Adsorption and detection of peptide nucleic acids at carbon paste electrodes

Peptide nucleic acids (PNA) are new DNA analogs which offer great promise for highly specific DNA biosensors, for use as antisense drugs, or for various molecular biology applications. This article evaluates the interfacial behavior of PNA at carbon paste electrodes, in comparison to DNA, While both PNA and DNA oligomers display a strong adsorption onto the carbon surface, they differ in their interfacial properties due to differences in charge and structure. Factors influencing the adsorption behavior, including the adsorption potential or time, PNA concentration, coexisting anions and cations, or buffer concentration, are explored. The strong adsorption is exploited for an effective preconcentration step prior to the chronopotentiometric measurement. The resulting adsorptive stripping potentiometric protocol offers convenient quantitation of ng/mL levels of PNA, as desired for future diagnostic, pharmaceutical and biological applications of these DNA analogs.