As shown in Figure 5C, the electrochemical response increases with increasing temperature from 25°C to 35°C and then decreases as the temperature further increased. MDV3100 research buy The sharp decrease of the
response was due to the denaturation of GOD at high temperatures. Although the response of the biosensor was greatest at 35°C, for practical reasons, it was suggested that room temperature be used to simplify the experimental procedure and prolong the useful lifetime of the biosensor given that most enzymes can be easily denatured at high temperature. Amperometric sensing of glucose In this work, PtAuNP/GSK1120212 concentration ss-DNA/GR nanocomposites were used to accelerate electron transfer between the electro-active sites embedded in GOD and the modified electrode. To investigate the effect of PtAuNP/ss-DNA/GR on the response current, as in Figure 6, we https://www.selleckchem.com/products/incb28060.html compared the amperometric responses of GOD/ss-DNA/GR (curve a), GOD/PtNP/ss-DNA/GR (curve b), and GOD/AuNP/ss-DNA/GR (curve c) modified electrodes for the successive addition of 0.1 mM glucose at an applied potential of -0.2 V. It can be seen from Figure 6 that the amperometric responses of GOD/PtAuNP/ss-DNA/GR (curve d) modified electrode were much larger than those of the GOD/ss-DNA/GR (curve a), GOD/PtNP/ss-DNA/GR (curve b), and GOD/AuNP/ss-DNA/GR (curve c) modified electrodes. The reason might be due to the extra active surface area provided by
PtAuNP/ss-DNA/GR composites and the synergistic action of PtAuNPs and GR. The GOD/PtAuNP/ss-DNA/GR modified electrode exhibited a linear response in the concentration range Edoxaban of 1.0 to 1,800 μM, with a correlation coefficient of 0.997. It was much wider than that of the ZnO/MWCNT/GOD electrode (6.67 to 1,290 μM) [39], Ag polydopamine@CNT/Nafion/GOD electrode (50 to 1,100 μM) [40], and GR quantum dot/GOD electrode (5 to 1,270 μM) [30]. The detection limit was estimated to be 0.3 μM (based on S/N = 3) for glucose, which was lower than 20 μM for MWCNT-GOD [41], 20 μM
for GR-chitosan/GOD [42], and 0.5 μM for polyaniline/CNT/Pt/GOD [43]. Figure 6 Amperometric responses of modified electrodes to additions of 0.1 mM glucose in 10-mL PBS at -0.2 V. GOD/ss-DNA/GR (curve a), GOD/PtNP/ss-DNA/GR (curve b), GOD/AuNP/ss-DNA/GR (curve c), and GOD/PtAuNP/ss-DNA/GR (curve d) modified electrodes. Left inset is the calibration curve of the biosensor. Selectivity, reproducibility, and stability of the biosensor In the present work, we studied the interference effect of ascorbic acid (1.0 mM), dopamine (1.0 mM), and uric acid (1.0 mM) on the amperometric response of 1 mM glucose, and the response is shown in Table 1. As shown, the biosensor showed excellent selectivity to glucose in the presence of ascorbic acid, dopamine, and uric acid. The good selectivity of this biosensor is largely attributed to the low working potential (-0.2 V).