Tag Archives: plasmonic nanoparticles

Nanoparticle computing

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I’m fascinated with this news and I’m pretty sure it’s my first exposure to nanoparticle computing so am quite excited about this ‘discovery of mine’.

A February 25, 2019 news item on Nanowerk announces the research from Korean scientists,

Computation is a ubiquitous concept in physical sciences, biology, and engineering, where it provides many critical capabilities. Historically, there have been ongoing efforts to merge computation with “unusual” matters across many length scales, from microscopic droplets (Science 315, 832, 2007) to DNA nanostructures (Science 335, 831, 2012; Nat. Chem. 9, 1056, 2017) and molecules (Science 266, 1021, 1994; Science 314, 1585, 2006; Nat. Nanotech. 2, 399, 2007; Nature 375, 368, 2011).

However, the implementation of complex computation in particle systems, especially in nanoparticles, remains challenging, despite a wide range of potential applications that would benefit from algorithmically controlling their unique and potentially useful intrinsic features (such as photonic, plasmonic, catalytic, photothermal, optoelectronic, electrical, magnetic and material properties) without human interventions.

This challenge is not due to the lack of sophistication in the the current state-of-the-art of stimuli-responsive nanoparticles, many of which can conceptually function as elementary logic gates. This is mostly due to the lack of scalable architectures that would enable systematic integration and wiring of the gates into a large integrated circuit.

Previous approaches are limited to (i) demonstrating one simple logic operation per test tube or (ii) relying on complicated enzyme-based molecular circuits in solution. It should be also noted that modular and scalable aspects are key challenges in DNA computing for practical and widespread use.

…

A February 23, 2019 Seoul National University press release on EurekAlert, which originated the news items, dives into more detail,

In nature, the cell membrane is analogous to a circuit board, as it organizes a wide range of biological nanostructures (e.g. proteins) as (computational) units and allows them to dynamically interact with each other on the fluidic 2D surface to carry out complex functions as a network and often induce signaling intracellular signaling cascades. For example, the membrane proteins on the membrane take chemical/physical cues as inputs (e.g. binding with chemical agents, mechanical stimuli) and change their conformations and/or dimerize as outputs. Most importantly, such biological “computing” processes occur in a massively parallel fashion. Information processing on living cell membranes is a key to how biological systems adapt to changes in external environments.

This manuscript reports the development of a nanoparticle-lipid bilayer hybrid-based computing platform termed lipid nanotablet (LNT), in which nanoparticles, each programmed with surface chemical ligands (DNA in this case), are tethered to a supported lipid bilayer to carry out computation. Taking inspirations from parallel computing processes on cellular membranes, we exploited supported lipid bilayers (SLBs)–synthetic mimics for cell surfaces–as chemical circuit boards to construct nanoparticle circuits. This “nano?bio” computing, which occurs at the interface of nanostructures and biomolecules, translates molecular information in solution (input) into dynamic assembly/disassembly of nanoparticles on a lipid bilayer (output).

We introduced two types of nanoparticles to a lipid bilayer that differ in mobility: mobile Nano-Floaters and immobile Nano-Receptors. Due to high mobility, floaters actively interact with receptors across space and time, functioning as active units of computation. The nanoparticles are functionalized with specially designed DNA [deoxyribonucleic acid] ligands, and the surface ligands render receptor-floater interactions programmable, thereby transforming a pair of receptor and floater into a logic gate. A nanoparticle logic gate takes DNA strands in solution as inputs and generates nanoparticle assembly or disassembly events as outputs. The nanoparticles and their interactions can be imaged and tracked by dark-field microscopy with single-nanoparticle resolution because of strong and stable scattering signals from plasmonic nanoparticles. Using this approach (termed “interface programming”), we first demonstrated that a pair of nanoparticles (that is, two nanoparticles on a lipid bilayer) can carry out AND, OR, INHIBIT logic operations and take multiple inputs (fan-in) and generate multiple outputs (fan-out). Also, multiple logic gates can be modularly wired with AND or OR logic via floaters, as the mobility of floaters enables the information cascade among several nanoparticle logic gates. We termed this strategy “network programming.” By combining these two strategies (interfacial and network programming), we were able to implement complex logic circuits such as multiplexer.

