Invasion of cancer cell induced by matrix metalloproteinase-9 (MMP-9) is one of pivotal steps in cancer metastasis. Herein, we investigated how cell invasion was regulated by berberine (BBR), an isoquinoline derivative alkaloid compound, in MDA-MB-231 human breast cancer cells. The basal level of MMP-9 activity and expression was dose-dependently increased by TNF-α, while TNF-α-induced MMP-9 gelatinase activity and expression was decreased by BBR. To investigate regulatory mechanism of TNF-α-induced MMP-9 expression, we pretreated cells with UO126 (MEK inhibitor), SB203580 (p38 inhibitor) and SP600125 (JNK inhibitor), respectively. Interestingly, TNF-α-induced MMP-9 activity and expression was decreased by UO126 and SB203580, but not by SP600125. Therefore, we further examined the effects of BBR on TNF-α-induced AP-1 DNA binding activity which is a downstream target of ERK and p38. Our data showed that TNF-α-induced AP-1 DNA binding activity was inhibited by BBR. Finally, we investigated the effect of BBR on TNF-α-induced cell invasion. TNF-α-induced cell invasion was significantly decreased by BBR treatment. Taken together, we suggest that TNF-α-induced MMP-9 expression and cell invasion are decreased by BBR through the suppression of AP-1 DNA binding activity in MDA-MB-231 human breast cancer cells.
Colloidal arrays show structural colors through wavelengthselective diffraction. The structural colors are dynamically tunable with mechanical deformation for a non-close-packed colloidal array embedded in an elastic matrix. However, such compositions usually render photonic materials transparent and structural color low saturated. In this work, we formulate colloidal inks to produce mechanochromic films and patterns that show consistent structural colors with high saturation. The inks are composed of a high-volume fraction of silica particles and a low fraction of polydopamine nanoparticles dispersed in an elastomer-forming resin. The silica particles have repulsive interparticle potential and form a non-closepacked array, whereas polydopamine nanoparticles are positioned in the interstitial areas. The colloidal arrays are captured in the elastomer by photopolymerization of the resin. As polydopamine nanoparticles reduce incoherent scattering and make the materials opaque, the structural color arisen from the colloidal array is pronounced and independent of the background. Moreover, the photonic materials show a dynamic and reversible change of structural color according to deformation. For large strains, the photonic effect is overwhelmed by absorption of polydopamine nanoparticles, rendering the materials dark brown. This unique mechanochromic property is used to make patterns that are reversibly color-tunable and hidable, which are appealing for user-interactive anti-counterfeiting and active camouflage.
Structural coloration provides a great potential for various applications due to unique optical properties distinguished from conventional pigment colors. Structural colors are nonfading, iridescent, and tunable, which is difficult to achieve with pigments. In addition, structural color is potentially less toxic than pigments. However, it is challenging to develop structural colors because elaborate nanostructures are a prerequisite for the coloration. Furthermore, it is highly suggested the nanostructures be patterned at various length scales on a large area to provide practical formats. There have been intensive studies to develop pragmatic methods for producing structural-color patterns in a controlled manner using either colloidal crystals or glasses. This article reviews the current state of the art in the structural-color patterning based on the colloidal arrays. We first discuss common and different features between colloidal crystals and glasses. We then categorize colloidal arrays into six distinct structures of 3D opals, inverse opals, non-close-packed arrays, 2D colloidal crystals, 1D colloidal strings, and 3D amorphous arrays and study various methods to make them patterned from recent key contributions. Finally, we outline the current challenges and future perspectives of the structural-color patterns.
Colloidal crystals have been used for creating stimuli-responsive photonic materials. Here, macroporous hydrogels are designed, through a simple and reproducible protocol, that rapidly and reversibly switch between highly transparent and structurally colored states. The macroporous hydrogels are prepared by film-casting photocurable dispersions of silica particles in hydrogel-forming resins and selectively removing silica particles. The silica particles spontaneously form a nonclose-packed array due to repulsive interparticle interaction, which form the regular array of cavities after removal. However, the cavities are randomly collapsed by drying, losing a long-range order and rendering the materials highly transparent. When the hydrogels are swollen by either water, ethanol, or the mixture, the regular array is restored, which develops brilliant structural colors. This switching is completed in tens of seconds and repeatable without any hysteresis. The resonant wavelength depends on the composition of the water-ethanol mixture, where the dramatic shift occurs in one-component-rich mixtures due to the composition of the hydrogel. Micropatterns can be designed to have distinct domains of the macroporous hydrogels, which are transparent at the dried state and disclose encrypted graphics and unique reflectance spectra at the wet state. This class of solvent-responsive photonic hydrogels is potentially useful for alcohol sensors and user-interactive anti-counterfeiting materials.
Structural color graphics with any design and color combination can be directly printed with high precision.
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