Nanogold hollow balls with dendritic surface for hybridization of DNA

Au hollow balls are fabricated by adsorption of gold 3.5 nm in diameter onto a mixed vesicle composed of mixed polymerized diacetylene which made of negative charged 10,12-pentacosadiynoic acid (PCDA) and positive charged 10,12-pentacosadiynoic acid 2′-aminoethylamide (PCDA-NH2). The morphology of these hollow spheres could be controlled by changing the ratio of PCDA and PCDA-NH2 and the immobilization and hybridization ability of the gold hollow ball have been investigated using a quartz crystal microbalance (QCM). It was found that a dendritic surface in an appropriate ratio existed. The hybridization amount of target DNA is about three to five times for the Au-mixed hollow ball at an optimal ratio (PCDA/PCDA-NH2 = 1/3) as compared with that for pure Au–PCDA-NH2, though the immobilization amount of ssDNA on these two samples are almost the same, and the detected limitation of target DNA is extend from 10−9 to 10−12 M. The stability against breakage by transportation, combined with the simplicity and efficiency of detection, would offer an important advantage over unpolymerized one. This result shows the possibility to control the morphology and surface of nanogold hollow spheres by changing the ratio of PCDA and PCDA-NH2 for the develop of a better DNA detection assay, further proving the idea that low surface coverage and higher DNA probe to target DNA ratios lead to optimal hybridization.