Subcompartmentalized Polymer Hydrogel Capsules with Selectively Degradable Carriers and Subunits

Subcompartmentalized hydrogel capsules (SHCs) with selectively degradable carriers and subunits are designed for potential applications in drug delivery and microencapsulated biocatalysis. Thiolated poly(methacrylic acid) and poly(N‐vinyl pyrrolidone) are used to assemble 3‐µm‐diameter carrier capsules and 300‐nm‐diameter subunits, independently stabilized by a diverse range of covalent linkages. This paper presents examples of SHCs with tens of subcompartments and their successful drug loading, as well as selective degradation of the SHC carrier and/or subunits in response to multiple chemical stimuli.     

Drug delivery: Layer‐By‐Layer‐Assembled Capsules and Films for Therapeutic Delivery (Small 17/2010)

Polymeric materials formed via layer‐by‐layer (LbL) assembly have promise for use as drug delivery vehicles. These multilayered materials, both as capsules and thin films, can encapsulate a high payload of toxic or sensitive drugs, and can be readily engineered and functionalized with specific properties. This review highlights important and recent studies that advance the use of LbL‐assembled materials as therapeutic devices. It also seeks to identify areas that require additional investigation for future development of the field. A variety of drug‐loading methods and delivery routes are discussed. The biological barriers to successful delivery are identified, and possible solutions to these problems are discussed. Finally, state‐of‐the‐art degradation and cargo release mechanisms are also presented.     

Core–Shell and Layer‐by‐Layer Assembly of 3D DNA Crystals

A long‐standing goal of DNA nanotechnology has been to assemble 3D crystals to be used as molecular scaffolds. The DNA 13‐mer, BET66, self‐assembles via Crick–Watson and noncanonical base pairs to form crystals. The crystals contain solvent channels that run through them in multiple directions, allowing them to accommodate tethered guest molecules. Here, the first example of biomacromolecular core–shell crystal growth is described, by showing that these crystals can be assembled with two or more discrete layers. This approach leads to structurally identical layers on the DNA level, but with each layer differentiated based on the presence or absence of conjugated guest molecules. The crystal solvent channels also allow layer‐specific postcrystallization covalent attachment of guest molecules. Through controlling the guest‐molecule identity, concentration, and layer thickness, this study opens up a new method for using DNA to create multifunctional periodic biomaterials with tunable optical, chemical, and physical properties.     

Micrometer‐Thick Graphene Oxide–Layered Double Hydroxide Nacre‐Inspired Coatings and Their Properties

Robust, functional, and flame retardant coatings are attractive in various fields such as building construction, food packaging, electronics encapsulation, and so on. Here, strong, colorful, and fire‐retardant micrometer‐thick hybrid coatings are reported, which can be constructed via an enhanced layer‐by‐layer assembly of graphene oxide (GO) nanosheets and layered double hydroxide (LDH) nanoplatelets. The fabricated GO–LDH hybrid coatings show uniform nacre‐like layered structures that endow them good mechanic properties with Young's modulus of ≈18 GPa and hardness of ≈0.68 GPa. In addition, the GO–LDH hybrid coatings exhibit nacre‐like iridescence and attractive flame retardancy as well due to their well‐defined 2D microstructures. This kind of nacre‐inspired GO–LDH hybrid thick coatings will be applied in various fields in future due to their high strength and multifunctionalities.