ChemComm
Communication
this assay coincided well with those obtained using Beckman
Coulter Unicel DxC600, indicating that the proposed method can
be successfully applied for detecting glucose in serum samples.
In conclusion, we have developed a novel label-free detec-
tion system containing SiQDs and glucose oxidase for quanti-
tative analysis of glucose. SiQDs with good photoluminescence,
favorable biocompatibility and high electron-transfer efficiency
may become promising nanomaterials for enzyme-catalyzed
events in biological samples. The mechanism of glucose
sensing can be ascribed to the H2O2 (generated from oxidation
of glucose)-induced quenching of the PL of SiQDs. On the other
hand, the proposed method has many advantages, such as
simple operation, high PL and excellent photostability of the
SiQDs, high sensitivity and good selectivity. In addition, the
research provides a new approach to further design of novel
nanosensors based on the assembly of SiQDs with other redox
enzymes as a new method for detection of biomolecules.
This work was supported by the National Natural Science
Foundation of China (20975037, 21075037 and 21275051) and
Aid program for Science and Technology Innovative Research
Team in Higher Educational Institutions of Hunan Province.
Fig. 3 Effects of the guest molecules (10ꢀ2 M) to 0.55 mM glucose on the PL
quenching efficiency of SiQDs containing 10 mg mLꢀ1 GOx.
function is (I0 ꢀ I)/I0 = 0.01898 + 4.594 ꢁ 10ꢀ4 C with a correlation
coefficient of R2 = 0.9854. The linear response of the PL quantum
yield versus the glucose concentration is shown in Fig. S7 (ESI†).
The limit of detection (LOD) was 0.68 mM (S/N = 3), which is much
lower than those obtained using other reported fluorescence
detection methods (Table S1, ESI†). However, at higher concen-
tration, the quenching curve tends to be flat. This tendency is in
accordance with the kinetics of enzyme-catalyzed reactions.8
To evaluate the specificity of developed biosensors for glucose, a
series of main, relevant glucide, metal ions and amino acids were
studied as a control. The results are shown in Fig. 3. Several glucose
analogues, including sucrose, fructose, mannose and galactose,
exhibited little influence on glucose detection even at concentrations
20 times higher than that of glucose, suggesting the high specificity
of GOx. Typical metal ions and amino acids also showed minimal
interference in glucose determination. These results clearly demon-
strate that the SiQD based PL sensors can serve as novel fluorescence
probes for highly selective and reliable glucose monitoring.
Notes and references
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glucose in real samples. Therefore, we further investigated the
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Fig. 4 Analytical results of glucose in serum obtained using the present
SiQD-based method (black) and using Beckman Coulter Unicel DxC600 (red).
All measurements were performed in PBS, pH = 7.4, thermostated at 40 1C
for 30 min.
c
614 Chem. Commun., 2013, 49, 612--614
This journal is The Royal Society of Chemistry 2013