Preparation and Performance of H-PDMS/PMHS/OTS Hybrid Nanosilica Hydrophobic and Self-Cleaning Coatings on Phosphogypsum Surface.

Hemihydrate phosphogypsum, an industrial solid waste product of phosphoric acid production, is abundant and inexpensive. If the problem of poor water resistance is solved, this material could be substituted for cement and other traditional energy-consuming cementitious materials in the construction industry. This approach would confer important economic and environmental benefits while promoting the resource utilization of phosphogypsum (PG). In this study, hydrophobic and self-cleaning coatings of H-PDMS/PMHS/OTS hybrid nanosilica were prepared on a post-hydroxylated PG surface using sol-gel and impregnation methods. The water contact angle, Fourier-transform infrared spectroscopy, Three-dimensional surface morphology and roughness analysis, X-ray photoelectron spectroscopy, scanning electron microscopy, surface abrasion tests, and tape adhesion tests were used to evaluate the hydrophobicity of the coatings. The results demonstrated that the in situ reaction produced a hydrophobic siloxane/nanosilica hybrid network that bonded to the PG surface via hydrogen bonding, making the otherwise completely hydrophilic PG hydrophobic (PGH-3, contact angle (CA) = 144.1°). The PGH-3 sample exhibited excellent chemical stability, maintaining a contact angle greater than 135° under strongly acidic or alkaline conditions. The contact angle remained at 123.7° after 50 tape-bonding tests. After 100 wear cycles, the contact angle remained at 121.9°. This study presents an environmentally friendly method and a straightforward application procedure to impart hydrophobicity to solid waste PG. Its potential is thus demonstrated in the field of PG-based construction materials and the comprehensive utilization of solid waste.

Lanthanides-Substituted Hydroxyapatite/Aloe vera Composite Coated Titanium Plate for Bone Tissue Regeneration.

PURPOSE: To develop the surface-treated metal implant with highly encouraged positive properties, including high anti-corrosiveness, bio-activeness and bio-compatibleness for orthopedic applications. METHODS: In this work, the surface of commercially pure titanium (Ti) metal was treated with bio-compatible polydopamine (PD) by merely immersing the Ti plate in PD solution. The composite of trivalent lanthanide minerals (La3+, Ce3+ and Gd3+)-substituted hydroxyapatite (MHAP) with Aloe vera (AV) gel was prepared and coated on the PD-Ti plate by electrophoretic deposition (EPD) method. The choice of trivalent lanthanide ions is based on their bio-compatible nature and bone-seeking properties. The formation of the PD layer, composites, and composite coatings on Ti plate and PD-Ti surface was confirmed by FT-IR, XRD, SEM and HR-TEM observations. In-vitro assessments such as osteoblasts like MG-63 cell viability, alkaline phosphatase activity and mineralization ability of the MHAP/AV composite were tested, and the composite-coated plate was implanted into a rat bone defect model for in-vivo bone regeneration studies. RESULTS: The coating ability of the MHAP/AV composite was highly preferred to PD-treated Ti plate than an untreated Ti plate due to the metal absorption ability of PD. This was confirmed by SEM analysis. The in-vitro and in-vivo studies show the better osteogenic ability of MHAP/AV composite at 14th day and 4th week of an experimental period, respectively. CONCLUSION: The osteoblast ability of the fabricated device without producing any adverse effect in the rat model recommends that the fabricated device would serve as a better platform on the hard tissue regeneration for load-bearing applications of orthopedics.

Synthesis of Biscoumarin and Dihydropyran Derivatives and Evaluation of Their Antibacterial Activity.

In an attempt to find a new class antibacterial agents, a series of biscoumarins (1-4) and dihydropyrans (5-13) were successfully prepared. The molecular structures of four representative compounds, that is, 4, 5, 8 and 12 were confirmed by single crystal X-ray diffraction study. These synthesized compounds were screened for their antibacterial activity in vitro against Staphylococcus aureus (S. aureus ATCC 29213), methicillin-resistant S. aureus (MRSA XJ 75302), vancomycin-intermediate S. aureus (Mu50 ATCC 700699), USA 300 (Los Angeles County clone, LAC), Staphylococcus epidermidis (S. epidermidis ATCC 14990), methicillin-resistant S. epidermidis (MRSE XJ 75284) and Escherichia coli (E. coli ATCC 25922). Additionally, there are two classical intramolecular O-H···O hydrogen bonds (HBs) in biscoumarins 1-4 and the corresponding HB energies were further performed with the density functional theory (DFT) [B3LYP/6-31G*] method.

A delivery system specifically approaching bone resorption surfaces to facilitate therapeutic modulation of microRNAs in osteoclasts.

