Microstructural Analysis of Hyaluronic Acid-Zinc Oxide Nanoparticle Composite Films: Investigation of Phase Separation and Interfacial Compatibility

Microstructure of composite films composed of polymers and nanoparticles is crucial for understanding the nanoparticles (NPs) dispersion and the role by colloidal stability played in the film formation process. The research aims to create composite films from the combination of hy-aluronic acid (HA) and zinc oxide nanoparticles (ZnO NPs) to produce materials that integrate an-timicrobial properties as a medical application interface. The main problem of composite films involving ZnO NPs is dispersion in polymer matrix which compromises mechanical integrity and structure performance. We discovered key parameters of phase separation influenced by ther-modynamic factors and then observed interfacial compatibility through a nanoscale resolution ZnO NPs dispersion, its adhesion mechanisms and defect distribution. We utilized a pH driven HA/ZnO electrostatic reaction by generating a protonation without any form of chemical change, using citric acid as stabilizing agent and this reverses the Zeta potential of the filler (ZnO NPs) to +25mV , and then we used atomic force microscopy (AFM) to study the microstructure of the films and optical microscope for the morphology. The process also covers surface modification of ZnO through PEGylation. The AFM analysis showed that surface roughness and particle size vary with respect to whether the ZnO nanoparticles were functionalized, unmodified or chelated. The research results will help create HA-based composite films and microneedles with specific nanostructures for wound healing and drug delivery administration.