Dendritic-like streptavidin/alkaline phosphatase nanoarchitectures for amplified electrochemical sensing of DNA sequences.

This study describes the development and characterization of a novel dendritic-like signal amplification pathway. Such an analytical strategy relies on the use of streptavidin and biotinylated alkaline phosphatase, which can be simply and conveniently self-assembled to build nanoarchitectures rich in enzyme labels. The performance of this enzyme-based amplification route was demonstrated in connection with the electrochemical sensing of DNA sequences. Compared to the commercially available streptavidin-conjugated alkaline phosphatase labels, a single generation of the streptavidin/biotinylated alkaline phosphatase assembly allowed a 15-20-fold enhancement of the electroanalytical signals. The higher sensitivity allowed by the dendritic-like route was attributed to the lower steric hindrance of the proteins employed for this amplification path. As low as 50 pmol/L of a 388-bp-long amplicon identifying Salmonella spp. was easily detected. The experimental results additionally demonstrated that the sensitivity of the method could be further increased in a linear fashion with the number of protein-enzyme generations.