Gecko-inspired chitosan adhesive for tissue repair

The advent of nanotechnology has opened the possibility of fabricating nanoscopic pillars on the surface of polymeric films mimicking the Gecko's foot, in an attempt to increase their adhesive capabilities enhanced by van der Waals forces. However, these forces are considerably weakened in a wet physiological environment. To circumvent this loss in force, current biocompatible adhesives with nanopillars require complex multiple-step fabrication, including an extra layer of adhesive coating to stabilize tissue bonding under physiological conditions. In this report, we describe a simple one-step fabrication process of a single-layer chitosan film that has pillars with base diameter in the range of 100-600 nm and a height of ~70 nm. The nanostructured adhesive is laser-bonded to tissue and does not require pillar coating to enhance bonding in water. In comparison with a 'flat' adhesive (without pillars), the nanostructured adhesive bonded significantly stronger to tissue under either stress or pressure. Atomic force spectroscopy also confirmed the superior bonding capability of the nanostructured adhesive. This study demonstrates a one-step fabrication technique to produce a monolayer gecko-inspired adhesive that is biocompatible and bonds effectively to tissue.