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EP-4320431-B1 - FIELD-EFFECT TRANSISTOR COMPRISING MIXED FUNCTIONALIZED GRAPHENE STRUCTURE AND CORRESPONDING FABRICATION METHOD

EP4320431B1EP 4320431 B1EP4320431 B1EP 4320431B1EP-4320431-B1

Inventors

  • Rebollo Piñeiro, Amaia
  • Arrastua Ceberio, María

Dates

Publication Date
20260506
Application Date
20220408

Claims (10)

  1. Method for preparing a Field-Effect Transistor (FET) chip comprising a mixed functionalized graphene structure, wherein the mixed functionalized graphene structure comprises: - a graphene surface; - 1-pyrenebutanoic acid succinimidyl ester (PBASE) molecules; - molecules of at least one type of polycyclic aromatic hydrocarbon (PAH) compounds, the PAH compound being pyrene; and - biomolecules; wherein both the molecules of PBASE and the molecules of pyrene are non-covalently linked to the graphene surface, wherein the biomolecules are linked to the PBASE molecules, and wherein the mixed functionalized graphene structure has a surface roughness (Rms) between around 0.75 nm and around 1.25 nm, wherein Rms is measured by atomic force microscopy (AFM) over a SiO 2 /Si substrate in a 2 × 2 µm 2 area and it is expressed respect to a bare graphene having a Rms value of around 1.00 nm, wherein the method comprises the following steps: a) incubating sequentially the PBASE molecules and the molecules of pyrene over the graphene surface and washing the resulting graphene structure, wherein the molar ratio between the PBASE and pyrene is between 1:5 and 5:1; and b) incubating the biomolecules over the graphene surface of the graphene structure resulting from the previous step and washing the resulting functionalized graphene structure.
  2. The method according to claim 1, wherein the molar ratio between the PBASE and pyrene in step (a) is 5:1.
  3. The method according to any of claims 1 or 2, wherein the PBASE molecules are incubated at a concentration between 2 mM and 10 mM.
  4. The method according to any of claims 1 to 3, wherein the molecules of pyrene are incubated at a concentration between 0.5 mM and 2 mM.
  5. A FET chip comprising a mixed functionalized graphene structure obtainable by the method according to any of claims 1 to 4, characterized in that the mixed functionalized graphene structure comprises: - a graphene surface; - 1-pyrenebutanoic acid succinimidyl ester (PBASE) molecules; - molecules of at least one type of polycyclic aromatic hydrocarbon (PAH) compounds, the PAH compound being pyrene; and - biomolecules; wherein both the molecules of PBASE and the molecules of pyrene are non-covalently linked to the graphene surface, wherein the biomolecules are linked to the PBASE molecules, and wherein the mixed functionalized graphene structure has a surface roughness (Rms) between around 0.75 nm and around 1.25 nm, wherein Rms is measured by atomic force microscopy (AFM) over a SiO 2 /Si substrate in a 2 × 2 µm 2 area and it is expressed respect to a bare graphene having a Rms value of around 1.00 nm.
  6. The FET chip comprising the functionalized graphene structure according to claim 5, wherein the biomolecules are antibodies.
  7. An electronic device for biological sample analysis characterized in that it comprises at least one FET chip according to any one of claims 5 or 6 as component.
  8. The electronic device for biological sample analysis according to claim 7, wherein said device is a biosensor.
  9. Method for electronic biological sample analysis comprising: a) introducing a biological sample to be analyzed in a device according to claim 8 to bring the biological sample in contact with the mixed functionalized graphene structure comprised in the FET chip of said device; b) applying a voltage to the device; and c) detecting a change of the conductive properties of the functionalized graphene structure comprised in the FET chip resulting in a change of the electric signal of the said device.
  10. Use of the FET chip comprising the mixed functionalized graphene structure according to any of claims 5 or 6 in FET biosensors.

