AsianScientist (Feb. 27, 2015) – Scientists have found an innovative use for a protein linked to Parkinson’s disease: synthesizing large sheets of monolayer nanoparticle films. Their results, published in Angewandte Chemie, further the development of flexible nanoelectronic devices.
Ultrathin films of nanoparticles are highly sought after for their potential use in optical and electronic devices. One approach has been to use gold nanoparticles attached to DNA, where the interaction between the DNA molecules gives rise to well-organized arrays. However, this method is limited to micrometer-scale fabrication and is not suitable for larger devices.
Instead of DNA, a team of researchers led by Seoul National University professor Paik Seung Ryeoul has turned to a protein, namely α-synuclein. Responsible for the regulation of dopamine release in the brain, α-synuclein is more famously known as the protein which forms fibril structures associated with neurodegenerative diseases such as Parkinson’s.
Making use of the strong tendency of α-synuclein to aggregate when misfolded, the researchers coated gold nanoparticles with a layer of the protein and then allowed the nanoparticle-protein conjugates to absorb onto a polycarbonate surface treated with oxygen plasma. The proteins bound to the surface and eventually formed a densely packed monolayer of gold nanoparticles held together through protein-protein interactions.
In the final step, the polycarbonate support was dissolved away with chloroform. At the same time, this solvent also triggers the misfolding of the proteins, which allows them to aggregate tightly and specifically, giving the free-standing monolayers necessary stability even after they are dried. In contrast to previously described methods, this technique can produce films with dimensions reaching the millimeter and centimeter range, and was used to coat a four inch wafer.
The color of the transparent films depends on the size of the gold particles used: 10 nm particle films are bright pink, 20 nm particle films are purple, and those made from 30 nm particles are dark blue. The films are so flexible that they can be crumpled up and then smoothed out again in a liquid. They can also encase round objects, such as silica spheres, without tearing.
The researchers were additionally able to use lithographically prepared surfaces to make films with patterns of holes. Sequential adsorption on the support also allowed them to make films with a color pattern made from nanoparticles of two different sizes.
The scientists hope to be able to add a variety of functionalities to their films, by using magnetic nanoparticles or quantum dots, for example. Potential areas of application include electronic components, ultrathin displays, and biocompatible sensors for the in vivo observation of organs and tissues. They expect these films to be used for not only controlling cellular activity like cancer treatment, but also cell-to-machine interface in the areas of neuroscience and robotics.
The article can be found at: Lee et al. (2015) Free-Standing Gold-Nanoparticle Monolayer Film Fabricated by Protein Self-Assembly of α-Synuclein.
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Source: Angewandte Chemie.
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