Cell Membrane Inspires Nanoparticle Computing

The lipid nanotablet platform uses lipid bilayer membranes as a ‘chip’ to control nanoparticles and create nanoparticle-based logic gates.

AsianScientist (Mar. 16, 2020) – We are now one step closer to being able to use nanoparticles for computing, thanks to research by scientists at Seoul National University (SNU), South Korea. Their findings, published in Science Advances, show that it is possible to assemble nanoparticle-based circuits on a lipid bilayer that mimics natural cell membranes.

Because of their small size, nanoparticles behave differently from materials at the bulk scale, exhibiting unique photonic, electrical and magnetic properties. Being able to do computation with nanoparticles would thus open up new possibilities. However, current nanoparticle computing approaches relying on stimuli-responsive nanoparticles are limited to one simple logic operation per test tube, while more complicated enzyme-based molecular circuits are too difficult too control in three dimensional space.

Instead, a team led by Nam Jwa-Min at SNU took a leaf out of Nature’s book, using the lipid bilayer of cell membranes as a starting point. The cell membrane is analogous to a circuit board in the sense that it organizes a wide range of biological nanostructures into units, allowing them to dynamically interact with each other on a two dimensional surface and carry out complex functions as a network. For example, membrane proteins take chemical or physical cues as inputs, changing their conformations as outputs.

Nam and his team mimicked the cell membrane by using two types of nanoparticles tethered to a supporting lipid bilayer: mobile Nano-Floaters and immobile Nano-Receptors. Both types of nanoparticles were functionalized with specially designed DNA ligands, which rendered the Floater-Receptor interactions programmable.

Using Floater-Receptor pairs as a logic gate, the researchers were able to use DNA strands as inputs to control nanoparticle assembly or disassembly as outputs. The nanoparticles and their interactions could be imaged and tracked by dark-field microscopy with single-nanoparticle resolution because of strong and stable scattering signals from plasmonic nanoparticles.

A supported lipid bilayer is used as a chemical circuit board to carry out molecular computation with a network of nanoparticles. Nanoparticle logic operations are monitored by scattering color change of nanoparticles using dark-field microscopy and analyzed by in-house nanoparticle imaging software. A nanoparticle logic gate takes DNA strands in solution as inputs and generates nanoparticle assembly or disassembly events as outputs. Photo: Nam Jwa-Min/SNU

Using this approach, the researchers demonstrated that pairs of nanoparticles can carry out AND, OR and INHIBIT logic operations, as well as take multiple inputs and generate multiple outputs. Also, they showed that multiple logic gates could be modularly wired with AND or OR logic, as the mobility of floaters enables information to cascade along several nanoparticle logic gates. By combining these two strategies, they were able to implement complex logic circuits such as multiplexer.

“When tethered to the lipid bilayer ‘chip,’ these nanostructures can be visualized and become controllable at the single-particle level; this dimensionality reduction, bringing the nanostructures from freely diffusible solution phase (3D) to fluidic membrane (2D), transforms a collection of nanostructures into a programmable, analyzable reaction network,” Nam explained.

Naming their invention the lipid nanotablet (LNT), Nam and his team said that the LNT platform can be designed to autonomously respond to molecular information, and that this capability will lead to exciting opportunities in biocomputation, nanorobotics, and artificial bio-interfaces.

The article can be found at: Seo et al. (2019) Nano-bio-computing Lipid Nanotablet.


Source: Seoul National University; Photo: Shutterstock.
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