Proteins can readily assemble into rigid, crystalline and functional structures such as viral capsids and bacterial compartments. Despite ongoing advances, it is still a fundamental challenge to design and synthesize protein-mimetic molecules to form crystalline structures. Here we report the lattice self-assembly of cyclodextrin complexes into a variety of capsid-like structures such as lamellae, helical tubes and hollow rhombic dodecahedra. The dodecahedral morphology has not hitherto been observed in self-assembly systems. The tubes can spontaneously encapsulate colloidal particles and liposomes. The dodecahedra and tubes are respectively comparable to and much larger than the largest known virus. In particular, the resemblance to protein assemblies is not limited to morphology but extends to structural rigidity and crystallinity—a well-defined, 2D rhombic lattice of molecular arrangement is strikingly universal for all the observed structures. We propose a simple design rule for the current lattice self-assembly, potentially opening doors for new protein-mimetic materials.
The development of a new generation of biomaterials with high osteogenic ability for treatment of osteoporotic fractures is being intensively investigated. The objective of this paper was to investigate new bone formation in an ovariectomized rat (OVX rat) calvarial model of critical size bone defects filled with Sr-containing α-calcium sulfate hemihydrate (SrCSH) cement compared to an α-calcium sulfate hemihydrate (α-CSH) cement and empty defect. X-ray diffraction analysis verified the partial substitution of Sr for Ca did not change the phase composition of α-CSH. Scanning electron microscopy showed that Sr-substituted α-CSH significantly increased the surface roughness. The effects of Sr substitution on the biological properties of SrCSH cement were evaluated by adhesion, proliferation, alkaline phosphatase (ALP) activity of osteoblast-like cells MC3T3-E1. The results showed that SrCSHs enhanced MC3T3-E1 cell proliferation, differentiation, and ALP activity. Furthermore, SrCSH cement was used to repair critical-sized OVX rat calvarial defects. The in vivo results revealed that SrCSH had good osteogenic capability and stimulated new blood vessel formation in a critical sized OVX calvarial defect within 12 weeks, suggesting that SrCSH cement has more potential for application in bone tissue regeneration.
Noble metal nanoparticles (NPs), owing to their unique optical and physicochemical properties, are routinely used for optical imaging and labeling of biological specimens. Even though they can provide vital information for studying multiple cellular events and their interplays at the same time, optically multiplexing and resolving specific NPs within a diffraction‐limited region labeled in complex biological specimens remains a fundamental challenge. By introducing and manipulating plasmonic resonance assisted saturable scattering effects, multiplexed fluorescence‐free super‐resolution imaging of gold NPs in tumor cells with remarkable subdiffraction resolution is demonstrated. The saturable scattering allows fluorescence‐free resolving single plasmonic nanoprobes with significantly improved resolution down to ≈100 nm. The revealed plasmonic resonance assisted saturation effect as well as the associated spectral flexibility to variant sizes provides access to multiplexing capability in complex bioenvironments. The demonstrated feasibility of two‐color super‐resolution cellular imaging is achieved at ultralow suppression powers ≈0.28 MW cm−2, corresponding to a two‐order of magnitude improvement compared to the state‐of‐the‐art of stimulated emission depletion (STED) nanoscopy.
Bone substitute offers a promising strategy for the reconstruction of large bone defects. It may be feasible to develop a better substitute material by enhancing the osteoinductivity and delaying the degradation of α-calcium sulfate hemihydrate. In this study, nano cerium oxide was incorporated with α-calcium sulfate hemihydrate at weight ratios of 5 and 10% to form nano cerium oxide-containing α-calcium sulfate hemihydrate. Extracts from α-calcium sulfate hemihydrate, 5 and 10% nano cerium oxide-containing α-calcium sulfate hemihydrate were prepared for in vitro treatment of cells. After critical bone defects were made on the left tibia of male Sprague–Dawley rats, the animals were randomly divided into four groups subjected to the filling with nothing (blank), α-calcium sulfate hemihydrate (control), 5 and 10% nano cerium oxide-containing α-calcium sulfate hemihydrate. Extraction from 5% nano cerium oxide-containing α-calcium sulfate hemihydrate composite stimulated cells proliferation and increased cell migration and mRNA expression of osteoblastic marker genes in primary bone marrow stromal cells. X-ray and micro-computed tomography analyses showed increased bone formation and reduced degradation, and histological analysis showed mineralized staining on the boundary area between composites and bone marrow in the nano cerium oxide-containing α-calcium sulfate hemihydrate group. Immunostaining of osteocalcin confirmed the increased bone formation in the nano cerium oxide-containing α-calcium sulfate hemihydrate group. Nano cerium oxide-containing α-calcium sulfate hemihydrate composite with 5% w/w nano cerium oxide showed a better capacity of enhancing osteogenesis and bone regeneration model than 10% cerium oxide-containing α-calcium sulfate hemihydrate composite. The findings suggested that the nano cerium oxide-containing α-calcium sulfate hemihydrate might be a potential material for bone substitutes since it may promote local bone regeneration.
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