Intersection-Free Fractal-Like Structuring of Recombinant Adhesive Proteins for Surface Functionalization

The advancement of biomaterials through innovative surface functionalization techniques is essential for enhancing the performance and functionality. Recombinant adhesive proteins (RAPs), engineered from mussel foot proteins and antimicrobial peptides, present unique opportunities for surface functionalization of biomaterials. Here, we reveal a previously unexplored property of RAPs: fractal-like structural growth that promotes efficient surface coverage and functionalization. This growth, driven by the formation and regulation of multiple nucleation sites, can be observed across diverse biomaterials. Analysis of the concentration-dependent nature of this phenomenon demonstrates a critical saturation range (20-40 μg/mL) that achieves maximal antimicrobial efficacy while minimizing protein usage. We further propose a mechanistic framework linking RAP domain interactions to observed self-assembly and intersection-free structuring. This work opens possibilities for protein-mediated surface structuring, highlighting a strategy for durable surface functionalization with an optimal resource efficiency. These findings provide new insights into tailored biomedical functionalization and antimicrobial materials with precisely controlled properties.