A novel dual-mode and label-free aptasensor based methodology for breast cancer tissue marker targeting

Tumor biomarkers are elements that are created by the tumor itself or other host cells in response to cancerous conditions. The detection of HER2, as one of these biomarkers, is important in order to prescribe Herceptin (trastuzumab). So, precise measurement of the HER2 status is vital to ensure that all patients with breast cancer who can use Herceptin are correctly identified. In this method, we used the optical properties of gold nanoclusters (AuNCs) in colorimetric and fluorescence assays in HER2 positive tumor. For this purpose, our method uses a high affinity single strand DNA aptamer against surface exposed HER2 molecules on cells. Here, we have demonstrated that the aptamer with an inserted C12 loop can be used as a convenient scaffold for AuNCs synthesis. So, an [email protected] modified cell/tumor-targeting nanostructure was engineered and demonstrated for an efficient HER2 positive cell/tumor imaging under UV illumination. In addition, on the basis of the catalytic activity of AuNCs, by immersing the HER2 positive tumor in a solution containing TMB, the solution color changes to green. Moreover, to compare other fluorescence probes we have developed a label-free [email protected] quantum dot system with high quantum yield in comparison with nanoclusters for the identification and imaging of HER2-positive cells/tumor. A good linear relationship for HER2 was obtained ranging from 15 to 1.5 × 106 cell/mL with R square value of 0.953 for [email protected] and R square value of 0.977 for [email protected] QDs.