The pro-active payload strategy significantly increases selective release from mesoporous nanocapsules.

The controlled release of payloads from mesoporous silica nanocapsules (SiNCs) consisting of stimulus-responsive shells is of considerable interest in applications such as self-healing materials and drug delivery. However, the release of payloads from SiNCs before application of external triggers (i.e. non-selective release) remains a formidable challenge. In fact, the non-selective release of payloads from SiNCs occurs because of the mesoporous nature of the silica shell that cannot trap payloads in the core of SiNCs perfectly. We establish an efficient and straightforward strategy based on the encapsulation of a pro-active payload to hinder the non-selective release of small payloads from mesoporous capsules. A pro-active payload is defined as a compound that is converted to an active functional molecule in the environment where it is needed. In this sense, it is a generalization of a prodrug. Encapsulating a pro-active payload instead of a payload allowed hindering the non-selective release of the payload from SiNCs. A selective release of the payload could be achieved upon reduction of the encapsulated pro-active payload. Furthermore, the total amount of released substance is significantly enhanced by introducing responsive groups in the silica shell. These results show that the pro-active payload strategy combined with the use of stimulus-responsive materials can be successfully exploited to achieve selective release of cargo from mesoporous nanocapsules.