New Insights for DNA Measurement by Memristive Biosensors

This paper proposes a novel approach to DNA measure based on memristive silicon nanowire (SiNW). The SiNWs are fabricated by a lithographic technique, representing hysteric electrical response. After bio-functionalization with probe Single-Stranded DNA (ssDNA), the device is able to measure target nucleic acid molecules on dried samples as a memristive biosensor. A comparative analysis of three amineterminated ssDNA immobilization strategies is investigated to design and optimize the approach for potential label-free measurements. The silicon nanowire surface is firstly silanized by (3-Glycidyloxypropyl)trimethoxysilane (GPTMS), where the epoxy group works as a linker. The condensation occurs between expoy groups and amino groups as the case of study via: (a) Direct immobilization of probe ssDNA on nanowire surface, named as ’’Direct method’’; (b) Alkaline ambience with KOH assisted probe ssDNA immobilization by activating amino group in an alkaline ambience, named as ’’KOH method’’; (c) NHS/EDC assisted probe ssDNA immobilization by activating epoxy group in a neutral ambience, named as ’’NHS/EDC method’’. After immobilization, fluorescence-labeled target nucleic acid molecules are hybridized on the device. The two-terminal electrical responses for each step are recorded. The variation of the voltage gap (Vg) reveals the mechanism behind the chemical reactions. It is demonstrated that the NHS/EDC assisted strategy and KOH strategy (PH around 9) present a similar significant voltage gap variation for DNA hybridization performance, while direct strategy shows no voltage gap change after immobilization. With such an approach, label-free measurements are proposed to detect target single-stranded DNA (ssDNA)/RNA with custom probe nucleic acid molecules.