Figure 3.

Characterization of aptamer-conjugated AuNPs. (A) Hydrodynamic diameter and Feret diameter of the aptamer AuNP conjugates as a function of the aptamer concentration used during laser ablation. (B) Suggested mechanism of the observed increase of the size of the conjugates. At low surface coverage, the negatively charged aptamer lays flat on the positively charged AuNP surface. With increasing surface coverage, the aptamers straightened up on the surface, resulting in an increased hydrodynamic diameter. Scale bars illustrate the proportions of linearized aptamer and AuNP.