A Study of the Behavior of HNT with DNA Intercalator Acridine Orange

Abstract

The interaction of nanomaterials with DNA and proteins is an area of great interest especially in the development of novel biosensors, and recently, it has become the focus of many multidisciplinary researches. DNA intercalating agent acridine orange interrupts the normal function of cellular DNA, leading to the inhibition of gene expressions. Many carcinogenic chemicals damage DNA either by intercalation or by cross-linkage. Numerous repair strategies are available to block the progressive DNA damage caused by DNA intercalators. These strategies aimed to prevent intercalation through the scavenging of the reactive moieties of the intercalators. In this report, we demonstrate binding of halloysite nanotubes (HNT) with a DNA intercalator, acridine orange (AO), through a hydrophobic interaction referred to as “polar bonding.” HNTs are composed of silica on their outer surface and alumina within their inner surface. The inner and outer surfaces of tubular walls confer a resultant negative charge which makes HNT polyanionic in nature, thus enhancing the potential for polar bonding between HNT and amino-substituted AO. This interaction can lead to a metachromatic shift due to π interactions between the aromatic entity of AO and the oxygen plane of the HNT. This shift was confirmed by Fourier transform infrared spectroscopy (FTIR) analysis whereby in the presence of HNT, the intercalator AO, intercalated within the DNA–AO complex, showed affinity for HNT as observed by the shift in FTIR peaks of halloysite nanotubes from 3,623, 1,722, and 1,038 cm⁻¹ to 3,612, 1,706, 1,083, and 963 cm⁻¹.