- Email: [email protected]
Nature-Inspired Color beyond Pigments
activity of 3.3 A/mg(Pt) for the oxygen reduction reaction. Nano Lett. 13, 3420– 3425. 8. Zhang, C., Sandorf, W., and Peng, Z. (2015). Octahedral Pt2CuNi uniform alloy nanoparticle catalyst with high activity and promising stability for oxygen
reduction reaction. ACS Catal. 5, 2296– 2300. 9. Cao, L., Zhao, Z., Liu, Z., Gao, W., Dai, S., Gha, J., Xue, W., Sun, H., Duan, X., Pan, X., et al. (2019). Differential surface elemental distribution leads to significantly enhanced stability of PtNi-
based ORR catalysts. Matter 1, this issue, 1567–1580. 10. 3.4 Fuel Cells, 2016 (Updated May 2017) (Department of Energy https://www.energy.gov/sites/prod/ files/2017/05/f34/ fcto_myrdd_fuel_cells.pdf).
Preview
Nature-Inspired Color beyond Pigments
polydopamine and graphene oxide encapsulated silica nanoparticles were obtained.
Lianxin Shi1 and Shutao Wang1,2,* Natural beauty is hard to be exhibited by the pale colors of man-made pigments. In this issue of Matter, Zhao and co-workers used graphene oxide-encapsulated silica nanoparticles to assemble polydopamine-adhered microsphere and provide brighter structural color with angle independence and optimal stability. Colors are regarded as the God-given gifts for human beings. As early as Middle Stone Age, Ochre—a natural red pigment—has been possibly used for decoration in Africa.1 Diverse colorful mineral, flowers, whelk, and even beetles were also triturated and refined for the scarce pigments. Bright colors became symbols of fames and status, such as the grand church murals and the royal gorgeous costumes, but these limited natural pigments were still insufficient for people’s colorful life. With the development of fossil industry and nanotechnology, man-made organic and inorganic pigments were well developed to enrich the color palette.2 However, those colors depend on the light with specific wavelengths that pigments absorb and reflect. Nature also provides another alternative strategy—pigment-independent structural color—to display its colorful beauty, like peacock feathers, butterfly wings, and beetle shells.3,4 People have attempted to mimic these structural colors by assembling colloidal particles,5 but the particles are limited in their insufficient color saturation and
weak adhesion particles.
between
colloidal
By mimicking the specific microstructure and the existence of melanosomes in bird feathers, Zhao and coworkers from China have recently developed a bio-inspired non-iridescent structural-color pigments with excellent brightness, robustness, and self-adhesivity (Figure 1).6 The unique pigments were fabricated by assembling the specially designed multi-shell silica nanoparticles. The original unmodified silica nanoparticles were first encapsulated by a polydopamine layer. Then, it was coated by a graphene oxide layer with the assistance of the polydopamine’s adhesivity. Here, graphene oxide was served as a dark element to mimic the melanosomes in birds’ feathers for enhancing the color saturation and brightness of the material, while the existence of polydopamine was aimed to improve the adhesivity of pigment components so as to increase the robustness of the resultant pigments. By repeating these two coating processes, the multi-shell
To achieve the generation of the specially-designed non-iridescent pigments, these multi-shell nanoparticles were served as elementary units of the pigments. These particles were first dispersed in absolute ethanol and then assembled into microspheres with different sizes after being sprayed under the near-infrared radiation. These formed microspheres exhibited amorphous structure, thus exhibiting non-iridescent properties, scilicet the angle-independent characteristic. It was interesting that the bio-inspired multi-shell nanoparticle-derived pigments showed much brighter structural colors and more robust stability after various destroying methods. Moreover, the research team also expanded the advanced functions of the pigments through the special features of graphene oxide. They generated inverse opal structured hydrogel patterns through negatively replicating the template pigments. Owing to the existence of graphene oxide in the resultant hydrogels, these hydrogel patterns were endowed with photothermal
1CAS
Key Laboratory of Bio-inspired Materials and Interfacial Science, CAS Center for Excellence in Nanoscience, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, P. R. China
2School
of Future Technology, University of Chinese Academy of Sciences, Beijing, P. R. China *Correspondence: [email protected] https://doi.org/10.1016/j.matt.2019.11.007
Matter 1, 1445–1455, December 4, 2019 ª 2019 Elsevier Inc. 1449
area production. There are still many efforts needed to be done to step over the proof-of-concept stage for realizing practical applications. Nevertheless, this work provides a promising bioinspired concept for creating pigments with superior performances. To combine two or more unique biological characters is emerging as an effective principle in design of new generation function materials.7 We believe this combined bioinspiration principle will accelerate the creation and functionalization of bio-inspired materials in future.
