Browsing by Author "Bakar F."

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On the effect of modified carbohydrates on the size and shape of gold and silver nanostructures
(2020-07-01) Yazgan I.; Gümüş A.; Gökkuş K.; Demir M.A.; Evecen S.; Sönmez H.A.; Miller R.M.; Bakar F.; Oral A.; Popov S.; Toprak M.S.
Gold (Au) and silver (Ag) nanostructures have widespread utilization from biomedicine to materials science. Therefore, their synthesis with control of their morphology and surface chemistry have been among the hot topics over the last decades. Here, we introduce a new approach relying on sugar derivatives that work as reducing, stabilizing, and capping agents in the synthesis of Au and Ag nanostructures. These sugar derivatives are utilized alone and as mixture, resulting in spherical, spheroid, trigonal, polygonic, and star-like morphologies. The synthesis approach was further tested in the presence of acetate and dimethylamine as size-and shape-directing agents. With the use of transmission electron microscopy (TEM), selected area electron diffraction (SAED), x-ray diffraction (XRD), scanning electron microscopy (SEM), and ultraviolet-visible (UV-vis) absorption spectroscopy techniques, the particle size, shape, assembly, aggregation, and film formation characteristics were evaluated. NPs’ attributes were shown to be tunable by manipulating the sugar ligand selection and sugar ligand/metal-ion ratio. For instance, with an imine side group and changing the sugar moiety from cellobiose to lactose, the morphology of the Ag nanoparticles (NPs) transformed from well dispersed cubic to rough and aggregated. The introduction of acetate and dimethylamine further extended the growth pattern and morphological properties of these NPs. As examples, L5 AS, G5AS, and S5AS ligands formed spherical or sheet-like structures when used alone, which upon the use of these additives transformed into larger multicore and rough NPs, revealing their significant effect on the NP morphology. Selected samples were tested for their stability against protein corona formation and ionic strength, where a high chemical stability and resistance to protein coating were observed. The findings show a promising, benign approach for the synthesis of shape-and size-directed Au and Ag nanostructures, along with a selection of the chemistry of carbohydrate-derivatives that can open new windows for their applications.
Plant and animal awareness in nature education perspectives: Where is blindness?
(2020-01-01) Bakar F.; Avan Ç.; Şeker F.; Aydinli B.
Awareness as a broad term is subject of many scientific disciplines such as psychology, education and biology etc. Thus the awareness study about our surrounding and environment can be called as a socio-scientific issues. The human species are often in interaction with almost all living and non-living things in the world. And we are not aware about these to some extent. The awareness changes according to the same variables such as mobility, color contrast and similarity to the human being. The living groups (plants and animals) come first rather than non-livings such as stones, water and air. It is the clear that people have higher awareness towards animals. Against plants and mushroom, the awareness is well below the desired level. In this study, it was tried to determine the changes in middle school students’ awareness towards animals, plants and mushrooms through nature education. Nature education connects individual with nature. During the education, students recognize livings in the nature and try to understand the importance of nature for a sustainable future. Within the scope of the study, 47 secondary school students were given one week of natural education. Students' answers were analyzed statistically. The pictorial information scales applied before and after the education reveal a significant increase in plant awareness, especially in a world where plant blindness is high.
Surface chemistry dependent toxicity of inorganic nanostructure glycoconjugates on bacterial cells and cancer cell lines
(2023-01-01) Sancak S.; Yazgan İ.; Bayarslan A.U.; Ayna A.; Evecen S.; Taşdelen Z.; Gümüş A.; Sönmez H.A.; Demir M.A.; Demir S.; Bakar F.; Dilek-Tepe H.; Kasemets K.; Otsus M.; Çeter T.
Surface functionalized nanostructures have outstanding potential in biological applications owing to their target-specific design. In this study, we utilized laboratory synthesized carbohydrate-derivatives (i.e., galactose, mannose, lactose, and cellobiose derivatives) for aqueous one-pot synthesis of gold (Au) and silver (Ag) nanostructure glycoconjugates (NSs), and iron metal-organic framework glycoconjugates (FeMOFs). This work aims to test whether differences in the surface chemistry of the inorganic nanostructures play roles in revealing their toxicities towards bacterial cells and cancerous cell lines. As of the first step, biological activity of AuNSs, AgNSs, and FeMOFs were tested against a variety of gram (−) and gram (+) bacterial strains, where AgNSs possessed moderate to high antibacterial activities against all the tested bacterial strains, while AuNSs and FeMOFs showed their bacterial toxicity mostly depending on the strain. Minimum inhibitory concentration (MIC) and Minimum bactericidal concentration (MBC) determination studies were performed for the nanostructure glycoconjugates, for which μg/mL MBC values were obtained such as (Cellobiose p-aminobenzoic acid_AgNS) CBpAB_AgNS gave 50 μg/mL MBC value for P.aeruginosa and S.kentucy. The activity of selected sugar ligands and corresponding glycoconjugates were further tested on MDA-MB-231 breast cancer and A549 lung cancer cell lines, where selective anticancer activity was observed depending on the surface chemistry as well. Besides, D-penicillamine was introduced to galectin specific sugar ligand coated AuNS glycoconjugates, which showed very strong anticancer activities even at low doses. Overall, the importance of this work is that the surface chemistry of the inorganic nanostructures can be critical to reveal their toxicity towards bacterial cells and cancerous cell lines.