Bio-inspired structural colors prepared by using hollow mesoporous silica spheres and carbon black

Abstract

Solid silica or polystyrene spheres have been widely used to mimic solid melanin for fabricating amorphous photonic structures (APSs) and non-iridescent structural colors. However, few studies have been reported about mimicking APSs from hollow melanosomes in biology. A combination of HMSSs and carbon black (CB) is put forward to mimic hollow melanosomes for obtaining APSs and non-iridescent structural colors. Varied structural colors and reflection peaks of APSs are fabricated by adjusting diameters of HMSSs, amounts of CB and mixing ratios of different HMSSs. The stopband shift (137 nm) of the HMSS APSs infiltrated in ethanol is larger than the 40 nm red shift of solid silica photonic crystals (PCs) and the 105 nm red shift of HMSS PCs. The APSs from HMSSs show high sensitivity in visual detection for the chemicals with similar refractive indices, such as homologues and isomers. Based on structural difference of solid silica spheres and HMSSs, the combined APSs-LR could be obtained from the left side of solid silica spheres and the right side of HMSSs, the APSs-LU are from the lower layer of solid silica spheres and the upper layer of HMSSs. They could be used for information encryption and anti-counterfeiting by adjusting combination ways and the effective refractive indexes. The APSs show great potential applications in display, visual detection, information encryption and anti-counterfeiting.