Electrochemistry of DNA films is used to monitor electron transfer through the DNA double helix. We calculated binding constants of DNA intercalators, such as methylene blue, daunomycin (a chemotherapeutic), and a Rhodium complex known as Chrisy Byp<sup>3+</sup> (a target drug to detect lesions in DNA), to measure their affinity for DNA. Our results imply that methylene blue, which has a binding constant of 2E6 M-1, and the Rhodium complex, which has a binding constant of 1.43E6 M-1, bind stronger to DNA than Daunomycin. Interestingly, the Rhodium complex appears to have a stronger affinity for DNA with base mismatches than for DNA with without lesions. We are currently studying the mechanism of electron transport through DNA and the affinity of the Rhodium complex for DNA with perturbations at the top, bottom, and middle of the DNA double helix.