Anti-microbial Activity Of Graphene Oxide Against Bacteria And Fungi

Graphene Oxide (GO) is a promising material for various applications. The team prepared GO from graphite and studied the interaction with different microorganisms. Anti-microbial properties were detected for the prepared GO. Anti-microbial activities of GO was tested against one eukaryotic fungi (Candida albicans) two prokaryotic bacteria Gram-negative bacilli (Escherichia coli ATCC 41570 and Pseudomonas aeruginosa ATCC 25619) and two prokaryotic bacteria Gram-positive cocci (Streptococcus feacalis 19433 and Staphylococcus aureus ATCC 11632). Spectrophotometer was used to measure the growth as an indirect method, viable cell counting was used as direct method. Readings were taken at successive incubated times. Results revealed that GO exhibited stronger antibacterial and anti-fungal activity against the used bacteria and fungi species. Acknowledgements: This research was made possible by NPRP grant (NPRP5-039-2-014) from the Qatar National Research Fund (a member of Qatar Foundation). The statement made herein are solely the responsibility of the author.qscienc

Mussel-mimicking sulfobetaine-based copolymer with metal tunable gelation, self-healing and antibacterial capability

In the present study, the sulfobetaine-based copolymer bearing a dopamine functionality showed gel formation adjusted by the application of metal salts for gelation and various values of pH. Normally, the liquid-like solution of the sulfobetaine-based copolymer and metal cross-linkers is transformed to a gel-like state upon increasing the pH values in the presence of Fe3+ and Ti3+. Metal-induced coordination is reversible by means of the application of EDTA as a chelating agent. In the case of Ag+ ions, the gel is formed through a redox process accompanied with the oxidative coupling of the dopamine moieties and Ag0 particle formation. Mussel-mimicking and metal-dependent viscoelastic properties were observed for Fe3+, Ti3+, and Ag+ cross-linking agents, with additionally enhanced self-healing behavior in comparison with the covalently cross-linked IO4 − analogues. Antibacterial properties can be achieved both in solution and on the surface using the proper concentration of Ag+ ions used for gelation; thus, a tunable amount of the Ag0 particles are formed in the hydrogel. The cytotoxicity was elucidated by the both MTT assay on the NIH/3T3 fibroblast cell line and direct contact method using human dermal fibroblast cell (F121) and shows the non-toxic character of the synthesized copolymer. © 2017 The AuthorsQatar University [QUUG-CAM-2017-1]; Ministry of Education, Youth and Sports of the Czech Republic - Program NPU I [LO1504]; Maersk Oil R&TC Qatar project; Qatar National Research Fund (Qatar Foundation) [9 - 219-2-105

New Processing Technique To Improve Physical And Mechanical Properties Of Graphene Nanocomposites

Nanocomposites are commonly used in many applications and new processing techniques are required to improve mechanical and physical properties of these materials. Graphene nanoplatelets (GNPs) have high aspect ratio and can maximize stress transfer in the composite. GNPs were added to linear low density polyethylene (LLDPE) at different weight percentage and different feeding and extruder speeds. 1,2,4,6,8 and 10% of graphene nanoplateletes loading were used for preparing the composites. Extruder and feeder speed were 50rpm,100rpm and 150 rpm. Higher content of GNPs and higher speed slightly improved crystallinity temperature due to the reduction of the agglomerates at higher speed and easy production of nucleation zones. Higher speeds improved the thermal degradation temperature as new barrier layers are formed and increase in thermal and electrical conductivity due to the good distribution of the fillers in the polymer matrix. Increase by 48% of tensile testing was achieved with the highest speed and 4% addition of GNPs. This enhancement in mechanical, thermal and electrical properties of GNPs/LLDPE nanocomposites achieved at high extruder speed with GNPs via melt mixing can open the door to industrial manufacturing of economical novel materials with superior tensile strength, thermal stability and electrical conductivity. Acknowledgements: This research was made possible by NPRP grant (NPRP5-039-2-014) from the Qatar National Research Fund (a member of Qatar Foundation). The statement made herein are solely the responsibility of the authors.qscienc