Over the past decade, drug delivery has evolved from oral, nasal, dermal administration and injections to delivery using nanoparticles, gels and scaffolds to more precisely control the release and local bioavailability of drug. To mimic the spatial and temporal precision of biological processes, researchers from Harvard’s Wyss Institute for Biologically Inspired Engineering and Royal College of Surgeons, Ireland have developed a new system for on-demand delivery of drugs. The paper, published recently in the journal Advanced Healthcare Materials, describes the fabrication and characterization of a hydrogel made of seaweed-derived alginate that contains gold nanoparticles for the delivery of BMP-2, a clinically used drug known to enhance fracture healing when introduced in a controlled manner.

The gold nanoparticles are entrapped in the hydrogel and are not released unless triggered by ultrasound, upon which there is an increase of 200 fold in particle and drug release after 24 hours, which goes up to 5000 fold after 5 days. As all the materials used in the system are already clinically available, the authors plan to carry out an in vivo study to test the efficacy of the system and its safety profile.

From the study abstract:

Natural biological processes are intricately controlled by the timing and spatial distribution of various cues. To mimic this precise level of control, the physical sizes of gold nanoparticles are utilized to sterically entrap them in hydrogel materials, where they are subsequently released only in response to ultrasound. These nanoparticles can transport bioactive factors to cells and direct cell behavior on-demand.

Study in Advanced Healthcare Materials: Switchable Release of Entrapped Nanoparticles from Alginate Hydrogels…