We have examined the adsorption of different DNA sequences to mercaptoethanol-capped CdS quantum dots, ∼40 Å diameter, as a minimalist model for nonspecific protein−DNA interactions, and compared these results to what we have previously found for Cd2+-surface-rich dots of the same size (Mahtab, R.; Rogers, J. P.; Murphy, C. J. J. Am. Chem. Soc. 1995, 117, 9099). We find that neutralization of the surface leads to no detectable binding, based on our luminescence assay, for “straight” and A-tract oligonucleotides, while a crystallographically “kinked” sequence does still bind, but by a factor of 4 less than that observed for a divalent metal ion-rich surface. The binding constants for both surfaces are within the range of nonspecific protein−DNA interactions. The kinetics of binding are also monitored and are compared to nonspecific protein−DNA interactions for large DNA fragments. Issues of biopolymer static bending vs flexibility are also addressed with fluorescence resonance energy transfer experiments.

A nano-architectural system that has high variability while maintaining component specificity is described. Tetraphenylcyclobutadiene(cyclopentadienyl)cobalt complexes and phenyleneethynylene trimers were synthesized and subsequently modified with oligonucleotides utilizing standard phosphoramidite chemistry. The resulting oligonucleotide modified organics (OMOs) were characterized by UV-vis spectroscopy, fluorescence spectroscopy, and phosphate analysis. Hybridization of these OMOs resulted in a series of self-assembled oligomeric hybrids of varying length and topology. These hybrids were characterized by melting temperature, polyacrylamide gel electrophoresis, and fluorescence spectroscopy. This model system demonstrates the power of DNA to self-assemble modules of interest-independent of the module itself.

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