Upconversion luminescence based inverted microfluidic chip for in situ CTCs capture, monitor and killing

Abstract

Real-time counting of circulating tumor cells (CTCs) can effectively reduce false-negative results, which, however, is a major stumbling block in the practical CTCs capture process. In this paper, upconversion luminescence is introduced into the inverted microfluidic chip to realize real-time ratiometric luminescence CTCs detection by utilizing its advantage of near-infrared light. In view of the low upconversion luminescence efficiency, a double-layer YVO4 inverse opal photonic crystal (IOPC) structure has been designed, which not only serves as a capture surface for CTCs via bionic macroporous structure but also uses its double bandgap effect to implement spontaneous emission adjustment, obtaining 32 times enhancement of upconversion luminescence. Combined with anti-EpCAM-Fe3O4@Ce6@Silane probes and the inverted microfluidic design, a capture efficiency of more than 95% was achieved. When CTCs were captured, the red light of Ce6 molecules in the CTCs targeting nano-probes and the enhanced upconversion luminescence were used for real-time and ratiometric CTCs monitoring. Moreover, Ce6 molecules in the nanoprobes perform the function of photodynamic effect under red light irradiation, leading to the in-situ killing of CTCs inside the channel, which is a very practical and meaningful exploration in the process of preventing tumor metastasis.