Efficient and large scale printing of photonic crystal patterns with multicolor, multigrayscale, and fine resolution is highly desired due to its application in smart prints, sensors, and photonic ...devices. Here, an electric‐field‐assisted multicolor printing is reported based on electrically responsive and photocurable colloidal photonic crystal, which is prepared by supersaturation‐induced self‐assembly of SiO2 particles in the mixture of propylene carbonate (PC) and trimethylolpropane ethoxylate triacrylate (ETPTA). This colloidal crystal suspension, named as E‐ink, has tunable structural color, controllable grayscale, and instantly fixable characteristics at the same time because the SiO2/ETPTA‐PC photonic crystal has metastable and reversible assembly as well as polymerizable features. Lithographical printing with photomask and maskless pixel printing techniques are developed respectively to efficiently prepare multicolor and high‐resolution photonic patterns using a single‐component E‐ink.
Electric‐field‐responsive and photocurable liquid photonic crystals composed of SiO2 particles, propylene carbonate, and trimethylolpropane ethoxylate triacrylate are used as E‐ink to prepare multicolor and high‐resolution photonic crystal patterns by lithographic and pixel printing methods, respectively.
An efficient and straightforward method is developed to prepare a mechanochromic photonic gel by fixing the metastable SiO2 colloidal crystalline array (CCA) in the mixture of ethylene glycol (EG) ...and poly(ethylene glycol) methacrylate (PEGMA) through photopolymerization. Thanks to the recent fabrication of solvent‐wrapped, metastable CCA, a high volume fraction of EG (46%) is introduced to the photonic gel before particle assembly, but not by swelling after polymerization, which leads to a more deformable composite than most reported opal gels. Compared to traditional photonic gels, this opal gel not only has improved mechanochromic sensitivity to weak external force and extended color tuning range from red to blue (Δλ = 150 nm), but also possesses fast and reversible response in millisecond level (20–200 ms), repeatable reflection signals in cycling and fatigue tests, and good resolution in response to localized deformation, which renders it an ideal deformation‐based photonic display screen. A new trigger system is designed to solve the large deformation causing color fading in conventional mechanochromic gels and brilliant red, green, and blue (RGB) pixels can be conveniently manipulated by ‘pushing’ operations.
A mechanochromic photonic gel is prepared by fixing metastable SiO2 colloidal crystalline array in the mixture of EG and PEGMA through photopolymerization. Compared to traditional opal gels, it has improved mechanochromic sensitivity, a broad color tuning range, fast response, repeatable reflection signals in cycling and fatigue tests, and good resolution for localized deformation, which makes it a good deformation‐based photonic display panel with controllable RGB pixels.
Invisible photonic prints shown by deformation are prepared by soaking the mechanochromic photonic paper with crosslinker (PEGDA) and subsequently crosslinking part of the paper through a photo ...lithography process. The key point of this new technique is creating patterns and background with very close photonic structures but different mechanochromic capabilities, so that the invisible photonic patterns in relaxed state can be revealed under deformation due to the nonuniform change in photonic structure. Based on the relationship between crosslinking level and the reflection changes during deformation, one can conclude that a low crosslinking level favors the hiding of invisible patterns and a high crosslinking level favors the showing of patterns. The as‐prepared samples can instantly and reversibly show the patterns by deformation and hide them by relaxation for many times, and the encapsulation by PDMS rubber prolongs its life time and enhances its durability in practical usages. The current printing technique is capable of creating invisible photonic prints in both macroscale and microscale range, which makes them potentially useful for security and antifraud applications in daily life.
An effective photonic printing method is developed to create patterns and background with very close photonic structures but different mechanochromic capabilities, so that the invisible photonic patterns in relaxed state can be revealed under deformation due to the nonuniform change in photonic structure. The patterns can be instantly and reversibly shown or hidden for many times, which could be a useful encryption or antifraud material in daily life.
