This work addresses the challenge of creating hollow nanocapsules with a controlled quantity of encapsulated molecules. Such nanocontainers or nanorattle-like structures represent an attractive platform for building functional devices, including nanoreactors and nanosensors. By taking advantage of the electrostatic attraction between oppositely charged cargo molecules and the surface of the templating bilayer of catanionic vesicles, formed by mixing single-tailed cationic and anionic surfactants, we were able to achieve a substantial increase in the local concentration of molecules inside the vesicle-templated nanocapsules. Control of electrostatic interactions through changes in the formulation of catanionic vesicles or the pH of the solution enabled fine tuning of the encapsulation efficiency in capturing ionic solutes. The ability to control the quantity of entrapped molecules greatly expands the application of nanocontainers in the creation of functional nanodevices.

Nanoprobes for surface-enhanced Raman scattering (SERS) were prepared by creating nanorattles, or yolk−shell structures, containing gold or silver nanoparticles entrapped in porous hollow polymer nanocapsules. Controlled permeability of the shells of nanocapsules, achieved by controlling the pore size and/or shell surface functionalization, resulted in size- and charge-selective SERS analyses. For example, a trace amount of phenanthroline, a model analyte, was detected in human blood plasma without preprocessing of plasma samples. Comparison with commercially available nanoparticles showed superior performance of the newly prepared nanorattle structures.

Nanoreactors were created by entrapping homogeneous catalysts in hollow nanocapsules with 200 nm diameter and semipermeable nanometer-thin shells. The capsules were produced by the polymerization of hydrophobic monomers in the hydrophobic interior of the bilayers of self-assembled surfactant vesicles. Controlled nanopores in the shells of nanocapsules ensured long-term retention of the catalysts coupled with the rapid flow of substrates and products in and out of nanocapsules. The study evaluated the effect of encapsulation on the catalytic activity and stability of five different catalysts. Comparison of kinetics of five diverse reactions performed in five different solvents revealed the same reaction rates for free and encapsulated catalysts. Identical reaction kinetics confirmed that placement of catalysts in the homogeneous interior of polymer nanocapsules did not compromise catalytic efficiency. Encapsulated organometallic catalysts showed no loss of metal ions from nanocapsules suggesting stabilization of the complexes was provided by nanocapsules. Controlled permeability of the shells of nanocapsules enabled size-selective catalytic reactions.Keywords: homogenous catalysis; immobilization; nanopores; nanoreactors; polymer nanocapsules; vesicles;

This work addresses the challenge of creating hollow polymer capsules with wall thickness in the single-nanometer range under mild conditions. We present a simple and scalable method for the synthesis of hollow polymer nanocapsules in the bilayers of spontaneously assembled surfactant vesicles. Polymerization is initiated thermally with the help of a peroxide initiator and an amine activator codissolved with monomers and cross-linkers in the hydrophobic interior of the surfactant bilayer. To avoid premature polymerization, the initiator and the activator were added separately to the mixtures of cetyltrimethylammonium tosylate (CTAT) and sodium dodecylbenzenesulfonate (SDBS) containing monomers and cross-linkers. Upon hydration and mixing of the aqueous solutions, equilibrium monomer-loaded vesicles formed spontaneously after a brief incubation. The removal of oxygen and further incubation at slightly elevated temperatures (35–40 °C) for 1 to 2 h has led to the formation of hollow polymer nanocapsules. Structural and permeability characterization supported the high yield of nanocapsules with no pinhole defects.

•Liposomes can deliver phosphodiesterase (PDE) inhibitors to erythrocytes.•No adverse effect of drug-loaded liposomes on erythrocytes was observed.•Release of ATP from erythrocytes of patients with type 2 diabetes was investigated.•Liposome-delivered PDE inhibitors restore the release of ATP in response to low O2.ATP release from erythrocytes in response to low oxygen tension requires an increase in cAMP, the level of which is regulated by phosphodiesterase 3 (PDE3). Such release is defective in erythrocytes of humans with type 2 diabetes (DM2). This study tested a hypothesis that direct delivery of the clinically useful PDE3 inhibitor, cilostazol, to erythrocytes of humans with type 2 diabetes using liposomes would restore low-oxygen tension-induced ATP release. Cilostazol was incorporated into liposomes prepared from dimyristoylphosphatidylcholine (DMPC). Liposome-delivery of cilostazol restored ATP release from DM2 erythrocytes to levels which were not different from that released from non-cilostazol treated healthy erythrocytes under the same conditions. There were no observed adverse effects of the liposomes on either healthy or DM2 erythrocytes. The directed liposomal delivery of PDE inhibitors to erythrocytes may help prevent or slow the development of peripheral vascular disease in individuals with DM2 by restoring an important physiological controller of microvascular perfusion while minimizing side effects associated with systemic delivery of some of these inhibitors.Download full-size image