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Selectively Sized Graphene-Based Nanopores for in Situ Single Molecule Sensing.

Crick CR, Sze JY, Rosillo-Lopez M, Salzmann CG, Edel JB - ACS Appl Mater Interfaces (2015)

Bottom Line: The precise tailoring of nanopore size is a significant step toward achieving this, as it would allow for a nanopore to be tuned to a corresponding analyte.The translocation of DNA is studied as the pore size is varied, allowing for subfeatures of DNA to be detected with slower DNA translocations at smaller pore sizes, and the ability to observe trends as the pore is opened.This approach opens the door to creating a device that can be target to detect specific analytes.

View Article: PubMed Central - PubMed

Affiliation: †Department of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom.

ABSTRACT
The use of nanopore biosensors is set to be extremely important in developing precise single molecule detectors and providing highly sensitive advanced analysis of biological molecules. The precise tailoring of nanopore size is a significant step toward achieving this, as it would allow for a nanopore to be tuned to a corresponding analyte. The work presented here details a methodology for selectively opening nanopores in real-time. The tunable nanopores on a quartz nanopipette platform are fabricated using the electroetching of a graphene-based membrane constructed from individual graphene nanoflakes (ø ∼30 nm). The device design allows for in situ opening of the graphene membrane, from fully closed to fully opened (ø ∼25 nm), a feature that has yet to be reported in the literature. The translocation of DNA is studied as the pore size is varied, allowing for subfeatures of DNA to be detected with slower DNA translocations at smaller pore sizes, and the ability to observe trends as the pore is opened. This approach opens the door to creating a device that can be target to detect specific analytes.

No MeSH data available.


(A) Nanopipette coating schematic. Steps include (i) dip-coatingpipettes into GNF solutions of various concentrations, (ii) leavingpipettes with tips pointing downward for 10 min of air drying, and(iii) vacuum annealing carried out at 900 °C and a pressure of∼1.5 × 10–5 mbar. (B) Shows an opticalimage of the nanopipette (scale bar inset). (C) A cartoon of an individualsmall GNF. The size of each GNF is ∼30 nm, and the edges ofthe GNF are functionalized with carboxylic acid groups. (D) AFM imageof a spin-coated GNFs annealed on a quartz substrate. The spin coatingwas carried out using a 1.5 mg mL–1 GNF solution,at a spin speed of 5000 rpm for 30 s. The individual features (ø∼30 nm) are the annealed GNFs, the measured surface roughnessindicates a multilayered arrangement (scale bar inset). (E) Ramanspectrum of the annealed GNF film on quartz substrates. The characteristicD and G bands present in graphene are indicated on the spectrum.
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fig1: (A) Nanopipette coating schematic. Steps include (i) dip-coatingpipettes into GNF solutions of various concentrations, (ii) leavingpipettes with tips pointing downward for 10 min of air drying, and(iii) vacuum annealing carried out at 900 °C and a pressure of∼1.5 × 10–5 mbar. (B) Shows an opticalimage of the nanopipette (scale bar inset). (C) A cartoon of an individualsmall GNF. The size of each GNF is ∼30 nm, and the edges ofthe GNF are functionalized with carboxylic acid groups. (D) AFM imageof a spin-coated GNFs annealed on a quartz substrate. The spin coatingwas carried out using a 1.5 mg mL–1 GNF solution,at a spin speed of 5000 rpm for 30 s. The individual features (ø∼30 nm) are the annealed GNFs, the measured surface roughnessindicates a multilayered arrangement (scale bar inset). (E) Ramanspectrum of the annealed GNF film on quartz substrates. The characteristicD and G bands present in graphene are indicated on the spectrum.

Mentions: The work presentedin this article aims to use multilayered graphene films to completelycover our nanopipette (see the Supporting Information for full experimental details). The aim of the experiments was tocompletely coat the pore at the end of the nanopipettes using waterdispersed graphene nanoflakes (GNFs). The GNFs used in the experimentare small portions of single layered graphene (ø ∼30 nm)that are able to be dispersed in a solvent (Figure 1C).49 Graphitic films are formedby annealing the GNF-coated nanopipettes in a vacuum oven. The nanoporecoating is analyzed using ionic conductivity measurements. Alternatingcurrent (AC) is used to etch away the membrane material with the frequencyapplied potential and overall treatment length tuned for steady poreopening. The AC opening technique provides the opportunity for graphenemembrane etching, electrical testing and DNA translocations to beperformed without interruption. The translocation of DNA is carriedout as the pores are opened, and any observed difference in DNA behavioris related to the effect of nanopore size. The reported techniqueaims to demonstrate precise in situ nanopore size control, which wouldbe a vital tool in generating effective and broadly functioning nanoporedevices.


