The Evaluation of Magnetic Polymethacrylate-based Microspheres Used for Solid Phase DNA Micro-Extraction

Using magnetic particles as a solid-phase extraction system is the most frequently used micro-technique for DNA isolation. Particles with a complete covering of magnetic cores by a polymer are hence preferred. Quantitative polymerase chain reaction (qPCR) was used for the evaluation of the polymer coating efficiency of hydrophilic magnetic poly(2-hydroxyethyl methacrylate-co-glycidyl methacrylate) (P(HEMA-co-GMA)) and poly(glycidyl methacrylate) (PGMA) microspheres with/without carboxyl groups. The inhibition effect of magnetic microspheres was identified by the shift in Cq values (ΔCq) after the addition of different amounts of microspheres to PCR mixtures. With the increase of microsphere concentrations, the shift in Cq values to higher values was usually observed. P(HEMA-co-GMA) microspheres containing carboxyl groups extinguished the fluorescence at concentrations over 2 mg mL−1 in a PCR mixture without any influence on the synthesis of PCR products. No PCR products (inhibition of DNA amplification) were detected in the presence of more than 0.8 mg mL−1 in the PCR mixture of PGMA microspheres. Atomic force microscopy (AFM) was used for the determination of the surface morphology of the microspheres. The microspheres were spherical, and their surface was non-porous.