Near-infrared quantum dots based fluorescent assay of Cu2+ and in vitro cellular and in vivo imaging

Compared to visible light, near infrared (NIR) light is attractive for the development of novel assay method because it can provide deeper imaging penetration and lower fluorescence background and scattering intensity. In this paper, near infrared (NIR) quantum dots (QDs) were synthesized under a convenient and mild condition, afterwards applied to highly sensitive detection of Cu 2+ and monitoring the change of Cu 2+ concentration through in vitro and in vivo fluorescent imaging. The quenching of NIR light was resulted from the aggregation of NIR QDs induced by the competitive binding between 3-mercaptopropionic acid (MPA) and the Cu 2+ present in the solution. A low detection limit of 5   ×   10 −8   M and a broad linear detection range from 1   ×   10 −7 to 5   ×   10 −5   M could be realized in this strategy for the quantitative evaluation of Cu 2+ . This NIR QDs based sensor possess high selectivity, rapid response and excellent photostability. Furthermore, the great potential of this NIR nanosensor has also been fully proved by the in vitro cellular imaging and in vivo imaging.