Size-selective pH-operated megagates on mesoporous silica materials.

pH-responsive megagates have been fabricated around mesoporous silica material SBA-15 in order to mechanize the mesopores. These megagates remain closed in neutral conditions, but open at pH 5. The capping components of the megagates were designed to be capable of controlling pores up to 6.5 nm in diameter. Selectivity of payloads with different sizes can be achieved through the use of different capping components. The operation of the megagates was demonstrated by time-resolved fluorescence spectroscopy which is capable of monitoring the release of both the payload and the cap. This study opens up new possibilities in the field of controllable release.