Figure 1. Bio-inspired Bright and Adhesive Non-iridescent Pigments Inspired by feathers’ brightness and mussels’ adhesivity, the non-iridescent structural-color pigments derived from polydopamine and graphene oxide encapsulated silica nanoparticles demonstrate high saturation and robustness. The pigment-derived inverse opal hydrogels also impart them with more advanced functions. Adapted from Zhao and co-workers. 6
responsiveness and self-healing capacity when pairing with different kinds of hydrogels like poly-N-Isopropylacrylamide (pNIPAM) and gelatin. The most important thing is that Liu et al.6 have demonstrated a feasible strategy of creating bio-inspired advanced pigments. The elementary units of the pigments contain both dark element for enhancing color brightness and adhesive component for improving materials robustness. The fast-assembly method of the elementary multi-shell nanoparticles
1450 Matter 1, 1445–1455, December 4, 2019
also ensures the amorphous microstructure of the derived pigments, which imparts the pigments with advantages of non-iridescent materials. Besides, the derivative inverse opal hydrogel patterns also broaden their range of applications. Therefore, the designed pigments are expected to have promising prospects in various application fields like decoration, medicine, sensing, and electronics. However, the current pigment creating system needs the assistance of near-infrared radiation throughout the whole generation process, which is hard to realize in large-
1. Henshilwood, C.S., d’Errico, F., van Niekerk, K.L., Coquinot, Y., Jacobs, Z., Lauritzen, S.E., Menu, M., and Garcı´a-Moreno, R. (2011). A 100,000-year-old ochre-processing workshop at Blombos Cave, South Africa. Science 334, 219–222. 2. Maile, F.J., Pfaff, G., and Reynders, P. (2005). Effect pigments - past, present and future. Prog. Org. Coat. 54, 150–163. 3. Zhao, Y., Xie, Z., Gu, H., Zhu, C., and Gu, Z. (2012). Bio-inspired variable structural color materials. Chem. Soc. Rev. 41, 3297–3317. 4. Zi, J., Yu, X., Li, Y., Hu, X., Xu, C., Wang, X., Liu, X., and Fu, R. (2003). Coloration strategies in peacock feathers. Proc. Natl. Acad. Sci. USA 100, 12576–12578. 5. Zhao, Y., Shang, L., Cheng, Y., and Gu, Z. (2014). Spherical colloidal photonic crystals. Acc. Chem. Res. 47, 3632–3642. 6. Liu, Y., Shao, C., Wang, Y., Sun, L., and Zhao, Y. (2019). Bio-inspired Self-Adhesive Bright Noniridescent Graphene Pigments. Matter 1, this issue, 1581–1591. 7. Park, K.C., Kim, P., Grinthal, A., He, N., Fox, D., Weaver, J.C., and Aizenberg, J. (2016). Condensation on slippery asymmetric bumps. Nature 531, 78–82.
reduction reaction. ACS Catal. 5, 2296– 2300. 9. Cao, L., Zhao, Z., Liu, Z., Gao, W., Dai, S., Gha, J., Xue, W., Sun, H., Duan, X., Pan, X., et al. (2019). Differential surface elemental distribution leads to significantly enhanced stability of PtNi-
based ORR catalysts. Matter 1, this issue, 1567–1580. 10. 3.4 Fuel Cells, 2016 (Updated May 2017) (Department of Energy https://www.energy.gov/sites/prod/ files/2017/05/f34/ fcto_myrdd_fuel_cells.pdf).
Preview
Nature-Inspired Color beyond Pigments
polydopamine and graphene oxide encapsulated silica nanoparticles were obtained.
Lianxin Shi1 and Shutao Wang1,2,* Natural beauty is hard to be exhibited by the pale colors of man-made pigments. In this issue of Matter, Zhao and co-workers used graphene oxide-encapsulated silica nanoparticles to assemble polydopamine-adhered microsphere and provide brighter structural color with angle independence and optimal stability. Colors are regarded as the God-given gifts for human beings. As early as Middle Stone Age, Ochre—a natural red pigment—has been possibly used for decoration in Africa.1 Diverse colorful mineral, flowers, whelk, and even beetles were also triturated and refined for the scarce pigments. Bright colors became symbols of fames and status, such as the grand church murals and the royal gorgeous costumes, but these limited natural pigments were still insufficient for people’s colorful life. With the development of fossil industry and nanotechnology, man-made organic and inorganic pigments were well developed to enrich the color palette.2 However, those colors depend on the light with specific wavelengths that pigments absorb and reflect. Nature also provides another alternative strategy—pigment-independent structural color—to display its colorful beauty, like peacock feathers, butterfly wings, and beetle shells.3,4 People have attempted to mimic these structural colors by assembling colloidal particles,5 but the particles are limited in their insufficient color saturation and
weak adhesion particles.
