https://hdl.handle.net/20.500.12573/207 2026-05-08T06:29:55Z https://hdl.handle.net/20.500.12573/2538 Horseradish peroxidase (HRP) nanoflowers-mediated polymerization of vinyl monomers Ozaydin, Gulbahar; Mirioglu, Muge; Kaplan, Naime; Dadi, Seyma; Ocsoy, Ismail; Gokturk, Ersen The effects of flower-shaped hybrid nano biocatalyst (hFe-NFs) from coordination between horseradish peroxidase (HRP) enzyme and Fe2+ ions on the free-radical polymerization reactions of three different vinyl monomers (styrene, methylmethacrylate and acrylamide) were investigated. Polymerizations of styrene and methylmethacrylate (MMA) were performed under emulsion conditions using three different surfactants in the presence of acetylacetone (AcAc) and hydrogen peroxide (H2O2) initiator. Polymerization of water soluble acrylamide was accomplished under surfactant-free media. According to the obtained outcomes, hFe-NFs exhibited higher catalytic activity towards polymerization of vinyl monomers compared to the free-HRP enzyme in terms of yields and the number average molecular weights (Mn) of the synthesized polymers. hFe-NFs also demonstrated very high thermal stability. While optimum polymerization of styrene was achieved at room temperature (RT), the highest polymerization yields for acrylamide and MMA were respectively accomplished at 70 and 60 degrees C in which free-HRP enzyme loses its catalytic activity. Preparation of the flower-shaped hFe-NFs, therefore, enables inexpensive and stable catalyst system for free-radical polymerization of vinyl monomers compared to free-HRP enzyme. Increasing catalytic activity and stability of hFe-NFs at higher reaction temperatures are very crucial for utilization of these types of catalysts in both scientific and industrial purposes. 2024-01-01T00:00:00Z https://hdl.handle.net/20.500.12573/2537 Electrochemical and Optical Multi-Detection of Escherichia coli Through Magneto-Optic Nanoparticles: A Pencil-on-Paper Biosensor Soysaldi, Furkan; Ekici, Derya Dincyurek; Soylu, Mehmet cagri; Mutlugun, Evren Escherichia coli (E. coli) detection suffers from slow analysis time and high costs, along with the need for specificity. While state-of-the-art electrochemical biosensors are cost-efficient and easy to implement, their sensitivity and analysis time still require improvement. In this work, we present a paper-based electrochemical biosensor utilizing magnetic core-shell Fe2O3@CdSe/ZnS quantum dots (MQDs) to achieve fast detection, low cost, and high sensitivity. Using electrochemical impedance spectroscopy (EIS) as the detection technique, the biosensor achieved a limit of detection of 2.7 x 10(2) CFU/mL for E. coli bacteria across a concentration range of 10(2)-10(8) CFU/mL, with a relative standard deviation (RSD) of 3.5781%. From an optical perspective, as E. coli concentration increased steadily from 10(4) to 10(7) CFU/mL, quantum dot fluorescence showed over 60% lifetime quenching. This hybrid biosensor thus provides rapid, highly sensitive E. coli detection with a fast analysis time of 30 min. This study, which combines the detection advantages of electrochemical and optical biosensor systems in a graphite-based paper sensor for the first time, has the potential to meet the needs of point-of-care applications. It is thought that future studies that will aim to examine the performance of the production-optimized, portable, graphite-based sensor system on real food samples, environmental samples, and especially medical clinical samples will be promising. 