To you, a slide may be just a slide. But to Carlo Pantano, that piece of glass represents countless opportunities for research. Pantano and a team of researchers at Penn State with collaborators at Schott Glass have come up with a new coating and a better kind of glass that Pantano says can improve the quality of microarray experiments by more than 50 percent.
Pantano’s certainly the one to do it. “I’ve been working on [glass and] coating glass for 20 years,” says the professor of material science and engineering and director of Penn State’s Materials Research Institute. “That’s what I do.” So it didn’t come as much of a surprise when companies involved in microarray development tracked him down and asked him for advice on how to improve their wares. What was new for Pantano was working with biological applications — this particular DNA-based project, funded by industry and NSF, started some three years ago.
What Pantano came up with is a two-pronged improvement for the microarray industry. The main part is a novel coating for the glass slide: Using a trifunctional amine (rather than the usual monofunctional amine) allows for better immobilization of DNA, he says. The amine group gives a positive charge to the glass surface, attracting the negatively charged DNA molecules. And having three linker sites means that DNA has a better chance of binding — as well as the flexibility to temporarily detach and reconnect to the surface during an experiment, Pantano says. “We’ve got to tether it to the surface without affecting its ability to wiggle around.”
The other component is a better type of glass, according to Pantano. Schott went through its glass libraries and came up with “what we call a low-fluorescence glass substrate,” Pantano says. “What gives glass its background fluorescence are the impurities” in the raw material used to make it. “You can imagine that they don’t use the highest-purity glass [for typical microscope slides],” he adds. Unlike regular slides, this borosilicate glass helps reduce background noise that can drown out fluorescent signals from actual DNA.
Right now, the only way to get access to these specially coated, low-fluorescent slides is to buy them from Schott. But Penn State owns the IP around Pantano’s invention, so conceivably other manufacturers could get in on the action as well.
Before that happens, Pantano is already hard at work on more improvements to the DNA chip. For one thing, he’d like to test the coated slide he has already developed to see if it can be reused — in theory, the higher DNA binding efficiency with the trifunctional amine groups might mean that the chips could be heated up after use to remove the hybridized strands but not the attached library. And in another effort, he’s looking into ways to vary the structure of the surface coating. Making it porous, he says, could add more surface area for the DNA to bind to; alternatively, etching patterns into the coating may give the slide a microfluidics capability.
— Markers by Meredith Salisbury