Electronic Supplementary Material on the Microchimica Acta publication entitled
Ultrasensitive chemiluminescence assay for the lung cancer biomarker cytokeratin 21-1 via a dual amplification scheme based on the use of encoded gold nanoparticles and a toehold-mediated strand displacement reaction
XuHun*, Bingru Liu, Yan Meng
College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Key Laboratory of Sensor Analysis of Tumor Marker, Ministry of Education, State Key Laboratory Base of Eco-chemical Engineering, Qingdao 266042, China
*Corresponding author: Fax: (86) 53284022750,Tel: (86) 53284022750, E-mail:
Delta G:-43.23 kcal/mole Base Pairs24
5' GAAGGGAGGAATGGTGTCAGGGGCGAGGGATAGGCACACGACATAATAGGCACCTTTCA S1
|||||||||||||||||||||||||
3' TATCCGTGTGCTGTATTATCCGTGCTTTCA S3
Delta G:-49.72 kcal/mole Base Pairs23
5' GAAGGGAGGAATGGTGTCAGGGGCGAGGGATAGGCACACGACATAATAGGCACCTTTCA S1
||||||||||||||||||||||||
3' TCCTTACCACAGTCCCCGCTCCCATGTTGATCTATCTCAATT S4
Delta G:-53.24 kcal/mole Base Pairs25
5' GAAGGGAGGAATGGTGTCAGGGGCGAGGGATAGGCACACGACATAATAGGCACCTTTCA S1
||||||||||||||||||||||||||
3' CTTCCCTCCTTACCACAGTCCCCGC T
Delta G:-94.53 kcal/mole Base Pairs47
5' GAAGGGAGGAATGGTGTCAGGGGCGAGGGATAGGCACACGACATAATAGGCACCTTTCA S1
|||||||||||||||||||||||||||||||||||||||||||||||
3' TCCTTACCACAGTCCCCGCTCCCTATCCGTGTGCTGTATTATCCGTG F
Fig.S1 (A) TEM images of synthesized AuNPs. (B) UV-visible spectra of S3(a), AuNPs(b), S2 and S3 labeled with AuNPs(c).
Optimization of method
Luminol-H2O2-Au3+ system was used for CL detection. For comparison, CL intensity of luminol-H2O2-AuNPs system was also measured. It was found that the CL intensity of luminol-H2O2-Au3+ system was 4.8 times higher than that of luminol-H2O2-AuNPs system (Fig. S2(A)). So the AuNPs in the output 1 and output 2 were dissolved to Au3+ for CL detection.
The order of adding of target DNA and fuel DNA severely affected the CL intensity. Various ways of adding of target DNA and fuel DNA, such as, target DNA and fuel DNA added simultaneously (way a), target DNA added after fuel DNA being added (way b), fuel DNA added after target DNA being added (way c), are studied systematically. It was found that way c gave the best CL signal (Fig. S2(B)). So way c was used in the following study.
Subsequently, the effect of hybridization time betweentarget with three-stranded substrate complex on the CL intensity was alsoinvestigated. It is found that the CL intensity significantly increased with the increasing of the hybridization time from 5 min to 25 min and then reached a plateau in 30 min (Fig. S3(C)). Therefore, 30 min was chosen as the optimum hybridization time. After hybridization target DNA with three-stranded substrate complex 30 min, fuel DNA was added. The incubation time also greatly the CL intensity. It was found that the CL intensity increased with the incubation time from 5 to 80 min. The biggest CL signal was gained when the incubation time reached at 90 min. Subsequently, there was a marked drop in the CL signal (Fig. S3(D)). So 90 min was chosen as the optimal incubation time.
Fig.S2CL intensity with Au3+ and AuNPs as catalyst (A). The effect of order of adding of target DNA and fuel DNA on CL signal (B). The effect of incubation time (C) and hybridization reaction (D) on CL signal.
1