Browsing by Author "Yazgan İ."

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Bienzymatic fluorescence detection based on paraoxonase and laccase on anthracene-sequestered polyamic acid films: A novel approach for inhibition-based sensors
(2020-12-01) Esen E.; Yazgan İ.; Odaci Demirkol D.
A fluorescence assay based on paraoxonase (PO) and laccase (Lac) immobilized on anthracene-sequestered polyamic acid films is now being reported for the first time for ciprofloxacin (CFx) detection. In enzymatic reaction, PO converts phenyl acetate (PA) to acetic acid and phenol. The formed phenol is further oxidized by laccase using oxygen as a co-substrate. For indirectly fluorescence measurements of PA hydrolysis, increased fluorescence intensity was measured after oxygen consumption by laccase. This is because oxygen is quencher of anthracene (Ant) incorporated in the sequestered poly(amic) acid (PAA) film. The detection mechanism was based on inhibition of PO activity by CFx. Using PAA provided the advantage of controlling the film thickness. Firstly, morphology of PAA-Ant polymeric film was characterized by scanning electron microcopy (SEM) and the success of PO-Lac immobilization on PAA-Ant was proven by SEM plus Energy-dispersive X-ray spectroscopy (SEM-EDX) and fluorescence measurements. Then Ant-PAA/PO/Lac is calibrated for PA and CFx without any interfering of some potential interferences. All results make it a promising tool for monitoring CFx at minute levels in samples.
Comparison of Blueberry and Dandelion Aqueous Extracts in the Synthesis of Gold and Silver Nanostructures, and Their Applications as Anti-Pseudomonas aeruginosa Agent
(2023-05-11) Dilek Tepe H.; Şeymanur Aktaş B.S.; Çeter T.; Yazgan İ.
We performed a comparative study using aqueous extracts of dandelion flowers and blueberry fruits to synthesize gold- (Au) and silver- (Ag) nanostructures (NSs). The blueberry extracts gave nanowire and spherical AuNSs upon changing the ratio of the extracts to Au3+precursor while altering the ratio for the dandelion extracts resulted in formation of only anisotropic AuNSs. Similar results were obtained during the AgNSs, where the dandelion extracts resulted in formation of quasi-spherical AgNSs at the tested ratio (extract/AgNO3 ratio) while altering the ratio for the blueberry extracts resulted in nanorod and nanoplates formation. We argued that this could be from dominancy of a lone compound or a group of compounds and tested this claim by introducing chrysin and amino acid mixtures to the blueberry extracts. Altering the added chrysin amount triggered nanoplate and spherical AuNSs formation while alteration in amino acid mixture content did not change the morphology, and spherical AuNSs were obtained. The antibacterial studies revealed the AgNSs are toxic to Pseudomonas aeruginosa with 8 μg/mL MBC (minimum bactericidal concentration) and 3 μg/mL values for the blueberry and dandelion extracts synthesized AgNSs while penicillin/streptomycin sulfate mixture carrying Dandelion-AuNSs gave 12-times lower MBC value in comparison to free penicillin/streptomycin sulfate mixture.
Comparison of direct and sandwich type immunoassays on electrospun nanofibers using of metal organic frameworks as a fluorescence probe
(2022-12-01) Kirbay F.O.; Yazgan İ.; Demirkol D.O.
Here, colloidal fluorescent Fe (III) metal organic frameworks (FeMOFs) were synthesized using FeCl3 as Fe3+ ion source and lactose 1-aminonaphthalene (L1AN) as an organic linker by one-step synthesis approach. C-reactive protein antibody (Anti-CRP) was conjugated to L1AN-FeMOF through amide bond formation, which was then applied to the detection of C-reactive protein (CRP) using sandwich-type and immunometric assays. To cover 96-well plate surfaces, polycaprolactone and poly (amic acid) (PCL/PAA) electrospun nanofibers were synthesized. Limit of detection (LOD) for CRP was obtained as 4.8 pg/mL for the sandwich assay and 9.0 pg/mL for the immunometric assay in buffer systems using high throughput sensing approach. Real sample applications in artificial saliva and simulated serum validated the reliability of the approach. Selectivity control tests were performed using common serum-based interferents, for which minimum to no interference was observed. Based on the findings, the developed assay can be offered as a new approach in the detection of CRP in clinical samples.
NMR-based structural characterization of common aromatic poly(amic acid) polymers
(2020-03-01) Yazgan İ.; Yazgan, I
Polyamic acid (PAA) has been widely synthesized as the precursor of polyimide for over 50 years. PAA has had recent attention when used as a final polymer in a variety of applications including sensors, flexible electronics, drug delivery and food packaging. In all cases, structural modifications are sought to advance usability of PAA polymers, where chemistry of the polymers plays a key role for further modifications. However, there is a gap in literature that would discuss structural and cis-/trans-isometric characterizations of the PAA polymers. In this study, common PAA polymers synthesized from the couples of (1) pyromellitic dianhydride and 4,4′-oxydianiline, (2) pyromellitic dianhydride-4-sulfonyldianiline, (3) 4,4′-carbonyldiphtalic dianhydride and 4,4′-oxydianiline and (4) pyromellitic dianhydride and 4,4′-ethylenedianiline were characterized with 1D and 2D NMR and supported with ATR-FTIR techniques. The findings revealed that both diamine and dianhydride sources along with the solvent choice are crucial for cis-/trans-binding of diamine to dianhydride monomers, average molecular weight and intramolecular interactions. The current study, to the best of our knowledge, is the first report on structural annotation of common PAA polymers along with the effect of the solvent on the isomers and average molecular weight.
NMR-based structural characterization of common aromatic poly(amic acid) polymers
(2020-03-01) Yazgan İ.
Polyamic acid (PAA) has been widely synthesized as the precursor of polyimide for over 50 years. PAA has had recent attention when used as a final polymer in a variety of applications including sensors, flexible electronics, drug delivery and food packaging. In all cases, structural modifications are sought to advance usability of PAA polymers, where chemistry of the polymers plays a key role for further modifications. However, there is a gap in literature that would discuss structural and cis-/trans-isometric characterizations of the PAA polymers. In this study, common PAA polymers synthesized from the couples of (1) pyromellitic dianhydride and 4,4′-oxydianiline, (2) pyromellitic dianhydride-4-sulfonyldianiline, (3) 4,4′-carbonyldiphtalic dianhydride and 4,4′-oxydianiline and (4) pyromellitic dianhydride and 4,4′-ethylenedianiline were characterized with 1D and 2D NMR and supported with ATR-FTIR techniques. The findings revealed that both diamine and dianhydride sources along with the solvent choice are crucial for cis-/trans-binding of diamine to dianhydride monomers, average molecular weight and intramolecular interactions. The current study, to the best of our knowledge, is the first report on structural annotation of common PAA polymers along with the effect of the solvent on the isomers and average molecular weight.
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.