Keywords β-Galactosidase, AIE, Fluorescence, Nanomaterials, Tumor
1 Introduction
β-Galactosidase (β-gal), an enzyme that catalyzes the hydrolysis of a glycosidic bond
of β-galactopyranoside within a carbohydrate such as lactose, ganglioside GM1, and
lactoceramides, is regarded as a very significant biomarker for cell senescence and
primary ovarian cancers [1, 2]. And its deficiency is reported to be associated with
β-galactosialidosis and Morquio B syndrome. On the other hand, β-gal serves as an
important reporter for verifying the efficiency of transcription and transfection as
well. Commonly, it acts as a biomarker to monitor the gene expression of lacZ1.
Moreover, β-gal has been studied as a potential therapeutic target for lactose
intolerance via gene replacement therapy in recent years [3]. According to the
great significance of β-gal, it has attracted many researchers’ attention in developing
highly selective and sensitive approaches to monitor the activity of the enzyme
in vitro and in vivo. There are various detection techniques, including MR [4],
single-photon emission computed tomography (SPECT) [5], positron emission
tomography (PET) [6], colorimetric [7], fluorogenic [8], chemiluminescence [9],
and bioluminescence [10] approaches. By contrast, fluorescent probes are of great
interest owing to their conveniences like high sensitivity, simple handling procedures, inexpensive instruments, and bioimaging ability. Herein, we reported the
progress of fluorescent nanomaterials in various fields, especially in chemical
sensing and biomedical imaging such as the detection of β-gal, and recent advances
related to the nanomaterial for β-gal detection have also been mentioned.
2 Fluorescent Probe for β-Galactosidase Activity Detection
2.1 Fluorescent Probe Based on Coumarins, Fluoresceins,
and Rhodamines
Recent research has illustrated that β-gal can be used as a molecular target for
visualizing peritoneal metastases originating from primary ovarian cancers. As a
result, great efforts have been devoted to developing a real-time tracking method
for β-gal. A number of fluorescent probes based on coumarins, fluoresceins, and
rhodamines have been synthesized for monitoring β-gal activity.
In 2014, Lee et al. [11] reported a two-photon β-gal fluorescent probe 1 and
applied it to the detection of β-gal activity quantitatively in living cells and in
aged tissues during cellular senescence. In their strategy, 6-(benzo[d]thiazol-2-yl)2-(methylamino)-naphthalene was used as the probe fluorophore and β-Dgalactopyranoside-derived benzyl carbamate as the β-gal hydrolytic site. After
186
A. Bi et al.
1 Introduction
β-Galactosidase (β-gal), an enzyme that catalyzes the hydrolysis of a glycosidic bond
of β-galactopyranoside within a carbohydrate such as lactose, ganglioside GM1, and
lactoceramides, is regarded as a very significant biomarker for cell senescence and
primary ovarian cancers [1, 2]. And its deficiency is reported to be associated with
β-galactosialidosis and Morquio B syndrome. On the other hand, β-gal serves as an
important reporter for verifying the efficiency of transcription and transfection as
well. Commonly, it acts as a biomarker to monitor the gene expression of lacZ1.
Moreover, β-gal has been studied as a potential therapeutic target for lactose
intolerance via gene replacement therapy in recent years [3]. According to the
great significance of β-gal, it has attracted many researchers’ attention in developing
highly selective and sensitive approaches to monitor the activity of the enzyme
in vitro and in vivo. There are various detection techniques, including MR [4],
single-photon emission computed tomography (SPECT) [5], positron emission
tomography (PET) [6], colorimetric [7], fluorogenic [8], chemiluminescence [9],
and bioluminescence [10] approaches. By contrast, fluorescent probes are of great
interest owing to their conveniences like high sensitivity, simple handling procedures, inexpensive instruments, and bioimaging ability. Herein, we reported the
progress of fluorescent nanomaterials in various fields, especially in chemical
sensing and biomedical imaging such as the detection of β-gal, and recent advances
related to the nanomaterial for β-gal detection have also been mentioned.
2 Fluorescent Probe for β-Galactosidase Activity Detection
2.1 Fluorescent Probe Based on Coumarins, Fluoresceins,
and Rhodamines
Recent research has illustrated that β-gal can be used as a molecular target for
visualizing peritoneal metastases originating from primary ovarian cancers. As a
result, great efforts have been devoted to developing a real-time tracking method
for β-gal. A number of fluorescent probes based on coumarins, fluoresceins, and
rhodamines have been synthesized for monitoring β-gal activity.
In 2014, Lee et al. [11] reported a two-photon β-gal fluorescent probe 1 and
applied it to the detection of β-gal activity quantitatively in living cells and in
aged tissues during cellular senescence. In their strategy, 6-(benzo[d]thiazol-2-yl)2-(methylamino)-naphthalene was used as the probe fluorophore and β-Dgalactopyranoside-derived benzyl carbamate as the β-gal hydrolytic site. After
186
A. Bi et al.