Graphene-Based Single-Bacterium Resolution Biodevice and DNA Transistor: Interfacing Graphene Derivatives with Nanoscale and Microscale Biocomponents

TLDR

Large‑contact‑area interfaces between sensitive nanostructures and microbes or mammalian cells promise valuable biodiagnostic and biomedical tools, and chemically modified graphene nanostructures—microscale, electrically sensitive, and chemically tunable—are ideal candidates for such biodevices. The study reports the fabrication and operation of a novel chemically modified graphene–based single‑bacterium biodevice, a label‑free DNA sensor, and a bacterial DNA/protein and polyelectrolyte chemical transistor. The authors fabricated CMG‑based devices by interfacing graphene derivatives with single bacteria and DNA, enabling charge‑carrier modulation and transistor behavior. The single‑bacterium biodevice generated ~1400 charge carriers upon attachment, the DNA sensor increased hole density by 5.61×10¹² cm⁻² upon hybridization, and device sensitivity, polarity specificity, and DNA attachment were tunable via surface chemistry and morphology.

Abstract

Establishing "large-contact-area" interfaces of sensitive nanostructures with microbes and mammalian cells will lead to the development of valuable tools and devices for biodiagnostics and biomedicine. Chemically modified graphene (CMG) nanostructures with their microscale area, sensitive electrical properties, and modifiable chemical functionality are excellent candidates for such biodevices at both biocellular and biomolecular scale. Here, we report on the fabrication and functioning of a novel CMG-based (i) single-bacterium biodevice, (ii) label-free DNA sensor, and (iii) bacterial DNA/protein and polyelectrolyte chemical transistor. The bacteria biodevice was highly sensitive with a single-bacterium attachment generating approximately 1400 charge carriers in a p-type CMG. Similarly, single-stranded DNA tethered on graphene hybridizes with its complementary DNA strand to reversibly increase the hole density by 5.61 x 1012 cm(-2). We further demonstrate (a) a control on the device sensitivity by manipulating surface groups, (b) switching of polarity specificity by changing surface polarity, and (c) a preferential attachment of DNA on thicker CMG surfaces and sharp CMG wrinkles.