A novel one-dimensional copper(II) coordination polymer and a trinuclear nickel(II) complex with a one-dimensional hydrogen-bonded structure.

In the Cu(II) compound catena-poly[[copper(II)-µ-[2-({2-[2-(naphthalen-2-yloxy)-1-oxidoethylidene]hydrazin-1-ylidene}methyl)phenolato]] dimethylformamide monosolvate monohydrate], {[Cu(C19H14N2O3)]·C3H7NO·H2O}n, (I), the Cu(II) cation is O,N,O'-chelated by one ligand and further N,O-chelated by a second ligand, and exhibits a distorted square-pyramidal coordination environment. The ligand acts as an overall pentadentate bridge between two metal ions, thus forming a novel coordination polymer. In the trinuclear Ni(II) compound diaquabis(1H-imidazole)bis[µ-2-oxido-N'-(1-oxido-2-phenoxyethylidene)benzohydrazidato]trinickel(II) dimethylformamide tetrasolvate, [Ni3(C15H11N2O4)2(C3H4N2)2(H2O)2]·4C3H7NO, (II), the three Ni(II) cations are directly linked by two trans diazine (N-N) bridges and are strictly collinear by symmetry. The central Ni(II) cation, located on an inversion centre, is coordinated by two water O atoms and is further N,O-chelated by two 2-oxido-N'-(1-oxido-2-phenoxyethylidene)benzohydrazidate(3-) ligands in an elongated octahedral coordination geometry. The two terminal centrosymmetrically related Ni(II) cations are coordinated by an imidazole ligand and O,N,O'-chelated by a hydrazidate ligand in a distorted square-planar coordination geometry. Hydrogen bonds link individual molecules of (II) into a chain along [100].

Cryogenic 3D printing of modified polylactic acid scaffolds with biomimetic nanofibrous architecture for bone tissue engineering.

The individualized polylactic acid (PLA) scaffolds fabricated by 3D printing technique have a good application prospect in the bone tissue engineering field. However, 3D printed PLA scaffold mainly manufactured by using a Fused Deposition Modelling fabrication technique (FDM) has some disadvantages, such as having smooth surface, strong hydrophobicity, poor cell adhesion, undesirable bioactivity, the degradation and deterioration at a high temperature triggering an inflammatory response. In this work, the aminated modified polylactic acid nanofibrous scaffold prepared by cryogenic 3D printing technology is designed to provide a feasible countermeasure to solve the key problems existing at present. The prepared scaffolds were fully characterized in terms of physico-chemical and morphological analyses, and the collected results revealed that the using of the cryogenic 3D printing technology can effectively avoid the degradation and deterioration of PLA at a high temperature required by FDM technique and promote the formation of nanofibrous structures. The in vitro tests with MC3T3-E1 cells confirmed that the cell-responsive biomimetic fibrous architecture and improved hydrophilicity due to the introduction of hydrophilic active amino groups provided a bioactive interface for cell adhesion and growth. Meanwhile, the active amino groups introduced by ammonolysis reaction can act as active sites for biomineralization. Thus, the as-prepared scaffolds may hold great potential for bone tissue engineering applications.

The fabrication of multifunctional sodium alginate scaffold incorporating ibuprofen-loaded modified PLLA microspheres based on cryogenic 3D printing.

A strategy to develop a multifunctional sodium alginate personalized scaffold with enhanced mechanical stability, osteogenesis activity and excellent anti-inflammatory activity by cryogenic 3 D printing combined with subsequent crosslinking with Sr2+ is proposed in this study. The ink for 3 D printing was prepared by dispersing modified PLLA droplets containing ibuprofen into sodium alginate aqueous solution using lecithin as stabilizer. The results showed that the drug-loaded microspheres formed from the low-temperature solidifying of the modified PLLA droplets were homogeneously dispersed in sodium alginate substrate, and the scaffold displayed a sustained drug release performance toward ibuprofen which endowed the scaffold with persistent anti-inflammatory effects. In vitro cell culture indicated that the lecithin not only acted as the stabilizer, but also stimulated the proliferation and mineralization of osteoblastic cells on the scaffold. Sr2+-crosslinking improved the mechanical properties and osteogenic activity of the scaffold.

Highly sensitive detection of H2S gas at low temperature based on ZnCo2O4 microtube sensors.

