Probing and repairing damaged surfaces with nanoparticle-containing microcapsules

Abstract

Nanoparticles have useful properties, but it is often important that they only start working after they are placed in a desired location. The encapsulation of nanoparticles allows their function to be preserved until they are released at a specific time or location, and this has been exploited in the development of self-healing materials and in applications such as drug delivery. Encapsulation has also been used to stabilize and control the release of substances, including flavours, fragrances and pesticides. We recently proposed a new technique for the repair of surfaces called 'repair-and-go'. In this approach, a flexible microcapsule filled with a solution of nanoparticles rolls across a surface that has been damaged, stopping to repair any defects it encounters by releasing nanoparticles into them, then moving on to the next defect. Here, we experimentally demonstrate the repair-and-go approach using droplets of oil that are stabilized with a polymer surfactant and contain CdSe nanoparticles. We show that these microcapsules can find the cracks on a surface and selectively deliver the nanoparticle contents into the crack, before moving on to find the next crack. Although the microcapsules are too large to enter the cracks, their flexible walls allow them to probe and adhere temporarily to the interior of the cracks. The release of nanoparticles is made possible by the thin microcapsule wall (comparable to the diameter of the nanoparticles) and by the favourable (hydrophobic-hydrophobic) interactions between the nanoparticle and the cracked surface.

The role of mechanics in biological and bio-inspired systems

“…With this approach, adaptive particles could embody an optimal travelling conformation, and then alter their shape via location-specific stimuli upon arrival. Drug release could be facilitated through the same principles present in self-cleaning biomimetic approaches 93 , and the materials of Fig. 4 provide many options for technological embodiment, thus leading to diverse design strategies for efficient and timely delivery of medicines.…”

Computational approaches to substrate-based cell motility

“…On the other hand, advances in modelling of motile cells can provide insights into the design of synthetic, biomimetic systems like actively self-healing materials. In that context self-propelled synthetic particle-laden capsules 174 or other 'healing agents' have been envisioned that are able to 'sense' a damage, migrate to the damaged sites and upon arrival rupture and repair the damage, similar as wound healing cells do in tissues. There are already successful experimental realizations of this idea, 175 using e.g., chemically powered catalytic gold-platinum rods that detect cracks and repair microscopic defects in electric pathways.…”

Nanotechnologies associated to floral resources in agri-food sector

“…Kratz, Narasimhan, Tangirala, Moon, Revanur, Kundu, Kim, Crosby, Russell, Emrick, Kolmakov & Balazs (2012), mentioned that the activity of nanoparticles is only initiated right after they are placed in a desired location. Therefore, nanoformulations must remain inactive until the active compound is released.…”