Synthesis of a Single‐Stranded DNA Aptamer Modified Near‐infrared, Water‐Soluble Fluorophore for Lung Cancer Cell Imaging

Abstract In recent years, aza‐boron dipyrromethene (aza‐BODIPY) derivatives have attracted considerable attention as fluorescent imaging agents. In this work, two polyethylene glycol functionalized water soluble aza‐BODIPY derivatives (a mono cycloaddition product 1PEG ‐ BOD and a double cycloaddition product 2PEG ‐ BOD ) were synthesized through a cycloaddition click reaction between aza‐BODIPY and N 3 ‐PEG 2000 ‐COOH. The absorption and fluorescence profiles of these two compounds were in near‐infrared region. The fluorescence quantum yield of 2PEG ‐ BOD was 20 times higher than 1PEG ‐ BOD in water. The attachment of an A549 lung cancer cell targeting aptamer with 2PEG ‐ BOD afforded APT ‐ PEG ‐ BOD . The average fluorescence intensity of APT ‐ PEG ‐ BOD (5 μmol/L) in A549 lung cancer cells calculated from confocal microscopy images was 25–33 times stronger than that in other cell lines, such as MDA‐MB‐231, HT1080 and LO2. These results indicated that APT ‐ PEG ‐ BOD shows high affinity to A549 lung cancer cells.