The
polysaccharide hyaluronan (HA) is a main component of peri-
and extracellular matrix, and an attractive molecule for materials
design in tissue engineering and nanomedicine. Here, we study the
morphology of complexes that form upon interaction of nanometer-sized
amine-coated gold particles with this anionic, linear, and regular
biopolymer in solution and grafted to a surface. We find that cationic
nanoparticles (NPs) have profound effects on HA morphology on the
molecular and supramolecular scale. Quartz crystal microbalance (QCM-D)
shows that depending on their relative abundance, cationic NPs promote
either strong compaction or swelling of films of surface-grafted HA
polymers (HA brushes). Transmission electron and atomic force microscopy
reveal that the NPs do also give rise to complexes of distinct morphologies–compact
nanoscopic spheres and extended microscopic fibers–upon interaction
with HA polymers in solution. In particular, stable and hydrated spherical
complexes of single HA polymers with NPs can be prepared when balancing
the ionizable groups on HA and NPs. The observed self-assembly phenomena
could be useful for the design of drug delivery vehicles and a better
understanding of the reorganization of HA-rich synthetic or biological
matrices