Voltammetric Sensor for Chemical Toxicity Using [Ru(bpy)2poly(4-vinylpyridine)10Cl)]+ as Catalyst in Ultrathin Films. DNA Damage from Methylating Agents and an Enzyme-Generated Epoxide

Films containing presynthesized [Ru(bpy)2poly(4-vinylpyridine)10Cl)]Cl and ds-DNA grown layer by layer by alternate electrostatic assembly were used to detect DNA damage from an epoxide metabolite and methylating agents on a reaction time scale of minutes. The redox polymer [Ru(bpy)2poly(4-vinylpyridine)10Cl)]Cl was used as an inner layer in films 14-25 nm thick to catalyze the voltammetric oxidation of guanine bases of ds-DNA in the outer layers. This film architecture provides a selfcontained, reagentless sensor for toxicity screening based on detection of DNA damage. Films were incubated with reactants and washed, and then DNA damage was analyzed by square wave voltammetry (SWV). Bioactivation of styrene to its metabolite styrene oxide was accomplished by incorporating the protein myoglobin into the films to catalyze the conversion. DNA damage caused the catalytic SWV peaks at ~0.75 V vs SCE to increase nearly linearly over the first 10-20 min of reaction, depending on the damage agent employed. Such prototype toxicity biosensors hold promise for in vitro screening of new agricultural chemicals and drugs for potential genotoxicity.