Dysregulated microRNAs in osteoclasts could cause many skeletal diseases. The therapeutic manipulation of these pathogenic microRNAs necessitates novel, efficient delivery systems to facilitate microRNAs modulators targeting osteoclasts with minimal off-target effects. Bone resorption surfaces characterized by highly crystallized hydroxyapatite are dominantly occupied by osteoclasts. Considering that the eight repeating sequences of aspartate (D-Asp8) could preferably bind to highly crystallized hydroxyapatite, we developed a targeting system by conjugating D-Asp8 peptide with liposome for delivering microRNA modulators specifically to bone resorption surfaces and subsequently encapsulated antagomir-148a (a microRNA modulator suppressing the osteoclastogenic miR-148a), i.e. (D-Asp8)-liposome-antagomir-148a. Our results demonstrated that D-Asp8 could facilitate the enrichment of antagomir-148a and the subsequent down-regulation of miR-148a in osteoclasts in vivo, resulting in reduced bone resorption and attenuated deterioration of trabecular architecture in osteoporotic mice. Mechanistically, the osteoclast-targeted delivery depended on the interaction between bone resorption surfaces and D-Asp8. No detectable liver and kidney toxicity was found in mice after single/multiple dose(s) treatment of (D-Asp8)-liposome-antagomir-148a. These results indicated that (D-Asp8)-liposome as a promising osteoclast-targeting delivery system could facilitate clinical translation of microRNA modulators in treating those osteoclast-dysfunction-induced skeletal diseases.

Pterostilbene exerts antitumor activity against human osteosarcoma cells by inhibiting the JAK2/STAT3 signaling pathway.

Osteosarcoma is a high-grade malignant bone tumor. Pterostilbene (PTE) is a natural, dimethylated analog of resveratrol with higher bioavailability. While PTE has been shown to have potent antitumor activity against various types of cancer, the molecular mechanisms underlying the effects of PTE remain largely unknown. The Janus kinase 2/Signal Transducer and Activator of Transcription 3 (JAK2/STAT3) signaling pathway plays a crucial role in tumorigenesis and immune development. In this study, we assessed the antitumor activity of PTE against human osteosarcoma cells and explored the role of JAK2/STAT3 and apoptosis-related signaling pathways on the activity of PTE. PTE treatment resulted in a dose- and time-dependent inhibition of osteosarcoma cell viability. Additionally, PTE exhibited strong antitumor activity, as evidenced not only by reductions in tumor cell adhesion, migration and mitochondrial membrane potential (MMP) but also by increases in the apoptotic index, reactive oxygen species (ROS) and several biochemical parameters. Furthermore, PTE treatment directly inhibited the phosphorylation of JAK2 at Tyr 1007 and the downstream activation of STAT3. PTE also down-regulated the expression of STAT3 target genes, including the anti-apoptotic proteins Bcl-xL and Mcl-1, leading to the up-regulation of mitochondrial apoptosis pathway-related proteins (Bax, Bak, cytosolic Cytochrome c, and cleaved Caspase3) and cyclin-dependent kinase inhibitors such as p21 and p27. PTE, used in combination with a known JAK2/STAT3 inhibitor, AG490, further decreased the viability of osteosarcoma cells. Taken together, PTE is a potent inhibitor of osteosarcoma cell growth that targets the JAK2/STAT3 signaling pathway. These data suggest that inhibition of JAK2/STAT3 signaling is a novel mechanism of action for PTE during therapeutic intervention in osteosarcoma cancers.

Tanshinone IIA improves impaired nerve functions in experimental diabetic rats.

Diabetic neuropathy is one of the most common complications in diabetes mellitus. Thus far, effective therapeutic agents for restoring the impaired motor and sensory nerve functions in diabetic neuropathy are still lacking. The antioxidant and neuroprotective properties of tanshinone IIA make it a promising candidate for the treatment of diabetic neuropathy. Therefore, the present study investigated the possible beneficial effect of tanshinone IIA on the impaired nerve functions displayed by a rat diabetic model. Insulin-dependent diabetes in rats was developed by a single dose of streptozotocin (STZ) at 50mg/kg. The diabetic rats were randomly divided into four groups (n=10 in each group), and were intraperitoneally administrated daily for 4 weeks with tanshinone IIA (20mg/kg, 50mg/kg and 100mg/kg), or normal saline from the fourth day after STZ injection, respectively. At the end of tanshinone IIA administration, thermal and mechanical nociceptive threshold were determined by a hot plate test and Von Frey hairs; motor nerve conducting velocity (MNCV) was determined by an electrophysiological method; nerve blood flow (NBF) was detected using a laser Doppler flow meter; Na(+),K(+)ATPase activity, the level of superoxide dismutase (SOD), catalase and malondialdehyde (MDA) in sciatic nerves, and the serum total antioxidant capability were also determined. We found that tanshinone IIA was capable of restoring diabetes-induced deficit in nerve functions (MNCV and NBF), and impairment in thermal and mechanical nociceptive capability. In addition, tanshinone IIA significantly increased the serum total antioxidant capability, improved the activities of Na(+),K(+)ATPase, increased the levels of SOD and catalase, and reduced the MDA level in sciatic nerves in diabetic rats. All the findings indicate the beneficial effect of tanshinone IIA on impaired nerve functions and raise the possibility of developing tanshinone IIA as a therapeutic agent for diabetic neuropathy.