The most important contributions of our paper are the conceptual one and the major advances in modular and scalable molecular computing (DNA computing in this case). LNT platform, for the first time, introduces the idea of using lipid bilayer membranes as key components for information processing. As the two-dimensional (2D) fluidic lipid membrane is bio-compatible and chemically modifiable, any nanostructures can be potentially introduced and used as computing units. 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. Moreover, we also developed a digitized imaging method and software for quantitative and massively parallel analysis of interacting nanoparticles. In addition, LNT platform provides many practical merits to current state-of-the-art in molecular computing and nanotechnology. On LNT platforms, a network of nanoparticles (each with unique and beneficial properties) can be design to autonomously respond to molecular information; such capability to algorithmically control nanoparticle networks will be very useful for addressing many challenges with molecular computing and developing new computing platforms. As the title of our manuscript suggests, this nano-bio computing will lead to exciting opportunities in biocomputation, nanorobotics, DNA nanotechnology, artificial bio-interfaces, smart biosensors, molecular diagnostics, and intelligent nanomaterials. In summary, the operating and design principles of lipid nanotablet platform are as follows:

(1) LNT uses single nanoparticles as units of computation. By tracking numerous nanoparticles and their actions with dark-field microscopy at the single-particle level, we could treat a single nanoparticle as a two-state device representing a bit. A nanoparticle provides a discrete, in situ optical readout of its interaction (e.g. association or dissociation) with another particle as an output of logic computation.

(2) Nanoparticles on LNT function as Boolean logic gates. We exploited the programmable bonding interaction within particle-particle interfaces to transform two interacting nanoparticles into a Boolean logic gate. The gate senses single-stranded DNA as inputs and triggers an assembly or disassembly reaction of the pair as an output. We demonstrated two-input AND, two-input OR and INHIBIT logic operations, and fan-in/fan-out of logic gates.

(3) LNT enables modular wiring of multiple nanoparticle logic gates into a combinational circuit. We exploited parallel, single-particle imaging to program nanoparticle networks and thereby wire multiple logic gates into a combinational circuit. We demonstrate a multiplexer MUX2to1 circuit built from the network wiring rules.

Here’s a link to and a citation for the team’s latest paper,

Nano-bio-computing lipid nanotablet by Jinyoung Seo, Sungi Kim, Ha H. Park, Da Yeon Choi, and Jwa-Min Nam. Science Advances 22 Feb 2019: Vol. 5, no. 2, eaau2124 DOI: 10.1126/sciadv.aau2124

This paper appears to be open access.

Multicolor, electrochromic glass

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Electrochromic (changes color to block light and heat) glass could prove to be a significant market by 2020 according to a March 8, 2017 news item on phys.org,

Rice University’s latest nanophotonics research could expand the color palette for companies in the fast-growing market for glass windows that change color at the flick of an electric switch.

In a new paper in the American Chemical Society journal ACS Nano, researchers from the laboratory of Rice plasmonics pioneer Naomi Halas report using a readily available, inexpensive hydrocarbon molecule called perylene to create glass that can turn two different colors at low voltages.

“When we put charges on the molecules or remove charges from them, they go from clear to a vivid color,” said Halas, director of the Laboratory for Nanophotonics (LANP), lead scientist on the new study and the director of Rice’s Smalley-Curl Institute. “We sandwiched these molecules between glass, and we’re able to make something that looks like a window, but the window changes to different types of color depending on how we apply a very low voltage.”

Adam Lauchner, an applied physics graduate student at Rice and co-lead author of the study, said LANP’s color-changing glass has polarity-dependent colors, which means that a positive voltage produces one color and a negative voltage produces a different color.

