Colloidal Crystallization of Virus-Like Particles with Polycations

Virus-like particles (VLPs) are protein nanocages capable of encapsulating or attaching guest molecules. Unlike viruses, they do not replicate in cells, making them promising candidates for advanced biomaterial design, particularly for biomedical applications such as drug delivery. However, the mechanisms governing VLP self-assembly into highly ordered suprastructures with enhanced functionality remain largely unexplored. This study investigates the development of pH-responsive biomaterials using the icosahedral Acinetobacter phage coat protein AP205 VLP with a diameter of around 28 nm. Small-angle X-ray scattering, dynamic light scattering, and zeta-potential measurements reveal that AP205 self-assembles with the polycation poly[2-(methacryloyloxy)ethyl] trimethylammonium chloride into highly ordered suprastructures. The structural organization is strongly influenced by composition, pH, and ionic strength. The findings provide insight into the directional interactions governing VLP self-assembly, enabling the design of tunable VLP-based biomaterials.