Surface interaction of polysaccharide thin model films and citrate- or protein-capped gold nanoparticles

Alginate and chitosan are commonly used materials for applications such as tissue engineering due to their biocompatibility and bioactivity that promotes growth and differentiation to interest cell types. A common modifying component to improve mechanical and electric properties are gold nanoparticles. However, the capping agent is rarely described and the interaction of them with the polysaccharides are understudied. This work used thin model films in sensors for QCM-D and MP-SPR to follow these interactions and better describe them. AFM images were obtained to correlate the adsorption measured with their arrangement on the surface. Herein, it was found that citrate-capped nanoparticles had the best adsorption behavior with chitosan, most likely driven by electrostatic interactions. Meanwhile, the addition of proteins such as BSA served to improve the nanoparticles dispersibility, both in solution and on surface, as well as their adsorption to the alginate/chitosan mix, which had lowered their capacity to form electrostatic interactions through their functional groups, which were utilized while forming the films. Hence, the BSA helped promote hydrophobic and entropic phenomena, driving the deposition onto the surface. This work proves that the capping agent had a great impact on the behavior of the materials, thus understanding them should serve for the betterment of scaffolding design.