Abstract: A T₁ magnetic resonance imaging (MRI) contrast agent specific to lung cancer stem cells Gd-DOTA-HCBP-1 was synthesized by solid-phase peptide synthesis technology. Its longitudinal relaxation rate (r₁) was 6.15 mmol^-1·L·s^-1, approximately 0.6 times higher than that of the commercial T₁ contrast agents Dotarem at 11.7 T. In vitro MRI experiments indicated that the detectability of the cancer stem cells could be significantly improved to about 2 000~4 000 cells per sphere by the use of the probe.

Key words: peptide molecular probe, lung cancer stem cells, MRI, T₁ contrast agent