Synergistically combining the merits of silica (e.g., mechanical robustness, biocompatibility and great versatility in surface functionalization) and capsular configurations (e.g., a large inner cavity, low density and favourable colloidal properties), silica-based nanocapsules (SNCs) with a size cutoff of ∼100 nm have gained growing interest in encapsulating bioactive molecules for bioimaging and controlled delivery applications. Within this context, this review provides a comprehensive overview of the synthetic strategies, structural control and biomedical applications of SNCs. Special emphasis is placed on size control at the nanoscale and material composition manipulation of each strategy and the newly emerging synthetic strategies. The applications of SNCs in bioimaging/diagnosis and drug delivery/therapy and the structure engineering that is critically important for the bio-performance of SNCs are also addressed in this review.

Synthetic water channels were developed with an aim to replace aquaporins for possible uses in water purification, while concurrently retaining aquaporins’ ability to conduct highly selective superfast water transport. Among the currently available synthetic water channel systems, none possesses water transport properties that parallel those of aquaporins. In this report, we present the first synthetic water channel system with intriguing aquaproin-like features. Employing a “sticky end”-mediated molecular strategy for constructing abiotic water channels, we demonstrate that a 20% enlargement in angstrom-scale pore volume could effect a remarkable enhancement in macroscopic water transport profile by 15 folds. This gives rise to a powerful synthetic water channel able to transport water at a speed of ∼3 × 109 H2O s–1 channel–1 with a high rejection of NaCl and KCl. This high water permeability, which is about 50% of aquaporin Z’s capacity, makes channel 1 the fastest among the existing synthetic water channels with high selectivity.

We describe here a modularly tunable molecular strategy for construction and combinatorial optimization of highly efficient K-selective channels. In our strategy, a highly robust supramolecular H-bonded 1D ensemble was used to order the appended crown ethers in such a way that they roughly stack on top of each other to form a channel for facilitated ion transport across the membrane. Among 15 channels that all prefer K over Na ions, channel molecule 5F8 shows the most pronounced optimum for K while disfavoring all other biologically important cations (e.g., Na, Ca and Mg). With a K/Na selectivity of 9.8 and an EC value of 6.2 μM for K ion, 5F8 is clearly among the best synthetic potassium channels developed over the past decades.