Multifunctional Polymer‐Coated Carbon Nanotubes for Safe Drug Delivery

Although progress in the use carbon nanotubes in medicine has been most encouraging for therapeutic and diagnostic applications, any translational success must involve overcoming the toxicological and surface functionalization challenges inherent in the use of such nanotubes. Ideally, a carbon‐nanotube‐based drug delivery system would exhibit low toxicity, sustained drug release, and persist in circulation without aggregation. Here, carbon nanotubes (CNTs) coated with a biocompatible block‐co‐polymer composed of poly(lactide)‐poly(ethylene glycol) (PLA‐PEG) are reported to reduce short‐term and long‐term toxicity, sustain drug release of paclitaxel (PTX), and prevent aggregation. The copolymer coating on the surface of CNTs significantly reduces in vitro toxicity. Moreover, the coating reduces the in vitro inflammatory response. Compared to non‐coated CNTs, in vivo studies show no long‐term inflammatory response with CNT coated with PLA‐PEG (CLP) and the surface coating significantly decreases acute toxicity by doubling the maximum tolerated dose in mice. In vivo biodistribution and histology studies suggest a lower degree of aggregation in tissues.     

Microcarriers: Elaborate Design Strategies Toward Novel Microcarriers for Controlled Encapsulation and Release (Part. Part. Syst. Charact. 1/2013)

Microencapsulation and the controlled release of bioactive agents have long been investigated and exploited to both improve the fundamental understanding of cell functionality and to develop efficient delivery vehicles for drugs, nutrients, and cosmetics. Conventional approaches to the synthesis of particles and capsules for practical applications have achieved only limited control over particle size, shape, functionality, and encapsulation efficiency. To overcome such limitations, a variety of approaches have been developed. Recent advances in microfluidics and other techniques have inspired the design of new microcarriers that efficiently encapsulate bioactive agents to enable the on‐demand release or functionalization of encapsulants. Here, the current state of the art in the area of elaborate design strategies for microcarriers that enable efficient encapsulation and controlled release for biological applications is described. This is discussed in three sections, which are categorized by microcarrier type: particle‐type carriers, capsule‐type carriers, and foldable microcarriers. In each section, new routes to fabricating microcarriers are discussed together with their functionalities; techniques based on droplet microfluidics, lithography, micromolding, and imprinting are covered. In addition, the synthetic routes and the microcarriers are evaluated by comparison with alternative routes. Finally, future perspectives for these new strategies are outlined briefly.