Figure 4.

(A) Tunable photon filtering from a white light source using the MNIH PCs, color shifted as the CCD images. (B) The visibly-highlighted structural coloration and transmission spectra of PCs, and spectral characters matched well with the microscale footprint coloration. (C) Phase image, fluorescence image, and merged image of the tested MNIHs in cell cytotoxicity test. Sample 1 was a single-layer PC, and sample 2 was an array of hollow hexahedrons, where the pencil-shape fibroblast cells were crawling on hydrogel block. (D) Cell viability summary of Figure 3C across 1 week on MNIHs. Both samples maintained cell viability ratio of over 95%. (E) The mechanism of self-assembling PEG molecules for repairing damaged fissures. (F) An impaired heart-shaped MNIH self-recovered to its initial symmetric shape. (G) A poked hole in planar MNIHs absorbed PEG-400 molecules to reconstruct the damaged areas, confirming the highly-valuable autonomic repairing process. (H) A similar self-healing process could be found in other mechanically-damaged flower-shaped MNIHs with the aid of PEG-400