Bioengineering / Biyomühendislik
Permanent URI for this collectionhttps://hdl.handle.net/11147/4529
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Article Citation - WoS: 76Citation - Scopus: 82Multicolor Emitting Carbon Dot-Reinforced Pva Composites as Edible Food Packaging Films and Coatings With Antimicrobial and Uv-Blocking Properties(American Chemical Society, 2022) Alaş, Melis Özge; Doğan, Gamze; Yalçın, Mustafa Serkan; Özdemir, Sadin; Genç, RükanActive food packaging has become attractive because of the possibility to provide a longer shelf-life by loading functional agents into the packages to maintain the quality of food products. Herein, photoluminescent and transparent polyvinyl alcohol (PVA)-based composites embedding multicolor fluorescent carbon dots (CD/PVA) were prepared by the solvent casting method. The prepared CDs emit a strong and stable fluorescence in solution while the CD/PVA composite films were transparent, flexible, and showed UV-blocking activity with a strong fluorescence emission. Blue color-emitting CDs showed the highest UV blockage at UVA (87.04%), UVB (87.04%), and UVC (92.22%) regions while PVA alone absorbed only less than 25% of the light in all UV regions. UV blockage capacity was shown to be decreased by half, in line with the emission color shift from blue to red. Thermal properties of the PVA film were improved by the addition of CDs to the polymer, and in vitro cell viability tests showed that none of the CDs were cytotoxic against the human lung fibroblast healthy cell line (MRC-F cells) when integrated into the PVA. The antimicrobial activity of CD/PVA nanofilms was qualitatively determined. The prepared films exhibited good antimicrobial activity against both Gram-positive and Gram-negative bacteria with mild antioxidant and metal chelating activity, and significant inhibition of biofilm formation with a strong link with emitted color and the concentration of the composites. Green- and red-emitting CD/PVA with the highest antimicrobial activity were then analyzed and compared with the plane PVA employing their effect on the shelf-life of strawberries as a model for perishable foods. Fresh strawberries dip coated with CD/PVA and PVA were monitored over time, and virtual evaluations showed that CDs/PVA film coating resulted in reduced weight and moisture loss and significantly inhibited the fungal growth and spoiling for over 6 days at RT and 12 days at fridge conditions maintaining the visual appearance and natural color of the fruit. The findings in this work indicated the potential of reported CD as non-cytotoxic, UV-blocking antimicrobial additives for the development of edible coatings and packages for their use in the food industry, as well as pharmaceutical and healthcare applications.Article Citation - WoS: 6Citation - Scopus: 6Benzodiazepine Derivatives From Marine-Derived Streptomyces Cacaoi 14cm034(ACG Publications, 2021) Çetinel Aksoy, Semiha; Küçüksolak, Melis; Uzel, Ataç; Bedir, Erdal7-methoxy-8-hydroxy cycloanthranilylproline (2), a new natural product with pyrrolobenzodiazepine (PBD) framework, was isolated from marine-derived actinobacterium Streptomyces cacaoi 14CM034, together with cycloanthranilylproline (1). Structural elucidation of the compounds was based on FTIR, 1D-(H-1 and C-13 NMR), 2D-NMR (COSY, HMBC and NOESY) and HR-MS analyses. Compounds 1 and 2 exhibited notable antimicrobial activity. The presence of PBD derivatives in S. cacaoi was first demonstrated with this study.Article Citation - WoS: 6Antioxidant, Antimicrobial and Cytotoxic Activities of Extracts From Some Selected Mediterranean Shrub Species (maquis)(Biointerface Research Applied Chemistry, 2016) Bayraktar, Oğuz; Altıok, Evren; Yılmazer, Özgür; Rusçuklu, Dane; Büyüköz, MeldaIn this study in vitro antioxidant, antimicrobial and cytotoxic activities of ethanol extracts of some plants from Urla region in Turkey were investigated. Plant material samples of Pistacia lentiscus, Vitex agnus-castus, Cistus creticus and Nerium oleander were collected in October, November and December. The harvesting time significantly affected their antioxidant, antimicrobial and cytotoxic activities of these plant extracts. The highest biological activities in terms of antioxidant, antimicrobial and cytotoxic activities were observed for the leaf extract of C. creticus. The applied doses of leaf extracts of C. creticus, P. lentiscus, and N. oleander resulted in higher Bax and GAPDH expressions than those for control cells. These plant extracts may trigger apoptosis and may be a promising natural source for prostate cancer treatment.Article Citation - WoS: 30Citation - Scopus: 35Bioactive Sheath/Core Nanofibers Containing Olive Leaf Extract(John Wiley and Sons Inc., 2016) Doğan, Gamze; Başal, Güldemet; Bayraktar, Oğuz; Özyıldız, Figen; Uzel, Ataç; Erdoğan, İpekThis study aimed at producing silk fibroin (SF)/hyaluronic acid (HA) and olive leaf extract (OLE) nanofibers with sheath/core morphology by coaxial electrospinning method, determining their antimicrobial properties, and examining release profiles of OLE from these coaxial nanofibers. Optimum electrospinning process and solution parameters were determined to obtain uniform and bead-free coaxial nanofibers. Scanning electron microscopy and transmission electron microscopy (TEM) were used to characterize the morphology of the nanofibers. The antimicrobial activities of nanofibers were tested according to AATCC test method 100. Total phenolic content and total antioxidant activity were tested using in vitro batch release system. The quality and quantity of released components of OLE were determined by high-performance liquid chromatography. The changes in nanofibers were examined by Fourier-transform infrared spectroscopy. Uniform and bead-free nanofibers were produced successfully. TEM images confirmed the coaxial structure. OLE-loaded nanofibers demonstrated almost perfect antibacterial activities against both of gram-negative and gram-positive bacteria. Antifungal activity against C. albicans was rather poor. After a release period of 1 month, it was observed that ∼70-95% of the OLE was released from nanofibers and it was still bioactive. Overall results indicate that the resultant shell/core nanofibers have a great potential to be used as biomaterials.Article Citation - WoS: 22Citation - Scopus: 24Optimization of Extraction Conditions for Active Components in Equisetum Arvense Extract(Ars Docendi, 2013) Uslu, Mehmet Emin; Erdoğan, İpek; Bayraktar, Oğuz; Ateş, MehmetResponse surface methodology was applied to predict optimum conditions for equisetum arvense extraction. Central composite design was used to monitor the effects of temperature, stirring speed, ethanol percent, extraction time, solid-liquid ratio on dependent variables such as, extract yield percent, total phenol content, total antioxidant capacity, silicic acid amount. According to the mathematical models obtained from the analysis, the highest values for yield percent, total phenol content, total antioxidant capacity and silicic acid amount were found to be 18.67 %, 123 mg gallic acid gr-1 dry weight extract, 1608 μM TEAC mg-1 dry weight extract and 0.0049 mg silicic acid mg-1 dry weight extract, respectively. The plant extracts were analyzed with HPLC to determine the phenolic content and compositional differences of extracts obtained at different extraction conditions. Plant extracts were also analyzed for their cytotoxic and antimicrobial activities. The high total antioxidant capacity and total phenolic content resulted in an increased cytotoxic effect on fibroblast cells. Equisetum arvense extracts showed antimicrobial activity against Staphylococcus epidermidis and Escherichia coli bacteria, however showed no effect against Candida albicans. © 2013 University of Bucharest.