for 5 min prior to the fluorescence measurement. The resulting
concentrations were calculated using the calibration curve and
are summarized in Table 1.
The PPi concentration observed in the urine sample was not
detectable. However, after spiking PPi at three levels, the % recovery
values of 99-106% were obtained. The recovery data obtained
by this sensor can be used to confirm the accuracy of the method.
The precision of the proposed sensor was also evaluated and reported
as % R.S.D. values of the three measurements. The obtained
% R.S.D. values were lower than 3%. These results confirm that the
proposed sensor provided good precision and could potentially be
used for the detection of PPi in real samples.
Conclusion
A fluorescence sensor was fabricated using water-soluble nanocrystalline
quantum dots capped with cysteamine for PPi sensing.
The sensor can be easily constructed by decorating Cys-CdS QDs
with Fe3+. The key sensing mechanism was based on the formation
of a strong complex between Fe3+ and PPi, which promoted the
electron transfer process between the Fe3+ complex and the QDs.
The decrease in the fluorescence intensity was an increasing linear
function of the PPi concentration, indicating that this sensor can be
used to detect PPi at the micromolar concentration level. The
feasibility of the proposed sensor was demonstrated by determining
the PPi content in urine samples with satisfactory results.