Nanoparticles reboot blood flow in brain after injury

August 27, 2012

Polyethylene glycol-hydrophilic carbon clusters (PEG-HCCs) rapidly restore cerebral blood flow in a mild traumatic brain injury to a rat model (credit: Brittany R. Bitner et al./ACS Nano)


“This might be a first line of defense against reactive oxygen species (ROS), which are always overstimulated during a medical trauma, whether that be to an accident victim or an injured soldier,” said Rice chemist and co-author James Tour, Rice’s T.T. and W.F. Chao Chair in Chemistry as well as a professor of mechanical engineering and materials science and of computer science. “They’re certainly exacerbated when there’s trauma with massive blood loss.”

Background: serious risks from brain injuries

In a traumatic brain injury, cells release an excessive amount of an ROS known as superoxide (SO) into the blood. Superoxides are toxic free radicals (molecules with one unpaired electron) that the immune system normally uses to kill invading microorganisms. Healthy organisms balance SO with superoxide dismutase (SOD), an enzyme that neutralizes it. But even mild brain trauma can release superoxides at levels that overwhelm the brain’s natural defenses.



PEG-HCC nanoparticles completely quench  superoxide activity

Combined polyethylene glycol-hydrophilic carbon clusters (PEG-HCC), which are already being tested to enhance cancer treatment, are also antioxidants. In animal studies, injections of PEG-HCC during initial treatment after an injury helped restore balance to the brain’s vascular system.



While an SOD enzyme can alter only one superoxide molecule at a time, a single PEG-HCC about the size of a large protein at 2–3 nanometers wide and 30–40 nanometers long can quench hundreds or thousands.



