Surface Charge Transduction Enhancement on Nano-Silica and - Alumina Integrated Planar Electrode for Hybrid DNA Determination

Abstract This study represents the surface charge transduction, an efficient and inexpensive biosensor with modifications by silica-alumina entities and determination of gene sequence hybridization. The sensing surface was made by the planar aluminium interdigitated electrode on silicon substrate. Silica and alumina nanoparticles were engineered on the planar transducer surface and the device sensitivity was investigated. The morphology of silica and alumina particles was characterized through the high-resolution election microscopic analyses and revealed the spherical shaped nanoscale sizes at the range of 45 to 100 nm. The elemental compositions of silica and alumina nanomaterial were affirmed through energy disperse spectroscopy as prominent peaks of Si, Al and O were observed. Selected area electron diffraction analysis of silica and alumina justified their crystalline and amorphous nature, respectively. XRD analysis revealed the expending cristobalite state of silica crystal and γ -alumina for planar electrode surface enhancement. Fourier transform infrared spectroscopy peak observed at 1094 cm-1 revealed the asymmetric stretching of silica nanoparticles whereas the projecting peak observed at 806 cm-1. Additionally, Al-O stretch and Al-O-Al bending modes were justified with the peaks at 585 and 825 cm-1, respectively. Band gap values of silica and alumina computed were 6.75 eV and 3.20 eV, respectively. The results of DNA probe immobilization and complementation have affirmed that silica modified transducer shows the lowest detection at 10 aM whereas alumina modified transducer displayed insignificant current signal and failed to detect DNA hybridization. To investigate the effect of silica entity and its nanocomposite in detecting DNA hybridization, aluminosilicate nanocomposite was deposited on transducer and attained highly sensitive gene detection. Based on the coefficient regression value, aluminosilicate nanocomposite modified planar transducer has shown good device sensitivity (R2 = 0.96) in contrast to silica and alumina entities.