Electronic Supplementary Material s24

Electronic Supplementary Material

Toehold-aided DNA recycling amplification using hemin and G-quadruplex reporter DNA on magnetic beads as tags for chemiluminescent determination of riboflavin

Yan Meng, Xu Hun, Yue Zhang1, Xiliang Luo2

Key Laboratory of Sensor Analysis of Tumor Marker, Ministry of Education, State Key Laboratory Base of Eco-chemical Engineering, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042, China

Optimization of method

In order to obtain higher sensitivity, the relative experiment conditions such as the incubation time of riboflavin with MBs modified with aptamer/DNA1 duplex, incubation time of DNA1 and report DNA with MBs modified with capture DNA, pH and concentration of luminol were systemically studied. The pH of luminol solution greatly affects the CL signal intensity. So, the effect of the pH on CL signal intensity was firstly investigated over the range of 9.0–12.0. It was observed that the CL signal intensity was enhanced significantly when the pH was increased from 9.0 to 11.0, and above pH 11.0, the CL signal intensity decreased with increasing the pH of luminol solution slowly, as shown in Fig S1A. Therefore, the pH of 11.0 was selected for further studies. The effect of luminol concentration was tested from 10-200 μM. The experimental results suggested that the CL signal intensity increased with increasing the concentration of luminol solution from 10 to 200 μM clearly, but the blank signal also increased (Fig S1 (B)). The best ratio of signal to blank was achieved at 80 μM. The effect of incubation time of riboflavin was tested from 1 to 20 min. Fig S1 (C) showed that the CL intensity increased as the recognition time increased from 1 to 10 min. and then reached a constant value at the recognition time 15 min. This result suggests that 15

1 Corresponding author, E-mail: [email protected]; 2 Corresponding author, E-mail: [email protected], Tel: +86-532-84022681; Fax: +86-532-84023927 min was enough for riboflavin to bind with aptamer and for DNA1 to release from the MBs. Then the effect of incubation time of DNA1 and report DNA with MBs modified with capture DNA was also investigated. The relationship between the CL response and the incubation time is shown in Fig S1 (D). The CL response increased with the increasing incubation time and reached a maximum at 30 min. However, there was no significant increase in the CL signal intensity observed after 30 min. Thus, 30 min was selected as the adequate incubation time for the DNA1 and report DNA to interact with capture DNA.

Fig. S1. Optimization of reaction parameters. Effect of pH (A) and concentration (B) of luminol, effect of incubation time of riboflavin (C), the effect of incubation time of DNA1 and report DNA (D) on CL intensity.