Release and Transport of Nanomaterials from Hydrogels Controlled by Temperature.

Understanding the transport of nanoparticles from and within hydrogels is a key issue for the design of nanocomposite hydrogels for drug delivery systems and tissue engineering. To investigate the translocation of nanocarriers from and within hydrogel networks triggered by changes of temperature, ultrasmall (8 nm) and small (80 nm) silica nanocapsules are embedded in temperature-responsive hydrogels and non-responsive hydrogels. The ultrasmall silica nanocapsules are released from temperature-responsive hydrogels to water or transported to other hydrogels upon direct activation by heating or indirect activation by Joule heating; while, they are not released from non-responsive hydrogel. Programmable transport of nanocarriers from and in hydrogels provides insights for the development of complex biomedical devices and soft robotics.

Encapsulation and Release of Essential Oils in Functional Silica Nanocontainers.

We describe the fabrication of mesoporous silica nanocontainers (SiO2NCs) that simultaneously encapsulate different antiseptic agents. Peppermint oil (PO), thyme oil (TO), cinnamon oil (CnO), and clove oil (CO), which are known to display antibacterial properties, are loaded in the core of the silica nanocontainers that are stabilized by antiseptic surfactants. The encapsulation efficiency, surface area, and pore size are controlled by the type of oil and surfactant. The release of essential oils is further controlled by grafting oxidized hyaluronic acid on silica nanocontainers functionalized with amino groups.

Assembly of biomimetic microreactors using caged-coacervate droplets.

Complex coacervates are liquid-like droplets that can be used to create adaptive cell-like compartments. These compartments offer a versatile platform for the construction of bioreactors inspired by living cells. However, the lack of a membrane significantly reduces the colloidal stability of coacervates in terms of fusion and surface wetting, which limits their suitability as compartments. Here, we describe the formation of caged-coacervates surrounded by a semipermeable shell of silica nanocapsules. We demonstrate that the silica nanocapsules create a protective shell that also regulates the molecular transport of water-soluble compounds as a function of nanocapasule size. The adjustable semipermeability and intrinsic affinity of enzymes for the interior of the caged-coacervates allowed us to assemble biomimetic microreactors with enhanced colloidal stability.

Nanocapsules with excellent biocompatibility and stability in protein solutions.

Silica nanocapsules (SiO2NCs) are usually prepared with cationic surfactants that are not cytocompatible. Dialysis can be used to remove surfactants but leads to instability of the SiO2NCs when they are in the presence of proteins or biological media. Herein, SiO2NCs stabilized with a reactive surfactant are synthesized to prevent leaching upon dialysis. The SiO2NCs show superior stability and biocompatibility compared with SiO2NCs prepared with conventional surfactants. The SiO2NCs can be used in self-healing materials, smart agriculture and biomedical applications.

Inflammation-responsive nanocapsules for the dual-release of antibacterial drugs.

Herein, we design inflammation-responsive nanocapsules containing two antibiotics. The releases are programmed to be triggered under conditions occurring at the different stages of wound healing. The nanocapsules exhibit excellent antibacterial activities against Gram-positive, Gram-negative, and antibiotic-resistant bacteria. Incorporation of small amounts of nanocapsules in hydrogels leads to efficient antibacterial wound dressings.