The creation of anti-reflective surfaces is reliant on the engineering of the surface textures and patterns to enable efficient trapping or transmission of light. Here we demonstrate anti-reflective layers composed of hierarchical nano/microscale features that are prepared on Si using a combination of wet and dry etching processes, and which are both scalable and affordable. The performance of the structured surfaces was tested through optical measurements of the reflectance, transmittance, and scattering spectra from the visible to mid-infrared wavelength regions, and the results were verified using numerical simulations to identify the performance of the textured anti-reflective layers. The anti-reflective properties of the layers were shown to be dramatically improved by the composite nanostructured surfaces over a broad spectral range, which thus provides a basis for the design rules that are essential for the progress towards effective anti-reflector fabrication. At normal incidence, the hierarchical surfaces achieve reflectances that are 10–80 times lower than that of conventional single-etch nano-microstructures. Portions of the absorbed, transmitted, scattered, and reflected light in the visible-IR spectrum are presented to illustrate the results.

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Premelanosome protein (PMEL), a melanocyte‐specific glycoprotein, has an essential role in melanosome maturation, assembling amyloid fibrils for melanin deposition. PMEL undergoes several post‐translational modifications, including N‐ and O‐glycosylations, which are associated with proper melanosome development. C‐mannosylation is a rare type of protein glycosylation at a tryptophan residue that might regulate the secretion and localization of proteins. PMEL has one putative C‐mannosylation site in its core amyloid fragment (CAF); however, there is no report focusing on C‐mannosylation of PMEL. To investigate this, we expressed recombinant PMEL in SK‐MEL‐28 human melanoma cells and purified the protein. Mass spectrometry analyses demonstrated that human PMEL is C‐mannosylated at multiple tryptophan residues in its CAF and N‐terminal fragment (NTF). In addition to the W153 or W156 residue (CAF), which lies in the consensus sequence for C‐mannosylation, the W104 residue (NTF) was C‐mannosylated without the consensus sequence. To determine the effects of the modifications, we deleted the PMEL gene by using CRISPR/Cas9 technology and re‐expressed wild‐type or C‐mannosylation‐defective mutants of PMEL, in which the C‐mannosylated tryptophan was replaced with a phenylalanine residue (WF mutation), in SK‐MEL‐28 cells. Importantly, fibril‐containing melanosomes was significantly decreased in W104F mutant PMEL‐re‐expressing cells compared with wild‐type PMEL, observed using transmission electron microscopy. Further, western blot and immunofluorescence analysis suggested that the W104F mutation may cause mild ER retention, possibly associated with early misfolding, and lysosomal misaggregation, thus, reducing functional fibril formation. Our results demonstrate that C‐mannosylation of PMEL is required for proper melanosome development by regulating PMEL‐derived fibril formation.