Abstract
Here, we report a high performance biosensor based on (i) a Cu2+-DNA/MoS2 hybrid structure and (ii) a field effect transistor, which we refer to as a bio-FET, presenting a high sensitivity of 1.7 × 103 A/A. This high sensitivity was achieved by using a DNA nanostructure with copper ions (Cu2+) that induced a positive polarity in the DNA (receptor). This strategy improved the detecting ability for doxorubicin-like molecules (target) that have a negative polarity. Very short distance between the biomolecules and the sensor surface was obtained without using a dielectric layer, contributing to the high sensitivity. We first investigated the effect of doxorubicin on DNA/MoS2 and Cu2+-DNA/MoS2 nanostructures using Raman spectroscopy and Kelvin force probe microscopy. Then, we analyzed the sensing mechanism and performance in DNA/MoS2- and Cu2+-DNA/MoS2-based bio-FETs by electrical measurements (ID-VG at various VD) for various concentrations of doxorubicin. Finally, successful operation of the Cu2+-DNA/MoS2 bio-FET was demonstrated for six cycles (each cycle consisted of four steps: 2 preparation steps, a sensing step, and an erasing step) with different doxorubicin concentrations. The bio-FET showed excellent reusability, which has not been achieved previously in 2D biosensors.
Highlights
Biosensors have been applied in various fields such as the food industry1, medical diagnostics and treatment2, national security applicaitons3, and environmental monitoring4
We study the influence of doxorubicin on DNA/MoS2 and Cu2+-DNA/MoS2 structures in detail with Raman spectroscopy, Kelvin probe force microscopy (KPFM), and electrical measurement (ID-VG)
The short distance between the biomolecules and the sensor surface, which could be achieved without using high-κdielectric layers in bio-field effect transistors (FETs), contributed to the high sensitivity
Summary
We demonstrated a Cu2+-DNA/MoS2 based bio-FET with an extremely high sensitivity of 1.7 × 103 A/A. We confirmed the successful operation of the Cu2+-DNA/MoS2 bio-FET for six cycles with different doxorubicin concentrations (each cycle consists of four steps; 1st and 2nd preparation, 3rd sensing, and 4th erasing steps). This excellent reusability has not been reported previously for 2D biosensors. Fabrication and electrical characterization of DNA/MoS2- and Cu2+-DNA/MoS2-based bio-FETs. For the fabrication of back-gated MoS2 transistors, source/drain electrode regions were patterned (channel length and width were 5 μm) on MoS2/SiO2/Si samples by optical lithography, followed by deposition of 10-nm-thick Ti and 50-nm-thick Au in an e-beam evaporator. All drain currents (IDS) were normalized by the channel width (W)
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