DNA-Based Gold Nanoparticle Sensor for Bladder Cancer Detection

A colorimetric assay based on gold nanoparticles (AuNPs) has been of great interest to biomedical applications, and this technique demonstrates a fast detection that can visually be observed by the naked eye. To further investigate an insight interaction of citrate-capped AuNP aggregation induced by salt ions, molecular dynamics (MD) simulation of a truncated octahedron containing Au(111) and Au(100) surfaces was performed along with an experimental setup to validate the conceptual approach. The computational results indicated that anionic citrate modified on the surface of AuNPs has the potential to prevent AuNP aggregation. Because of the presence of an anti-DNA target, the negative charges of single-strand DNA stabilized the AuNPs and they remained a red color. After hybridization with a DNA target, the complementary binding influenced the anti-DNA target away from the AuNP surface. Thus, the AuNPs became aggregation-induced by a high NaCl concentration, and the experiment revealed that a color solution change from red to purple was observed when a 25 nM DNA target was added. Furthermore, the result showed a linear regression in the range of 25–500 nM, and the limit of detection was calculated to be 45 nM. From the obtained findings, they are in respectable agreement with the computational results and experimental support, which verify the validity of the approach.