Slippery by design: Mechanistic insights and biomedical applications of zwitterionic polymer interfaces

The low-friction property of interfaces is indispensable for both sustaining normal physiological functions and enabling diverse biomedical applications, serving as a critical underpinning for processes spanning joint movement, cellular transport, the performance of medical devices, and the functionality of diagnostic tools. Zwitterionic polymers, owing to their unique charge characteristics, can form stable hydrated layers that provide lubricity and environmental stability. Moreover, their ability to remain adaptable to complex biological conditions makes them a highly promising option for constructing high-performance low-friction interfaces. This review begins with the classification of the zwitterionic polymers. The discussion then shifts to hydration lubrication mechanisms and relevant characterization techniques that guide the design and evaluation of biolubricating materials. From the perspectives of disease treatment, tissue protection, and medical device enhancement, the biomedical applications of zwitterionic lubricants are systematically reviewed. Finally, several key challenges and promising future research directions are highlighted. Statement of significance Low-friction interfaces are vital in biology and medicine. Zwitterionic polymers, which form ultra-lubricious and stable hydrated layers, are ideal for constructing such interfaces. However, a clear roadmap connecting their fundamental lubrication mechanisms to practical biomedical design has been lacking. This review addresses this gap by systematically linking chemical structures and hydration mechanisms to specific applications in disease treatment, tissue protection, and medical devices, while also outlining challenges and key future research directions to advance the field.