Tiny gold rods may provide intractable pain relief
A team of scientists at Kyoto University's Institute for Integrated Cell-Material Sciences (iCeMS) has developed a technique that could lead to therapies for pain relief in people with intractable pain, potentially including cancer-related pain by using tiny gold rods to target pain receptors.
In comparison to a human hair that is 100,000 nanometers wide, these gold nanorods are 1-100 nanometers wide and long. The team coated them with a special type of protein that transports fat within the body known as a lipoprotein and allowed them to bind efficiently to nerve cell membranes bearing a pain receptor called TRPV1 (transient receptor potential vanilloid type 1).
The nanorods gets heated up when come in contact with infrared light, thereby activating the pain receptors to allow an influx of calcium ions through the membrane. Moreover, prolonged activation of TRPV1 is known to subsequently lead to their desensitization, bringing pain relief and more importantly, heating the gold nanorods enabled safe activation of the TRPV1 pain receptors alone, without affecting the membrane in which they lie. Although previous studies had shown that magnetic nanoparticles are also able to activate TRPV1 receptors by applying a magnetic field and the target cells in this method, however, require genetic modification for it to work. The nanorods were found to have at least 1,000 times greater efficiency than magnetic nanoparticles in heat generation and in activating TRPV1 receptors.
"The gold nanorods can be retained in the body for a prolonged period," says Tatsuya Murakami, the principal investigator of this study. "Local injection of our gold nanorods might enable repetitive and on-demand treatment for people experiencing intractable pain because prior genetic engineering of the target cells is unnecessary."