Metasurface-Enabled Holographic Lithography for Impact-Absorbing Nanoarchitected Sheets.

Nanoarchitected materials represent a class of structural meta-materials that utilze nanoscale features to achieve unconventional material properties such as ultralow density and high energy absorption. A dearth of fabrication methods capable of producing architected materials with sub-micrometer resolution over large areas in a scalable manner exists. A fabrication technique is presented that employs holographic patterns generated by laser exposure of phase metasurface masks in negative-tone photoresists to produce 30-40 µm-thick nanoarchitected sheets with 2.1 × 2.4 cm2 lateral dimensions and ≈500 nm-wide struts organized in layered 3D brick-and-mortar-like patterns to result in ≈50-70% porosity. Nanoindentation arrays over the entire sample area reveal the out-of-plane elastic modulus to vary between 300 MPa and 4 GPa, with irrecoverable post-elastic material deformation commencing via individual nanostrut buckling, densification within layers, shearing along perturbation perimeter, and tensile cracking. Laser induced particle impact tests (LIPIT) indicate specific inelastic energy dissipation of 0.51-2.61 MJ kg-1 , which is comparable to other high impact energy absorbing composites and nanomaterials, such as Kevlar/poly(vinyl butyral) (PVB) composite, polystyrene, and pyrolized carbon nanolattices with 23% relative density. These results demonstrate that holographic lithography offers a promising platform for scalable manufacturing of nanoarchitected materials with impact resistant capabilities.

Enzymatic Synthesis of Resveratrol α-Glucoside by Amylosucrase of Deinococcus geothermalis.

Glycosylation of resveratrol was carried out by using the amylosucrase of Deinococcus geothermalis, and the glycosylated products were tested for their solubility, chemical stability, and biological activities. We synthesized and identified these two major glycosylated products as resveratrol-4'-O-α-glucoside and resveratrol-3-O-α-glucoside by nuclear magnetic resonance analysis with a ratio of 5:1. The water solubilities of the two resveratrol-α-glucoside isomers (α-piceid isomers) were approximately 3.6 and 13.5 times higher than that of ß-piceid and resveratrol, respectively, and they were also highly stable in buffered solutions. The antioxidant activity of the α-piceid isomers, examined by radical scavenging capability, showed it to be initially lower than that of resveratrol, but as time passed, the α-piceid isomers' activity reached a level similar to that of resveratrol. The α-piceid isomers also showed better inhibitory activity against tyrosinase and melanin synthesis in B16F10 melanoma cells than ß-piceid. The cellular uptake of the α-piceid isomers, which was assessed by ultra-performance liquid chromatography (UPLC) analysis of the cell-free extracts of B16F10 melanoma cells, demonstrated that the glycosylated form of resveratrol was gradually converted to resveratrol inside the cells. These results indicate that the enzymatic glycosylation of resveratrol could be a useful method for enhancing the bioavailability of resveratrol.

Bacillus subtilis Fermentation of Malva verticillata Leaves Enhances Antioxidant Activity and Osteoblast Differentiation.

Malva verticillata, also known as Chinese mallow, is an herbaceous plant with colorful flowers and has been used as a medicine for thousands of years. This study investigated this herb for potential antioxidant activity or an association with osteoblast differentiation. M. verticillate leaves were fermented with B. subtilis MV1 at 30 °C for 7 days to enhance their biological activities. The resultant aqueous extract (MVW) and the fermented leaves (MVB) were measured for antioxidant and osteoblast differentiation. The results showed that the total phenolic, flavonoid, and antioxidant activity, as well as the osteoblast differentiation of the MVB increased (2 to 6 times) compared with those of the MVW. MVB induced phosphorylation of p38, extracellular signal-regulated kinase in C3H10T1/2 cells, and the phosphorylation was attenuated via transforming growth factor-ß (TGF-ß) inhibitors. Moreover, runt-related transcription factor 2 and osterix in the nucleus increased in a time-dependent manner. The messenger RNA expression of alkaline phosphatase and bone sialoprotein increased about 9.4- and 65-fold, respectively, compared to the non-treated cells. MVB stimulated C3H10T1/2 cells in the osteoblasts via TGF-ß signaling. Thus, fermented M. verticillata extract exhibited enhanced antioxidant activity and osteoblast differentiation.