Europium Ion-Based Magnetic-Trapping and Fluorescence-Sensing Method for Detection of Pathogenic Bacteria.

Europium ions (Eu) have been utilized as a fluorescence-sensing probe for a variety of analytes, including tetracycline (TC). When Eu is chelated with TC, its fluorescence can be greatly enhanced. Moreover, Eu possesses 6 unpaired electrons in its f orbital, which makes it paramagnetic.

Rapid Detection of Pathogenic Bacteria by the Naked Eye.

O157:H7 and are common pathogens. Gram-negative bacteria, such as , contain high concentrations of endogenous peroxidases, whereas Gram-positive bacteria, such as , possess abundant endogenous catalases. Colorless 3,5,3',5'-tetramethyl benzidine (TMB) changes to blue oxidized TMB in the presence of and a low concentration of HO (e.