Diverse ranking metamaterial inverse design based on contrastive and transfer learning.

Metamaterials, thoughtfully designed, have demonstrated remarkable success in the manipulation of electromagnetic waves. More recently, deep learning can advance the performance in the field of metamaterial inverse design. However, existing inverse design methods based on deep learning often overlook potential trade-offs of optimal design and outcome diversity. To address this issue, in this work we introduce contrastive learning to implement a simple but effective global ranking inverse design framework. Viewing inverse design as spectrum-guided ranking of the candidate structures, our method creates a resemblance relationship of the optical response and metamaterials, enabling the prediction of diverse structures of metamaterials based on the global ranking. Furthermore, we have combined transfer learning to enrich our framework, not limited in prediction of single metamaterial representation. Our work can offer inverse design evaluation and diverse outcomes. The proposed method may shrink the gap between flexibility and accuracy of on-demand design.

Bifunctional sensing based on an exceptional point with bilayer metasurfaces.

Exceptional points (EPs), the critical phase transition points of non-Hermitian parity-time (PT) systems, exhibit many novel physical properties and associated applications, such as ultra-sensitive detection of perturbations. Here, a bilayer metasurface with two orthogonally oriented split-ring resonators (SRRs) is proposed and a phase transition of the eigenpolarization states is introduced via changing the conductivity of vanadium dioxide (VO2) patch integrated into the gap of one SRR. The metasurface possesses a passive PT symmetry and an EP in polarization space is observed at a certain conductivity of the VO2. Two sensing schemes with the metasurface are proposed to achieve high-sensitivity sensing of temperature and refractive index in the terahertz (THz) range. The metasurface is promising for applications in THz biosensing and polarization manipulation.

Retraction Notice to: Silencing of the MEKK2/MEKK3 Pathway Protects against Spinal Cord Injury via the Hedgehog Pathway and the JNK Pathway.

[This retracts the article DOI: 10.1016/j.omtn.2019.05.014.].

Erratum: A novel vehicle-like drug delivery 3D printing scaffold and its applications for a rat femoral bone repairing in vitro and in vivo: Erratum.

[This corrects the article DOI: 10.7150/ijbs.37552.].

A novel 3D printed bioactive scaffolds with enhanced osteogenic inspired by ancient Chinese medicine HYSA for bone repair.

Some traditional Chinese medicine (TCM) has been applied in bone repair, however, hydroxy-safflower yellow A (HYSA), one composition of safflower of the typical invigorating the circulation of TCM, has little been studied in orthopedics field for osteogenesis and angiogenesis clinically. Herein, we hypothetically speculated that the synthetic bioactive glasses (BG, 1393) scaffolds carried HYSA by a 3D print technique could enhance osteogenic repair properties. Notably, scaffolds coating chitosan/sodium alginate endowed with excellent drug control release ability, and significantly improved the BG mechanical strength. HYSA was loaded into BG scaffolds by coating chitosan/sodium alginate film, and the osteogenesis and angiogenesis of the HYSA/scaffolds were evaluated in vitro and in vivo. In vitro the cell culture results exhibited that the high dose of HYSA (0.5 mg/ml) loaded scaffolds can promote the proliferation of bone marrow stromal cells (rBMSCs) and migration, tubule formation of human umbilical vein endothelial cells (HUVECs). The active alkaline phosphatase (ALP) of rBMSCs can also be improved by the high dose of HYSA/scaffolds. Results of qRT-PCR and Western blot indicated that the high dose of HYSA/scaffolds can up-regulate ALP, OCN, OPN and RUNX-2 expression and relative protein secretion of the HIF-1α and BMP-2. In the animal experiment, the high dose of HYSA/scaffolds has a significantly better capacity to promote new bone formation than the undoped scaffolds at 8 weeks post-surgery. Thus, our results claimed that the novel HYSA/scaffolds hold the substantial potential to be further developed as effective and safe bone tissue engineering biomaterials for bone regeneration by combining enhanced osteogenesis and angiogenesis.

A novel vehicle-like drug delivery 3D printing scaffold and its applications for a rat femoral bone repairing in vitro and in vivo.

