Aptamer-based fluorescence "off-on" sensor for EGFR-positive lung cancer CTCs using streptavidin magnetic beads and N-CQDs@Ag⁺.

Authors

Chaoqi He, Chong Yu, Wenqian Xu, Qiongdan Zhang, Jiangfeng Shang, Da Qian, Liquan Zhu

Published in

Mikrochimica acta. Volume 193. Issue 8. Jul 14, 2026. Epub Jul 14, 2026.

Abstract

Circulating tumor cells (CTCs) are rare but critical biomarkers for lung cancer diagnosis and metastasis monitoring. We report an aptamer-based fluorescence "off-on" sensor for the sensitive and specific detection of epidermal growth factor receptor (EGFR)-positive lung cancer CTCs. The sensor integrates streptavidin magnetic beads (MBs) for target capture and nitrogen-doped carbon quantum dots complexed with silver ions (N-CQDs@Ag⁺) for signal readout. In the absence of target cells, the system remains in a fluorescence "off" state due to efficient quenching by Ag⁺. Upon recognition of EGFR-positive CTCs by the biotinylated aptamer, a complementary S2 strand containing a polyC sequence is released and competitively binds Ag⁺, restoring the fluorescence of N-CQDs ("on" state). Under optimal conditions, the sensor achieves a detection limit of 50 cells/mL in buffer and 96 cells/mL in human serum, with excellent selectivity. This aptamer-based off-on sensor provides a simple and reliable platform for lung cancer CTC detection.

PMID:
42446745
Bibliographic data and abstract were imported from PubMed on 14 Jul 2026.

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