Ultrasensitive electrochemical detection of protein tyrosine kinase-7 by gold nanoparticles and methylene blue assisted signal amplification.
We present here an ultrasensitive and simple strategy for protein tyrosine kinase-7 (PTK7) detection based on the recognition-induced structure change of sgc8 aptamer, and the signal change of methylene blue (MB) that interacted with sandwiched DNA complex. To construct such a sensor, an homogeneous nano-surface was formed firstly on the glass carbon electrode (GCE) by using negatively charged Nafion (Nf) as the inner layer and positively charged gold nanoparticles ((+)AuNPs) as the outer layer, followed by the immobilization of sgc8 aptamer based on Au-S bond. In the presence of helper probe (HP), sandwiched DNA complex was formed between the sgc8 aptamer and the DNA modified gold nanoparticle probe (DNA-AuNPs). Then, a strong current signal was produced due to the capture of abundant MB molecules by both the sandwiched DNA complex and the multiple DNAs that modified on AuNPs surface. However, the specific binding of sgc8 aptamer with PNK7 would trigger a structure transition of it, and directly prevented the following formation of sandwiched structure and the capture of MB. Thus, PTK7 detection could be realized based on monitoring the signal reduction of MB upon incubation of sgc8 aptamer with PTK7. Under optimal conditions, a low detection limit of 372 fM was obtained for PNK7 detection. Due to the employment of sgc8 aptamer, the proposed biosensor exhibited high selectivity to PNK7. Moreover, satisfactory results were obtained when the proposed method was applied for PNK7 detection in cellular debris.
School of Life Science, Jiangsu Normal University, Xuzhou 221116, PR China. Electronic address: mxm0107@jsnu.edu.cn.
Xiangmin
X
Miao
School of Life Science, Jiangsu Normal University, Xuzhou 221116, PR China.
Zongbing
Z
Li
School of Life Science, Jiangsu Normal University, Xuzhou 221116, PR China.
Aihua
A
Zhu
School of Life Science, Jiangsu Normal University, Xuzhou 221116, PR China.
Zhaozhong
Z
Feng
School of Life Science, Jiangsu Normal University, Xuzhou 221116, PR China.
Jun
J
Tian
School of Life Science, Jiangsu Normal University, Xuzhou 221116, PR China.
Xue
X
Peng
D052157:Aptamers, Nucleotide / Q000737:chemistry*; D015374:Biosensing Techniques / Q000379:methods*; D015815:Cell Adhesion Molecules / Q000032:analysis*; D045744:Cell Line, Tumor; D055664:Electrochemical Techniques / Q000379:methods*; D006046:Gold / Q000737:chemistry*; D006801:Humans; D057230:Limit of Detection; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D008751:Methylene Blue / Q000737:chemistry*; D020794:Receptor Protein-Tyrosine Kinases / Q000032:analysis*
D052157:Aptamers, Nucleotide; D015815:Cell Adhesion Molecules; D006046:Gold; C096905:PTK7 protein, human; D020794:Receptor Protein-Tyrosine Kinases; D008751:Methylene Blue
DNA modified AuNPs probes; Electrochemical aptasensor; Methylene blue; Nafion; Positively charged gold nanoparticles; Protein tyrosine kinase-7