Autonomously Propelled Colloids for Penetration and Payload Delivery in Complex Extracellular Matrices

Abstract

For effective treatment of diseases such as cancer or fibrosis, it is essential to deliver therapeutic agents such as drugs to the diseased tissue, but these diseased sites are surrounded by a dense network of fibers, cells, and proteins known as the extracellular matrix (ECM). The ECM forms a barrier between the diseased cells and blood circulation, the main route of administration of most drug delivery nanoparticles. Hence, a stiff ECM impedes drug delivery by limiting the transport of drugs to the diseased tissue. The use of self-propelled particles (SPPs) that can move in a directional manner with the application of physical or chemical forces can help in increasing the drug delivery efficiency. Here, we provide a comprehensive look at the current ECM models in use to mimic the in vivo diseased states, the different types of SPPs that have been experimentally tested in these models, and suggest directions for future research toward clinical translation of SPPs in diverse biomedical settings.

Active control of equilibrium, near-equilibrium, and far-from-equilibrium colloidal systems

“…Targeted drug delivery approaches can maximize the efficacy of the drug and minimize toxicity to non-targeted sites. 166,167 Colloidal particles have been proposed as agents for drug delivery, and targeted drug delivery contains two stages that would potentially benefit from active control: site-targeting transport of the drug carrier and release of pharmaceutical agents after reaching the destination. [25][26][27]167 The following examples illustrate the potential benefits of using actively controlled dynamic colloids to aid drug delivery.…”

“…Controlled release of drugs after the drug delivery agents reach their destination could maximize the efficacy as well as minimize the adverse effects of therapy. 166,167 Responsive surfactants have been suggested as ideal materials for soft medical microrobots due to their ability to change shape and size in response to external stimuli, which also makes them ideal candidates as actively controlled systems. 173,174 Take responsive hydrogel colloids as an example, where hydrogels can fold and unfold for targeted delivery in response to temperature or light.…”