DNA recovery from a single bacterial cell using charge-reversible magnetic nanoparticles

[Display omitted] •DNA was recovered from a single bacterial cell using the magnetic nanoparticles.•The magnetic nanoparticles were modified with imidazole moieties.•The imidazole-modified magnetic nanoparticles (Imi-MNPs) response pH change.•DNA adsorption and desorption on the Imi-MNPs are controllable by changing pH. Highly efficient DNA recovery from a single bacterial cell was performed by means of imidazole-modified magnetic nanoparticles (Imi-MNPs). The modification by imidazole was confirmed by Fourier transform infrared spectroscopy. The Imi-MNPs were highly efficient at DNA extraction owing to the charge-reversible properties of Imi-MNPs, whereby DNA is attached to the particles at low pH and eluted at high pH because of electrostatic interactions. The DNA recovery ratio was determined by real-time PCR, and it revealed that complete recovery was guaranteed at ≥103 genome copies of Bacillus subtilis. Extraction of DNA from single bacterial cells was followed by PCR amplification of 16S rDNA and capillary electrophoresis. We achieved detection of single bacterial cells with a detection rate of 80%. We believe that our DNA recovery strategy may serve as a powerful tool for efficient DNA extraction and should be useful for quality control of cosmetics, foods, and pharmaceutical products.