Seeing is believing. A novel multicomponent gold nanoparticle-based nanoprobe is assembled with a thiolated DNA detection probe, horseradish peroxidase (HRP), and bovine serum albumin (BSA). In this nanoprobe, the DNA detection probe is used to construct complexes for "sandwich" -based DNA detection, HRP translates this hybridization event into an enzymatic catalysis-based optical signal, while and BSA acts as a non-specific blocker.