Remote control of aptamer function has allowed us to control protein function in space and time. Here, we propose a novel control system for aptamer function by radiofrequency magnetic field- (RFMF-) induced local heating of a gold nanoparticle conjugated with an aptamer. In this study, we used a 31-mer thrombin-binding aptamer (TBA), which can inhibit thrombin activity, as a model aptamer. We evaluated the RFMF control of the inhibitory activity of a gold nanoparticle-conjugated TBA. To evaluate the effect of RFMF on enzymatic activity, we utilized a complementary DNA strand that maintains the broken structure during the activity assay. We observed a decrease in the inhibitory activity of TBA after RFMF irradiation. It indicates that RFMF is capable of controlling the TBA structure. Because RFMF allows noninvasive control of aptamer function, this strategy is expected to be novel way of controlling aptamer drug activity. 1. Introduction Aptamers, single-stranded DNA or RNA molecules, recognize various target molecules on forming a particular three-dimensional structure [1, 2]. Each aptamer has a different topology and three-dimensional structure that recognizes a target [3]. Although most proteins lose their function by denaturing their structure irreversibly, aptamers can form correct structures reversibly even after denaturation of their structure. Therefore, aptamer function can be controlled reversibly by controlling the structures. Many researchers have reported the remote control of functional nucleic acids by UV light irradiation. Caged compounds, which can be controlled by light, have been utilized for the remote control of aptamers and siRNA [4, 5]. However, because only a small amount of UV light penetrates deep tissues and also damages DNA structure, the application of UV light would be limited unless specific devices are used that generate two-photon absorption [6]. Hamad-Schfferil et al. have reported remote electronic control of the DNA structure by inductive coupling of a radiofrequency magnetic field to a metal nanocrystal covalently linked to DNA [7]. Gold nanoparticles were heated by irradiation of a radiofrequency magnetic field (RFMF), leading to denaturation of a DNA and leaves the surrounding molecules relatively unaffected. In this study, we propose a novel system for controlling aptamer function by RFMF irradiation (Figure 1). Local heating of a gold nanoparticle by RFMF irradiation would destabilize the aptamer structure and result in a decrease in aptamer function. However, the aptamer can easily refold to its native structure
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