Nanostructured gold dsDNA sensor for early detection of breast cancer by beta protein 1 (BP₁)

Beta protein 1 (BP₁) is a homeobox protein expressed in 80% of breast cancer cells in either estrogen receptor (ER) positive or ER negative breast cancer. However, it is barely detectable in normal breast tissues. In this project we present an electrochemical DNA nanostructured gold biosensor for detection of BP₁. The gold sensor is first electrochemically nanostructured in 0.5 M sulfuric acid to reach superior conductivity, larger surface area, and higher stability. Nanostructured gold surface was characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The nanostructured gold sensor is then modified with double-stranded (ds) DNA mapping the genomic sequence that contains the binding site for BP₁. A redox-active probe (methylene blue) was intercalated in dsDNA to monitor the binding event of BP₁. A linear correlation of the electrochemical response by concentration of BP₁ was obtained (R² = 0.998) with a limit of detection of 1.2 nM. This nanostructured gold dsDNA sensor is shown to be sensitive, selective, stable, and reusable allowing for its potential clinical use.