Assembly of Guanine Crystals as a Low-Polarizing Broadband Multilayer Reflector in a Spider, Phoroncidia rubroargentea

Synthesis of Chlorophylls-Doped Guanine Crystals with High Reflection and Depolarization for Green Camouflage Coating

Hyperspectral imaging technology can record the spatial and spectral information of the targets and significantly enhance the levels of military reconnaissance and target detection. It has scientific importance to mimic "homochromatic and homospectral" camouflage materials that have hyperspectral similarity with the green vegetation, one of the most common natural backgrounds. It is a big challenge to exquisitely simulate the spectral of green vegetation in visible and near-infrared windows because of the slight differences between the artificial green dyes and vegetation, the instability of chlorophylls, and the easy loss of hydroxide bands due to the loss of water from the camouflage materials. Herein, a novel kind of biomimetic material of green vegetation was designed through the incorporation of chlorophylls into the crystal lattices of single-crystalline anhydrous guanine microplates for the first time. The synthesized chlorophylls-doped anhydrous guanine crystals exhibit high reflectance intensity and depolarization effect, thus can be applied as biomimetic camouflage materials that mimic green vegetation with high reflectivity and low polarization in the visible and near-infrared regions. The factors influencing the formation of dye-doped organic crystals under mild conditions were thoroughly investigated and the characterizations using electron microscopies and fluorescence confocal laser scanning microscopy clearly confirm the occlusion of chlorophylls into the crystal lattices of guanine crystals. The thermal stability experiments clearly indicate that the chlorophylls-doped guanine crystals possess long-term stability at high temperature. This study provides a new strategy for the synthesis of multifunctional materials comprised of organic crystals.

SeFilter-DIA: Squeeze-and-Excitation Network for Filtering High-Confidence Peptides of Data-Independent Acquisition Proteomics

Mass spectrometry is crucial in proteomics analysis, particularly using Data Independent Acquisition (DIA) for reliable and reproducible mass spectrometry data acquisition, enabling broad mass-to-charge ratio coverage and high throughput. DIA-NN, a prominent deep learning software in DIA proteome analysis, generates peptide results but may include low-confidence peptides. Conventionally, biologists have to manually screen peptide fragment ion chromatogram peaks (XIC) for identifying high-confidence peptides, a time-consuming and subjective process prone to variability. In this study, we introduce SeFilter-DIA, a deep learning algorithm, aiming at automating the identification of high-confidence peptides. Leveraging compressed excitation neural network and residual network models, SeFilter-DIA extracts XIC features and effectively discerns between high and low-confidence peptides. Evaluation of the benchmark datasets demonstrates SeFilter-DIA achieving 99.6% AUC on the test set and 97% for other performance indicators. Furthermore, SeFilter-DIA is applicable for screening peptides with phosphorylation modifications. These results demonstrate the potential of SeFilter-DIA to replace manual screening, providing an efficient and objective approach for high-confidence peptide identification while mitigating associated limitations.

Macromolecular sheets direct the morphology and orientation of plate-like biogenic guanine crystals

Animals precisely control the morphology and assembly of guanine crystals to produce diverse optical phenomena in coloration and vision. However, little is known about how organisms regulate crystallization to produce optically useful morphologies which express highly reflective crystal faces. Guanine crystals form inside iridosome vesicles within chromatophore cells called iridophores. By following iridosome formation in developing scallop eyes, we show that pre-assembled, fibrillar sheets provide an interface for nucleation and direct the orientation of the guanine crystals. The macromolecular sheets cap the (100) faces of immature guanine crystals, inhibiting growth along the π-stacking growth direction. Crystal growth then occurs preferentially along the sheets to generate highly reflective plates. Despite their different physical properties, the morphogenesis of iridosomes bears a striking resemblance to melanosome morphogenesis in vertebrates, where amyloid sheets template melanin deposition. The common control mechanisms for melanin and guanine formation inspire new approaches for manipulating the morphologies and properties of molecular materials.