interaction between α-CD and p-nitrophenol. Feng’s group reported a universal
fluorescence biosensor for glycosidase assay and inhibitor screening using
β-CD-functionalized carbon quantum dots (β-CD-CQDs) as the nanoprobes
[67]. As shown in Fig. 9, taking β-galactosidase as the target example, its introduction initiated the rapid hydrolysis of 4-nitrophenyl-β- D -galactopyranoside into
p-nitrophenol, and the generated p-nitrophenol was driven by the host-guest
recognization to enter the β-CD cavity of nanoprobes. A sharp decrease in the
fluorescence emission of β-CD-CQDs was obtained by a static quenching mechanism. As a consequence, a good linear relationship between the fluorescence intensity and β-galactosidase level was established with a low detection limit of
0.6 U L
À1
. The inhibitor screening function of this strategy was also investigated
by choosing D-galactal as an effective inhibitor of β-galactosidase, and obvious
fluorescence recovery results confirmed the feasibility to screen potential inhibitors.
In addition, the developed biosensor was successfully applied to monitor the
β-galactosidase expression level in ovarian cancer cells. On account of the increased
recognization sites from α-CD-encapsulated gold/silica core-shell nanoparticles
(Au/SiO 2 /α-CD), Zhao et al. established a sensitive ECL biosensor to test the activity
of human 8-oxoguanine DNA glycosylase (hOGG 1) [68]. Guest-labeled ECL probe
was firstly attached to the Au/SiO 2 /α-CD nanocomposite-modified electrode surface
for the preparation of ECL sensing platform. In the presence of hOGG 1, targetinduced terminal protection happened and inhibited the digestion of exonuclease I
(Exo I) and exonuclease III (Exo III) toward the guest-labeled ECL probe. The
Fig. 9 Schematic illustration of the universal detection strategy for glycosidase activity based on a
combined host-guest recognition and specific static quenching-induced signal transduction mechanism by taking β-galactosidase as the example [67]
242
J. Jiang et al.
fluorescence biosensor for glycosidase assay and inhibitor screening using
β-CD-functionalized carbon quantum dots (β-CD-CQDs) as the nanoprobes
[67]. As shown in Fig. 9, taking β-galactosidase as the target example, its introduction initiated the rapid hydrolysis of 4-nitrophenyl-β- D -galactopyranoside into
p-nitrophenol, and the generated p-nitrophenol was driven by the host-guest
recognization to enter the β-CD cavity of nanoprobes. A sharp decrease in the
fluorescence emission of β-CD-CQDs was obtained by a static quenching mechanism. As a consequence, a good linear relationship between the fluorescence intensity and β-galactosidase level was established with a low detection limit of
0.6 U L
À1
. The inhibitor screening function of this strategy was also investigated
by choosing D-galactal as an effective inhibitor of β-galactosidase, and obvious
fluorescence recovery results confirmed the feasibility to screen potential inhibitors.
In addition, the developed biosensor was successfully applied to monitor the
β-galactosidase expression level in ovarian cancer cells. On account of the increased
recognization sites from α-CD-encapsulated gold/silica core-shell nanoparticles
(Au/SiO 2 /α-CD), Zhao et al. established a sensitive ECL biosensor to test the activity
of human 8-oxoguanine DNA glycosylase (hOGG 1) [68]. Guest-labeled ECL probe
was firstly attached to the Au/SiO 2 /α-CD nanocomposite-modified electrode surface
for the preparation of ECL sensing platform. In the presence of hOGG 1, targetinduced terminal protection happened and inhibited the digestion of exonuclease I
(Exo I) and exonuclease III (Exo III) toward the guest-labeled ECL probe. The
Fig. 9 Schematic illustration of the universal detection strategy for glycosidase activity based on a
combined host-guest recognition and specific static quenching-induced signal transduction mechanism by taking β-galactosidase as the example [67]
242
J. Jiang et al.