DNA Hybridization Measured with Graphene Transistor Arrays

• Published in: Advanced healthcare materials 2020-08, Vol.9 (16), p.e2000260-n/a
• Main Authors: Mensah, Kokoura, Cissé, Ismaïl, Pierret, Aurélie, Rosticher, Michael, Palomo, José, Morfin, Pascal, Plaçais, Bernard, Bockelmann, Ulrich
• Format: Article
• Language: English
• Subjects: Aluminum oxide; Arrays; Biocompatibility; Biosensing Techniques; Chemical vapor deposition; Condensed Matter; Contamination; Deoxyribonucleic acid; DNA; DNA hybridization; DNA probes; electronic detection; Gene sequencing; Graphene; Graphite; Hybridization; Immobilization; In situ measurement; Lysine; Mesoscopic Systems and Quantum Hall Effect; Nucleic Acid Hybridization; Nucleotide sequence; Nucleotides; Photolithography; Physics; Polymers; real‐time hybridization measurement; Semiconductor devices; transistor arrays; Transistors; Transistors, Electronic
• ISSN: 2192-2640; 2192-2659
• DOI: 10.1002/adhm.202000260

Arrays of field‐effect transistors are fabricated from chemical vapor deposition grown graphene (GFETs) and label‐free detection of DNA hybridization performed down to femtomolar concentrations. A process is developed for large‐area graphene sheets, which includes a thin Al2O3 layer, protecting the graphene from contamination during photolithographic patterning and a SiOx capping for biocompatibility. It enables fabrication of high‐quality transistor arrays, exhibiting stable close‐to‐zero Dirac point voltages under ambient conditions. Passivation of the as‐fabricated chip with a layer composed of two different oxides avoids direct electrochemical contact between the DNA solutions and the graphene layer during hybridization detection. DNA probe molecules are electrostatically immobilized via poly‐l‐lysine coating of the chip surface. Adsorption of this positively charged polymer induces a positive shift of the Dirac point and subsequent immobilization of negatively charged DNA probes induces a negative shift. Spatially resolved hybridization of DNA sequences is performed on the GFET arrays. End‐point as well as real‐time in situ measurements of hybridization are achieved. A detection limit of 10 fm is observed for hybridization of 20‐nucleotide DNA targets. Typical voltage signals are around 100 mV and spurious drifts below 1 mV per hour. Arrays of field‐effect transistors are fabricated from chemical vapor deposition grown graphene and DNA hybridization is detected down to femtomolar concentrations. A thin protection layer prevents contamination of graphene during photolithographic patterning and hybridization. DNA probes are electrostatically immobilized. Hybridization of target DNA induces shifts of the Dirac point. End‐point and in situ measurements of hybridization are presented.