Engineered gold nanoparticles can be like ice cream scoops covered in chocolate sprinkles

There are many ways to interrogate molecular phenomenon. You might think that this is restricted to physical measurements such as direct observation with a microscope, a laser, or more seemingly arcane observation with nuclear magnetic resonance (NMR). But I’m happy to report that observation of computer simulations is yet another, as long as our models are sufficiently accurate that they mimic reality perfectly. In today’s age when it’s hard to see the difference between CGI and real humans, this may not sound surprising. Nevertheless, the question is what can we learn from observation of real and simulated systems in tandem?

I’m happy to report that my student Gene Chong and Cathy Murphy’s student Meng Wu did precisely this parallel study. Gene made simulations of a simpler system, involving nanoparticles covered by lipids called MUTABs. Meng made NMR measurements of nanoparticles covered by a similar but somewhat longer lipids called MTABs. (Note that if you are worried about the term nuclear in NMR, as in nuclear energy, don’t be. We are just looking at the positions of the nuclei, not spitting them apart. It was the concern over this misunderstanding that led to the use of such a device to look at your body in detail to be called MRI instead of NMR!) The happy result was that the two observations agreed. But only together did Meng’s and Gene’s observations show clearly that the lipids didn’t always cover the nanoparticle smoothly like melted chocolate on ice cream, but rather assembled like sprinkles all pointing out in the same direction packed together in different islands on the surface. This structure means that lipid-decorated nanoparticles will have shape and response to other systems that you might not otherwise anticipate. And this opens the question to our next set of investigations as we chart a course to understand the interactions between nanoparticles and biological components such as membranes.

If you want more detail, check out our article in JACS, just recently published!  That is, JACS 141, 4316 (2019), and I'm happy to report that it was funded by the NSF CCI program for our Center for Sustainable Nanotechnology.

Sustainable Nanotechnology - Designing green materials in the nanoparticle age

The birth control pill turned 50 recently, and it was a reminder of the great power of a chemical compound, estrogen, to affect social and political change. A little less attention was given to the role that estrogen levels in our water streams have had on fish in water streams. (See for example, a Scientific American article from 2009 on the possible implications of estrogen in waterways. ) There’s some debate as to where the leading sources of estrogen come from. While most studies indicate that the birth control pill is not the major contributor to its presence in the waterways, there is no doubt that estrogen pollution exists. Regardless, when the birth control pill was introduced, I suspect that few even considered the possibility that estrogen would be a factor in the health of fish in waterways such as the Potomac and Shenandoah rivers.

In this century, there is little doubt that nanoparticles comprise a class of chemical compounds that are revolutionizing nearly everything that we touch, see or smell. Indeed, I am tempted to argue that this century might be called the “nanoparticle age” in the same way that history named the last century as the “industrial age.” The challenge to chemists (and material scientists) is not just designing nanoparticles to solve particular problems, but to do so with materials that have no unintended consequences. Anticipating such unknown unknowns is a grand challenge, and the solution requires a team of scientists with expertise in making, measuring, and modeling the nanoparticles in the upstream design side and in biology and ecology on the downstream side. The Center for Sustainable Nanotechnology (CSN) is taking this challenge head-on. I’m happy and exited to say that I have joined the CSN as part of the modeling team!

Please also check out the announcement of the start of the 5-year effort of the CSN through an NSF CCI Phase II grant CHE-1503408. 

Sustainable Nano on Open Access Sustainably

(This article is a cross-post between EveryWhereChemistry and Sustainable-Nano!)

Sustainability’s future is now. Our recent article was just published in an all-electronic journal, ACS Central Science, which is among the first of the American Chemical Society (ACS) journals offered without a print option. It therefore embodies sustainability as it requires no paper resources, thereby limiting the journal’s carbon footprint to only what is required for maintaining the information electronically in perpetuity. It is also completely Open Access, which means our article is available for all to read. Does this equal accessibility (called “flat” because there is no hierarchy in levels of access) amount to yet another layer of sustainability? More on that question in a moment. Meanwhile as the article itself is about sustainability, it embodies the repetitive word play in the title of this post.

But there is another double meaning in the publishing of this work: The flatness underlying the vision of Open Access is also at play in how the work was done. ELEVEN different research groups were involved in formulating the ideas and writing the paper. This lot provided tremendous breadth of expertise, but the flatness in the organizational effort allowed us to merge it all together. Of course, it wouldn’t have happened without significant leadership, and Cathy Murphy, the paper’s first author, orchestrated us all magnificently. While flatness in organizational behavior isn’t typically considered part of sustainability, in this case it provided for the efficient utilization of resources (that is, ideas) across a broader cohort.

So what is our article about? Fifteen years into the 21st century, it is becoming increasingly clear that we need to develop new materials to solve the grand challenges that confront us in the areas of health, energy, and the environment. Nanoparticles are playing a significant role in new material development because they can provide human-scale effects with relatively small amounts of materials. The danger is that because of their special properties, the use of nanoparticles may have unintended consequences. Thus, many in the scientific community, including those of us involved in writing this article, are concerned with identifying rules for the design and fabrication of nanoparticles that will limit such negative effects, and hence make the particles sustainable by design. In our article, we propose that the solution of this grand challenge hinges on four critical needs:

1. Chemically Driven Understanding of the Molecular Nature of Engineered Nanoparticles in Complex, Realistic Environments
2. Real-Time Measurements of Nanomaterial Interaction with Living Cells and Organisms That Provide Chemical Information at Nanometer Length Scales To Yield Invaluable Mechanistic Insight and Improve Predictive Understanding of the Nano−Bio Interface.
3. Delineation of Molecular Modes of Action for Nanomaterial Effects on Living Systems as Functions of Nanomaterial Properties
4. Computation and Simulation of the Nano−Bio Interface.

In more accessible terms, this translates to: (1) It’s not enough to know how the nanoparticles behave in a test tube under clean conditions as we need to know how they might behave at the molecular scale in different solutions. (2) We also need to better understand and measure the effects of nanoparticles at contact points between inorganic materials and biological matter. (3) Not only do we need to observe how nanoparticles behave in relation to living systems, but to understand what drives that behavior at a molecular level. (4) In order to accelerate design and discovery as well as to avoid the use of materials whenever possible, we also need to design validated computational models for all of these processes.

Take a look at the article for the details as we collectively offer a blueprint for what research problems need to be solved in the short term (a decade or so), and how our team of nanoscientists, with broad experience in making, measuring, and simulating nanoparticles in complex environments, can make a difference.

The title of the article is "Biological Responses to Engineered Nanomaterials: Needs for the Next Decade.” The work was funded by the NSF as part of the Phase I Center for Sustainable Nanotechnology (CSN, CHE-124051). It was just released at ACS Central Science, XXXX (2015) as an ASAP Article. The author list is C. Murphy, A. Vartanian, F. Geiger, R. Hamers, J. Pedersen, Q. Cui, C. Haynes, E. Carlson, R. Hernandez, R. Klaper, G. Orr, and Z. Rosenzweig,

It’s available as Open Access right now at http://dx.doi.org/10.1021/acscentsci.5b00182