Application of Gold Nanoparticles for Electrochemical DNA Biosensor

Abstract

An electrochemical DNA biosensor was successfully fabricated by using (3-aminopropyl)triethoxysilane (APTES) as a linker molecule combined with the gold nanoparticles (GNPs) on thermally oxidized SiO2 thin films. The SiO2 thin films surface was chemically modified with a mixture of APTES and GNPs for DNA detection in different time periods of 30 min, 1 hour, 2 hours, and 4 hours, respectively. The DNA immobilization and hybridization were conducted by measuring the differences of the capacitance value within the frequency range of 1 Hz to 1 MHz. The capacitance values for DNA immobilization were 160 𝜇F, 77.8 𝜇F, 70 𝜇F, and 64.6 𝜇F, respectively, with the period of time from 30 min to 4 hours. Meanwhile the capacitance values for DNA hybridization were 44 𝜇F, 54 𝜇F, 55 𝜇F, and 61.5 𝜇F, respectively. The capacitance value of bare SiO2 thin film was 0.42 𝜇F, which was set as a base line for a reference in DNA detection. The differences of the capacitance value between the DNA immobilization and hybridization revealed that the modified SiO2 thin films using APTES and GNPs were successfully developed for DNA detection.