Self-assembly of semiconductor quantum-dots on electrodes for photoelectrochemical biosensing
Freeman, Ronit; Gill, Ron; Beissenhirtz, Moritz; Willner, Itamar; Freeman Ronit; Institute of Chemistry and the Farkas Center for Light-Induced Processes, The Hebrew University of Jerusalem; Gill Ron; Institute of Chemistry and the Farkas Center for Light-Induced Processes, The Hebrew University of Jerusalem; Beissenhirtz Moritz; Institute of Chemistry and the Farkas Center for Light-Induced Processes, The Hebrew University of Jerusalem; Willner Itamar; Institute of Chemistry and the Farkas Center for Light-Induced Processes, The Hebrew University of Jerusalem
Журнал:
Photochemical & Photobiological Sciences
Дата:
2007
Аннотация:
CdS nanoparticles linked through a duplex DNA to a Au electrode do not lead to a noticeable photocurrent upon their illumination in the presence of triethanolamine, TEOA, 20 mM, pH = 7.2. The intercalation of doxorubicin into the duplex DNA stimulates, however, the generation of a photocurrent. This is attributed to the trapping of photoexcited conduction-band electrons by the intercalator units that facilitates, by a hopping mechanism, the electron transport to the electrode. The oxidation of TEOA by valence band holes allows the formation of a steady state photocurrent. This basic phenomenon is used to probe the operation of a DNA-based machine through the assembly of CdS nanoparticles on a Au electrode. The machine includes a nucleic acid â trackâ , (1), that binds a primer, (2), through hybridization to a predefined domain. In the presence of polymerase, the nucleotide mixture, dNTPs, and the nicking enzyme, the autonomous replication, nicking and displacement of the â waste productâ , (3), are activated. The â waste productâ bridges the (4)-functionalized CdS nanoparticles and the nucleic acid (5)-functionalized Au electrode, resulting in the assembly of the nanoparticles on the electrode. The intercalation of doxorubicin into the DNAâ CdS nanostructures results in the generation of photocurrents upon illumination in the presence of TEOA, pH = 7.2. The photocurrents are controlled by the time intervals used to operate the DNA machine.
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