Background-free and signal-amplified upconversion fluorescent biosensing platform for sensitive detection of CYFRA21-1.

Accurate and ultrasensitive detection of cytokeratin 19 fragment (CYFRA21-1) is of vital importance for screening and diagnosis of potential lung cancer patient. In this paper, surface-modified upconversion nanomaterials (UCNPs) capable of aggregation by atom transfer radical polymerization (ATRP) were used as luminescent materials for the first time to achieve signal-stable, low-biological background, and sensitive detection of CYFRA21-1. Upconversion nanomaterials (UCNPs) feature extremely low biological background signals and narrow emission peaks, making them ideal sensor luminescent materials. The combination of UCNPs and ATRP not only improves sensitivity, but also reduces biological background interference for detecting CYFRA21-1. The target CYFRA21-1 was captured by specific binding of the antigen and the antibody. Subsequently, the end of the sandwich structure with the initiator reacts with monomers modified on UCNPs. Then, massive UCNPs are aggregated by ATRP that amplify the detection signal exponentially. Under optimal conditions, a linear calibration plot of the logarithm of CYFRA21-1 concentration versus the upconversion fluorescence intensity was obtained in the range of 1 pg/mL to 100 μg/mL with a detection limit of 38.7 fg/mL. The proposed upconversion fluorescent platform can distinguish the analogues of the target with excellent selectivity. Besides, the precision and accuracy of the developed upconversion fluorescent platform were verified by clinical methods. As an enhanced upconversion fluorescent platform of CYFRA21-1, it is expected to be useful in screening potential patients with NSCLC and provides a promising solution for the high-performance detection of other tumor markers.