Enhancing the electrical, optical, and magnetic characteristics of DNA thin films through Mn2+ fortification

Abstract

DNA is one of the most propitious biomaterials for use in nanoscience and nanotechnology because of its exceptional characteristics, i.e. self-assembly and sequence-programmability. In this study, we fabricate sequence-designed double-crossover (DX) DNA lattices and naturally available salmon DNA (SDNA) thin films modified with the transition metal ion Mn2+. Phase transition of DX DNA lattices from crystalline to amorphous form controlled by varying the concentration of Mn2+ is discussed and a critical transition concentration ([Mn2+]C) is estimated. In addition, the electrical, optical, and magnetic properties of Mn2+-modified SDNA thin films including current, absorbance, photoluminescence, the X-ray photoelectron spectrum, and magnetization are studied to understand their conductivity, binding modes, energy transfer characteristics, chemical composition, and magnetism. Interestingly, the physical values such as the maximum current and photoluminescence, and the minimum absorbance, occur at around [Mn2+]C =4 mM, which may be due to the optimal incorporation of Mn2+ into the SDNA. The magnetization and susceptibility of SDNA thin films with Mn2+, served as magnetic dipoles, are studied under different temperature and magnetic field. The magnetization of SDNA thin films with [Mn2+]C shows an S-shaped curve, indicating ferromagnetism.