Effective detection and cell imaging of prion protein with new prepared targetable yellow-emission silver nanoclusters

Silver nanoclusters (AgNCs) have gained considerable attention over a wide range from chemical detection to bioimaging applications. Herein we developed a facile way to synthesize water-soluble, intense fluorescent targetable AgNCs with yellow-emission by using DNA via a chemical reduction method. The sequence of DNA was designed to contain two fragments, one of which is the DNA aptamer fragment which can selectively bind to the target, and the other is rich in cytosine sequence fragments that can result in a high quantum efficiency. The as-prepared targetable AgNCs (Apt-AgNCs) through the reduction of silver ions (Ag+) by NaBH4 have a very strong fluorescence emission, which, was greatly quenched upon specific binding to prion protein (PrPC). As a result, Apt-AgNCs were demonstrated as a novel, effective and sensitive probe for both detection and intracellular fluorescent imaging with high selectivity through the strong binding affinity between the aptamer and its target.