Synthetic DNA nanopore selects and transports macromolecules across cell membranes.

In the vast microscopic world contained within the human body, a universal component of all cell membranes is known as a lipid bilayer, a biological membrane consisting of two layers of lipid molecules. As it is highly impermeable large molecules and small polar molecules cannot cross the cell membrane, without the assistance of other structures.

To allow the transport of macromolecules and ions across the cell membrane, structural pores made up of transmembrane proteins create hollow water-filled channels across the bilayer. It is therefore highly desirable to develop synthetic structural pores in the cell membrane surface for single-cell disease and homeostatic detection.

Synthetic nanopores for selectivity

Now, a study from researchers led by Aarhus University develops a synthetic DNA nanopore capable of selectively transport protein-sized macromolecules across lipid bilayers. The team states their DNA nanopore will potentially enable the insertion of a sensor to detect diseased cells, to one day allow diagnosis at a single-cell level. The opensource study is published in the journal Nature Communications.

Previous studies show the first commercial DNA nanopore sequencing device was based on a synthetically engineered transmembrane protein. DNA nanopore sequencing allows long DNA strands to be channeled through the central lumen of the pore where changes in the ionic current work as a sensor of the individual bases in the DNA.

Researchers are now looking to develop larger pores to hold proteins with the potential for single-cell sensing purposes. The current study engineers a large synthetic nanopore based on artificial folding of DNA into complex structures, known as the 3D-origami method.

The current study utilizes DNA origami to manufacture a synthetic 9 nm wide DNA nanopore, controlled by programmable, lipid-based flaps and equipped with a size-selective gating system for the translocation of macromolecules. Results show the nanopore structure translocates large protein-sized macromolecules between compartments isolated by a lipid bilayer. Data findings show the functional gating system inserted into the pore allows biosensing of very few molecules in solution.

Optical microscopes were used to track the flow of molecules through each nanopore. Results show the insertion of a controllable plug into the pore enables size-selective control of the flow of macromolecules and demonstration of real-time, label-free biosensing of a trigger molecule.

Synthetic nanopores in sensors

The group states a set of controllable flaps was attached to the pore to enable targeted insertion into membranes. They go on to add this mechanism could allow the insertion of the sensor into diseased cells to enable diagnosis at the single-cell level.

The team surmises they have developed a synthetic DNA nanopore with the ability to select a trigger molecule whilst translocating macromolecules across a lipid bilayer. For the future, the researchers state they now plan to develop more controllable plugs to insert into the pores to provide label-free sensing for a wider range of molecules.

Source: Aarhus University

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