Cationic Hyperbranched Polymers with Biocompatible Shells for siRNA Delivery.

Cationic hyperbranched polymers (HBP) were prepared by self-condensing vinyl polymerization of an atom transfer radical polymerization (ATRP) inimer containing a quaternary ammonium group. Two types of biocompatible shells, poly(oligoethylene glycol) methacrylate (polyOEGMA) and poly(2-(methylsulfinyl) ethyl methacrylate) (polyDMSO), were grafted respectively from HBP core to form core-shell structures with low molecular weight dispersity and high biocompatibility, polyOEGMA-HBP and polyDMSO-HBP. Both of the structures showed low cytotoxicity and good siRNA complexing ability. The efficacy of gene silencing against Runt-related transcription factor 2 ( Runx2) expression and the long-term assessment of mineralized nodule formation in osteoblast cultures were evaluated. The biocompatible core-shell structures were crucial to minimizing undesired cytotoxicity and nonspecific gene suppression. polyDMSO-HBP showed higher efficacy of forming polyplexes than polyOEGMA-HBP due to shell with lower steric hindrance. Overall, the gene silencing efficiency of both core-shell structures was comparable to commercial agent Lipofectamine, indicating long-term potential for gene silencing to treat heterotopic ossification (HO).

Iron Oxide Nanoparticles with Grafted Polymeric Analogue of Dimethyl Sulfoxide as Potential Magnetic Resonance Imaging Contrast Agents.

Novel water-dispersible hybrid iron oxide nanoparticles grafted with a polymeric analogue of dimethyl sulfoxide (DMSO) were prepared. Superparamagnetic iron oxide nanoparticles with immobilized atom-transfer radical polymerization (ATRP) initiators were prepared via an in situ method using 12-(2-bromoisobutyramido)dodecanoic acid as a surface ligand/initiator. The initiator-functionalized particles were employed in a surface-initiated initiator for continuous activator regeneration ATRP to graft poly(2-(methylsulfinyl)ethyl acrylate) (a polyacrylate analogue of DMSO) from the surface. The resulting hybrid nanoparticles showed a high magnetic relaxivity ratio ( r2/ r1) of 600 at 7 T in fetal bovine serum, and a good biocompatibility up to 1000 mg L-1.

Osteoconductive Enhancement of Polyether Ether Ketone: A Mild Covalent Surface Modification Approach.

Polyether ether ketone (PEEK, 1) is an important material for the fabrication of implants employed in spinal fusion surgery. Although its radiolucency and favorable elastic modulus have made PEEK an attractive choice for interbody fusion devices, its poor osseointegrative properties prevent the formation of a strong union between implant and surrounding bone structures and remain a major liability. Recent advancements in PEEK surface technology have resulted in improved osseointegration; however, the identification of an ideal implant material has proven challenging. In this manuscript, we describe our preliminary investigation into the realm of PEEK-based fusion devices that has culminated in the discovery of a mild, solution-based process for the preparation of covalently surface modified PEEK biomaterials that display enhanced osteoconductive properties. Surface modification occurred under mild reaction conditions via the acid-mediated addition of various commercially available hydrophilic oxyamine and hydrazine nucleophiles to the diaryl ketone moiety of PEEK. The resulting modified surfaces have been confirmed by contact angle measurements and X-ray photoelectron spectroscopy (XPS). Subsequent in vitro studies demonstrated the enhanced capability of several modified PEEK variants to promote osteogenic differentiation and mineralized calcium deposition relative to unmodified PEEK surfaces.

Development of 16 microsatellite markers within the Camassia (Agavaceae) species complex and amplification in related taxa.

PREMISE OF THE STUDY: The North American genus Camassia is an ecologically important group whose variability and evolution are little understood, being influenced by hybridization and geographic isolation. We developed microsatellite markers to investigate patterns of gene flow, population structure, and taxonomic relationships within this group. • METHODS AND RESULTS: Using a traditional approach with biotin-labeled probes, we developed 16 microsatellite primers in three species of Camassia: C. howellii, C. leichtlinii, and C. quamash. The number of alleles per locus averaged 3.94 per species, and levels of heterozygosity ranged from 0.000 to 1.00 and 0.033 to 0.917 for observed and expected heterozygosities, respectively. All primers amplified to varying extents in additional species (C. angusta, C. cusickii, C. scilloides) and in putative species in a related genus (Hastingsia alba, H. atropurpurea, H. bracteosa, H. serpentinicola). • CONCLUSIONS: These microsatellite markers exhibit variation and are useful for ongoing studies of integrative taxonomy and population differentiation within this species complex.