The efficient recognition of circulating
tumor cells (CTCs) with
an aptamer probe confers numerous benefits; however, the stability
and binding affinity of aptamers are significantly hampered in real
biological sample matrices. Inspired by the efficient preying mechanism
by multiplex tubing feet and endoskeletons of sea urchins, we engineered
a superefficient biomimetic single-CTC recognition platform by conjugating
dual-multivalent-aptamers (DMAs) Sgc8 and SYL3C onto AuNPs to form
a sea urchin-like nanoprobe (sea urchin-DMA-AuNPs). Aptamers Sgc8
and SYL3C selectively bind with the biomarker proteins PTK7 and EpCAM
expressed on the surface of CTCs. CTCs were captured with 100% efficiency,
followed by sorting on a specially designed multifunctional microfluidic
configuration, integrating a single-CTC separation unit and a hydrodynamic
filtrating purification unit. After sorting, background-free analysis
of biomarker proteins in single CTCs was undertaken with inductively
coupled plasma mass spectrometry by measuring the amount of 197Au isotope in sea urchin-DMA-AuNPs. With respect to a single-aptamer
nanoprobe/-interface, the dual-aptamer nanoprobe improves the binding
efficiency by more than 200% (K
d <
0.35 nM). The microchip facilitates the recognition of single CTCs
with a sorting separation rate of 93.6% at a flow rate of 60 μL
min–1, and it exhibits 73.8 ± 5.0% measurement
efficiency for single CTCs. The present strategy ensures the manipulation
and detection of a single CTC in 100 μL of whole blood within
1 h.
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