Electrochemical aptasensor based on anisotropically modified (Janus-type) gold nanoparticles for determination of C-reactive protein.

Novel Janus nanoparticles based on Au colloids anisotropically modified with polyamidoamine dendrons were prepared though a masking/toposelective modification approach. These nanomaterials were further functionalized with horseradish peroxidase on the dendritic face and provided on the opposite metal surface with a ssDNA aptamer for C-reactive protein (CRP). The resulting nanoparticles were employed as biorecognition/signaling elements to construct an amperometric aptasensor with sandwich-type architecture for the specific detection of this cardiac biomarker. To do this, screen-printed carbon electrodes modified with electrodeposited Au nanoparticles and functionalized with anti-CRP aptamers were used as transduction interface. The aptasensor was employed for the amperometric detection of CRP (working potential: - 200 mV vs pseudo-Ag/AgCl) in the broad range from 10 pg·mL-1 to 1.0 ng·mL-1 with a detection limit of 3.1 pg·mL-1. This electroanalytical device also showed good specificity, reproducibility (RSD = 9.8%, n = 10), and stability and was useful to quantify CRP in reconstituted human serum samples, with a RSD of 13.3%.