Fructose determination in fruit juices using an electrosynthesized molecularly imprinted polymer on reduced graphene oxide modified electrode.

The present work reports the development of a novel electrochemical sensor for the selective detection of fructose. The sensor was developed through electropolymerization of a molecularly imprinted polymer film on a reduced graphene oxide modified electrode. The modified electrode was characterized by cyclic voltammetry, electrochemical impedance spectroscopy, scanning electron microscopy, atomic force microscopy and RAMAN spectroscopy. Through the application of the modified electrode, the recognition of fructose molecules occurred in a concentration range of 1.0 × 10-14 to 1.0 × 10-11 mol L-1, under a Langmuir adsorption isothermal model. The sensitivity and limits of detection and quantification obtained for the sensor were 9.9 × 107 A L mol-1, 3.2 × 10-15 mol L-1 and 1.1 × 10-14 mol L-1, respectively. The analytical method used for the detection of fructose presented good reproducibility, stability and accuracy, and was successfully applied for the quantification of this sugar in orange, apple and grape juices.

A mitochondria targetable two-photon excited near-infrared fluorescent probe for imaging of H2O2 in live cells and tissues.

Hydrogen peroxide (H2O2), a member of small-molecule reactive oxygen species (ROS), plays an important role in physiological and/or pathological process within live systems. Herein, to quantitatively investigate the biological role of H2O2 in subcellular level, we constructed of a novel two-photon (TP) in near-infrared (NIR) out fluorescent probe (TP-NIR-H2O2) for visualization of mitochondria H2O2 in living cells and tissues. Specifically, TP-NIR-H2O2 utilized the oxonium ion as the mitochondrial targeting unit and phenylboric acid as the H2O2 reaction moiety. After the phenylboric acid moiety reaction with H2O2, TP-NIR-H2O2 displayed a ~105-fold fluorescence intensity enhancement in 665 nm. Selectivity experiment demonstrated that the probe can detect H2O2 with high selectivity over other ROS. Moreover, TP-NIR-H2O2 could be employed for imaging H2O2 in mice liver tissues with large tissue-image depth (50-170 µm) under two-photon excitation (800 nm).