Herein, we present a systematic study on the preparation of polydopamine (PDA) hollow capsules by templating silica particles which were subsequently removed by a PDA mediated water dissolution process without using any harsh chemical treatment. It was found that the time required for silica removal varied depending on the PDA coating and dissolution conditions. Factors that could influence the core removal process including the PDA thickness and coating temperature, silica calcination duration and the availability of water were then examined in detail. Additionally, catalase was used as a model enzyme to be encapsulated into PDA hollow capsules and its bio-functionality was found to remain active. The bioactivity test results also indicated that the as-synthesized PDA capsules possessed a porous structure, which allows the penetration of small molecules such as H2O2. This study offers a better insight into silica dissolution process that mediated by PDA and contributes to the development of an eco-friendly approach for the fabrication of hollow capsules that have promising applications in drug delivery systems.
Keywords: enzyme encapsulation; green synthesis; hollow capsules; mesoporous silica; polydopamine.