“That’s pretty novel,” Lauchner said. “Most color-changing glass has just one color, and the multicolor varieties we’re aware of require significant voltage.”

Glass that changes color with an applied voltage is known as “electrochromic,” and there’s a growing demand for the light- and heat-blocking properties of such glass. The projected annual market for electrochromic glass in 2020 has been estimated at more $2.5 billion.

A March 8, 2017 Rice University news release (also on EurekAlert), which originated the news item, provides more detail about the research,

Lauchner said the glass project took almost two years to complete, and he credited co-lead author Grant Stec, a Rice undergraduate researcher, with designing the perylene-containing nonwater-based conductive gel that’s sandwiched between glass layers.

“Perylene is part of a family of molecules known as polycyclic aromatic hydrocarbons,” Stec said. “They’re a fairly common byproduct of the petrochemical industry, and for the most part they are low-value byproducts, which means they’re inexpensive.”

Grant Stec and Adam Lauchner

Grant Stec and Adam Lauchner of Rice University’s Laboratory for Nanophotonics have used an inexpensive hydrocarbon molecule called perylene to create a low-voltage, multicolor, electrochromic glass. (Photo by Jeff Fitlow/Rice University)

There are dozens of polycyclic aromatic hydrocarbons (PAHs), but each contains rings of carbon atoms that are decorated with hydrogen atoms. In many PAHs, carbon rings have six sides, just like the rings in graphene, the much-celebrated subject of the 2010 Nobel Prize in physics.

“This is a really cool application of what started as fundamental science in plasmonics,” Lauchner said.

A plasmon is [a] wave of energy, a rhythmic sloshing in the sea of electrons that constantly flow across the surface of conductive nanoparticles. Depending upon the frequency of a plasmon’s sloshing, it can interact with and harvest the energy from passing light. In dozens of studies over the past two decades, Halas, Rice physicist Peter Nordlander and colleagues have explored both the basic physics of plasmons and potential applications as diverse as cancer treatment, solar-energy collection, electronic displays and optical computing.

The quintessential plasmonic nanoparticle is metallic, often made of gold or silver, and precisely shaped. For example, gold nanoshells, which Halas invented at Rice in the 1990s, consist of a nonconducting core that’s covered by a thin shell of gold.

Grant Stec, Naomi Halas and Adam Lauchner

Student researchers Grant Stec (left) and Adam Lauchner (right) with Rice plasmonics pioneer Naomi Halas, director of Rice University’s Laboratory for Nanophotonics. (Photo by Jeff Fitlow/Rice University)

“Our group studies many kinds of metallic nanoparticles, but graphene is also conductive, and we’ve explored its plasmonic properties for several years,” Halas said.

She noted that large sheets of atomically thin graphene have been found to support plasmons, but they emit infrared light that’s invisible to the human eye.

“Studies have shown that if you make graphene smaller and smaller, as you go down to nanoribbons, nanodots and these little things called nanoislands, you can actually get graphene’s plasmon closer and closer to the edge of the visible regime,” Lauchner said.

In 2013, then-Rice physicist Alejandro Manjavacas, a postdoctoral researcher in Nordlander’s lab, showed that the smallest versions of graphene — PAHs with just a few carbon rings — should produce visible plasmons. Moreover, Manjavacas calculated the exact colors that would be emitted by different types of PAHs.

“One of the most interesting things was that unlike plasmons in metals, the plasmons in these PAH molecules were very sensitive to charge, which suggested that a very small electrical charge would produce dramatic colors,” Halas said.

Electrochromic glass that glass that turns from clear to black

Rice University researchers demonstrated a new type of glass that turns from clear to black when a low voltage is applied. The glass uses a combination of molecules that block almost all visible light when they each gain a single electron. (Photo by Jeff Fitlow/Rice University)

Lauchner said the project really took off after Stec joined the research team in 2015 and created a perylene formulation that could be sandwiched between sheets of conductive glass.

