Surface-wettable nonenzymatic fiber-optic sensor for selective detection of hydrogen peroxide.

A micro-nanostructure-based surface-modified fiber-optic sensor has been developed herein to selectively detect hydrogen peroxide (H2O2). In our design, phenylboronic ester-modified polymers were used as a modified cladding medium that allows chemo-optic transduction. Sensing is mechanistically based on oxidation and subsequent hydrolysis of the phenylboronic ester-modified polymer, which modulates hydrophobic properties of fiber-optic devices, which was confirmed during characterization of the chemical functional group and hydrophobicity of the active sensing material. This work illustrates a useful strategy of exploiting principles of chemical modifications to design surface-wettable fiber-optic sensing devices for detecting reactive species of broad relevance to biological and environmental analyses.

Visualizing nitroreductase activity in living cells and tissues under hypoxia and hepatic inflammation.

Detecting nitroreductase (NTR) activity in hypoxic cells and tissues in situ represents an important step toward accurate delineation of hypoxic disease loci. However, it remains challenging to develop fluorescent probes with the necessary attributes of selectivity, sensitivity, precise targeting and aqueous solubility. Herein, two kinds of fluorescent probes (NNP and cRGD-NNP) built on a 2-nitroimidazole sensing platform were synthesized for the detection of NTR activity in cell and in vivo models of hypoxia. In the presence of NADH, NNP displayed high selectivity for NTR, a strong fluorescence enhancement (108 fold), and a low detection limit (3.6 ng mL-1). Benefiting from the hydrophilic structure and tumor-targeting properties of the cRGD cyclopeptide group, the probe cRGD-NNP efficiently detected NTR activity in MCF cancer cells under hypoxia. In addition, the liposome-encapsulated probe was successfully applied to visualize NTR during liver inflammation in mice.