Recyclable magnetite nanoparticle coated with cationic polymers for adsorption of DNA.

Magnetite nanoparticle (MNP) grafted with a cationic copolymer between poly(2-(N,N-diethylamino) ethyl methacrylate) and poly(poly(ethylene glycol) methyl ether methacrylate)) for efficient and recyclable adsorption of 5'-fluorescein-tagged DNA (FAM-dT9) was prepared. MNP having highest degree of positive charge (+32.1 ± 1.9 mV) retained 100% adsorption of FAM-dT9 during eight adsorption-separation-desorption cycles. The MNP having lower degree of positive charge showed a slight decrease in adsorption percentages (94-98% adsorption) after multiple recycling processes. This biocompatible hybrid material with charged surface and magnetic-responsive properties might be applicable for use as a nanosolid support for efficient and facile separation of various bioentities.

Magnetite nanoparticle with positively charged surface for immobilization of peptide nucleic acid and deoxyribonucleic acid.

We herein report the surface modification of magnetite nanoparticle (MNP) with the (co)polymer of poly(ethylene glycol) methyl ether methacrylate (PEGMA) and/or diethylamino ethyl methacrylate (DEAEMA) via atom transfer radical polymerization (ATRP) for use as anion exchanger solid support for detection of DNA sequence using peptide nucleic acid (PNA) probe. Molar ratio of the PEGMA:DEAEMA (co)polymer was systematically varied to tune the positive charges on the particle surface. Kinetic studies of the (co)polymerizations were investigated via 1HNMR to disclose the relative reactivity of the (co)polymers in the reaction. Zeta potential of the (co)polymer-grafted MNP was analyzed by photo correlation spectroscopy (PCS). Transmission electron microscopy (TEM) and PCS indicated an improvement in the particle dispersibility in water upon quaternization of the DEAEMA entities grafted on the particle surface. From the preliminary results, these (co)polymer-grafted MNPs can be used as a nanosolid support to differentiate between full match and single-base mismatch DNA sequences using an acpcPNA probe. These novel cationic MNPs might be efficiently applicable for use as a magnetically guidable tool for detection of DNA sequences.