between
colloidal
By mimicking the specific microstructure and the existence of melanosomes in bird feathers, Zhao and coworkers from China have recently developed a bio-inspired non-iridescent structural-color pigments with excellent brightness, robustness, and self-adhesivity (Figure 1).6 The unique pigments were fabricated by assembling the specially designed multi-shell silica nanoparticles. The original unmodified silica nanoparticles were first encapsulated by a polydopamine layer. Then, it was coated by a graphene oxide layer with the assistance of the polydopamine’s adhesivity. Here, graphene oxide was served as a dark element to mimic the melanosomes in birds’ feathers for enhancing the color saturation and brightness of the material, while the existence of polydopamine was aimed to improve the adhesivity of pigment components so as to increase the robustness of the resultant pigments. By repeating these two coating processes, the multi-shell
To achieve the generation of the specially-designed non-iridescent pigments, these multi-shell nanoparticles were served as elementary units of the pigments. These particles were first dispersed in absolute ethanol and then assembled into microspheres with different sizes after being sprayed under the near-infrared radiation. These formed microspheres exhibited amorphous structure, thus exhibiting non-iridescent properties, scilicet the angle-independent characteristic. It was interesting that the bio-inspired multi-shell nanoparticle-derived pigments showed much brighter structural colors and more robust stability after various destroying methods. Moreover, the research team also expanded the advanced functions of the pigments through the special features of graphene oxide. They generated inverse opal structured hydrogel patterns through negatively replicating the template pigments. Owing to the existence of graphene oxide in the resultant hydrogels, these hydrogel patterns were endowed with photothermal
1CAS
Key Laboratory of Bio-inspired Materials and Interfacial Science, CAS Center for Excellence in Nanoscience, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, P. R. China
2School
of Future Technology, University of Chinese Academy of Sciences, Beijing, P. R. China *Correspondence: [email protected] https://doi.org/10.1016/j.matt.2019.11.007
Matter 1, 1445–1455, December 4, 2019 ª 2019 Elsevier Inc. 1449
area production. There are still many efforts needed to be done to step over the proof-of-concept stage for realizing practical applications. Nevertheless, this work provides a promising bioinspired concept for creating pigments with superior performances. To combine two or more unique biological characters is emerging as an effective principle in design of new generation function materials.7 We believe this combined bioinspiration principle will accelerate the creation and functionalization of bio-inspired materials in future.
Figure 1. Bio-inspired Bright and Adhesive Non-iridescent Pigments Inspired by feathers’ brightness and mussels’ adhesivity, the non-iridescent structural-color pigments derived from polydopamine and graphene oxide encapsulated silica nanoparticles demonstrate high saturation and robustness. The pigment-derived inverse opal hydrogels also impart them with more advanced functions. Adapted from Zhao and co-workers. 6
responsiveness and self-healing capacity when pairing with different kinds of hydrogels like poly-N-Isopropylacrylamide (pNIPAM) and gelatin. The most important thing is that Liu et al.6 have demonstrated a feasible strategy of creating bio-inspired advanced pigments. The elementary units of the pigments contain both dark element for enhancing color brightness and adhesive component for improving materials robustness. The fast-assembly method of the elementary multi-shell nanoparticles
1450 Matter 1, 1445–1455, December 4, 2019
also ensures the amorphous microstructure of the derived pigments, which imparts the pigments with advantages of non-iridescent materials. Besides, the derivative inverse opal hydrogel patterns also broaden their range of applications. Therefore, the designed pigments are expected to have promising prospects in various application fields like decoration, medicine, sensing, and electronics. However, the current pigment creating system needs the assistance of near-infrared radiation throughout the whole generation process, which is hard to realize in large-
1. Henshilwood, C.S., d’Errico, F., van Niekerk, K.L., Coquinot, Y., Jacobs, Z., Lauritzen, S.E., Menu, M., and Garcı´a-Moreno, R. (2011). A 100,000-year-old ochre-processing workshop at Blombos Cave, South Africa. Science 334, 219–222. 2. Maile, F.J., Pfaff, G., and Reynders, P. (2005). Effect pigments - past, present and future. Prog. Org. Coat. 54, 150–163. 3. Zhao, Y., Xie, Z., Gu, H., Zhu, C., and Gu, Z. (2012). Bio-inspired variable structural color materials. Chem. Soc. Rev. 41, 3297–3317. 4. Zi, J., Yu, X., Li, Y., Hu, X., Xu, C., Wang, X., Liu, X., and Fu, R. (2003). Coloration strategies in peacock feathers. Proc. Natl. Acad. Sci. USA 100, 12576–12578. 5. Zhao, Y., Shang, L., Cheng, Y., and Gu, Z. (2014). Spherical colloidal photonic crystals. Acc. Chem. Res. 47, 3632–3642. 6. Liu, Y., Shao, C., Wang, Y., Sun, L., and Zhao, Y. (2019). Bio-inspired Self-Adhesive Bright Noniridescent Graphene Pigments. Matter 1, this issue, 1581–1591. 7. Park, K.C., Kim, P., Grinthal, A., He, N., Fox, D., Weaver, J.C., and Aizenberg, J. (2016). Condensation on slippery asymmetric bumps. Nature 531, 78–82.