H O NiFe O O H e br Additionally

H2 O NiFe 2 O4 O 2 + 4 H+ + 4e
Additionally, the ECL behaviors of lucigenin was discussed via adding different substances, as described in Fig. 4B. It’s evident that [email protected] modified electrode exhibited a higher ECL signal (curve
b) than that of sole lucigenin (curve a), which was benefited from the high surface area of h-BN, leading to a large quantity loading of luci-genin. When H2O2 was added into the detection solution, an slightly increased ECL signal was observed (curve c), which was in agreement with previous report [34]. Nevertheless, a remarkably enhanced ECL
Fig. 5. (A) ECL responses of ratiometric biosensor and (B) Calibration plot of the ECL intensity with different concentrations of HE4 from 10 fg/ml to 10 ng/ml in 0.1 M PBS containing 0.5% DBAE, 10 mM H2O2 and 10 mM NaOH. (C) The selective of the proposed ratiometric ECL biosensor and (D) the 3X FLAG Peptide of the proposed ratiometric ECL biosensor under consecutive cyclic potential scans for 10 cycles.
signal was obtained after Envision complex being poured into the de- several experimental parameters such as the immobilization time of Ab1,
tection solution (curve d). The reason was HRP contained in Envision Ab2 and the incubation time of HE4, [email protected]@Ab2 bioconju-
complex possessed intrinsically catalytic performance for the split of gates were studied in Fig. S4. It’s apparent that the ECL intensity declined
H2O2 to output O2%−, just as Eq. (2), which participated in the lucigenin until the immobilization time of Ab1 up to 50 min and then tended to be
ECL reaction. It was worth emphasizing that the ECL of lucigenin was stable (Fig. S4 A). Thus, 50 min was chose as the optimal immobilization
initiated under alkaline condition, certifying the importance of OH− in time of Ab1. Similarly, the ECL signal dropped with the increasing im-
ECL reaction. Therefore, the luminescence mechanism can be eluci- mobilization time of Ab2 and reached a Haploid platform at 30 min (Fig. S4B),
dated by the following equations:
thus the ideal immobilization time of Ab2 was 30 min. From Fig. S4C, the
Luc ( OH)+ (9) ECL intensity decreased gradually as the incubation time increased, and a
stable ECL intensity was obtained at 50 min, which was regarded as the
e
Luc ( OH)• (10) optimal incubation time. Remarkably, the ECL signal from DBAE was
descended and which from lucigenin was rose (Fig. S4D). Finally, two
NMA* NMA hv (12) as the best incubation time of [email protected]@Ab2 bioconjugates.
3.6. Analytical performance of the ECL biosensor
3.5. Optimization of experiment conditions
Under the optimal conditions, two ECL signals from DBAE and luci-
To ensure wonderful analytical performance in ECL detection, several
genin were researched when different concentrations of HE4 was in-
elements including the concentration of NiFe2O4 NTs, the adsorption cubated into the biosensor. Apparently, the ECL intensity of DBAE de-
time of lucigenin and the concentration of NaOH were investigated. Seen clined while the ECL intensity of lucigenin increased with the increasing
from Fig. S3 A, the highest ECL signal was realized at 1.0 mg/mL. concentrations of HE4, demonstrated in Fig. 5A. Fig. 5B indicated a good
Therefoe, 1.0 mg/mL was identified as the optimal concentration of linear relationship between the ECL intensity ratio of lucigenin to DBAE
NiFe2O4 NTs. Moreover, the adsorption time of lucigenin on h-BN was and the logarithm concentration of HE4 in the range of 10 fg/ml to
reached a crest value at 3 h. Therefore, 3 h was selected as the optimum