Demethylation of Cancer DNAs by Resonant High-Power Terahertz Irradiation

Terahertz (THz) radiation, spanning the frequency range of 0.1 to 10 THz, has emerged as an attractive light source for exploring light-matter interactions at low-energy scales [1]. With its low photon energy compared to visible or UV light, THz radiation minimizes the risk of photo-induced damage to biomolecules, making it ideal for applications in sensing and biological modulation. Recent studies using THz time-domain spectroscopy have revealed a resonance frequency at 1.6 THz shared by various cancer DNAs [2]. Intense THz radiation centered at this resonance frequency has been shown to effectively reduce methylation levels in cancer DNA [2-4]. The underlying mechanism of this phenomenon is believed to involve the abundant chemical bonds between methyl groups and cytosines in cancer DNA, which contribute to the resonance at approximately 1.6 THz. It is hypothesized that intense THz radiation at this frequency disrupts the chemical bonds through molecular resonance. However, recent studies suggest that the observed resonant feature may arise from surrounding materials, such as ice, rather than cancer DNA itself [5]. This highlights the importance of conducting systematic studies under water-free conditions to isolate this effect. To address this uncertainty, we built a THz system capable of generating 10 mW-level broadband THz radiation and fabricated band-pass and notch filters centered at 1.6 THz. Based on them, we investigated the resonance frequency effect on demethylation. Methyl group concentrations were measured via enzyme-linked immunosorbent assay (ELISA) following 30 minutes of irradiation with various filters.