Fig A shows the electrochemical and ECL properties

Fig. 4A shows the electrochemical and ECL properties of the β-CD-MPA-CdTe QDs in air-saturated 0.1 M phosphate buffer solution (PBS, NHS Biotin 8.0) under potential scan from 0 to 1.0 V at 100 mV/s. It is observed that the β-CD-MPA-CdTe QDs showed an intensive anodic ECL emission at the ITO electrode with the peak emission at 1.0 V and onset potential of ca. 0.8 V. In addition, in the absence of QDs, the ECL emission was not observed, suggesting that the anodic ECL emission was produced from the QDs. In comparison, β-CD-CdTe QDs did not show noticeable ECL emission under the same condition, which may be ascribed to the incomplete passivation of the QDs surface, leading to nonradiative emission. Previous report shows glycogen the capping agent plays an important role in affecting the photoluminescence property of the QDs [8]. The above results demonstrated that the ECL behavior of the β-CD-MPA-CdTe QDs was also influenced by the capping agent. It is reported that QDs capped with dual-stabilizers not only showed improved ECL efficiency and higher ECL intensity due to the effective removal of the nonradiative surface state and deep surface trap of QDs [23], but also exhibited desired functionality [16]. Therefore, MPA, as another stabilizer, was introduced to improve the ECL behavior of the QDs, while retaining the molecular recognition capability of the surface-immobilized β-CD.