A Label-Free Impedimetric DNA Sensor Based on a Nanoporous SnO2 Film: Fabrication and Detection Performance

Abstract

Nanoporous SnO2 thin films were elaborated to serve as sensing electrodes for label-free DNA detection using electrochemical impedance spectroscopy (EIS). Films were deposited by an electrodeposition process (EDP). Then the non-Faradic EIS behaviour was thoroughly investigated during some different steps of functionalization up to DNA hybridization. The results have shown a systematic decrease of the impedance upon DNA hybridization. The impedance decrease is attributed to an enhanced penetration of ionic species within the film volume. Besides, the comparison of impedance variations upon DNA hybridization between the liquid and vapour phase processes for organosilane (APTES) grafting on the nanoporous SnO2 films showed that vapour-phase method is more efficient. This is due to the fact that the vapour is more effective than the solution in penetrating the nanopores of the films. As a result, the DNA sensors built from vapour-treated silane layer exhibit a higher sensitivity than those produced from liquid-treated silane, in the range of tested target DNA concentration going to 10 nM. Finally, the impedance and fluorescence response signals strongly depend on the types of target DNA molecules, demonstrating a high selectivity of the process on nanoporous SnO2 films.

A Highly Sensitive Impedimetric DNA Biosensor Based on Hollow Silica Microspheres for Label-Free Determination of E. coli

“…DNA is a conductive biomolecule and abundant base pairs are counted as systems facilitating electron transfer to electrodes [33]. Hydrophilic double-strand DNA can partially increase electron transfer of molecules from electrolytes to electrodes, followed by infiltration through the cavity structure [32]. The interaction of HSMs and DNA is proposed in Figure 4b.…”

“…It was found that the value of R CT for the hybridized DNA with the target DNA was lower than probe DNA and non-target DNA. The negative charge on the DNA was increased due to the formation of double-stranded DNA [31,32]. DNA is a conductive biomolecule and abundant base pairs are counted as systems facilitating electron transfer to electrodes [33].…”

Vanadium Pentoxide Nanorods Anchored to and Wrapped with Graphene Nanosheets for High‐Power Asymmetric Supercapacitors

“…The latter is the cathodic electrodeposition of Sn NPs followed by an oxidizing annealing. The process is described elsewhere 33.…”

Sensitive and Selective Ammonia Gas Sensor Based on Molecularly Modified SnO2

“…This step generates a film terminated by amine groups (SnO2-APTES) which will act as a substrate for the second step of modifications. Silanization in liquid phase has been described elsewhere [4]. In a first step, SnO2 sensors were immersed in 50 mM APTES dissolved in 95% absolute ethanol and 5% of deionized water for 5 h under stirring at room temperature.…”