Ratiometric fluorescence sensors for heparin and heparinase based on enhanced excimer emission of perylene probe induced by cationic silver nanoparticles
Abstract Herein, cationic MUTAB Ag NPs of different sizes were synthesized and their interactions with a negatively charged perylene probe, N,N' bis(6 caproic acid) 3,4:9,10 perylenediimide (PDI COOH) were investigated. MUTAB Ag NPs could result in significant monomer quenching and excimer formation by inducing probe aggregation due to the strong electrostatic attractive interactions between them. Moreover, significant excimer emission could be observed at extremely low probe concentration when induced by larger MUTAB Ag NPs. A possible mechanism of metal enhanced fluorescence was proposed, which is evidenced by the strong dependence between surface plasmon resonance absorption spectra of MUTAB Ag NPs and the excimer emission spectra of PDI COOH, together with the sharp decrease in fluorescence lifetime of excimer compared with that induced by poly(allylamine) Consequently, ratiometric fluorescence sensors for heparin and heparinase were developed based on the Ag NP induced excimer emission of PDI COOH. The adsorption of heparin on the surface of MUTAB Ag NPs led to the release of monomer, while the degradation of heparin by heparinase facilitated the formation of PDI COOH excimer. The monomer excimer transition signal was harnessed for heparin and heparinase sensing, which exhibited good sensitivity and excellent selectivity. Finally, application of the present system for detection of heparin and heparinase in human serum sample was successfully demonstrated.