Browsing by Author "Yazgan I."

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A versatile strategy to synthesize sugar ligand coated superparamagnetic iron oxide nanoparticles and investigation of their antibacterial activity
(2021-03-20) Saladino G.M.; Hamawandi B.; Demir M.A.; Yazgan I.; Toprak M.S.
For the time being, a great attention has been given to the search of green and reusable materials with antibacterial properties. The present research focused on the design and synthesis of hybrid structures constituting superparamagnetic iron oxide nanoparticles (SPIONs) coated with sugar ligands (SL), synthesized using a green and efficient microwave (MW)-assisted hydrothermal synthesis. The sugar ligands were selectively engineered to obtain antibacterial characteristics towards multi-drug resistant bacterial strains, which are among the most problematic bacterial species in antibiotic development efforts. The superparamagnetic behavior was obtained by synthesizing core iron oxide nanoparticles with a diameter below twenty nm. The MW-assisted hydrothermal method yielded a uniform coating of SPIONs with several sugar ligands, granting strongly negative-charged surfaces, which have eventually contributed to their bactericidal activity. The research work allowed to get insights into the magnetic properties of the sugar ligand coated SPIONs, as well as on morphological and functional characteristics of the hybrid nanoparticles, by employing both spectroscopy and imaging techniques, such as FT-IR, Scanning/Transmission Electron Microscopy (S/TEM). Detailed characterizations of the nanoparticles’ charge, using zeta potential analysis helped to identify the highly charged hybrids for antibacterial applications. Furthermore, studies on the bactericidal properties of selected SL-SPION hybrids highlighted a high selectivity towards both gram-negative and gram-positive bacteria along with improving bactericidal activity of streptomycin/penicillin mixture. Detailed studies done on Pseudomonas aeruginosa revealed that the SPIONs selectively downregulated the virulence factor pyoverdine and altered bacterial morphology depending on the SL chemistry. The synthesized materials with antibacterial activity pave the way for an effective path towards the design and development of nanostructures and coatings against antibiotic-resistant bacterial species.
Carbon quantum dots conjugated rhodium nanoparticles as hybrid multimodal contrast agents
(2021-09-01) Saladino G.M.; Kilic N.I.; Brodin B.; Hamawandi B.; Yazgan I.; Hertz H.M.; Toprak M.S.
Nanoparticle (NP)‐based contrast agents enabling different imaging modalities are sought for non‐invasive bio‐diagnostics. A hybrid material, combining optical and X‐ray fluorescence is presented as a bioimaging contrast agent. Core NPs based on metallic rhodium (Rh) have been demonstrated to be potential X‐ray Fluorescence Computed Tomography (XFCT) contrast agents. Microwave‐assisted hydrothermal method is used for NP synthesis, yielding large‐scale NPs within a significantly short reaction time. Rh NP synthesis is performed by using a custom designed sugar ligand (LODAN), constituting a strong reducing agent in aqueous solution, which yields NPs with primary amines as surface functional groups. The amino groups on Rh NPs are used to directly conjugate excitation‐independent nitrogen‐doped carbon quantum dots (CQDs), which are synthesized through citrate pyrolysis in ammonia solution. CQDs provided the Rh NPs with optical fluorescence properties and improved their biocompatibility, as demonstrated in vitro by Real‐Time Cell Analysis (RTCA) on a macrophage cell line (RAW 264.7). The multimodal characteristics of the hybrid NPs are confirmed with confocal microscopy, and X‐ray Fluorescence (XRF) phantom ex-periments.
Green Biobatteries: Hybrid Paper–Polymer Microbial Fuel Cells
(2018-10-01) Mohammadifar M.; Yazgan I.; Zhang J.; Kariuki V.; Sadik O.A.; Choi S.
Paper-based electronics have recently emerged as a simple, biodegradable, and low-cost paradigm for disposable electronics and may be an excellent way to reduce the dramatic increase in electronic waste. Paper-based batteries are imperative for stand-alone and self-sustained paper-based electronics. Ideally, paper-based batteries must be simple, biodegradable, inexpensive, and provide realistic and accessible power. Among many paper-based batteries, paper-based microbial biobatteries attract significant attention because of their self-sustainability, cost-effectiveness, eco-friendliness, and potential for energy accessibility in resource-constrained settings. However, the promise of this technology has not translated into practical power applications because of its low performance. Furthermore, its biodegradability remains questionable. In this work, an easily biodegradable paper-polymer substrate is engineered as a part of a novel, high-performance microbial battery. Poly (amic) acid and poly(pyromellitic dianhydride-p-phenylenediamine) are processed and incorporated into a porous, hydrophilic network of intertwined cellulose fibers to revolutionize oxygen-blocking, proton-exchanging, and biodegrading properties of the paper-based microbial biobatteries, which ultimately offer the transformative potential of “green” electronics. Furthermore, the battery, formed by adding engineered polymers to the paper, exhibits a much higher power-to-cost ratio than all previously reported paper-based microbial batteries. The biobattery clearly biodegrades without the requirements of special facilities, conditions, or introduction of other microorganisms.
Laccase assay based on electrochemistry and fluorescence detection via anthracene sequestered poly(amic acid) films
(2018-10-01) Esen E.; Yazgan I.; Demirkol D.O.; Timur S.