Solvent wrapped “metastable” crystalline colloidal arrays (CCAs) have been prepared by supersaturation induced precipitation and self-assembly of monodisperse particles in polar/nonpolar organic ...solvents. These metastable CCAs possess ordered structures but with less stability comparing with traditionally fixed colloidal crystal systems. They are stabilized by the balance between long-range attraction and electrostatic repulsion of neighboring like-charged particles. Monitoring the reflection intensity during evaporation suggests that these crystals can exist for several hours at 90 °C and even longer at room temperature. Based on the evolution of particle volume fraction in whole suspension (ϕSiO2 ), crystal phase (ϕcrystal), and liquid phase (ϕliquid), the formation of metastable CCAs can be understood as a microscopic phase separation process, where the homogeneous dispersion will separate into a “crystal phase” with orderly stacked particles and a “liquid phase” with randomly dispersed particles. Further calculation of the volume fraction of crystal phase (V crystal/V total) and the ratio of particles in crystal phase (f crystal) shows that with the increase of designed ΦSiO2 , more particles precipitate to form colloidal crystals with larger sizes but the lattice spacing of the microcrystals remains constant. Unlike fixed or traditional responsive CCAs, these metastable CCAs can reversibly assemble and disassemble with great ease, because little energy is involved or required in this transformation. Therefore, they can sense weak external disturbances, including subtle motion and slight friction or shearing forces.
A soaking based invisible photonic print is prepared by regionally selective hydrophobization of SiO
2
/PEGMA photonic paper under a mask. The patterns on the prints are invisible in a dry state but ...visible in water, because the nonuniform swelling behavior of the hydrophilic and hydrophobic regions of the paper induces a different lattice expansion and a large color contrast between the pattern and the background. Due to the uncrosslinked characteristic and the superior swelling ability of the current photonic paper, the invisible patterns printed on it can be reversibly shown and hidden in several seconds and its resolution reaches the micrometer scale, both of which favor its application in antifraud labels or in the identification recognition in our daily lives.
High-resolution invisible patterns printed on uncrosslinked SiO
2
/PEGMA photonic paper can be quickly revealed by water soaking and hidden by drying.
Monodisperse SiO2 colloids are assembled into colloidal crystals in the mixture of monomer and solvent, which is transformed into a mechanochromic photonic crystal paper by polymerization. Following ...the relief printing strategy, the printing plates are pressed onto the paper to generate letters or images due to the contrast of structural color between the deformed and the undeformed paper, and the images can be permanently retained through UV curing. The wide tunable range of structural color for the current paper under deformation helps to realize multi-color printing. The localized deformation among or even inside the colloidal microcrystals renders the paper with a precise mechanochromic response to the printing plates and leads to the production of high resolution photonic crystal patterns.
Photonic crystal (PC) films are prepared by precipitation of colloidal crystal seeds in supersaturated solution of particles, followed by crystal growth and structure fixing with ...photo‐polymerization. As the liquid monomer becomes a solid matrix, the highly concentrated particles are forced to precipitate into colloidal microcrystals in short time, and ‘polymerization‐induced colloidal assembly’ (PICA) is shown to be the major driving force to form colloidal crystals. PICA is intrinsically different from evaporation‐induced colloidal assembly, because the seed formation and crystal growth are separated into two independent steps, which makes the synthesis more flexible, controllable, and efficient. The PICA process is capable of quickly producing PC films with an ultra‐narrow bandgap, tunable thickness, and large size. Based on these characteristics and the blocking effect of the outer PC layer to the reflection signal of inner layer, a coding–decoding system is developed in which the film's composition and stacking sequence can be identified by its distinctive reflection spectrum.
Polymerization‐induced colloidal assembly is developed to prepare photonic crystal films with an ultra‐narrow bandgap and tunable thickness and size. As the liquid monomer becomes solid polymer, the highly concentrated particles are driven to precipitate into colloidal microcrystals. Based on this synthesis, a coding–decoding system is developed in which the film's composition and stacking sequence can be identified by its distinctive reflection spectrum.