In their experiments, the researchers found that applying just 4 volts was enough to turn the clear window greenish-yellow and applying negative 3.5 volts turned it blue. It took several minutes for the windows to fully change color, but Halas said the transition time could easily be improved with additional engineering.

Stec said the team’s other window, which turns from clear to black, was produced later in the project.

“Dr. Halas learned that one of the major hurdles in the electrochromic device industry was making a window that could be clear in one state and completely black in another,” Stec said. “We set out to do that and found a combination of PAHs that captured no visible light at zero volts and almost all visible light at low voltage.”

Here’s a link to and a citation for the paper,

Multicolor Electrochromic Devices Based on Molecular Plasmonics by Grant J. Stec, Adam Lauchner, Yao Cui, Peter Nordlander, and Naomi J. Halas. ACS Nano, Article ASAP DOI: 10.1021/acsnano.7b00364 Publication Date (Web): February 22, 2017

Copyright © 2017 American Chemical Society

This paper is behind a paywall.

University of Toronto’s Ted Sargent and his colloidal quantum dots make news again

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Ted Sargent at the University of Toronto is one of the most consistent communicators, in Canada, about nanoscale research. His work is focused on solar panels/cells and colloidal quantum dots and according to a Mar. 7, 2013 news release on EurekAlert, there have been some new developments,

A new technique developed by U of T Engineering Professor Ted Sargent and his research group could lead to significantly more efficient solar cells, according to a recent paper published in the journal Nano Letters.

The paper, “Jointly-tuned plasmonic-excitonic photovoltaics using nanoshells,” describes a new technique to improve efficiency in colloidal quantum dot photovoltaics, a technology which already promises inexpensive, more efficient solar cell technology. Quantum dot photovoltaics offers the potential for low-cost, large-area solar power – however these devices are not yet highly efficient in the infrared portion of the sun’s spectrum, which is responsible for half of the sun’s power that reaches the Earth.

The solution? Spectrally tuned, solution-processed plasmonic nanoparticles. These particles, the researchers say, provide unprecedented control over light’s propagation and absorption.

The new technique developed by Sargent’s group shows a possible 35 per cent increase in the technology’s efficiency in the near-infrared spectral region, says co-author Dr. Susanna Thon. Overall, this could translate to an 11 per cent solar power conversion efficiency increase, she says, making quantum dot photovoltaics even more attractive as an alternative to current solar cell technologies.

The University of Toronto Mar. 7, 2013 news release written by Terry Lavender, which is the original of the one on EurekAlert, goes on to explain the interest in colloidal quantum dots and to describe the new technique,

“There are two advantages to colloidal quantum dots,” Thon says. “First, they’re much cheaper, so they reduce the cost of electricity generation measured in cost per watt of power. But the main advantage is that by simply changing the size of the quantum dot, you can change its light-absorption spectrum.

“Changing the size is very easy, and this size-tunability is a property shared by plasmonic materials: by changing the size of the plasmonic particles, we were able to overlap the absorption and scattering spectra of these two key classes of nanomaterials.”

Sargent’s group achieved the increased efficiency by embedding gold nanoshells directly into the quantum dot absorber film. Gold is not usually thought of as an economical material but researchers say lower-cost metals can be used to implement the same concept proved by Thon and her co-workers.

It’s exciting work and a 35% increase in efficiency sounds great, although the base efficiency isn’t mentioned. If your base is one and you increase it to two, you have a 100% increase. As I noted in my July 30, 2012 posting about the team’s last breakthrough which showed a 37% increase in efficiency for their technique but actually worked out to a 7% increase for solar cell efficiency,

I think the excitement over 7% indicates just how much hard work the researchers have accomplished to achieve this efficiency. It reminds me of reading about the early development of electricity (Power struggles; Scientific authority and the creation of practical electricity before Edison by Michael Brian Schiffer)  where accomplishments we would now consider minuscule built careers.

These increases  may be small but they are important not only for the development of solar cells but also as an illustration of how scientific breakthroughs are often a series of small steps and of the infinite patience exercised by researchers.