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a Field-Effect Transistor chip comprising a mixed functionalized graphene structure as well as the method for preparing it and to its use. Additionally, the present invention relates to a biosensor comprising said mixed functionalized graphene structure and to a method for electronic analysis of biological samples. BACKGROUND OF THE INVENTION The immobilization of biomolecules on a surface is a key factor in the functionalization process for the development of biosensors. The orientation is very critical for a good recognition event with the target molecule, and the specific orientation of immobilized biomolecules is not easily achieved. However, it is essential to immobilize biomolecules on surfaces without altering their binding activity, specificity and chemical structure. Different strategies for immobilization may result in specific or random orientation of the biomolecules. The orientation on shelf-organizing capacity of the biomolecules may be steered by specific reactive groups on the surface, on biomolecules or on both. Graphene Field Effect Transistors (GFETs) are transistors based on graphene and work based on the modulation of the graphene channel conductance between the source and the drain upon the application of an external electric field through the gate electrode. This graphene channel has revolutionary sensitivity thanks to the thickness of only one atom, which can be exploited on a wide variety of applications such as biosensing (Y. M. Lei et al., Biosens. Bioelectron. 2017, 91, 1-7; L. Zhou et al., Biosens. Bioelectron. 2017, 87, 701-707). Graphene is a two-dimensional material, mono-atomic, planar network of sp2-bonded carbon atoms arranged in a honeycomb lattice. However, its chemical stability, biocompatibility, significant surface-to-volume ratio and field effect make this material very attractive for biosensing applications ("Biocompatible graphene for bioanalytical applications". Y. Hu et al. Springer, 2015). This significant surface-to-volume ratio plays a key role for chemical immobilization of biomolecules onto its surface via covalent or non-covalent functionalization procedures. The covalent functionalization results in stable products, but involves the saturation of some of the double bonds affecting the electronic properties of graphene (WO 2008/097343A2 A2). The non-covalent functionalization allows its solubilization while preserving the structural and electronic features (N. Kozhemyakina et al., Advanced Mater. 2010, 22, 5483-7). PBASE molecules are commonly used as a conventional method to functionalize graphene as non-covalent method, and it is widely studied in many publications (e.g., US 2017/0081195 A1). This chemical modification of graphene with different electroactive molecules through non-covalent interactions, specifically π-π stacking, is widely investigated due to the preservation of the π-conjugated system of graphene. For that reason, it is not strange that a vast majority of the examples related with the non-covalent functionalization of graphene employ planar aromatic molecules and their derivatives. For instance, pyrene derivatives are known to feature strong affinities towards the graphene basal plane via π-π stacking (US 2014/0147938 A1). De Almeida et al., Development of a Graphene-Based Biosensor for Detecting Recombinant Cyanovirin-N. Biosensors. 2020; 10(12):206 discloses a graphene-based biosensor selective to an antiviral protein. The graphene monolayer devices are modified with 1-pyrenebutanoic acid succinimidyl ester. Tween-20 is used to passivate the uncoated graphene surface. In spite of the above-discussed functionalization methods, there remains a need for more controlled and efficient means of preparing chemically modified graphene surface, whilst simultaneously preserving its interesting and desirable properties for exploitation in biosensor applications. BRIEF DESCRIPTION OF THE INVENTION The inventors of the present invention have developed a mixed functionalization of graphene that causes a better interaction of biomolecules to the functionalized graphene surface. A method for preparing a Field-Effect Transistor (FET) chip comprising a mixed functionalized graphene structure is defined in claim 1. A FET chip comprising a mixed functionalized graphene structure obtainable by the method is defined in claim 5. This mixed non-covalent functionalization of graphene results in a specific packing wherein the PAH molecules establish π-π stacking with graphene surface and PBASE molecules are more packed and organized to biomolecules which will react covalently with the ester groups of PBASE molecules adopting more suitable conformations at their binding sites for their target recognition in biosensors. The method as described in claim 1 allows a more controlled and efficient means of preparing chemically modified graphene surfaces. The chemical functionalization of graphene surfac