Researchers Develop Nanosponges Using ‘Hairy’ Nanocellulose As Sustainable Alternative For Drug Delivery

Chemists from McGill University have discovered the possibility of creating biopolymer-based “nanosponges” using milled softwood pulp, a sustainable and less toxic alternative to current drug delivery systems. Although the structures developed by the researchers are too big for anti-cancer drug delivery by injection or oral intake, they could potentially be used in dressing wounds, for medical implants, and to capture unwanted materials in wastewater.

Nanosponges are network structures developed by the researchers which have nanopores through which drugs can diffuse, while also being able to absorb water. What makes these structures ‘hairy’ are the long, thin rods that form the morphology of the nanocelluloses used. From each end of these rods, cellulose chains stick out. “We call these protruding chains “hairs,” which have the advantage that they can be readily chemically modified to make networks with cyclodextrins,” said Theo van de Ven, Professor and Sir William C. Macdonald Chair in Chemistry at McGill.

Starting with cellulose (the major component of trees and plants) and cyclodextrin, a member of the class of dextrins usually made from starch, van de Ven and the research team made a network of hairy nanocellulose and cylodextrin. They then succeeded in loading an anti-cancer drug in a cavity in the cyclodextrin molecule.

“Many drug delivery systems are not sustainable as they contain synthetic polymers and crosslinkers,” Van de Ven said. But cellulose, as found in milled softwood pulp, is the most abundant biodegradable and renewable biomaterial on Earth. Its strong mechanical properties, tunable aspect ratio, and low density make it particularly attractive as a sustainable alternative to synthetic materials.

Although the structures developed could not penetrate cancer cells—a requirement of efficient drug delivery—the researchers found that “the network structures we developed in close contact with cancer cells did kill the cells, as the drug could diffuse out of the carrier system and into the cancer cells.” Van de Ven said his research team is developing smaller carriers to circumvent the issue of size, but the larger structures developed could potentially be used to prevent a cancer from reappearing.

Additionally, the study may lead to potential applications of the biopolymer-based network due to the biocompatibility and versatility of the nanostructures. Namely, the structures could be applied to wound dressing and to capturing antibiotics, dyes, and organic compounds from wastewater.

The study “Hairy Nanocellulose-Based Supramolecular Architectures for Sustained Drug Release” by M. Heidari Nia, S. Ashkar, J. G. Munguia-Lopez, J. M. Kinsella, and T.G.M. van de Ven, is published in Biomacromolecules.