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Theranostics 2017; 7(1):31-39. doi:10.7150/thno.16671 This issue Cite

Research Paper

From Interface to Solution: Integrating Immunoassay with Netlike Rolling Circle Amplification for Ultrasensitive Detection of Tumor Biomarker

Chang Feng^1*, Bing Bo^2*, Xiaoxia Mao¹, Hai Shi¹, Xiaoli Zhu^1,3✉, Genxi Li^1,3✉

1. Center for Molecular Recognition and Biosensing, School of Life Sciences, Shanghai University, Shanghai 200444, P. R. China;
2. Department of Medical Oncology, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai 200433, P. R. China;
3. State Key Laboratory of Pharmaceutical Biotechnology and Collaborative Innovation Center of Chemistry for Life Sciences, Department of Biochemistry, Nanjing University, Nanjing 210093, P. R. China.
^*These authors contributed equally to this work.

✉ Corresponding authors: E-mail addresses: xiaolizhuedu.cn (X. Zhu), genxiliedu.cn (G. Li). Fax: +86 21 66137541 (X. Zhu), +86 25 83592510 (G. Li).

Abstract

Both the 3D solution and the 2D interface play important roles in bioanalysis. For the former, reactions can be carried out adequately; while for the latter, interfering substance can be eliminated simply through wash. It is a challenge to integrate the advantages of solution-based assays and the interface-based assays. Here, we report an immuno-NRCA (netlike rolling circle amplification) strategy, which integrates immunoassay with NRCA for the ultrasensitive detection of tumor biomarker, by taking the assay of a tumour marker as an example. In this strategy, immunoreactions occur on interface, while the target-induced signal amplification can be completed totally in solution. As a result, this system has the merits of both solution- and interface-based assays. The whole procedure of this novel strategy is similar to the conventional ELISA, inheriting the usability. But in comparison with ELISA, the performance is greatly improved. The detection limit can be lowered to 5.5 fg/L, making it possible to detect the target tumour marker in one drop of blood. Also, in comparison with established immuno-PCR method, which integrates immunoassay with the commonly used nucleic acid amplification approach, this system has no requirement for thermal cycler owing to the isothermal amplification, and it has the ability to retain the immunoreactivities. So, the new immunoassay method proposed in this study may have more feasible applications in the future.

Keywords: tumor marker, immunoassay, isothermal amplification, netlike rolling circle amplification, ELISA.

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