2024-01-01T00:00:00Z https://hdl.handle.net/20.500.12573/2536 Discovery of a C-S lyase inhibitor for the prevention of human body malodor formation: tannic acid inhibits the thioalcohol production in Staphylococcus hominis Fidan, Ozkan; Karipcin, Ayse Doga; Kose, Ayse Hamide; Anaz, Ayse; Demirsoy, Beyza Nur; Arslansoy, Nuriye; Sun, Lei; Mujwar, Somdutt Human body odor is a result of the bacterial biotransformation of odorless precursor molecules secreted by the underarm sweat glands. In the human axilla, Staphylococcus hominis is the predominant bacterial species responsible for the biotransformation process of the odorless precursor molecule into the malodorous 3M3SH by two enzymes, a dipeptidase and a specific C-S lyase. The current solutions for malodor, such as deodorants and antiperspirants are known to block the apocrine glands or disrupt the skin microbiota. Additionally, these chemicals endanger both the environment and human health, and their long-term use can influence the function of sweat glands. Therefore, there is a need for the development of alternative, environmentally friendly, and natural solutions for the prevention of human body malodor. In this study, a library of secondary metabolites from various plants was screened to inhibit the C-S lyase, which metabolizes the odorless precursor sweat molecules, through molecular docking and molecular dynamics (MD) simulation. In silico studies revealed that tannic acid had the strongest affinity towards C-S lyase and was stably maintained in the binding pocket of the enzyme during 100-ns MD simulation. We found in the in vitro biotransformation assays that 1 mM tannic acid not only exhibited a significant reduction in malodor formation but also had quite low growth inhibition in S. hominis, indicating the minimum inhibitory effect of tannic acid on the skin microflora. This study paved the way for the development of a promising natural C-S lyase inhibitor to eliminate human body odor and can be used as a natural deodorizing molecule after further in vivo analysis. 2025-01-01T00:00:00Z https://hdl.handle.net/20.500.12573/2531 N-Type Molecular Thermoelectrics Based on Solution-Doped Indenofluorene-Dimalononitrile: Simultaneous Enhancement of Doping Level and Molecular Order Wang, Suhao; Wei, Huan; Rillaerts, Antoine; Deneme, Ibrahim; Depriester, Michael; Manikandan, Suraj; Andreasen, Jens Wenzel; Daoudi, Abdelylah; Peralta, Sebastien; Longuemart, Stephane; Usta, Hakan; Cornil, Jerome; Hu, Yuanyuan; Pisula, Wojciech The development of n-type organic thermoelectric materials, especially π-conjugated small molecules, lags far behind their p-type counterparts, due primarily to the scarcity of efficient electron-transporting molecules and the typically low electron affinities of n-type conjugated molecules that leads to inefficient n-doping. Herein, the n-doping of two functionalized (carbonyl vs dicyanovinylene) indenofluorene-based conjugated small molecules, 2,8-bis(5-(2-octyldodecyl)thien-2-yl)indeno[1,2-b]fluorene-6,12-dione (TIFDKT) and 2,2′-(2,8-bis(3-alkylthiophen-2-yl)indeno[1,2-b]fluorene-6,12-diylidene)dimalononitrile (TIFDMT) are demonstrated, with n-type dopant N-DMBI. While TIFDKT shows decent miscibility with N-DMBI, it can be hardly n-doped owing to its insufficiently low LUMO. On the other hand, TIFDMT, despite a poorer miscibility with N-DMBI, can be efficiently n-doped, reaching a respectable electrical conductivity of 0.16 S cm−1. Electron paramagnetic resonance measurements confirm the efficient n-doping of TIFDMT. Based on density functional theory (DFT) calculations, the LUMO frontier orbital energy of TIFDMT is much lower, and its wave function is more delocalized compared to TIFDKT. Additionally, the polarons are more delocalized in the n-doped TIFDMT. Remarkably, as indicated by the grazing-incidence wide-angle X-ray scattering (GIWAXS), the molecular order for TIFDMT thin-film is enhanced by n-doping, leading to more favorable packing with edge-on orientation and shorter π-π stacking distances (from 3.61 to 3.36 Å). This induces more efficient charge transport in the doped state. Upon optimization, a decent thermoelectric power factor of 0.25 µWm−1K−2 is achieved for n-doped TIFDMT. This work reveals the effect of carbonyl vs dicyanovinylene on the n-doping efficiency, microstructure evolution upon doping and thermoelectric performance, offering a stepping stone for the future design of efficient n-type thermoelectric molecules. 2025-01-01T00:00:00Z