Method of assembling pure Langmuir–Blodgett DNA films using TBE buffer as the subphase

Abstract

The advantage of using Langmuir–Blodgett (LB) method in assembling thin films refers mainly to the effective deposition of mono- and multilayer films with an organized, well-defined molecular orientation and ordered layer structure. Deoxyribonucleic acid (DNA), in recent times, has also been deposited using LB technique to form films on solid substrates for various studies. However, it has been quite a challenge for researchers to obtain pure homogenous DNA film due to the hydrophilic nature of DNA that makes it unable to float on water subphase. In this work, an unconventional approach was employed by suspending synthetic DNA molecules on a subphase of Tris base, Boric acid with ethylenediamine tetra acetic acid (EDTA) (TBE) buffer instead of deionized water. Spectroscopic, morphological, and electrical characterisations were then carried out for further understanding of the resulting DNA film on solid substrates. The obtained results confirmed DNA layer functionality with uniform film formation, which demonstrated a strong rectification when electrical studies were conducted. For this purpose, we employed the LB-derived pure DNA films integrated within a metal–semiconductor or Schottky junction, confirming previous reports on semiconductor-like behaviour of DNA molecules. We believe, the possibility of obtaining pure DNA film using the LB method may allow in-depth investigations pertaining to DNA interaction with various other macromolecules besides exciting applications in various electronic devices, especially in the field of biosensors.