Versatile Double Bandgap Photonic Crystals of High Color Saturation.

Double bandgap photonic crystals (PCs) exhibit significant potential for applications in various color display-related fields. However, they show low color saturation and inadequate color modulation capabilities. This study presents a viable approach to the fabrication of double bandgap photonic inks diffracting typical secondary colors and other composite colors by simply mixing two photonic nanochains (PNCs) of different primary colors as pigments in an appropriate percentage following the conventional RGB color matching method. In this approach, the PNCs are magnetically responsive and display three primary colors that can be synthesized by combining hydrogen bond-guided and magnetic field (H)-assisted template polymerization. The as-prepared double bandgap photonic inks present high color saturation due to the fixed and narrow full-width at half-maxima of the parent PNCs with a suitable chain length. Furthermore, they can be used to easily produce a flexible double bandgap PC film by embedding the PNCs into a gel, such as polyacrylamide, facilitating fast steady display performance without the requirement of an external magnetic field. This research not only presents the unique advantages of PNCs in constructing multi-bandgap PCs but also establishes the feasibility of utilizing PNCs in practical applications within the fields of anti-counterfeiting and flexible wearable devices.

Heterogeneous Thermochromic Hydrogel Film Based on Photonic Nanochains.

The rapid and robust response to external stimulus with a large volume deformation is of huge importance for the practical application of thermo-responsive photonic crystal film (TRPCF) in actuators, colorimetric sensors, and other color-related fields. Generally, decreasing the size of thermo-responsive photonic crystals and introducing micropores are considered to be two effective approaches to improve their responsiveness. However, they usually result in a poor mechanical property, which leads to optical instability. To solve these problems, a heterogeneous thermo-responsive photonic crystal film was developed here by integrating a thermosensitive hydrogel matrix poly(N-isopropylacrylamide-co-N-methylolacrylamide) (P(NIPAM-co-NHMA)) with high-modulus, but non-thermosensitive poly(acrylic acid -co-2-hydroxyethyl methacrylate (P(AA-co-HEMA)) hydrogel-based photonic nanochains (PNCs). The as-obtained TRPCF based on PNCs (TRPCF-PNC) well combined the rapid response and improved the mechanical property. Typically, it can complete a response within 12 s from 26 to 44 °C, which was accompanied by a larger deformation of the matrix than that of the PNCs. The unique rapid thermochromic mechanism of the TRPCF-PNC is revealed here. Furthermore, it exhibits a high tensible property along the PNC-orientation direction and excellent optical stability. The response time of the TRPCF-PNC can conveniently modulate by changing the cross-linking degree of the PNCs or the content of the thermosensitive component in the matrix. The heterogeneous TRPCF-PNC is believed to have potential applications in artificial muscle and quick-response actuation devices.

Glucose-Sensing Photonic Nanochain Probes with Color Change in Seconds.

Glucose-sensing photonic crystals are promising for the significant advance of continuous glucose monitoring systems due to the naked-eye colorimetric readouts and noninvasive detection of diabetes, but the long response time hampers their practical applications. Here, for the first time probes of photonic nanochains (PNCs) are demonstrated that are capable of continuously and reversibly sensing glucose concentration ([glucose]) variation within seconds by color change without power consumption, much faster by 2-3 orders of magnitude than previous ones. They are comprised of 1D equidistant arrays of magnetic nanoparticles enveloped by tens-of-nanometer-thick phenylboronic acid-functionalized hydrogels, and fabricated by developing selective concentration polymerization of monomers in binary microheterogeneous solvents of dimethyl sulfoxide (DMSO) and H2 O. In this process, both 3-acrylamido phenylboronic acid (AAPBA) and N-2-hydroxyethyl acrylamide (HEAAm) are preferentially dissolved in the small volume of free DMSO concentrated in the vicinity of poly vinylpyrrolidone coated Fe3 O4 colloidal nanoparticles (Fe3 O4 @PVP), yielding Fe3 O4 @PVP@poly(AAPBA-co-HEAAm) PNCs after UV irradiation under magnetic field. The PNCs in phosphate buffered solution have a wavelength-shift range up to 130 nm when [glucose] changes from 0 to 20 × 10-3 m. The results can facilitate real-time glucose monitoring and provide an alternative to produce functional organic-inorganic nanostructures.

Complete genome sequencing and analysis of six enterovirus 71 strains with different clinical phenotypes.

BACKGROUND: Hand, foot and mouth diseases (HFMD) caused by enterovirus 71(EV71) presents a broad spectrum of clinical manifestations ranging from mild febrile disease to fatal neurolocal disease. However, the mechanism of virulence is unknown. METHODS: We isolated 6 strains of EV71 from HFMD patients with or without neurological symptoms, and sequenced the whole genomes of the viruses to reveal the virulence factors of EV71. RESULTS: Phylogenetic tree based on VP1 region showed that all six strains clustered into C4a of C4 sub-genotype. In the complete polypeptide, 298 positions were found to be variable in all strains, and three of these positions (Val(P814)/Ile(P814) in VP1, Val(P1148)/Ile(P1148) in 3A and Ala(P1728)/Cys)/Val(P1728) in 3C) were conserved among the strains with neurovirulence, but variable in strains without neurovirulence. In the 5'-UTR region, it showed that the first 10 nucleotides were mostly conserved, however from the 11th nucleotide, nucleotide insertions and deletions were quite common. The secondary structure prediction of 5'-UTR sequences showed that two of three strains without neurovirulence (SDLY11 and SDLY48) were almost the same, and all strains with neurovirulence (SDLY96, SDLY107 and SDLY153) were different from each other. SDLY107 (a fatal strain) was found different from other strains on four positions (C(P241)/T(P241), A(P571)/T(P571), C(P579)/T(P579) in 5'-UTR and T(P7335)/C(P7335) in 3'-UTR). CONCLUSIONS: The three positions (Val(P814)/Ile(P814) in VP1, Val(P1148)/Ile(P1148) in 3A and Ala(P1728)/Cys(P1728)/Val(P1728) in 3C), were different between two phenotypes. These suggested that the three positions might be potential virulent positions. And the three varied positions were also found to be conserved in strains with neurovirulence, and variable in strains without neurovirulence. These might reveal that the conservation of two of the three positions or the three together were specific for the strains with neurovirulence. Varation of secondary structure of 5'-UTR, might be correlated to the changes of viral virulence. SDLY107 (a fatal strain) was found different from other strains on four positions, these positions might be related with death.