Charge transfer across the nanocrystalline-DNA interface: Probing DNA recognition

Hybrid nanocomposites that electronically link TiO₂ nanoparticles to DNA oligonucleotides were developed. The linking of biomolecules with inorganic components was achieved by using bridging enediol ligands, such as dopamine (DA), which facilitate hole transfer across the interface, establishing efficient crosstalk between the biomolecule and metal oxide nanoparticles. The inherent programmability of oligonucleotides builds recognition properties into the hybrid system, allowing selective binding of nanoparticles to targeted molecules. The inorganic nanoparticles are inherently photoresponsive and therefore serve as a source of photogenerated charges that act as reporters of the electronic properties of the biomolecules. These photoactive bioinorganic TiO₂/DA/DNA triads are capable of complex photo chemistries such as light induced manipulation of biomolecules and their switching functions. Consequently, light induced extended charge separation in these systems was found to be a fingerprint of DNA oligonucleotide hybridization.