455670 Repeatable and Adjustable on-Demand Local Anesthesia By Phototriggerable Liposomes
Here we demonstrate a phototriggerable local anesthesia system that can realize this goal. A near infrared (NIR) light-absorbing photosensitizer was encapsulated within liposomes composed of lipids labile to reactive oxygen species (ROS) (6). Upon irradiation with NIR light, the photosensitizer released singlet oxygen, inducing lipid peroxidation and enhancing the permeability of liposomal lipid bilayers, resulting in the release of encapsulated drug. A potent local anesthetic, tetrodotoxin (TTX), was loaded into these phototriggerable liposomes (Lipo-PS-TTX). In vitro experiments showed repeatable phototriggered TTX release with 730-nm laser irradiation (7). In vivo injections of Lipo-PS-TTX percutaneously onto the rat sciatic nerve induced an initial sciatic nerve block, and subsequent irradiations at 730 nm induced repeated sciatic nerve block. The timing, intensity and duration of nerve block were adjustable by the parameters of irradiation. Nerve block duration showed a clear relationship with irradiation energy density, demonstrating the controllability of the system. On-demand phototriggerable nerve block systems may allow pain treatment to be personalized and substantially improve pain management.
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