Apr 19, 2011
Simple pulling process creates nanopore for single-molecule sensing
More and more, nanopores are being used as stochastic sensors for biological molecules. Solid-state nanopores are good candidates for such a device and are often fabricated in an insulating membrane. However, membrane nanopores can be easily broken or stripped off from the substrate due to surface tension or salt solution corrosion. Now, researchers in China have shown that glass capillaries can be used to form nanopores for sensing and DNA sequencing applications, as well as controlled delivery and ion conductance microscopy.
The team, which includes scientists from Southeast University, forms a single nanopore at the molecular scale by pulling a glass tube in a two-step process. The principle of the fabrication is based on the physical footprint of the phase change of paraffin sealed inside a glass tube to create a nanocavity in the broken terminal during the second step of the pulling process.
The glass nanopore fabrication process is simple and requires no special or expensive equipment. Furthermore, the electrical noise of the nanopore is low. The noise of the current was about 1.6 pA, which is comparable to the noise level of 1.2–11.8 pA in a α-hemolysin nanopore.
The stable structure of the nanopore and the low level of electrical noise are ideal for electrically addressing single-molecule blocked events. IgG molecule translocation is detected with low electrical noise. The researchers found that the salt concentration affects the pulse signal modes as biomolecules pass through the device.
A full description of the method and images of glass nanopores made using the technique can be found in the journal Nanotechnology.
About the author
The study was conducted by researchers from the Jiangsu Key Laboratory for the Design and Manufacture of Micro-Nano Biomedical Instruments at Southeast University in Nanjing, China. The team is funded by the National Basic Research Program of China (2011CB707605) and the Natural Science Foundation of China (50875047, 50925519 and 51005048). Dr Sha is a faculty member based in the mechanical engineering school at Southeast University. She created the nanopore in a glass capillary and performed the molecule translocation experiments. Prof. Ni is head of the nanostructure physics group. Dr Liu performed the chemical analysis. Prof. Yi is head of the lab. Prof. Chen is group leader. He has a strong interest in force analysis at the nanoscale.