Silicon nanoparticles for oral administration of molecular hydrogen

Medical use of hydrogen gas (H₂) has been given increasing attention over the past 15 years with numerous clinical trials for a variety of indications. The biological activity of H₂ includes antioxidant properties and thereby the ability to neutralize damaging reactive oxygen species (ROS). Administration of hydrogen as a medical gas is limited by the poor water solubility and by the flammability of H₂ in air. Therefore, nanocarriers have been investigated for safer and more efficient administration of hydrogen. Silicon particles are suggested for oral administration with the ability to undergo a redox reaction with water to produce H₂in vivo. The purpose of this work was to investigate the hydrogen generating abilities of silicon particles synthesized by centrifugal chemical vapor deposition (cCVD). High hydrogen generation rates up to 1310 ml/g at physiological pH 7.4 (82 % yield) were observed. An in vitro model of oral administration showed that pretreatment in artificial gastric juice did not affect hydrogen generation. Thus, the cCVD silicon particles seem to be suitable for in vivo hydrogen generation. A surface carbon coating or addition of surfactants or albumin hindered hydrogen generation. The addition of egg white reduced hydrogen generation but did not block it.