Label-free detection of DNA using high-kappa Lu2Ti2O7 electrolyte-insulator-semiconductors

In this study, we propose a disposable poly-N-isopropylacrylamide (PNIPAAm) as an immobilizing biological material based electrolyte-insulator-semiconductor (EIS) device for DNA detection, prepared from a high-kappa Lu2Ti2O7 sensing membrane. X-ray diffraction, X-ray photoelectron spectroscopy, and atomic force microscopy were used to investigate the structural and morphological features of these films annealed at various annealing temperatures. The high-kappa Lu2Ti2O7 EIS device annealed at 900 degrees C exhibited a higher sensitivity of 60.04 mV/pH, a smaller hysteresis voltage of 3 mV, and a lower drift rate of 0.623 mV h(-1) than those at other annealing temperatures. These results are attributed to the large surface roughness and the small number of crystal defects. In the biosensing experiments, the immobilization of a negatively charged single-stranded DNA probe (ssDNA) on the Lu2Ti2O7 surface caused an increase in the reference voltage value, whereas the hybridization of complementary target DNA ( cDNA) decreased the reference voltage value. The Lu2Ti2O7 EIS biosensor using a ssDNA-immobilized PNIPAAm gel was successfully used for the detection of DNA hybridization. The detection limit of complementary DNA was as low as 10 pM, and the output signal of the Lu2Ti2O7 biosensor increased linearly with the logarithm of cDNA concentration in the range of 10(-11) to 10(-4) M.