Dissolution of different forms of partially porous silicon wafers under simulated physiological conditions

Silicon (Si) in the form of orthosilicic acid (Si(OH)4) is vital for normal bone and connective tissue homeostasis. Porous Si films release Si(OH)4 in aqueous solutions in the physiological pH range. This study investigates the release of Si(OH)4 from porous Si films under physiological conditions with the aim of developing a bioavailable form of Si. Using a standardised technique, porous Si films released increasing Si with time. Dissolution was significant at pH 7 and above, and at a temperature of 37 °C. Higher porosity generally promoted dissolution, however multiple layer films did not show enhanced solubility over corresponding single layer controls. These properties will be used to optimise Si nanostructures that slowly deliver orthosilicic acid in the digestive tract.