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    Effect of vgb gene on microbial chondroitin sulfate production in recombinant Escherichia coli pETM6-PACF-vgb and physicochemical characterization of produced chondroitin sulfate
    (Cellular and Molecular Biology Association, 2025) Erenler, Ayse Sebnem; Unver, Tuba; Ceylan, Ahmet Faruk; Ozcan, Imren; Geckil, Hikmet
    Chondroitin Sulfate (CS) is an essential component of the extracellular matrix and is a sulfated glycosaminoglycan structurally composed of a polysaccharide chain consisting of N-acetyl galactosamine and glucuronic acid. The use of CS of animal origin is common in pharmacological research. The disadvantages of traditional sources and methods used in the production of CS, which is used in various applications in the medicine, veterinary, pharmacy, and cosmetic sectors, have made microbial production a vital alternative. In this study, recombinant Escherichia coli (pETM6-PACF-vgb) strain, in which kfoA, kfoC, kfoF and vgb gene regions are co-expressed, and E. coli pETM6-PACF strain, which does not contain the vgb gene, were used in the microbial production of CS. The vgb gene is the region responsible for expressing the bacterial protein Vitreoscilla hemoglobin (VtHb). This study investigated the effect of the expression of VtHb in E. coli on increasing bacterial cell respiration and, therefore, how ATP production would affect cell growth and the acquisition of chondroitin and microbial chondroitin sulfate (MCS) from biomass. The analysis results determined a 23.07% increase in the amount of MCS produced from the vgb+ strain. The presence of vgb had positively affected culture age and reproductive kinetics. Spectrophotometric measurements, NMR, HPLC, FT-IR, TGA, DTA, and DSC analyses for the reproductive values and physicochemical characterization of the obtained MCS were applied to discuss this production process. For more detailed results on this subject, future research focused on optimization is needed. © 2025 Cellular and Molecular Biology Association. All rights reserved.
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    Investigation of the structural, thermal, magnetic and cell viability properties of Ce/Sr co-doped hydroxyapatites
    (Elsevier, 2023) Ates, Hulya Gunes; Kaygili, Omer; Bulut, Niyazi; Osmanlioglu, Fatih; Keser, Serhat; Tatar, Beyhan; Ozcan, Imren
    The present study aims to give a more detailed report on the structural, thermal, magnetic and in vitro cell viability properties of the hydroxyapatites (HAps) co-doped with Sr and Ce at different amounts. Besides these experimental analyses, this study also includes the theoretical calculation results obtained from the modeled systems for the as-prepared samples. Diamagnetic behavior was observed for all the samples, as well as their high cell compatibilities. All the samples showed a thermally stable behavior, and the mass change mechanism and specific heat capacity were affected by the amount of the codopants. The bandgap value and linear absorption coefficient varied with the amount of both co-dopants. (c) 2023 Elsevier B.V. All rights reserved.
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    The effects of Zn and Yb co-dopants on the electronic, radiation shielding, structural, thermal and spectroscopic properties of hydroxyapatite
    (Elsevier, 2024) Ayhan, Yasemin Merve; Ates, Tankut; Seckin, Turgay; Ozcan, Imren; Bulut, Niyazi; Kurucay, Ali; Kaygili, Omer
    This work presents a comprehensive investigation of the electronic properties of hydroxyapatite (HA) doped with zinc (Zn) and ytterbium (Yb). Four different compositions, namely 0.33Zn-0.33Yb-HA, 0.33Zn-0.66Yb-HA, 0.66Zn-0.33Yb-HA, and 0.66Zn-0.66Yb-HA, were studied using Density of States (DOS) and band structure calculations. The computed band gap values for each composition were determined to be 4.3097 eV, 4.1324 eV, 4.2527 eV, and 4.2088 eV, respectively. The observed decrease in the band gap energy from 0.33Zn-0.33Yb-HA to 0.66Zn-0.66Yb-HA signifies a significant impact of the dopant composition on the electronic properties of the material. Furthermore, the inclusion of ytterbium in the HA matrix resulted in the formation of a distinct band and peak in the density of states. This indicates the emergence of specific energy levels associated with Yb, suggesting a distinct influence on the electronic structure of the material. These findings provide valuable insights into the tunability of the electronic properties of HA through controlled doping with Zn and Yb. Such knowledge is crucial for tailoring materials with desired electronic characteristics, thus holding promise for various applications in electronic devices and biocompatible coatings. The as-modeled structures were synthesized via a wet chemical route. Fourier transform infrared (FTIR), Raman, and X-ray diffraction (XRD) analyses verified the formation of the HA structure for each sample. Differential thermal analysis (DTA) results showed that all the as-prepared samples were thermally stable. The negligible mass losses were detected for all the samples in the thermogravimetric analysis (TGA) measurements. The addition of both co-dopants affected crystal structure related parameters and decreased the crystallinity and cell viability.
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    Tuning electronic properties of hydroxyapatite through controlled doping using zinc, silver, and praseodymium: A density of states and experimental study
    (Elsevier Sci Ltd, 2024) Sahin, Binnur; Ates, Tankut; Acari, Idil Karaca; Barzinjy, Azeez A.; Ates, Burhan; Ozcan, Imren; Kaygili, Omer
    This study presents a comprehensive exploration of the electronic properties of hydroxyapatite (HA) doped with zinc (Zn), silver (Ag), and praseodymium (Pr). Five distinct compositions-0.4Pr-HA, 0.4Zn-0.4Pr-HA, 0.8Zn0.4Pr-HA, 0.4Ag-0.4Pr-HA, and 0.8Zn-0.4Pr-HA were systematically investigated through Density of States (DOS) and band structure calculations. The computed band gap values, ranging from 4.4037 to 4.1554 eV, revealed a progressive decrease in band gap energy from 0.4Pr-HA to 0.8Ag-0.4Pr-HA, emphasizing the substantial impact of dopant composition on electronic properties. Additionally, the incorporation of Pr induced distinct bands and peaks in the density of states, signifying the emergence of specific energy levels associated with Pr and suggesting a clear effect on the electronic structure. Furthermore, the study explores the influences of dopant type and quantity on the electronic structure, microstructure, spectral, thermal, and in vitro cell viability properties of Pr-based HA samples. Theoretical results demonstrated a continuous decrease in the bandgap with Ag or Zn dopants, and the study observed controllable changes in LAC values based on co-dopant type and quantity. Experimental outcomes revealed significant effects on crystallinity, crystallite size, lattice parameters, and unit cell volume, confirmed through XRD, SEM, EDX, FTIR, and Raman analyses. These findings provide valuable visions into the tunability of the electronic properties of HA through controlled doping with Zn, Pr, and Ag. This knowledge is crucial for modifying materials with desirable electronic properties, and thus holds promise for various applications in electronic devices and biocompatible coatings.