Under an electron microscope, the coated nanodevices closely resembled an enveloped virus.
Perrault then demonstrated that the new nanodevices survived in the body, by loading them with fluorescent dye, injecting them into mice, and using whole-body imaging to see what parts of the mouse glowed.
Just the bladder glowed in mice that received uncoated nanodevices, which meant that the animals broke them down quickly and were ready to excrete their contents. But the animals' entire body glowed for hours when they received the new, coated nanodevices. This showed that nanodevices remained in the bloodstream as long as effective drugs do.
The coated devices also evade the immune system. Levels of two immune-activating molecules were at least 100-fold lower in mice treated with coated nanodevices as opposed to uncoated nanodevices.
In the future, cloaked nanorobots could activate the immune system to fight cancer or suppress the immune system to help transplanted tissue become established.
"Activating the immune response could be useful clinically or something to avoid," Perrault said. "The main point is that we can control it."
"Patients with cancer and other diseases would benefit enormously from precise, molecular-scale tools to simultaneously diagnose and treat diseased tissues, and making DNA nanoparticles last in the body is a huge step in that direction," said Wyss Institute Founding Director Don Ingber, M.D., Ph.D.
Wyss Institute Core Faculty member William Shih and Technology Development Fellow Steven Perrault explain why DNA nanodevices need protection inside the body and how a virus-inspired strategy helps protect them.
(Photo Credit: Harvard's Wyss Institute)
An enveloped virus (left) coats itself with lipid as part of its life cycle. New lipid-coated DNA nanodevices (right) closely resemble those viruses and evade the immune defenses of mice.
(Photo Credit: Steven Perrault/Harvard's Wyss Institute)
Source: Wyss Institute for Biologically Inspired Engineering at Harvard