Selectively Sized Graphene-Based Nanopores for in Situ Single Molecule Sensing.

Crick CR, Sze JY, Rosillo-Lopez M, Salzmann CG, Edel JB - ACS Appl Mater Interfaces (2015)

(A) Nanopipette coating schematic. Steps include (i) dip-coatingpipettes into GNF solutions of various concentrations, (ii) leavingpipettes with tips pointing downward for 10 min of air drying, and(iii) vacuum annealing carried out at 900 °C and a pressure of∼1.5 × 10–5 mbar. (B) Shows an opticalimage of the nanopipette (scale bar inset). (C) A cartoon of an individualsmall GNF. The size of each GNF is ∼30 nm, and the edges ofthe GNF are functionalized with carboxylic acid groups. (D) AFM imageof a spin-coated GNFs annealed on a quartz substrate. The spin coatingwas carried out using a 1.5 mg mL–1 GNF solution,at a spin speed of 5000 rpm for 30 s. The individual features (ø∼30 nm) are the annealed GNFs, the measured surface roughnessindicates a multilayered arrangement (scale bar inset). (E) Ramanspectrum of the annealed GNF film on quartz substrates. The characteristicD and G bands present in graphene are indicated on the spectrum.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4543996&req=5

fig1: (A) Nanopipette coating schematic. Steps include (i) dip-coatingpipettes into GNF solutions of various concentrations, (ii) leavingpipettes with tips pointing downward for 10 min of air drying, and(iii) vacuum annealing carried out at 900 °C and a pressure of∼1.5 × 10–5 mbar. (B) Shows an opticalimage of the nanopipette (scale bar inset). (C) A cartoon of an individualsmall GNF. The size of each GNF is ∼30 nm, and the edges ofthe GNF are functionalized with carboxylic acid groups. (D) AFM imageof a spin-coated GNFs annealed on a quartz substrate. The spin coatingwas carried out using a 1.5 mg mL–1 GNF solution,at a spin speed of 5000 rpm for 30 s. The individual features (ø∼30 nm) are the annealed GNFs, the measured surface roughnessindicates a multilayered arrangement (scale bar inset). (E) Ramanspectrum of the annealed GNF film on quartz substrates. The characteristicD and G bands present in graphene are indicated on the spectrum.
Mentions: The work presentedin this article aims to use multilayered graphene films to completelycover our nanopipette (see the Supporting Information for full experimental details). The aim of the experiments was tocompletely coat the pore at the end of the nanopipettes using waterdispersed graphene nanoflakes (GNFs). The GNFs used in the experimentare small portions of single layered graphene (ø ∼30 nm)that are able to be dispersed in a solvent (Figure 1C).49 Graphitic films are formedby annealing the GNF-coated nanopipettes in a vacuum oven. The nanoporecoating is analyzed using ionic conductivity measurements. Alternatingcurrent (AC) is used to etch away the membrane material with the frequencyapplied potential and overall treatment length tuned for steady poreopening. The AC opening technique provides the opportunity for graphenemembrane etching, electrical testing and DNA translocations to beperformed without interruption. The translocation of DNA is carriedout as the pores are opened, and any observed difference in DNA behavioris related to the effect of nanopore size. The reported techniqueaims to demonstrate precise in situ nanopore size control, which wouldbe a vital tool in generating effective and broadly functioning nanoporedevices.

Bottom Line: The precise tailoring of nanopore size is a significant step toward achieving this, as it would allow for a nanopore to be tuned to a corresponding analyte.The translocation of DNA is studied as the pore size is varied, allowing for subfeatures of DNA to be detected with slower DNA translocations at smaller pore sizes, and the ability to observe trends as the pore is opened.This approach opens the door to creating a device that can be target to detect specific analytes.

View Article: PubMed Central - PubMed

Affiliation: †Department of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom.

ABSTRACT
The use of nanopore biosensors is set to be extremely important in developing precise single molecule detectors and providing highly sensitive advanced analysis of biological molecules. The precise tailoring of nanopore size is a significant step toward achieving this, as it would allow for a nanopore to be tuned to a corresponding analyte. The work presented here details a methodology for selectively opening nanopores in real-time. The tunable nanopores on a quartz nanopipette platform are fabricated using the electroetching of a graphene-based membrane constructed from individual graphene nanoflakes (ø ∼30 nm). The device design allows for in situ opening of the graphene membrane, from fully closed to fully opened (ø ∼25 nm), a feature that has yet to be reported in the literature. The translocation of DNA is studied as the pore size is varied, allowing for subfeatures of DNA to be detected with slower DNA translocations at smaller pore sizes, and the ability to observe trends as the pore is opened. This approach opens the door to creating a device that can be target to detect specific analytes.

No MeSH data available.