The United States Patent Office has issued Associate Professor Sarah Perry of the Chemical Engineering Department a patent for her “Graphene Based Electro-Microfluidic Devices and Methods for Protein Structural Analysis.”
Perry’s patent not only relates to microfluidic devices – a kind of technology that uses tiny amounts of fluid ranging from a nanoliter to a milliliter in containers that are as thin as a human hair – but to X-ray analysis and structural biology.
In particular, her new patent is concerned with the development of microfluidic devices that utilize graphene films as architectural materials that provide both X-ray transparency, because of their atomically thin nature, and conductivity. This combination of features is important because traditionally conductive materials such as metals would interfere with the X-ray analysis.
As background for her invention, Perry explains that microfluidic and microscale devices have a demonstrated track record for enabling protein crystallization. Much of our knowledge of how proteins function comes from diffraction studies on protein crystals.
As Perry explains, “Think of all of the images of SARS-CoV-2 and its spike protein that we have seen over the last two years. Many of those structures are the result, at least in part, of protein crystallography.”
In addition to facilitating the growth of protein crystals, microfluidic platforms have been increasingly harnessed to facilitate diffraction studies as well.
“Protein crystals are very delicate and can be easily dried out or damaged,” says Perry. “Being able to analyze the crystals directly inside of the device where they were grown can make a significant difference in the level of detail that can be seen in a structure.”
A core feature of her invention, says Perry, is that it harnesses the intrinsic conductivity of graphene to enable electro-crystallization experiments in the precisely controlled microfluidic geometry her newly patented array of devices, along with in situ X-ray analysis of the resulting crystals. Thus, the new devices and methods of the patent afford faster nucleation and crystal growth, as well as potentially better diffraction data obtained from crystals prepared in the presence of an applied electric field.
Perry’s new devices and methods can also be used to examine the effects of an electric field on the structure and structural dynamics of the crystal. While proteins are dynamic molecular machines that move as they function, the vast majority of structures are merely still photographs.
As Perry says, “Imagine trying to watch a soccer match through just a series of still images. You see a picture of a player charging towards the goal, then you see a photograph of a celebration, but you don’t really know how the point was scored. This is what trying to understand protein function is like.”
Perry goes on to explains that “The brilliance of X-ray free-electron lasers (XFELs) has created a revolution in the field of structural biology. XFELs generate ultra-fast X-ray pulses that can effectively be used to create a video of a protein as it functions. However, the intensity of the X-rays also means that each pulse destroys the sample as it makes the measurement. Scientists have gotten around this challenge by supplying a large number of crystals to the X-ray beam in a ‘serial’ fashion.”
But such analysis carries a built-in set of problems, as Perry notes: “These large-scale serial methods suffer from the need to grow and manipulate a large number of high-quality crystals. These issues are then further compounded by the need to deliver such samples efficiently to the X-ray beam and the challenge of synchronizing structural dynamics within crystals.”
As Perry notes, “Once you are able to grow high-quality crystals, the challenge with time-resolved crystallography is the need to trigger all of the protein molecules in a crystal to move at the same time.”
Continuing with the soccer analogy, “If you look at all of the people in the stadium, it seems like they are just moving randomly. However, if somebody can coordinate everyone to get a wave going, you see it as a clear, concerted movement. This is what we need to achieve in order to watch proteins function.”
The vast majority of studies reported to date have taken advantage of proteins where this kind of functional motion can be triggered by light. Unfortunately, there are very few proteins for which this strategy works. One potential solution is to try and use an electric field to trigger dynamics.
“We are working very closely with several collaborators on this project, and our graphene-based microfluidic devices have tremendous promise to help make these very challenging experiments easier.”
The new patent is yet another pioneering development for the Perry Research Group, which utilizes self-assembly, molecular design, and microfluidic technologies to generate biomimetic microenvironments to study and enable the implementation of biomolecules to address real-world challenges.