Hydration behaviors of nonfouling zwitterionic materials

• Published in: Chemical science (Cambridge) Vol. 14; no. 27; pp. 75 - 7511
• Main Authors: Sarker, Pranab, Lu, Tieyi, Liu, Di, Wu, Guangyao, Chen, Hanning, Jahan Sajib, Md Symon, Jiang, Shaoyi, Chen, Zhan, Wei, Tao
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 12.07.2023; The Royal Society of Chemistry
• Subjects: Biomolecules; Bonding strength; Charge transfer; Chemistry; Dipole interactions; Dipole moments; Fouling; Hydration; Hydrogen bonding; Molecular dynamics; Separation; Structural stability; Trimethylamine; Zwitterions
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/d3sc01977b

Zwitterionic materials have emerged as highly effective ultralow fouling materials for many applications, however the underlying mechanism of fouling resistance remains unclear. Using ab initio molecular dynamics simulations and surface-sensitive sum frequency generation vibrational spectroscopy, we studied the hydration behaviors of zwitterionic materials, including trimethylamine- N -oxide (TMAO) and carboxybetaines of different charge-separation distances, to understand their fouling-resistant mechanism and provide a design principle for improved performance. Our study reveals that the interplay among hydrogen bonding, net charge, and dipole moment is crucial to the fouling-resistant capabilities of zwitterionic materials. Shortening of the zwitterionic spacing strengthens hydrogen bonding with water against biomolecule attachment due to the increased electrostatic and induction interactions, charge transfer, and improved structural stability. Moreover, the shortened charge separation reduces the dipole moment of zwitterionic materials with an intrinsic near-neutral net charge, decreasing their electrostatic and dipole-dipole interactions with biofoulers, and increasing their resistance to fouling. Compared to carboxybetaine compounds, TMAO has the shortest zwitterionic spacing and exhibits the strongest hydrogen bonding, the smallest net charge, and the minimum dipole moment, making it an excellent nonfouling material. Understanding the nonfouling mechanism of zwitterionic materials is crucial for their broad applications. Our study reveals the importance of strong hydration bonding, near-neutral net charge, and small dipole moment in achieving fouling resistance.