Nucleic acid-regulated perylene probe-induced gold nanoparticle aggregation: a new strategy for colorimetric sensing of alkaline phosphatase activity and inhibitor screening.

A positively charged perylene probe (probe 1) could induce aggregation of the gold nanoparticles (Au NPs). As a result, significant assay solution color changes were observed. A duplex DNA (DNA-1) could induce aggregation of the perylene probe. It was observed that DNA-1 could efficiently regulate the probe 1-induced Au NP aggregation. When probe 1 and DNA-1 were first mixed, DNA-1 induced aggregation of the perylene probe. Au NPs were subsequently added, and no induced aggregation of the Au NPs was observed. Thus the color of the assay solution remained to be red. The assay is quite sensitive; 200 pM DNA-1 could cause a clear solution color change. On the basis of this observation, a novel method for the detection of alkaline phosphatase (ALP) activity has been demonstrated. Our method does not require covalent immobilization of the nucleic acid, or the addition of an excess amount of salt. It is sensitive and convenient.