SERS- and luminescence-active Au–Au–UCNP trimers for attomolar detection of two cancer biomarkers†
Alpha-fetoprotein (AFP) and mucoprotein1 (mucin-1) are two important disease biomarkers. Self-assembled gold nanoparticles (AuNPs) and upconversion nanoparticle (Au–Au–UCNP) trimers based on aptamers were developed for the ultrasensitive detection of AFP and mucin-1. The Au–Au–UCNP trimers produced ideal optical signals, with prominent Raman enhancement and fluorescence quenching effects. The surface-enhanced Raman scattering (SERS) intensity decreased in the presence of mucin-1 and the luminescence intensity increased in the presence of AFP. A limit of detection (LOD) of 4.1 aM and a wide linear range of 0.01–10 fM for the detection of mucin-1 were obtained with this SERS-encoded sensing system. Using the luminescence-encoded sensing system, a LOD of 0.059 aM and a wide linear range of 1–100 aM for the detection of AFP were obtained. These LODs are the lowest values reported so far. This approach has the advantage of detecting two disease biomarkers simultaneously.