Piezoelectric DNA Sensor Based On Gold Nanoparticle Amplification

DNA sensor technology is paid close attention because it has the advantages of saving time, determining the quality and quantity of samples simultaneously, as well as high sensitivity and excellent selectivity. In recent years, the combination of nanotechnology and DNA sensor technology is becoming an important developing direction.This work integrated nanotechnology, biotechnology and QCM technology to improve the sensitivity of DNA detection. The main content is as follows:1. The preparation of nanogold. The prepared samples were analyzed by UV-visible spectrophotometer, nanoparticle size analyzer and transmission electron microscopy. It indicated that the nanogolds dispersed well, and the diameter of nanogolds is uniform.2. QCM flowing system was designed and fabricated so that flowing detection and rinsing on line were achieved. Comparing with the self-assembly of DNA in three cases: quiescent mode under open conditions, quiescent mode under sealed conditions; and flowing mode under sealed conditions, the frequency change of the former reached 93 Hz, which is much more than the latter two modes (59Hz and 56Hz respectively). At the same time, QCM flowing system is more stable, which can satisfy the detection demands of piezoelectric DNA sensor.3. Nanogold was used as mass amplifier to improve the sensitivity of DNA detection. The optimal conditions were: 5 nm diameter of nanogold, 7μl nanogold stock solution: 50μl buffer solution. The sensitivity of once amplification of nanogold was 100 fM, and the frequency change of complementary DNA: one-base mismatched DNA was 2.26:1.The sensitivity of twice amplification of nanogold was 10 fM, and the frequency change of complementary DNA: one-base mismatched DNA was 2.17:1.4. Detection of 677TT mutation genotype of MTHFR gene. The sensitivity of once amplification of nanogold was 100 fM, and the frequency change of complementary DNA: one-base mismatched DNA was 2:1.The sensitivity of twice amplification of nanogold was 10 fM, and the frequency change of complementary DNA: one-base mismatched DNA was 2.4:1. The detection limit of twice amplification was one order of magnitude higher than that of once amplification.