High-performance of deep eutectic solvent based aqueous bi-phasic systems for the extraction of DNA

Aqueous bi-phasic systems (ABSs) based on deep eutectic solvents (DESs) are efficient and eco-friendly separation processes. Four kinds of novel green DESs were synthesized based on tetrabutylammonium bromide, ethylene glycol, propylene glycol, butylene glycol, and butyl alcohol, respectively. DES-based aqueous bi-phasic systems (ABSs) were developed and applied in the rapid and efficient extraction of DNA from salmon testes. Tetrabutylammonium bromide-ethylene glycol and sodium sulfate were selected as the appropriate phase components. Single factor experiments proved that the extraction efficiency of DNA was influenced by the mass of DES, the salt concentration, the temperature, the separation time, the pH value, and the ionic strength value. After extraction, 99.98% of the DNA was transferred to the DES-rich top phase. In order to meet the requirements of downstream applications and obtain high purity DNA, the back extraction experiments were carried out and 89.69% of the DNA could be back extracted into the salt-rich phase. Then the extraction and back-extraction were each applied to DNA complex samples containing protein, which proved that DNA could be selectively separated from complex samples. The outstanding results demonstrated that DES-based ABS is an effective and eco-friendly DNA selective separation method. Finally, FT-IR spectra, circular dichroism spectra, dynamic light scattering and transmission electron microscopy were combined to investigate the binding characteristics and the extraction mechanism.