Adsorption and desorption of DNA on bovine serum albumin modified gold nanoparticles

Adsorption and desorption behaviors of DNA on bovine serum albumin (BSA) modified 40 nm gold nanoparticles (NPs) were investigated. It was identified that the modified particles presented almost the same isoelectric point (IEP) as that of BSA (∼4.6). At pH 3.0, DNA can be absorbed effectively on the positively charged particle surface by direct electrostatic attraction. The adsorption capacity could be as high as 1.8 mg DNA/mg NPs under this pH. At pH 9.0, DNA can be eluted almost completely from the negatively charged particle surface. Such a simple approach to fabricate charge reversible particles switched by pH not only has potential applications in highly efficient DNA extraction, but also could benefit the study on the interactions between proteins and DNA.