Ultrasensitive Label-Free DNA Detection Based on Solution-Gated Graphene Transistors Functionalized with Carbon Quantum Dots

Abstract

Developing highly sensitive, reliable, cost-effective label-free DNA biosensors is challenging with traditional fluorescence, electrochemical, and other techniques. Most conventional methods require labeling fluorescence, enzymes, or other complex modification. Herein, we fabricate carbon quantum dot (CQD)-functionalized solution-gated graphene transistors for highly sensitive label-free DNA detection. The CQDs are immobilized on the surface of the gate electrode through mercaptoacetic acid with the thiol group. A single-stranded DNA (ssDNA) probe is immobilized on CQDs by strong π–π interactions. The ssDNA probe can hybridize with the ssDNA target and form double-stranded DNA, which led to a shift of Dirac voltage and the channel current response. The limit of detection can reach 1 aM which is 2–5 orders of magnitude lower than those of other methods reported previously. The sensor also exhibits a good linear range from 1 aM to 0.1 nM and has good specificity. It can effectively distinguish one-base mismatched target DNA. The response time is about 326 s for the 1 aM target DNA molecules. This work provides good perspectives on the applications in biosensors.

Rapid and Unamplified Detection of SARS-CoV-2 RNA via CRISPR-Cas13a-Modified Solution-Gated Graphene Transistors

“…It is equivalent to applying an offset voltage ( V offset ) in the gate electrode. The V offset can be expressed by the following equation , V offset = normalΔ q C where the amount of charge change (Δ q ) is induced by the hybridization of target RNAs, and C is the total capacitance of the SGGT. According to eq , V offset is determined by the total charges of the target RNA specifically recognized with Cas13a RNPs.…”

“…It is equivalent to applying an offset voltage (V offset ) in the gate electrode. The V offset can be expressed by the following equation 39,40…”

Graphene-Based Field-Effect Transistors in Biosensing and Neural Interfacing Applications: Recent Advances and Prospects

“…The device exhibited excellent sensing capability with a detection limit down to 1 nM and high specificity against noncomplementary DNAs. Another study has shown that the functionalization of CQDs with the graphene channel surface in the SG-GFET configuration exhibits detection of DNA with much higher sensitivity down to 1 aM concentration (Figure E) . In this work, the CQDs were immobilized on the graphene surface through mercaptoacetic acid to form the thiol group, and then the ssDNA probe was immobilized on CQD via π–π stacking interactions (lower panel in Figure E).…”

“…Another study has shown that the functionalization of CQDs with the graphene channel surface in the SG-GFET configuration exhibits detection of DNA with much higher sensitivity down to 1 aM concentration (Figure 4E). 112 In this work, the CQDs were immobilized on the graphene surface through mercaptoacetic acid to form the thiol group, and then the ssDNA probe was immobilized on CQD via π−π stacking interactions (lower panel in Figure 4E). Hybridization of target ssDNA with the ssDNA probe leads to the formation of dsDNA, resulting in the shift of V Dirac .…”

Applications of Carbon Dots in Electrochemical Energy Storage

“…There is a certain amount of conjugated sp 2 carbon segments in CDs, so most CDs possess good electrical conductivity and an excellent photoelectric conversion capability, favoring charge transport, exciton separation and sensing improvement. 29 In early work, a field-effect transistor (FET) device of glucose-derived CQDs showed ambipolar behaviors, with electron and hole mobilities as high as 8.49 × 10 −5 and 3.88 × 10 −5 cm 2 V −1 s −1 . The carrier mobility is also dependent on the length of the ligand attached to the CQDs.…”