Abstract
The dynamic structural behavior in DNA due to interaction with cisplatin is essential for the functionality of platinum-based anti-cancer drugs. Here we report a novel method to monitor the interaction progress in DNA-cisplatin reaction in real time with a solid-state nanopore. The interaction processes are found to be well elucidated by the evolution of the capture rate of DNA-cisplatin complex, which is defined as the number of their translocation events through the nanopore in unit time. In the first stage, the capture rate decreases rapidly due to DNA discharging as the positive-charged hydrated cisplatin molecules initially bond to the negative-charged DNA and form mono-adducts. In the second stage, by forming di-adducts, the capture rate increases as DNA molecules are softened, appears as the reduced persistence length of the DNA-cisplatin adducts. In the third stage, the capture rate decreases again as a result of DNA aggregation. Our study demonstrates a new single-molecule tool in exploring dynamic behaviors during drug-DNA reactions and may have future application in fast drug screening.
Highlights
Platinum-based drugs are widely used in nowadays cancer chemotherapy[1,2,3]
To be consistent with such procedure, the cisplatin used in our experiments is pre-activated as well with the method described by Hou et al.[15]. It is diluted in sodium acetate buffer (1 M NaAc, 10 mM HEPES and pH = 7 .8) which contains 1 nM 10 kbp double strand DNA, corresponding to a 10 μM basepair concentration Cbp
Three stages of DNA-cisplatin interaction are revealed by monitoring the capture rate of DNA translocation through a solid-state nanopore
Summary
It has been revealed that the drug molecules disable the physiologic activities of DNA and induce cell apoptosis by bonding with the N7 atom of guanine or adenine along a DNA molecule to form mono- and di-adducts[4,5,6] Certain cancers, such as testicular cancer, can be cured with great success by cisplatin, one of the most effective platinum-based drugs[7,8,9,10]. Nanopore is a novel technology that detects a single biomolecule by monitoring conductance blockade due to translocation of the molecule through a nanometer-sized pore[19] Such devices have been employed to explore various biomolecules such as DNA20, RNA21, protein[22] and their complexes[23,24], especially DNA sequencing with MspA nanopores[25,26]. Combining the pre-exponential invariant as a constant A, the total capture rate J is derived as follows: J=
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