Monodisperse SiO
2
colloids are assembled into colloidal crystals in the mixture of monomer and solvent, which is transformed into a mechanochromic photonic crystal paper by polymerization. Following ...the relief printing strategy, the printing plates are pressed onto the paper to generate letters or images due to the contrast of structural color between the deformed and the undeformed paper, and the images can be permanently retained through UV curing. The wide tunable range of structural color for the current paper under deformation helps to realize multi-color printing. The localized deformation among or even inside the colloidal microcrystals renders the paper with a precise mechanochromic response to the printing plates and leads to the production of high resolution photonic crystal patterns.
Relief printing is applied to prepare multi-color and high resolution patterns on mechanochromic photonic crystal paper. When the printing plate is pressed to the paper, corresponding pattern appears due to different structural colors of deformed and undeformed paper, and it will be fixed through UV curing afterwards.
No reliable method for evaluating intestinal fibrosis in Crohn’s disease (CD) exists; therefore, we developed a computed-tomography enterography (CTE)–based radiomic model (RM) for characterizing ...intestinal fibrosis in CD.
This retrospective multicenter study included 167 CD patients with 212 bowel lesions (training, 98 lesions; test, 114 lesions) who underwent preoperative CTE and bowel resection at 1 of the 3 tertiary referral centers from January 2014 through June 2020. Bowel fibrosis was histologically classified as none–mild or moderate–severe. In the training cohort, 1454 radiomic features were extracted from venous-phase CTE and a machine learning–based RM was developed based on the reproducible features using logistic regression. The RM was validated in an independent external test cohort recruited from 3 centers. The diagnostic performance of RM was compared with 2 radiologists’ visual interpretation of CTE using receiver operating characteristic (ROC) curve analysis.
In the training cohort, the area under the ROC curve (AUC) of RM for distinguishing moderate–severe from none–mild intestinal fibrosis was 0.888 (95% confidence interval CI, 0.818–0.957). In the test cohort, the RM showed robust performance across 3 centers with an AUC of 0.816 (95% CI, 0.706–0.926), 0.724 (95% CI, 0.526–0.923), and 0.750 (95% CI, 0.560–0.940), respectively. Moreover, the RM was more accurate than visual interpretations by either radiologist (radiologist 1, AUC = 0.554; radiologist 2, AUC = 0.598; both, P < .001) in the test cohort. Decision curve analysis showed that the RM provided a better net benefit to predicting intestinal fibrosis than the radiologists.
A CTE-based RM allows for accurate characterization of intestinal fibrosis in CD.
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Yohimbine hydrochloride (YH) is a prescription drug to treat erectile dysfunction. It also had potential in fighting high blood pressure and diabetic neuropathy as well as promoting weight loss.
The ...aim of the study is to investigate the anti-melanogenic function of yohimbine hydrochloride and reveal its underlying molecular mechanism.
B16F10 mouse melanoma cells, Melan-A murine melanocyte, Zebrafish embryos and C57BL/6 mouse ear skins were treated with different concentrations of YH. The extracellular and cellular melanin content was detected by spectrometry. The expression of microphthalmia-associated transcription factor (MITF), tyrosinase and the activities of Wnt/β-catenin and p38/MAPK signal pathways were determined by RT-qPCR, Western blot analysis and immunofluorescent staining.
Melanin production could be effectively inhibited by YH at the safe concentration in vitro and in vivo. Q-PCR and WB results showed that the expression of MITF and tyrosinase were strongly downregulated after YH treatments along with the reduction of tyrosinase activity. YH markedly inhibited β-catenin nuclear accumulation and p38 phosphorylation in B16F10 cells compared with the untreated controls. Importantly, the increase of MITF expression induced by β-catenin activator BIO and p38 activator anisomycin could be fully reversed by YH treatments.
These results indicate that YH can function as an anti-melanogenic agent, at least in part, by inhibiting Wnt/β-catenin and p38/MAPK signal pathways. Therefore, YH may be potentially used as a skin-whitening compound for preventing hyperpigmentation disorders in the future.
•This manuscript extends the novel function of YH as the anti-melanogenic agents.•It is first to report YH could inhibit β-catenin nuclear accumulation and p38 phosphorylation.•YH downregulates MITF expression via regulating Wnt/β-catenin and p38/MAPK signal pathways.
