Modification of Ti6Al4V Substrates with Well-defined Zwitterionic Polysulfobetaine Brushes for Improved Surface Mineralization

Osteoconductive mineral coatings are beneficial for improving the osteointegration of metallic orthopedic/dental implants, but achieving adequate structural integration between the surface minerals and underlying metallic substrates has been a significant challenge. Here, we report covalent grafting of zwitterionic poly(sulfobetaine methacrylate) (pSBMA) brushes on the Ti6Al4V substrates to promote the surface-mineralization of hydroxyapatite with enhanced surface mineral coverage and mineral-substrate interfacial adhesion. We first optimized the atom transfer radical polymerization (ATRP) conditions for synthesizing pSBMA polymers in solution. Well-controlled pSBMA polymers (relative molecular weight up to 26,000, PDI = 1.17) with high conversions were obtained when the ATRP was carried out in trifluoroethanol/ionic liquid system at 60 °C. Applying identical polymerization conditions, surface-initiated atom transfer radical polymerization (SI-ATRP) was carried out to graft zwitterionic pSBMA brushes (PDI \u3c 1.20) from the Ti6Al4V substrates, generating a stable superhydrophilic and low-fouling surface coating that inhibited non-specific protein absorptions without compromising the bulk mechanic property of the Ti6Al4V substrates. The zwitterionic pSBMA surface brushes, capable of attracting both cationic and anionic precursor ions during calcium phosphate apatite mineralization, increased the surface mineral coverage from 32% to 71%, and significantly reinforced the attachment of the apatite crystals on the Ti6Al4V substrate. This facile approach to surface modification of metallic substrates can be exploited to generate multifunctional polymer coatings and improve the performance of metallic implants in skeletal tissue engineering and orthopedic and dental care

MDT-28/PLIN-1 mediates lipid droplet-microtubule interaction via DLC-1 in Caenorhabditis elegans

Ectopic lipid accumulation in lipid droplets (LD) has been linked to many metabolic diseases. In this study, DHS-3::GFP was used as a LD marker in C. elegans and a forward genetic screen was carried out to find novel LD regulators. There were 140 mutant alleles identified which were divided into four phenotypic categories: enlarged, aggregated, aggregated and small, and decreased. After genetic mapping, mutations in three known LD regulatory genes (maoc-1, dhs-28, daf-22) and a peroxisome-related gene (acox-3) were found to enlarge LDs, demonstrating the reliability of using DHS-3 as a living marker. In the screen, the cytoskeleton protein C27H5.2 was found to be involved in LD aggregation, as was the LD resident/structure-like protein, MDT-28/PLIN-1. Using yeast two-hybrid screening and pull-down assays, MDT-28/PLIN-1 was found to bind to DLC-1 (dynein light chain). Fluorescence imaging confirmed that MDT-28/PLIN-1 mediated the interaction between DHS-3 labeled LDs and DLC-1 labeled microtubules. Furthermore, MDT-28/PLIN-1 was directly bound to DLC-1 through its amino acids 1-210 and 275-415. Taken together, our results suggest that MDT-28/PLIN-1 is involved in the regulation of LD distribution through its interaction with microtubule-related proteins

Genetic diversity and molecular discrimination of wild tea plants from Yunnan Province based on inter-simple sequence repeats (ISSR) markers

To efficiently assess and discriminate wild tea germplasms, inter-simple sequence repeats (ISSR) were used to determine genetic relationships among 40 wild tea plants. A total of 275 bands were generated with 15 ISSR primers, of which 274 (99.6%) were polymorphic. The mean genetic similarity coefficient, the mean Nei’s gene diversity (h) and the mean Shannon’s information index (I) of tea cultivars were 0.4180, 0.3797 and 0.5586, respectively. This suggested that the genetic diversity of wild tea trees and the genetic base were very wide. Unweighted pair group method with arithmetic mean (UPGMA) cluster analysis showed clear genetic relationships among these germplasms, and the major clusters were related to known pedigree relationships. Besides, from the bands amplified, there were three independent ways to identify the tea varieties, such as unique ISSR markers, unique band patterns and a combination of the band patterns provided by different primers. Finally, the ISSR fingerprints of 40 tea germplasms were constructed by the combination of the band patterns. This research indicated that ISSR markers were very effective in differentiating the wild tea varieties, too.Keywords: Wild tea plants, inter-simple sequence repeats (ISSR), molecular discrimination, genetic diversit

The fabrication of an eccentric three-core fiber and its application as a twist sensor

The fabrication and application for twist sensing of an eccentric three-core fiber were demonstrated. The fiber was made by stack-and-draw technique, in which silica rods and core canes were put in a tube and drawn on a fiber drawing tower. Three cores formed a Mach-Zehnder interferometer, where the lights transmitted in the three cores interfered with each other, resulted in the formation of envelopes on spectrum. Because two of the cores were off axis, phase differences among the cores varied with twist due to different stretches on each core, which caused shift of the spectral envelopes of the interference signal. Wide range twist measurement can be realized with relatively high sensitivity by tracking lower dips of the envelopes. Experimental results revealed that the dips shift quadratically with twist angle, which means that the sensitivity increases with twist. The compensation of temperature influence was also implemented by inscribing a Bragg grating on one of the cores with femtosecond laser. Because the fiber can be mass-produced, it is suitable for twist sensing in practical application for its low cost

Synthesis and antitumor efficacy of daunorubicin-loaded magnetic nanoparticles

Jun Wang1, Baoan Chen1, Jian Chen1, Xiaohui Cai1, Guohua Xia2, Ran Liu1, Pingsheng Chen2, Yu Zhang3, Xuemei Wang31Department of Hematology and Oncology, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, China 210009; 2Medical School, Southeast University, Nanjing; 3State Key Laboratory of Bioelectronics, Southeast University, Nanjing, China 210009Background: A promising approach to optimize the disposition of daunorubicin-loaded magnetic nanoparticles (DNR-MNPs) was developed to minimize serious side effects of systematic chemotherapy for cancer.Methods: The physical properties of DNR-MNPs were investigated and their effect on leukemia cells in vitro was evaluated by a standard WST-1 cell proliferation assay. Furthermore, cell apoptosis and intracellular accumulation of DNR were determined by FACSCalibur flow cytometry.Results: Our results showed that the majority of MNPs were spherical and their sizes were from 10 to 20 nm. The average hydrodynamic diameter of DNR-MNPs in water was 94 nm. The in vitro release data showed that the DNR-MNPs have excellent sustained release property. Proliferation of K562 cells was inhibited in a dose-dependent manner by DNR in solution (DNR-Sol) or by DNR-MNPs. The IC50 for DNR-MNPs was slightly higher than that for DNR-Sol. DNR-MNPs also induced less apoptosis in K562 cells than did DNR-Sol. Detection of fluorescence intensity of intracellular DNR demonstrated that DNR-MNPs could be taken up by K562 cells and persistently released DNR in cells.Conclusion: Our study suggests that optimized DNR-MNPs formulation possesses sustained drug-release and favorable antitumor properties, which may be used as a conventional dosage form for antitumor therapy.Keywords: daunorubicin, magnetic iron oxide nanoparticles, drug delivery system, target selection, K562 cell