A new carbazole based fluorescent probe with AIE characteristic for detecting and imaging hydrazine in living cells, mungbean sprouts, Arabidopsis thaliana, and practical samples.

In this study, we report a new carbazole-malononitrile fluorescent probe CBC with an interesting aggregation-induced emission (AIE) characteristic. Probe CBC could rapidly and selectively detect hydrazine (N2H4) in ～100% aqueous media, and also exhibit an exceedingly low detection limit of 6.3 nM for sensitively detecting N2H4. The sensing mechanism of CBC towards N2H4 has been well demonstrated through the spectra of 1H NMR, HRMS and FTIR. Interestingly, probe CBC was applied to visualize and detect gaseous and aqueous N2H4 with sensitive color changes. Importantly, probe CBC was applied to effectively detect N2H4 in practical samples such as soil, human serum, human urine, plants, foods and beverages, as well as sensitively sense and image N2H4 in biological systems including living mungbean sprouts, Arabidopsis thaliana, and HeLa cells.

New dual-responsive fluorescent sensor for hypochlorite and cyanide sensing and its imaging application in live cells and zebrafish.

Excessive levels of cyanide (CN-) and hypochlorite (ClO-) anions are the significant threats to the human health and the environment. Thus, great efforts have been to design and synthesize molecular sensors for the simple, instantaneous and efficient detecting environmentally and biologically important anions. Currently, developing a single molecular sensor for multi-analyte sensing is still a challenging task. In our present work, we developed a new molecular sensor (3TM) based on oligothiophene and Meldrum's acid units for detecting cyanide and hypochlorite anions in biological, environmental and food samples. The detecting ability of 3TM has been examined to various testing substances containing amino acids, reactive oxygen species, cations and anions, showing its high selectivity, excellent sensitivity, short response time (ClO-: 30 s, CN-: 100 s), and broad pH working range (4-10). The detection limits were calculated as 4.2 nM for ClO- in DMSO/H2O (1/8, v/v) solution and 6.5 nM for CN- in DMSO/H2O (1/99, v/v) solution. Sensor 3TM displayed sharp turn-on fluorescence increasement (555 nm, 435 nm) and sensitive fluorescence color changes caused by CN-/ClO-, which is ascribed to the nucleophilic addition and oxidation of ethylenic linkage by cyanide and hypochlorite, respectively. Moreover, sensor 3TM was applied for hypochlorite and cyanide detecting in real-world water, food samples and bio-imaging in live cells and zebrafish. To our knowledge, the developed 3TM sensor is the seventh single-molecular sensor for simultaneous and discriminative detecting hypochlorite and cyanide in food, biological and aqueous environments using two distinct sensing modes.

A dual-responsive fluorescent turn-on sensor for sensitively detecting and bioimaging of hydrazine and hypochlorite in biofluids, live-cells, and plants.

Hydrazine (N2H4) and hypochlorite (ClO-) are extremely harmful to the public health, so it is vitally necessary to detect them in living system. Herein, we developed a new phenthiazine-thiobarbituric acid based dual-analyte responsive fluorescent sensor PT for visually distinguishing and detecting N2H4 and ClO-. PT underwent N2H4/ClO--induced CC breakage, achieving olive-drab/brilliant green fluorescence lighting-up response towards N2H4/ClO- with superb specifity, ultra-sensitivity (detection limit: 15.4 nM for N2H4, 13.7 nM for ClO-), and ultra-fast response (N2H4: <15 s, ClO-: <20 s). The mechanisms for sensing N2H4 and ClO- were investigated with support of spectral measurements and DFT investigation. Sensor based paper-strip/silica-gel device was developed for in-field supervision and on-site monitoring of gaseous and aqueous N2H4 and ClO- solution. In addition, the PT was also applied for quantitatively detecting N2H4 and ClO- in soil, food, plants and bio-fluids. Moreover, PT was utilized to visualize exogenous N2H4 and ClO- in living plants and live-cells, demonstrating this sensor utilized as a powerful tool to detect N2H4 and ClO- in biological fields.

Detection and Location of Surface Damage Using Third-Order Combined Harmonic Waves Generated by Non-Collinear Ultrasonic Waves Mixing.

Metals which are widely used in many types of industries are usually subjected to fatigue and surface corrosion. There is a demand to detect the surface damage caused by fatigue and corrosion at an early stage to ensure the structural integrity. In this paper, a novel nonlinear ultrasonic technique based on the measure of third-order combined harmonic generation, is proposed to detect and locate the surface damage in 6061 aluminum alloy. Third-order combined harmonic generation caused by non-collinear mixing of one longitudinal wave and one transverse wave at different frequencies, is firstly analyzed and experimentally observed. An experimental procedure of nonlinear scanning is proposed for the damage detection and location by checking the variation of frequency nonlinear response. The correlations of nonlinear frequency mixing responses and surface damage in the specimens are obtained. Results show that the nonlinear response caused by fatigue damage and surface corrosion can be identified and located by this method. In addition, this approach can exclude the nonlinearity induced by the instruments and simplify the signal processing.