Mussel Adhesive Protein-Assisted Magnetic Recovery of Microplastics from Aquatic Environments

Microplastic pollution poses a severe threat to aquatic environments. The development of efficient and sustainable methods for the recovery of microplastics from aquatic environments is challenging but must be achieved. Mussel adhesive proteins (MAPs) are strong underwater adhesives with a dual adhesive property that binds to both inorganic and organic surfaces. Here, we used this MAP's ability for the magnetic recovery of microplastics. We used InaKC-Fp1, which is composed of a type of MAP Fp1 and the soluble protein InaKC, connected by a cleavable site. Once Fp1 becomes free by protease-mediated cleavage, Fp1 can adhere to a variety of surfaces to form complexes with different types of materials, such as magnetite (inorganic) and plastic (organic) microparticles. Polystyrene (PS) microbeads were used as microplastic materials in this study. The controlled agglomeration of magnetite with PS beads was assessed, and the agglomerate formed underwater showed a strong interaction between the PS beads and magnetite with free Fp1. The agglomerates were separated from the water by magnetic recovery. The results of the MAP-assisted magnetic recovery of PS microbeads showed a recovery rate of 99.6%. This study lays the foundation for using Fp1 as a biocompatible, nontoxic, and environmentally friendly solution for microplastic recovery, emphasizing the novelty and significant potential of this approach for sustainable water purification strategies.