The failure of prosthesis after total joint replacement is mainly due to dysfunctional osseointegration and implant infection. There is a critical need for orthopedic implants that promote rapid osseointegration and prevent bacterial colonization, particularly when placed in bone compromised by disease or physiology of the patients. The aim of this study was to fabricate a novel coaxial electrospun polycaprolactone (PCL)/polyvinyl alcohol (PVA) core-sheath nanofiber (NF) blended with both hydroxyapatite nanorods (HA) and type I collagen (Col) (PCL(Col)/PVA(HA)). Doxycycline (Doxy) and dexamethasone (Dex) were successfully incorporated into the PCL(Col)/PVA(HA) NFs for controlled release. The morphology, surface hydrophilicity and mechanical properties of the PCL/PVA NF mats were analyzed by scanning electron microscopy, water contact angle and atomic force microscopy. The PCL(Col)/PVA(HA) NFs are biocompatible and enhance the adhesion and proliferation of murine pre-osteoblastic MC3T3 cells. The release of Doxy and Dex from coaxial PCL(Col)/PVA(HA) NFs showed more controlled release compared with the blended NFs. Using an ex vivo porcine bone implantation model we found that the PCL(Col)/PVA(HA) NFs bind firmly on the titanium rod surface and the NFs coating remained intact on the surface of titanium rods after pullout. No disruption or delamination was observed after the pullout test. These findings indicate that PCL(Col)/PVA(HA) NFs encapsulating drugs have great potential in enhancing implant osseointegration and preventing implant infection.

The failure of prosthesis after total joint replacement is due to the lack of early implant osseointegration. In this study polyvinyl alcohol-collagen-hydroxyapatite (PVA-Col-HA) electrospun nanofibrous meshes were fabricated as a biomimetic bone-like extracellular matrix for the modification of orthopedic prosthetic surfaces. In order to reinforce the PVA nanofibers, HA nanorods and Type I collagen were incorporated into the nanofibers. We investigated the morphology, biodegradability, mechanical properties and biocompatibility of the prepared nanofibers. Our results showed these inorganic-organic blended nanofibers to be degradable in vitro. The encapsulated nano-HA and collagen interacted with the PVA content, reinforcing the hydrolytic resistance and mechanical properties of nanofibers that provided longer lasting stability. The encapsulated nano-HA and collagen also enhanced the adhesion and proliferation of murine bone cells (MC3T3) in vitro. We propose the PVA-Col-HA nanofibers might be promising modifying materials on implant surfaces for orthopedic applications.

Porous organic polymers (POPs) have been considered as prominent adsorbents for volatile iodine. So far, both crystalline and amorphous POPs have accomplished excellent iodine capture capability. Considering the difficulty and challenges in preparing perfect crystalline POPs, more explorations into developing versatile amorphous POPs are needed. Herein, amorphous POPs based on the Schiff-base reaction were designed and synthesized for volatile iodine removal. Four amorphous POPs products named as NDB-H, NDB-S, ADB-HS, and ADB-S obtained under different solvothermal conditions were investigated in terms of their morphologies, porosity, and their iodine enrichment performance in detail. It is noteworthy that excellent efficiency for removing iodine vapor was acquired for NDB-S (≈425 wt %), ADB-HS (≈345 wt %), and ADB-S (≈342 wt %). Remarkably, NDB-H exhibited an iodine capture capacity up to ≈443 wt %. Excellent reusability was obtained as well. Amorphous NDB-H has accomplished an extremely high iodine capture performance, illustrating the great chance to exploit versatile amorphous POPs for iodine enrichment and removal based on Schiff-base chemistry.

No abstract

No abstract

A new tubRZ operon involved in the maintenance of the Bacillus sphaericus mosquitocidal plasmid pBsph pBsph is a mosquitocidal plasmid first identified from Bacillus sphaericus, encoding binary toxins (Bin toxins) that are highly toxic to mosquito larvae. This plasmid plays an important role in the maintenance and evolution of the bin genes in B. sphaericus. However, little is known about its replication and partitioning. Here, we identified a 2.4 kb minimal replicon of pBsph plasmid that contained an operon encoding TubR-Bs and TubZ-Bs, each of which was shown to be required for plasmid replication. TubR-Bs was shown to be a transcriptional repressor of tubRZ-Bs genes and could bind cooperatively to the replication origin of eleven 12 bp degenerate repeats in three blocks, and this binding was essential for plasmid replication. TubZ-Bs exhibited GTPase activities and interacted with TubR-Bs : DNA complex to form a ternary nucleoprotein apparatus. Electron and fluorescence microscopy revealed that TubZ-Bs assembled filaments both in vitro and in vivo, and two point mutations in TubZ-Bs (T114A and Y260A) that severely impaired the GTPase and polymerization activities were found to be defective for plasmid maintenance. Further investigation demonstrated that overproduction of TubZ-Bs-GFP or its mutant forms significantly reduced the stability of pBsph. Taken together, these results suggested that TubR-Bs and TubZBs are involved in the replication and probably in the partitioning of pBsph plasmid, increasing our understanding of the genetic particularity of TubZ systems.

The random copolymers poly(LA-ran-CL) have improved properties of degradability, mechanical strength, elasticity, and permeability over the PLA and PCL homopolymers. However, the synthesis of such copolymers is still a great challenge in polymer chemistry. In this contribution, we develop a simple but well-designed phenoxyimine Al complex (4) with bulky Ph 2 CH groups, which achieves controlled random copolymerization of rac-LA and E-CL in a living manner (Ð 5 1.06-1.09). The reactivity ratios of rac-LA and E-CL (r LA and r CL ) are 1.09 and 1.05 and the average sequence lengths of the lactidyl unit (L LA ) and the caproyl unit (L CL ) are in the range of 1.9-2.0 at different stages of conversion. In marked contrast, Al complexes (1-3) having less bulky substituents on the ligands only produce gradient copolymers. Furthermore, this strategy of catalyst design would be readily extended to other catalytic systems including b-ketiminato Al complex (5). V C 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 611-617

This study demonstrated that periprosthetic EM delivery reduced periprosthetic inflammation and improved the quality of surrounding bone.