NANOPARTICLE-APTAMER: AN EFFECTIVE GROWTH INHIBITOR FOR HUMAN CANCER CELLS

摘要

Semiconductor nanocrystals have unique optical properties due to quantum confinement effects, and a variety of promising approaches have been devised to interface the nanomaterials with biomolecules for bioimaging and therapeutic applications. Such bio-interface can be facilitated via a DNA template for nanoparticles as oligonucleotides can mediate the aqueous-phase nucleation and capping of semiconductor nanocrystals.rnHere, we report a novel scheme of synthesizing fluorescent nanocrystal quantum dots (NQDs) using DNA aptamers and the use of this biotic/abiotic nanoparticle system for growth inhibition of MCF-7 human breast cancer cells for the first time. Particularly, we used two DNA sequences for this purpose, which have been developed as anti-cancer agents: ~5-GGT GGT GGT GGT TGT GGT GGT GGT GG-~3 (also called, AGRO) and ~5-(GT)_(15)-~3.~([3-5]) This study may ultimately form the basis of unique nanoparticle-based therapeutics with the additional ability to optically report molecular recognition.rnFigure la shows the photoluminescence (PL) spectra of GT- and AGRO-passivated PbS QD that fluoresce in the near IR, centered at approximately 980 run. A typical synthesis procedure involves rapid addition of sodium sulfide in the mixture solution of DNA and Pb acetate at a molar ratio of 2:4:1. The resulting nanocrystals are washed to remove unreacted DNA and ions by adding mixture solution of NaCl and isopropanol, followed by centrifugation. The precipitated nanocrystals are collected and re-suspended in aqueous solution by mild sonication. Optical absorption measurements reveal that approximately 90 and 77% of GT and AGRO DNA is removed after the washing process. The particle size distribution in Figure 1b suggests that the GT sequence-capped PbS particles are primarily in 3-5 nm diameter range. These nanocrystals can be easily incorporated with mammalian cellsrnand remain highly fluorescent in sub-cellular environments. Figure 1c serially presents an optical image of a MCF-7 cell and a PL image of the AGRO-capped QD incorporated with the cell.