Polymer Nanoparticles Encased in a Cyclodextrin Complex Shell for Potential Site‐ and Sequence‐Specific Drug Release

Time‐staggered combination chemotherapy strategies show immense potential in cell culture systems, but fail to successfully translate clinically due to different routes of administration and disparate formulation parameters that preclude a specific order of drug presentation. A novel platform consisting of drug‐containing PLGA polymer nanoparticles, stably fashioned with a shell composed of drug complexed with cationic cyclodextrin, capable of releasing drugs time‐ and sequence‐specifically within tumors is designed. Morphological examination of nanoparticles measuring 150 nm highlight stable and distinct compartmentalization of model drugs, rhodamine and bodipy, within the core and shell, respectively. Sequential release is observed in vitro, owing to cyclodextrin shell displacement and subsequent sustained release of core‐loaded drug, kinetics preserved in breast cancer cells following internalization. Importantly, time‐staggered release is corroborated in a murine breast cancer model following intravenous administration. Precise control of drug release order, site‐specifically, potentially opens novel avenues in polychemotherapy for synergy and chemosensitization strategies.     

Electro‐Drawn Drug‐Loaded Biodegradable Polymer Microneedles as a Viable Route to Hypodermic Injection

Hypodermic needle injection is still the most common method of drug delivery despite its numerous limitations and drawbacks, such as pain, one‐shot administration, and risk of infection. Seeking a viable, safe, and pain‐free alternative to the over 16 billion injections per year has therefore become a top priority for our modern technological society. Here, a system that uses a pyroelectric cartridge in lieu of the syringe piston as a potential solution is discussed. Upon stimulation, the cartridge electro‐draws, at room temperature, an array of drug‐encapsulated, biodegradable polymer microneedles, able to deliver into hypodermic tissue both hydrophobic and hydrophilic bioactive agents, according to a predefined chrono‐programme. This mould‐free and contact‐free method permits the fabrication of biodegradable polymer microneedles into a ready‐to‐use configuration. In fact, they are formed on a flexible substrate/holder by drawing them directly from drop reservoirs, using a controlled electro‐hydrodynamic force. Tests of insertion are performed and discussed in order to demonstrate the possibility to prepare microneedles with suitable geometric and mechanical properties using this method.     

Drug Delivery: Wavelength‐Selective Light‐Induced Release from Plasmon Resonant Liposomes (Adv. Funct. Mater. 6/2011)

Biodegradable, spectrally tunable plasmon resonant nanocapsules are created via the deposition of gold onto the surface of 100 nm diameter thermosensitive liposomes. These nanocapsules exhibit selective release of encapsulated contents upon illumination with light of a wavelength matching their distinct resonance bands. In this study, 760 and 1210 nm laser illumination elicits complete release from gold‐coated liposomes with a corresponding resonance, while causing minimal release from liposomes with an unmatching resonance. Spectrally selective release is accomplished through the use of multiple, low‐intensity laser pulses delivered over a period of minutes, ensuring that illumination affects the gold‐coated liposomes without heating the surrounding media. The use of pulsed illumination to achieve spectral selectivity is validated experimentally and through modeling of the heat equation. The result of this illumination scheme for selective release using multiple wavelengths of light is a biologically safe mechanism for realizing drug delivery, microfluidic, and sensor applications.