Tiny Treatment Delivers Big Pain Relief

In that a human hair measures 100,000 nanometers wide, gold nanorods are tiny rods that are 1-100 nanometers wide and long. Tatsuya Murakami, from Kyoto University's Institute for Integrated Cell-Material Sciences (Japan), and colleagues coated gold nanorods with a lipoprotein – a special type of protein that transports fat within the body, allowing the nanorods to bind efficiently to nerve cell membranes bearing a pain receptor called TRPV1 (transient receptor potential vanilloid type 1). Applying near-infrared light to the nanorod-coated pain receptors, the nanorods heated up and activated the pain receptors to allow an influx of calcium ions through the membrane. Prolonged activation of TRPV1 is known to subsequently lead to their desensitization, bringing pain relief. Importantly, heating the gold nanorods enabled safe activation of the TRPV1 pain receptors alone, without affecting the membrane in which they lie.The study authors report that: “ Our method provides an optogenetic platform without the need for prior genetic engineering of the target cells and might be useful for novel TRPV1-targeted phototherapeutic approaches.”