It is extremely necessary to detect Hydrogen sulfide (H2S) due to the hazardous nature. Thus, it is required to design a material which can detect H2S gas at low temperature. In this work, ZnCo2O4 microtubes are prepared by using absorbent cotton as template, combining immersion method in metal salt solution (Zn:Co=1:2) with calcination treatment in air. The influence of calcination temperature on the particle size and sensing property was also discussed. The diameter of particles on the ZnCo2O4 microtubes increases with increasing calcination temperature. The hollow microtubes of ZnCo2O4 materials calcined at 600 °C (ZCO-600) exhibit superb sensing performance to H2S at 90 °C with the lowest detection limit of 50 ppb. The optimum operating temperature (90 °C) was lower than the other reported ZnCo2O4 sensors. ZCO-600 sensor also shows excellent selectivity, repeatability, stability, humidity resistance and the good linear relationship in ppb and ppm level H2S. In addition, the feasible sensing mechanism of ZCO-600 to H2S is explored on the basis of XPS analysis. Thus, ZnCo2O4 as a sensing material possesses widespread application prospects for the detection of trace H2S gas.

Bis[µ-N'-(2-methyl-1-oxidopropanyl-idene)-2-oxidobenzohydrazidato]tetra-pyridine-trinickel(II).

The asymmetric unit of the title trinuclear Ni(II) compound, [Ni(3)(C(11)H(11)N(2)O(3))(C(5)H(5)N)(4)], contains two independent mol-ecules which are located on individual inversion centres. The central Ni atom, located on an inversion centre, is coordinated by two pyridine N atoms and is further N,O-chelated by two N-(2-methyl-propano-yl)salicyloylhydrazidate anions in an elongated octa-hedral coordination geometry. The terminal Ni atom is coordinated by a pyridine ligand and is further N,N',O-chelated by an N-(2-methyl-propano-yl)salicyloyl-hydrazidate anion in a distorted square-planar coordination geometry. Weak intra-molecular C-H⋯O hydrogen bonding is observed in the structure.

Biomimetic mineralization of nanocrystalline hydroxyapatites on aminated modified polylactic acid microspheres to develop a novel drug delivery system for alendronate.

EPLA/nHAp composite microsphere, a novel drug delivery system potentially useful for the local delivery of alendronate (AL) to bone tissue was developed via the biomimetic mineralized deposition of nano-hydroxyapatite (nHAp) crystals on the surface of aminated modified polylactic acid (EPLA) microspheres. Scanning electron microscopy (SEM) observation showed that this system consisted of a polymer core with nanofiber network structure and inorganic coating composed of countless rod-like nanocrystalline particles, Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction analysis (XRD) confirmed that these particles were nHAp crystals. An efficient AL-loading can be realized by facile impregnation-adsorption method under suitable conditions due to the high adsorption capacity of EPLA/nHAp composite microspheres. The drug loading efficiency of microspheres was detected by indirect ultraviolet spectrophotometry. It was found that the adsorption capacity of EPLA/nHAp composite microsphere towards AL was increased nearly 5-fold compared with that of bare EPLA microspheres owing to the strong interaction between alendronate and hydroxyapatite. Meanwhile, in vitro release study showed that AL-loaded EPLA/nHAp microspheres had a more sustained drug release than AL-loaded EPLA microspheres, all these results demonstrated that the as-prepared EPLA/nHAp composite microsphere is an efficient carrier for the delivery and sustained release of AL. Furthermore, an in vitro cell culture study revealed that these composite microspheres presented a good biocompatibility, showing great potential for the applications in the biomedical field.

Preparation of TiO2 nanotubes/mesoporous calcium silicate composites with controllable drug release.

Nanotube structures such as TiO2 nanotube (TNT) arrays produced by self-ordering electrochemical anodization have been extensively explored for drug delivery applications. In this study, we presented a new implantable drug delivery system that combined mesoporous calcium silicate coating with nanotube structures to achieve a controllable drug release of water soluble and antiphlogistic drug loxoprofen sodium. The results showed that the TiO2 nanotubes/mesoporous calcium silicate composites were successfully fabricated by a simple template method and the deposition of mesoporous calcium silicate increased with the soaking time. Moreover, the rate of deposition of biological mesoporous calcium silicate on amorphous TNTs was better than that on anatase TNTs. Further, zinc-incorporated mesoporous calcium silicate coating, produced by adding a certain concentration of zinc nitrate into the soaking system, displayed improved chemical stability. A significant improvement in the drug release characteristics with reduced burst release and sustained release was demonstrated.