The high surface area ratio and special structure of mesoporous bioactive glass (MBG) endow it with excellent physical adsorption of various drugs without destroying the chemical activity. Silicate 1393 bioactive glass (1393) is famous for its fantastic biodegradability and osteogenesis. Herein, we have built a novel vehicle-like drug delivery 3D printing scaffold with multiplexed drug delivery capacity by coating MBG on the surface of 1393 (1393@MBG). Furthermore, we have applied DEX and BMP-2 on the 1393@MBG scaffold to endow it with antibacterial and osteogenic properties. Results indicated that this 1393@MBG scaffold could effectively load and controlled release BMP-2, DNA and DEX, which can be applied for orthopedic treatment. The in vitro study showed that the DEX loaded 1393@MBG exhibited excellent antibacterial ability, which was evaluated by Staphylococcus aureus (S. aureus), and the BMP-2 loaded 1393@MBG can improve the alkaline phosphatase (ALP) activity and upregulate the expression of osteogenesis-related genes (OCN and RUNX2) of human bone mesenchymal stem cells (hBMSCs). Moreover, the in vivo study further confirmed that the BMP-2 loaded 1393@MBG group showed better osteogenic capacity as compared to that of the 1393 group in a rat femoral defect. Together, these results suggested that the vehicle-like drug delivery 3D printing scaffold 1393@MBG could be a promising candidate for bone repair and relative bone disease treatment.

Silencing of the MEKK2/MEKK3 Pathway Protects against Spinal Cord Injury via the Hedgehog Pathway and the JNK Pathway.

Spinal cord injury (SCI) is a devastating medical condition, often accompanied by motor and sensory dysfunction. The Hedgehog (Hh) pathway has a protective role in pathological injury after SCI. However, the specific mechanism remains unclear. The present study aimed to confirm the effects of the mitogen-activated protein kinase kinase-2 (MEKK2)/MEKK3/JNK/Hh pathway on SCI. SCI rat models were established and then inoculated with plasmids overexpressing MEKK2/MEKK3 or with small interfering RNA (siRNA) against MEKK2/MEKK3. The expression of MEKK2 and -3 was detected in dorsal root ganglia (DRG) cells. The motor function of hindlimbs, the expression of the c-Jun N-terminal kinase (JNK)- and Hh-pathway-related genes, and the level of neurofilament-200 (NF-200) and glial fibrillary acidic protein (GFAP) were measured. MEKK2 and -3 were expressed at a high level in DRG cells. The silencing of MEKK2/MEKK3 in rats caused an increase in the expression of glioma-associated oncogene homolog-1 (Gli-1), Nestin, smoothened (Smo), and Sonic Hedgehog (Shh). The Basso, Beattie, and Bresnahan (BBB) rating and the level of NF-200 protein also increased. However, the expression of monocyte chemoattractant protein-1 (MCP-1), macrophage inflammatory protein-1ß (MIP-1ß), MIP-3α, p-JNK/JNK, and p-c-Jun/c-Jun and the level of GFAP were reduced. Downregulation of MEKK2/MEKK3 ameliorated the symptoms of SCI by promoting neural progenitor cell differentiation via activating the Hh pathway and disrupting the JNK pathway. The findings in this study reveal a potential biomarker for SCI treatment.

Hypoxia-Mimicking Cobalt-Doped Borosilicate Bioactive Glass Scaffolds with Enhanced Angiogenic and Osteogenic Capacity for Bone Regeneration.

The osteogenic capacity of synthetic bone substitutes is will be highly stimulated by a well-established functional vascularized network. Cobalt (Co) ions are known that can generate a hypoxia-like response and stimulates the production of kinds of angiogenic factors. Herein, we investigated the mechanism of cobalt-doped bioactive borosilicate (36B2O3, 22CaO, 18SiO2, 8MgO, 8K2O, 6Na2O, 2P2O5; mol%) glass scaffolds for bone tissues repairing and blood vessel formation in the critical-sized cranial defect site of rats and their effects on the hBMSCs in vitro were researched. The scaffolds can control release Co2+ ions and convert into hydroxyapatite soaking in simulative body fluids (SBF). The fabircated scaffolds without cytotoxic strongly improves HIF-1α generation, VEGF protein secretion, ALP activity and upregulates the expression of osteoblast and angiogenic relative genes in hBMSCs. Eight weeks after implantation, the bioactive glass scaffolds with 3wt % CoO remarkablely enhance bone regeneration and blood vascularized network at the defective site. In conclusion, as a graft material for bone defects, low-oxygen simulated cobalt-doped bioactive glass scaffold is promising.