Poly(acrylic acid)-regulated Synthesis of Rod-Like Calcium Carbonate Nanoparticles for Inducing the Osteogenic Differentiation of MC3T3-E1 Cells.

Calcium carbonate, especially with nanostructure, has been considered as a good candidate material for bone regeneration due to its excellent biodegradability and osteoconductivity. In this study, rod-like calcium carbonate nanoparticles (Rod-CC NPs) with desired water dispersibility were achieved with the regulation of poly (acrylic acid). Characterization results revealed that the Rod-CC NPs had an average length of 240 nm, a width of 90 nm with an average aspect ratio of 2.60 and a negative ζ-potential of -22.25 ± 0.35 mV. The degradation study illustrated the nanoparticles degraded 23% at pH 7.4 and 45% at pH 5.6 in phosphate-buffered saline (PBS) solution within three months. When cultured with MC3T3-E1 cells, the Rod-CC NPs exhibited a positive effect on the proliferation of osteoblast cells. Alkaline phosphatase (ALP) activity assays together with the osteocalcin (OCN) and bone sialoprotein (BSP) expression observations demonstrated the nanoparticles could induce the differentiation of MC3T3-E1 cells. Our study developed well-dispersed rod-like calcium carbonate nanoparticles which have great potential to be used in bone regeneration.

Synthesis of membrane-type graphene oxide immobilized manganese dioxide adsorbent and its adsorption behavior for lithium ion.

Recently, there has been an urgent need to develop new materials and technologies for extracting lithium ions. Herein, the membrane-type adsorbent of manganese dioxide (MnO2) is prepared by a vacuum filtration method using graphene oxide (GO) as a binder and amino-ß-cyclodextrin (amino-ß-CD) as an adjuvant. The results of thermogravimetric analysis show that MnO2 is successfully immobilized on GO layers with a content of about 24 wt%, which enabled rapid adsorb lithium ions from the ionic solution. In addition, the permeation experiment shows the membrane has specific selectivity for lithium ion transport and adsorption, which is manifested in the selectivity ratios of K+/Li+, Na+/Li+ and K+/Na+ to 2.5, 3.2 and 0.8, respectively. Adsorption experiments show that GO-ß-CD/MnO2 membrane has a high adsorption capacity for lithium ions (37.5 mg g-1). The adsorption kinetic curve indicates that the lithium adsorption process is controlled by the chemical adsorption mechanism. In the enrichment experiment, the concentration of lithium ions from seawater can be enriched to 1.2 mg L-1 after 100 cycles. The results suggest that the developed GO-ß-CD/MnO2 membrane could effectively extract lithium ions from seawater.

Silk Fibroin/Collagen Blended Membrane Fabricated via a Green Papermaking Method for Potential Guided Bone Regeneration Application: In Vitro and In Vivo Evaluation.

Guided bone regeneration (GBR) technology is a commonly used surgical procedure for the repair of damaged periodontal tissues. Poor mechanical property and rapid degradation rate are the major reasons for GBR membrane failure in clinical applications. Herein, we applied a green papermaking method to fabricate silk fibroin (SF) membranes blended with collagen and tested their performance. The results showed that the blended SF75 (SF and collagen in a weight ratio of 75:25) membranes are biocompatible with good mechanical properties in the wet condition and appropriate biodegradation rate. MC3T3-E1 osteoblast cell adhesion and proliferation on the membranes were improved by the hybrid biological functions of SF and collagen. Subcutaneous implantation in rats for 9 weeks demonstrated that the membranes induced a less severe inflammatory response. The biodegradation time of the SF75 membranes was appropriate for tissue regeneration. This research, for the first time, reports a blended membrane prepared from silk fibroin and collagen with an ecofriendly method, which shows promise for application in guided bone regeneration.

Facile synthesis of wavy carbon nanowires via activation-enabled reconstruction and their applications towards nanoparticles separation and catalysis.

We report a facile synthesis of wavy carbon nanowires (WCNWs) derived from polyurethane via KOH activation. The success of this synthesis relies on a carefully designed activation procedure, which involved one pre-activation stage to form suitable precursor and one high-temperature activation stage to allow directional carbon reconstruction. In particular, PU was initially mixed with KOH and thermally treated sequentially at 400 °C and 800 °C for 1 hour, respectively. The resultant products exhibit high purity in the shape of wavy wire, together with a uniform diameter of 51 ± 5.2 nm and the length in the range of 2-8 µm. Systematic studies have been conducted to investigate the effect of reaction parameters in two activation stages on the morphology and structure of final products. It is worth noting that the as-prepared WCNWs could find promising use in the field of both nanoparticle separation and catalysis. For example, they exhibit outstanding separation abilities towards Au nanospheres with different sizes and enhanced catalytic performance when serving as the catalyst support for Pd towards ethanol oxidation reaction. Particularly, the peak current density of Pd/WCNWs catalysts can reach 2126 mA mgPd -1 and the value of its electrochemical active surface area is 60.5 m2 gPd -1.

Biomimetic apatite formed on cobalt-chromium alloy: A polymer-free carrier for drug eluting stent.

In this study, sirolimus (SRL) was loaded within biomimetic apatite formed on cobalt-chromium (Co-Cr) alloy, which has been reported for the first time, to inhibit the in-stent restenosis. Two different groups of loading SRL within biomimetic apatite were prepared: Group A (mono-layer of apatite/SRL) and Group B (bi-layer of apatite/SRL). Group A and Group B showed the biphasic pattern of SRL release up to 40 and 90days, respectively. The attachment of human artery smooth muscle cell (HASMC) for both Group A and Group B was significantly inhibited, and proliferation dramatically decreased with the release of SRL. Noteworthily, biomimetic apatite alone also suppressed the SMC proliferation. The porous biomimetic apatite uniformly covered Co-Cr stent without crack or webbings. After balloon expansion, the integrity of biomimetic apatite was sufficient to resist delamination or destruction. Thus, this study demonstrated that biomimetic apatite is a promising drug carrier for potential use in stents.

Silk fibroin membrane used for guided bone tissue regeneration.

With the aim to develop a novel membrane with an appropriate mechanical property and degradation rate for guided bone tissue regeneration, lyophilized and densified silk fibroin membrane was fabricated and its mechanical behavior as well as biodegradation property were investigated. The osteoconductive potency of the silk fibroin membranes were evaluated in a defect rabbit calvarial model. Silk fibroin membrane showed the modulated biodegradable and mechanical properties via ethanol treatment with different concentration. The membrane could prevent soft tissue invasion from normal tissue healing, and the amounts of new bone and defect closure with silk fibroin membrane were similar to those of commercially available collagen membrane.