Aptamer-functionalized polydiacetylene liposomes act as a fluorescent sensor for sensitive detection of MUC1 and targeted imaging of cancer cells

Mucin 1 (MUC1) is an important biomarker that has been shown to participate in the metastasis and invasion of various types of cancers. Simple yet sensitive methods for the detection of MUC1 in liquid and in situ imaging of MUC1 at cellular level are crucial for early diagnosis of cancers as well as monitoring their progression. Herein, a polydiacetylene (PDA) liposome-based sensing system functionalized with Cy3-labeled MUC1 binding aptamer (Cy3-Apt) was developed as a fluorescence "turn-on" nanosensor for the detection of MUC1. In the sensing system, the fluorescence of Cy3-Apt could be directly quenched due to the energy transfer between the fluorogen and PDA conjugated backbone. In the presence of MUC1, the recognition of MUC1 with its aptamer induces the structure switching of both PDA liposomes and the aptamer, recovering the red fluorescence. Sensitive and selective analysis of MUC1 in aqueous media could be achieved with a limit of detection around 0.8 nM. The feasibility of the nanosensor was further demonstrated by mapping the spatial expression of MUC1 in cancer cells with excellent sensitivity.