Browsing by Author "Akcali, Alper"

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Milk Hydrogels as Nutrient Media and Survival Rate Enhancer Under Cryogenic Conditions for Different Microorganisms
(Springer, 2016) Alpaslan, Duygu; Sahiner, Mehtap; Yuceer, Yonca; Akcali, Alper; Aktas, Nahit; Sahiner, Nurettin
Milk-containing hydrogels from 2-hydroxyethylmethacrylate (HEMA) and acrylamide (AAm) as p(HEMA)/whole milk, p(HEMA)/semi-skimmed milk, p(HEMA)/skimmed milk, p(AAm)/whole milk, p(AAm)/semi-skimmed milk, p(AAm)/skimmed milk were synthesized by conventional redox polymerization technique using corresponding monomers and milk as solvents. The aim of this study was to investigate the use of milk-containing hydrogels as a nutritional medium, e.g., up 124 days for enhanced or longer cryostorage media for various microorganisms such as Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus subtilis, and fungi, Aspergillus niger, Aspergillus fumigates, and a yeast Candida albicans. It was shown that milk hydrogels can be used as nutritional media for the growth of these microorganisms, whereas the control hydrogels cannot be used for the same purpose. The survival rates of p(HEMA)/whole milk and p(AAm)/whole milk hydrogels for E. coli after 124 days were found to exceed those of the control p(HEMA) and p(AAm) hydrogels by 109- and 56-fold, respectively. Moreover, the survival rates for S. aureus were calculated to be 42 and 24 times longer than the controls, as the hydrogels containing whole milk were used as storage media in comparison with the bare hydrogels. Furthermore, the cryogenic survival rates of p(HEMA)/whole milk and p(AAM)/whole milk were compared with whole milk and nutrient broth used as a control, and calculated to be 67-, 171-, 35-, and 89-fold greater, respectively, than those of the control samples for E. coli.
P(4-Vp) Based Nanoparticles and Composites With Dual Action as Antimicrobial Materials
(Elsevier Science Bv, 2010) Ozay, Ozgur; Akcali, Alper; Otkun, Mueserref Tatman; Silan, Coskun; Aktas, Nahit; Sahiner, Nurettin
Polymeric 4-VP (p(4-VP)) particles were synthesized in an oil-in-water microemulsion system using various amounts of ethylene glycol dimethacrylate (EGDMA) as crosslinker. The prepared p(4-VP) particles were chemically modified to obtain positively charged particles as polyelectrolytes. Furthermore, these p(4-VP) particles were used for in situ Ag and Cu metal nanoparticle syntheses to provide dual action with an additional advantage as bactericidal particles. The synthesized p(4-VP) particles with positive charges and metal constituents were tested for potential antibacterial action against various bacteria such as Staphylococcus aureus ATCC6538, Pseduomonas aeruginosa ATCC9027, Bacillus subtilis ATCC6633, Escherichia coli ATCC8739. It was found that p(4-VP) particles, especially the positively charged forms had potential as antibacterial materials. The synthesized particle dimensions were characterized with TEM, and DLS measurements. Chemical modification of the particles was confirmed by FT-IR spectroscopy and zeta potential measurements, and the metal nanoparticle contents were determined with thermogravimetric (TGA) studies. (C) 2010 Elsevier B.V. All rights reserved.