Controlling the morphology and surface properties of nanoparticles allows fine tuning of their inherent physicochemical properties, which can translate to more effective use of these materials for various applications, such as biomedical imaging and catalysis. Recent reports have shown that capping ligands such as DNA can mediate shape control of metal nanoparticles in a sequence dependent manner. DNA’s excellent sequence programmability with the four nucleotides cytosine (C), guanine (G), adenine (A) and thymine (T) and its ease of chemical modification gives one access to a large range of possible nanoparticle morphologies. Most studies so far, however, have been focused only on DNA-encoded growth of monometallic particles such as gold and silver nanoparticles. We report the shape-control of bimetallic nanoparticles using DNA-based ligands. The presence of different homo-oligomer DNA sequences containing 10 deoxy-ribonucleotides of thymine, adenine, cytosine, or guanine results in the growth of four distinct morphologies of a Pd-Au shell on a Pd cubic core. Detailed kinetic studies by absorption spectroscopy, scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM) reveal the underlying role of DNA in controlling Pd−Au nanoparticle growth morphologies. One major function of DNA is affecting various properties of the incoming metal atoms, including their diffusion and deposition on the Pd nanocube seed. Interestingly, the growth in the presence of the homo-oligomers follows different growth mechanisms determined by the binding affinities of each of the bases. The key steps involved in the growth bring us a step closer to using DNA-based ligands for controlling not only bimetallic nanoparticle morphologies, but potentially more complex hybrid materials. The capability to finely tune multi-metallic nanoparticle morphology stems from the versatile structure that is unique to DNA in comparison to conventionally used capping agents in colloidal nanomaterial synthesis.

DNA-encoded control of morphologies of bimetallic nanoparticles

254th National Meeting (2017)

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