Anion-exchanged nanosolid support of magnetic nanoparticle in combination with PNA probes for DNA sequence analysis

Poly((2-diethylamino) ethyl methacrylate) (poly(DEAEMA))-grafted magnetite nanoparticle (MNP) with a positively charged surface was used as an anion exchanger for detection of deoxyribonucleic acid (DNA) sequences by employing peptide nucleic acid (PNA) as a probe. The cationic MNP with a size ranging between 6 and 10 nm in diameter can electrostatically adsorb DNA with a capacity of 171 nmol nucleotide/g MNP. The electrostatically neutral pyrrolidinyl PNA-bearing prolyl-2-aminocyclopentane carboxylic acid backbone (acpcPNA) can be adsorbed by the cationic MNP only when the sequence of the PNA and DNA is complementary, and the presence of adsorbed PNA could be examined by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Two DNA sequences, the sequence stimulating Kirsten Rat Sarcoma (K-ras) gene and the sequence having 5' methylated CpG site, were used in this study. It was found that the particles can be used as nanosolid support to differentiate between complementary and single-base mismatched DNA sequences using both single and two acpcPNA probes. This polymer-grafted MNP might be applicable for use as a magnetically guidable tool for detection of real DNA samples in the future.