Ultrasensitive electrochemical dna biosensors based on the detection of a highly characteristic solid-state process

A study was conducted to demonstrate an ultrasensitive electrochemical DNA sensing strategy that utilized neutral peptide nucleic acid (PNA) as probes and amine-finctionalized positively charged Ag nanoparticles as electroactive labels. The electroactive labels were detected through a highly characteristic solid-state Ag/AgCl reaction. Neutral PNA probes were selected in place of negatively charged DNA probes due to comparatively reduced background signal. Monodisperse dodeclyamine-capped Ag nanoparticles were synthesized in a a toluene solution to conduct the investigations. A reverse-micelle-mediated polymerization method was used to introduce a polymer coating of N-(3-aminopropyl) methaacrylamide hydrochloride to the nanoparticle surface with persulfate as the the oxidant. It was observed that the resulting particle was highly stable in the pH range of 4-7.5 and positively charged.