Preventing biofouling is challenging for a wide range of biomedical applications. Although materials with good anti-biofouling properties are reported, their antifouling functions are readily lost when detachments or scratches occur through physical damage and chemical degradation by water, oxygen, or possible catalytic ions in water containing reactive environments. Consequently, it is important to develop durable anti-biofouling materials with healing abilities. This review summarizes the important developments in five kinds of antibiofouling materials categorized according to healing mechanisms and material properties in the recent five years, namely structural rearrangement-, reaction-, ionic bond-, and hydrogel-based healing materials, as well as other healable antifouling materials. The healing mechanisms and potential biomedical applications of these healable anti-biofouling materials are emphasized.We focus on the "functional" self-healing, i.e., the recovery of anti-biofouling properties. Five types of anti-biofouling and healable materials are discussed in detail based on the healing mechanisms and material properties. Potentials of these antifouling mechanisms in various biomedical applications and some future perspectives are proposed.
Anti-Biofouling and Healable MaterialsThe general requirements of designing antifouling and healable materials are introduced in detail in this section based on healing mechanisms and the materials used. Three types of anti-biofouling and healable materials, namely, structural rearrangement-, reaction-, and ionic bond-based antifouling healable materials were classified based on the healing mechanisms. Additionally, hydrogel-based antifouling self-healing materials were listed as a specific class of materials. Each item was discussed and summarized in Table 1 with several recent examples reported by various research groups. In addition, some other antifouling healable materials were also introduced briefly.Generally, the healing process is characterized by morphology-based methods such as rheology, tensile tests, and cut-/scratch-healing tests with the assistance of scanning electron microscopy (SEM), optical microscope images, and atomic force microscopy (AFM), which also quantify the healing efficiency. Infrared (IR) spectroscopy or linear Raman spectra can monitor the formation or cleavage of chemical bonds and supramolecular interactions in the healing process. Recently, Popp and co-workers proposed that coherent anti-Stokes Raman scattering, a nonlinear Raman variant can be used as molecular characterization of healing process. It acquires morphological and molecular information simultaneously and thus offers a different observation from conventional morphological-based methods. [12] The anti-biofouling properties are usually evaluated by wettability measurements as well as the resistance ability to proteins, cells, bacteria, algas, and other microorganisms. In the wettability measurements, contact angle (CA) and contact angle hysteresis (CAH) experiments are used ...