through resonance energy transfer (RET) between the CdTe
quantum dots (QDs) and cyanine-3 labeled aptamer [20]. However,
they still suffered from high cost, complicated preparation and
complex purification procedures.
In recent years, QDs were usually modified with some
biomolecules and used as a special receptor for bioanalysis
[25]. Chen et al. linked ATP molecules to the surface of CdSe/CdS/
ZnS QDs, and investigated the transport and circulation of ATP in
cell [26]. However, these QD-based assays relied on pre-
synthesized semiconductor QDs and the process was usually
rigorous. Recently, Pavlov’s team reported a series of research
work about simple and fast
fluorescence enzymatic assays based
on the enzymatic formation of QDs with thiol as stabilizers
[27–29]. In this paper, we developed a simple and fast route to
detect ATP based on the formation of CdS QDs with ATP as
stabilizers. And this analysis system does not need the pre-
synthesis of semiconductor QDs and DNA aptamer.
Alkaline phosphatase (ALP) is one of the most commonly
assayed enzymes in clinical practice, because the change of ALP
level is usually connected with a variety of physiological
diseases, such as bone diseases, hepatitis, obstructive jaundicel,
and diabetes, etc [30–34]. ALP, as a membrane-bound enzyme
widely existed in the tissues of living organisms, is responsible
for the removal of phosphate groups from proteins, nucleic
acids, and small molecules. Until now, most
fluorescence
analysis for ALP was based on the
fluorescent copolymer and
small molecular probes [35–40]. Yu et al. designed a
tetracationic perylene probe for the real-time
fluorescent
turn-on assay of ALP activity. The
fluorescence of the probe
could be efficiently quenched by ATP due to the aggregation of
probe, and it could be recovered due to the dephosphorylation
of ALP [35].
In this paper, CdS QDs were generated in the presence of Cd2+
and S2 with ATP as stabilizers, and its
fluorescence was enhanced
with the increasing of the ATP concentration. ALP can effectively
hydrolyze ATP molecule to produce adenosine and phosphoric acid
based on its enzymatic dephosphorylation. And the
fluorescent
CdS QDs cannot be generated in the presence of Cd2+ and S2 only
with adenosine and phosphoric acid as stabilizers. Therefore, the
analysis system could be also utilized to detect ALP.