Delphine Gourdon looks to nature as her guide when developing materials to improve the human condition. "As a bio-materials person, I see what nature is doing best and try to reproduce it," she says. If Gourdon can mimic a substance made by microalgae found in the Red Sea, it could become a new lubricant for artificial joints. "Right now they use HA, hyaluronic acid. And it's great because it works for a certain amount of time, but then it's squeezed out of the joint," she
explains. "So we try to find superlubricants that can be injected after surgery and stay in contact to lubricate it forever."
Lubricants for artificial joints must be slippery, but they also must stick around, even under the enormous pressure generated by activities like running. "It needs to be super, super lubricating when it's in contact with one surface, but at the same time it really needs to be adhering well at the surface bearing it or it will leave before it's done its job," explains Gourdon. "I try to reproduce the same ability to lubricate and to resist high pressure using natural materials."
The nontoxic algae Gourdon is trying to mimic produces a polysaccharide made of several different polymers. "The algae wrap up their cells with this to prevent them from attaching anywhere or aggregating with all the other little microalgae," she says. It's used as a natural extracellular matrix lubricant."
Gourdon is also trying to copy the way mussels permanently attach to just about anything. "I want to use the adhesive properties of what these mussels are using," she says. "These proteins are able to bridge permanently two surfaces together in liquid. That would work in our bodies for bandages in wound healing or for dental implants."
The mussel puts these adhesive proteins into filaments that make up its beard, also known as byssus. "It's a little bit like a spider. The foot will open up and you have all the wire making inside the foot that will end up in the plaque on the surface." Gourdon says. "If the mussel wants to move it opens up and cuts all of them, because it's so strong that you cannot detach them, you cannot remove this plaque."
Gourdon is also collaborating on some more fundamental studies of the role of proteins in the extracellular matrix. This network of fibers gives tissues stiffness and is also used by cells to communicate with each other and their environment. "Fibronectin is the one I study the most. It's called a mechanotransducer," says Gourdon. "The cells continually push and pull and remodel these fibers, so mechanically they are able to stretch these fibers and this gives rise to changes of their biochemical activity."
A better understanding of this process could lead to improved drug delivery. "I really want to correlate the mechanical properties of these networks with the biochemical function of these fibers," says Gourdon. "We want to use the ability of this fibronectin to bind when it's in its unfolded state to very specific sites because we want to bind it to drugs, for example anticancer drugs, and use this extracellular matrix as a way to direct the behavior of tumor cells, instead of directly acting on the cells."