A fluorescence turn-on assay for simple and sensitive determination of hemin and blood stains

Hemin, a sort of important Fe(III)-coordinated protoporphyrin IX complexes, plays critical roles in many biological processes. Besides, hemin and its derivatives have been considered as biochemical markers to distinguish blood against other colored samples. The development of simple and sensitive methods for hemin determination is thus becoming important. In this research, a novel dihydrofluorescein derivative has been synthesized and applied as the fluorescence reporter. Inorganic H2O2 and organic tert-butyl hydroperoxide (TBHP), artemisinin (ART) have been used as peroxide sources to generate reactive radical species under hemin catalysis, which subsequently oxidize non fluorescent dihydrofluorescein to its fluorescent form. The limit of detection (LOD) was found down to picomolar levels (64 pM, 350 pM, 420 pM for H2O2, TBHP, ART systems respectively). Moreover, a simple detection strip has been prepared by incorporating both ART and fluorescence reporter into the filter papers, which offers a simple strategy to conveniently distinguish blood stains against other colored stains.