Abstract
Epithelial cell adhesion molecules (EpCAMs) play a significant role in tumorigenesis and tumor development. EpCAMs are considered to be tumor signaling molecules for cancer diagnosis, prognosis and therapy. Herein, an enzyme-free and highly sensitive fluorescent biosensor, with a combined aptamer-based EpCAM recognition and toehold-aided DNA recycling amplification strategy, was developed for sensitive and specific fluorescence detection of EpCAMs. Due to highly specific binding between EpCAMs and corresponding aptamers, strand a, which is released from the complex of aptamer/strand a in the presence of EpCAMs which is bound to the corresponding aptamer, triggered the toehold-mediated strand displacement process. An amplified fluorescent signal was achieved by recycling strand a for ultrasensitive EpCAM detection with a detection limit as low as 0.1 ng mL−1, which was comparable or superior to that of reported immunoassays and biosensor strategies. In addition, high selectivity towards EpCAMs was exhibited when other proteins were selected as control proteins. Finally, this strategy was successfully used for the ultrasensitive fluorescence detection of EpCAMs in human serum samples with satisfactory results. Importantly, the present strategy may be also expanded for the detection of other targets using the corresponding aptamers.
Highlights
Nowadays, cancer has become a worldwide problem which threatens public health and is the leading cause of death in China and the second leading cause of death in the United States.[1,2] Efforts in the ght against cancer will need sustained clinical and basic research to improve the effectiveness of diagnostic techniques and screening programs, which is critical for reversing the cancer epidemic worldwide.[2]
Due to this differential expression of Epithelial cell adhesion molecules (EpCAMs) between human cancers and normal healthy cells, EpCAM plays a signi cant role in tumorigenesis and tumor development and it is considered to be one of the prognostic tumor signaling molecules for cancer diagnosis, prognosis and therapy.[16,17]
Considering the speci city of aptamer-based biosensors and the intriguing characteristics of toehold-aided DNA recycling ampli cation, the combination of the two strategies is promising for the speci c and sensitive detection of EpCAM
Summary
Cancer has become a worldwide problem which threatens public health and is the leading cause of death in China and the second leading cause of death in the United States.[1,2] Efforts in the ght against cancer will need sustained clinical and basic research to improve the effectiveness of diagnostic techniques and screening programs, which is critical for reversing the cancer epidemic worldwide.[2]. The sensitivity of these reported aptamerbased uorescence detection systems is compromised To overcome these limitations, signal ampli cation strategies, including enzyme-aided signal ampli cation (nicking endonucleases, exonucleases, DNAzymes, etc.),[23,30,31,32,33] catalyzed hairpin assembly (CHA),[34] molecular machines,[35,36] the hybridization chain reaction (HCR),[37] rolling circle ampli cation,[38] nanoparticle-assisted ampli cation[39] and toehold-aided DNA recycling ampli cation,[40,41] have recently been developed to achieve the sensitive detection of biomolecules in the eld of bio-analytical sciences. Considering the speci city of aptamer-based biosensors and the intriguing characteristics of toehold-aided DNA recycling ampli cation, the combination of the two strategies is promising for the speci c and sensitive detection of EpCAM. The developed strategy will become a promising and reliable method for the ultrasensitive detection of EpCAM in the early clinical diagnosis of cancers and medical research
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