Phenols are among the most problematic organic compounds, which manipulates metabolism of living organisms and pose threat to environment. Detection of total phenol at the lowest allowable concentration is critical, so development of sensitive and easy to use methods have been heavily investigated. Hereby, for the first time, anthracene (Ant) was sequestered into poly(amic acid) (PAA) to form fluorescent and conductive film support for laccase (Lac) immobilization to quantify total phenol content at high specificity and selectivity. Ant-PAA/Lac films were applied to fluorescent and electrochemical quantification of phenol, which provided high sensitivity (LOD 46 μM) and reproducibility (RSD, 0.5%) for the tested 10 phenolic compounds including phenol, catechol, 3-acetominophenol, hydroquinone, L-DOPA, 2,6-dimethylphenyl, syringalzadine, 3,5-dimethoxy-4-hydroxycinnamic acid, 2,5-dimethoxyaniline and guaiacol. The sensor system showed strong rejection to common organic interferent while real sample application revealed the applicability of the sensor. Therefore, the results can call the sensor system, particularly fluorescence-based quantification in 96-well plate, is an alternative approach for high-throughput screening of total phenolic compounds in waste-water at cost-effective manner.
Modification of chitosan-bead support materials with l-lysine and l-asparagine for Α-amylase immobilization
(2018-03-01) Yazgan I.; Turner E.; Cronmiller L.; Tepe M.; Ozturk T.; Elibol M.
Maltose syrups have got wide-range utilizations in a variety of applications from bakery to drug-development. α-Amylases are among the most widely utilized industrial enzymes due to their high specificity in production of maltose syrup from starch. However, enzymes are not stable in ex vivo conditions towards alteration in pH, temperature, and such other parameters as high salt concentrations and impurities, where immobilization is required to advance the stability of the enzyme with which approach the requirement of isolation of the enzyme from media is eliminated as well. In this study, Termamyl® α-amylase was immobilized on the none-modified chitosan beads (NMCB), l-lysine-modified chitosan beads (LMCB), and l-asparagine-modified chitosan beads (AMCB) to assess effects of the support material on optimum conditions and kinetic parameters of the α-amylase activity in production of maltose from starch. Immobilization on NMCB, LMCB, and AMCB puts a strong influence on optimum pH, optimum temperature, stability, and kinetic parameters of α-amylase. Modification of chitosan beads with l-lysine and l-asparagine dramatically altered the overall immobilization yield, and enzyme’s response to pH and temperature variations and the kinetic parameters. AMCB provided the best immobilization yield (49%), while LMCB only improved the yield by 2% from 22 to 24%.
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.
Selective Sensing and Imaging of Penicillium italicum Spores and Hyphae Using Carbohydrate-Lectin Interactions
(2018-03-23) Yazgan I.; Zhang J.; Kariuki V.; Akgul A.; Cronmiller L.E.; Akgul A.; Osonga F.; McMahon A.; Gao Y.; Eshun G.; Choi S.; Sadik O.A.
The blue-green mold Penicillium italicum is among the most problematic post-harvest plant infections limiting the integrity of citrus and many other crops during storage and transportation, but there is no sensor for its on-site or field detection. We hereby, for the first time, report the development of novel biomolecular sensor for assessing the presence of P. italicum spores and hyphae using carbohydrate-lectin recognitions. Two approaches were developed: (i) lateral tests using standalone poly(amic) acid (PAA) membranes and glass surfaces and (ii) quantitative tests on 96-well polystyrene plates and paper electrodes. In both cases, the surfaces were functionalized with novel derivatized sugar based ligands while staining was performed with gold nanoparticles. Both approaches provided strong signals for 104 spores/mL of P. italicum isolated from experimentally infected lemons as the lowest-reliable concentration. The 96-well plate-based gave the most sensitive detection with a 4 × 102 spores/mL limit of detection, a linear dynamic range between 2.9 × 103 and 6.02 × 104 spores/mL (R2 = 0.9939) and standard deviation of less than 5% for five replicate measurements. The selectivity of the ligands was tested against Trichaptum biforme, Glomerulla cingulata (Colletotrichum gloeosporioides), and Aspergillus nidulans fungi species. The highest selectivity was obtained using the sugar-based gold-nanoparticles toward both the spores and the hyphae of P. italicum. The advanced specificity was provided by the utilized sugar ligands employed in the synthesis of gold nanoparticles and was independent from size and shapes of the AuNPs. Accuracy of the sensor response showed dramatic dependence on the sample preparation. In the case of 5-10 min centrifugation at 600 rpm, the spores can be isolated free from hyphae and conidiophore, for which spiked recovery was up to 95% (std ±4). In contrast, for gravity-based precipitation of hyphae, the spiked recovery was 88% (std 11).
Speleotherapy in the scope of health tourism: case of Çankırı salt cave in Turkey
(2022-01-01) Çılgınoğlu H.; Yazgan I.
Cave therapy, also called speleotherapy, is in high demand among health tourism consumers. This study aims to shed light on how Çankırı Salt Cave (Turkey) can contribute to health tourism in the Çankırı region. Semi-structured interviews are conducted with 35 respondents working in tourism and health in the Çankırı region. The results show that the main challenges to the contribution of the Çankırı salt cave to health tourism are the lack of promotion in social media, the poor infrastructure around the salt cave and the lack of scientific reports on the effectiveness of salt therapy. If these challenges are overcome, the Çankırı Salt Cave has the potential to contribute to regional health tourism.