PAMAM dendrimer functionalized magnetic particles developed for voltammetric DNA analysis

Abstract

In the present study, the functionalization of the magnetic particles (MP) with dendrimer was performed in order to obtain an enhanced voltammetric detection of nucleic acids upon to the electrode response. For this purpose, the streptavidin coated MPs were functionalized using the fourth generation poly(amidoamine) (PAMAM) dendrimer with 1,4-diaminobutane core (PDR) and then, they were applied for the first time in the literature for voltammetric DNA detection. After PDR modification onto the surface of MPs, the phosphate labeled DNA oligonucleotide (DNA ODN) was immobilized onto the surface of PDR/MPs by covalent coupling between amino groups of PDR and phosphate groups of DNA ODN. The microscopic characterization of MPs was performed by scanning electron microscopy (SEM) technique. The changes at the oxidation signals of PDR and guanine were evaluated by using differential pulse voltammetry (DPV) technique in combination with pencil graphite electrodes (PGEs). The enhanced electrode response with two folds increase at guanine signal was recorded by PDR/MPs comparison to the one of unmodified MPs. The concentrations of PDR and DNA ODN were optimized according to the changes at the electrode response. The detection limit was found to be 4.09μg/mL (equals to 70pmol in 110μL sample).