Near-infrared fluorescence probe for the determination of acid phosphatase and imaging of prostate cancer cells

In this paper, we developed a near-infrared mercaptopropionic acid (MPA)-capped CuInS2 quantum dot (QD) fluorescence probe for the detection of acid phosphatases (ACP), which is an important biomarker and indicator of prostate cancer. The fluorescence of CuInS2 QDs could be quenched by Cu2+, and then the addition of adenosine-5′-triphosphate (ATP) could effectively turn on the quenched fluorescence due to the strong interaction between Cu2+ and ATP. The ACP could catalyze the hydrolysis of ATP, which would disassemble the complex of Cu2+–ATP. Therefore, the recovered fluorescence could be quenched again by the addition of ACP. In our method, the limit of detection (LOD) is considerably low for ACP detection in solution. Using the CuInS2 QDs fluorescence probe, we successfully performed in vitro imaging of human prostate cancer cells.