Preparation And Application Of Aptamer-Ag-Au Putamen Nanostructures In Lung Cancer Cell Detection And Photothermal Therapy

Lung cancer is the leading cause of cancer death worldwide. Tthe prognosis of patients with lung cancers strongly depends on the stage of the disease, as the5-year survival rate decreases from60%at clinical stage I to1%at stage IV. Its early detection is of paramount importance for diagnosis, classification, treatment, and improvement of survivorship. However, current methods (X-ray, CT imaging, Bronchoscopy and CT-guided biopsy) are not sensitive enough to detect the lung cancer in its nascent stage. Testing for cancerous cells is a very promising method to diagnosis of cancers especially in their nascent stage, since the occurrence and development of cancer are closely related to the change of cells. Aptamer is short, single-stranded DNA or RNA that could form unique3-dimensional structures that specifically recognize a wide variety of targets from small organic molecules, proteins, cells to complex living organisms with high affinity. We report an aptamer-Ag-Au shell-core nanostructure-based surface-enhanced Raman scattering (SERS) assay for specific detection, near-infrared (NIR) nanotherapy, and monitoring of photothermal nanotherapy process of the lung adenocarcinoma cells (A549cells). The aim results are as follows:1. We synthesized the Ag-Au shell-core nanostructures by sequent reduction of AuCl4-and Ag+ions with use of citrate ions, and then labeled the nanoparticles with Rh6G. The size of the nanostructures is about30nm with a4.5nm thick shell. And Its average AEF is calculated as～1.8×106. Such a unique shell-core feature of the synthesized nanostructures possesses the good biocompatibility of gold and high SERS activity of the shell-core nanostructures, and therefore can provide high sensitive and specific detection of cancer cells.2. We developed an assay for specifically detecting lung cancer cell (A549) at-10cells level based on the specific interaction of the cell with its aptamer and the high surface-enhanced Raman scattering (SERS) activity of the Ag-Au shell-core nanostructures. The approach can distinguish A549cells at very low abundance (～10cells) from other types of cancer cells (HeLa and MCF-7cells) and subtypes of lung cancer cells (NCI-H157, NCI-H520, NCI-H1299, andNCI-H446cells).3. Based on the nanostructures’high capability of adsorption NIR irradiation, we also performed photothermal therapy of the cells at very low irradiation power density (0.20W/cm2) without destroying the healthy cells and the surrounding normal tissues. We also monitor the photothermal therapy process of the cancer cells Based on the SERS signal. Therefore, this nanostructure-based assay is significant for diagnosis of the tumors in its nascent stage and has a great potential useful in photothermal therapy of the lung cancers.