalytical and biomedical applications.

Two-photon fluorescent probe for detecting cell membranal liquid-ordered phase by an aggregate fluorescence method

The cell membranal liquid-ordered (Lo) phase can control the structure and function of cell membranes. In this study, we have engineered a novel two-photon (TP) fluorescent probe, TP-HVC18, which remarkably displayed two different fluorescence emission profiles in the aggregate and solution states in distinct polar environments. In accordance with its aggregate fluorescence, TP-HVC18 also can emit a red fluorescence signal in Lo phase vesicles. Taking advantage of this unique feature, we have demonstrated that the new TP probe TP-HVC18 is suitable for imaging membranal Lo phase by an aggregate fluorescence method. Furthermore, the robust probe also exhibited uncontinuous red fluorescence distribution in the cell membranal Lo phase. Based on this intriguing character, we also successfully showed that the novel probe can be employed to exhibit uncontinuous distribution of cell membranal Lo phase by a 3D imaging technique. We expect that this aggregation-based fluorescent platform may be extended for the development of a wide variety of TP fluorescent probes for detecting several biological species.

Novel alkyl chain-based fluorescent probes with large Stokes shifts used for imaging the cell membrane and mitochondria in different living cell lines

Fluorescent dyes with large Stokes shifts play a key role in developing multi-purpose fluorescent probes for a wide variety of targets. In this study, we developed two novel alkyl chain-based fluorescent probes (CA-C12 and CA-C2) with large Stokes shifts. The alkyl chain length of the probes affect the membrane permeability, and hence both probes can be successfully applied for sensing the cell membrane and mitochondria in different living cell lines. Furthermore, the probes CA-C12 and CA-C2 exhibited large Stokes shifts and excellent photostability in the different cell lines. The fluorescent dyes with large Stokes shifts were expected to have broader applications for developing various fluorescent probes with excellent optical properties.