Graphene nanopipette enabled liquid delivery at zeptoliter precision

TL;DR

This paper introduces a graphene nanopipette capable of delivering liquids at zeptoliter precision, enabling advanced nanocharacterization and biological analysis with high accuracy and control.

Contribution

The study presents a novel graphene nanopipette with controllable liquid encapsulation at zeptoliter scale, suitable for multiple nanocharacterization techniques and biological applications.

Findings

Achieved liquid delivery at zeptoliter scale using GNP.

Demonstrated GNP as a nanocharacterization tool with isotope-labeled glucose.

Validated controlled liquid encapsulation through experiments and finite element analysis.

Abstract

Accurate extraction of liquid is the first step towards low-volume liquid delivery and nanocharacterization, which plays a significant role in biomedical research. In this study, a tip-shaped graphene nanopipette (GNP) is proposed by encapsulating the biomolecule solution on the prefabricated metal tip with graphene. The volume of the encapsulated liquid is highly controllable at zeptoliter precision by tuning the encapsulating speed and the number of graphene encapsulation rounds. Using protein (ferritin) solution as an example, it has been confirmed by finite element analysis and the controlled experiments that the GNP allows the delivery of ferritin solution at the zeptoliter-scale. Furthermore, GNP is demonstrated as a new type of tip-shaped liquid cell, which is suitable for multiple nanocharacterization techniques. In particular, due to the ultra-sharp tip shape, isotope (13C)-labelled glucose solution encapsulated in GNP has been characterized by atom probe tomography (APT) in the laser-pulsed mode. Analysis of the mass spectrum and the reconstructed three-dimensional chemical maps reveals the quantitative distribution and the compositions of individual glucose molecules. The GNP is expected to be introduced to deliver liquid in the range of zeptoliters to attoliters, and brings a new capability for characterization of biological specimens in their near-native state.