Electrically conductive nanofibrous scaffold composed of poly(ethylene glycol)-modified polypyrrole and poly(ε-caprolactone) for tissue engineering applications.

The aim of this study was to developing two novel nanofibrous scaffolds composed of poly(ethylene glycol)-modified polypyrrole [PEG-b-(PPy)4] and poly(ε-caprolactone) (PCL) for tissue engineering (TE) applications. For this purpose, pyrrole-functionalized PEGs AB4 macromonomers (PyPEGsM) were synthesized through the Steglich esterification of PEGs ends-caped tetraol [PEGs(OH)4] using pyrrole-2-carboxylic acid. These macromonomers were subsequently copolymerized with pyrrole monomer using chemical oxidation polymerization approach to produce PEGs-b-(PPy)4 copolymers. A solution of PCL and the synthesized PEGs-b-(PPy)4 copolymers were electrospun to fabricate uniform, conductive, and biocompatible nanofibrous scaffolds. The performances of the fabricated nanofibers as TE scaffolds were examined in terms of biological (biocompatibility and biodegradability) as well as physicochemical (electroactivity, conductivity, mechanical properties, and morphology) features. As the results, the fabricated electrospun nanofibers were found as proper scaffolds for use in TE applications that require electroactivity.

PEGylated graphene oxide/Fe3O4 nanocomposite: Synthesis, characterization, and evaluation of its performance as de novo drug delivery nanosystem.

This paper describes the development of mitoxantrone-loaded PEGylated graphene oxide/magnetite nanoparticles (PEG-GO/Fe3O4-MTX), and investigation of its preliminary drug delivery performance. For this, the GO was synthesized through oxidizing graphite powder, and subsequently carboxylated using a substitution nucleophilic reaction. The carboxylated GO (GO-COOH) was then conjugated with amine end-caped PEG chains by Steglich esterification. Afterward, GO-PEG/Fe3O4 nanocomposite was synthesized through the anchoring of Fe3O4 nanoparticles onto the surface of GO-PEG during the sonication. The biocompatibility and MTX-loading capacity of the synthesized GO-PEG/Fe3O4 nanocomposite were evaluated. The pH dependent drug release behavior and cytotoxicity effect of the MTX-loaded GO-PEG/Fe3O4 nanocomposite were also studied. According to biocompatibility, pH dependent drug release behavior as well as superior physicochemical and biological characteristics of graphene and magnetite nanoparticles, it is expected that the GO-PEG/Fe3O4 nanocomposite may be applied as de novo drug delivery system (DDS) for cancer therapy using both chemo- and photothermal therapy approaches.

Microbial quality of water in dental unit waterlines.

BACKGROUND: Dental unit waterlines (DUWLs) are ideal environment for development of microbial biofilms. Microbial contamination of water in DUWLs is thought to be the result of biofilm formation as it could serves as a haven for pathogens. The aim of this study was to assess microbial quality of water in dental unit waterlines of dental units located at the dental school of Isfahan University of Medical Sciences. METHODS: Water samples were collected from air/water syringe and high-speed handpiece. Generally, 100-200 ml water samples were collected aseptically in sterile containers with sodium thiosulfate at the beginning of the day after a 2 minute purge. Samples were transferred to the laboratory in insulated box with cooling packs and examined for total viable heterotrophic bacteria and fungi. RESULTS: The heterotrophic plate count levels were significantly exceeded the American Dental Association recommendations for DUWL water quality (< 200 CFU/ml), in both air/water syringe (84%, CFU/ml: 500-20000) and high-speed handpiece (96%, CFU/ml: 710-36800) samples. However, there was no significant difference between the level of contamination in the air/water syringe and high-speed handpiece. Fungi were found in 28% and 36% of air/water syringe and high-speed handpiece samples, respectively; and filamentous fungi were the most frequently isolated fungi. CONCLUSIONS: DUWLs should be subjected to routine microbial monitoring and to a decontamination protocol in order to minimize the risk of exposure to potential pathogens from dental units.