İstanbul Sağlık ve Teknoloji Üniversitesi Kurumsal Akademik Arşivi
DSpace@İSTÜN, Üniversite mensupları tarafından doğrudan ve dolaylı olarak yayınlanan; kitap, makale, tez, bildiri, rapor, araştırma verisi gibi tüm akademik kaynakları uluslararası standartlarda dijital ortamda depolar, Üniversitenin akademik performansını izlemeye aracılık eder, kaynakları uzun süreli saklar ve telif haklarına uygun olarak Açık Erişime sunar.
Güncel Gönderiler
Waste toner particles based dispersive solid phase extraction for the trace determination of cadmium in cinnamon tea samples by flame atomic absorption spectrometry
(Elsevier, 2026) Ali, Büşra; Büyük, Muhammed Ali; Bayraktar, Ahsen; Serbest, Hakan; Bakırdere, Sezgin
This study presents a dispersive solid phase extraction (DSPE) protocol for the sensitive and accurate determi nation of trace levels of cadmium ions (Cd2+) by flame atomic absorption spectrometry (FAAS). Toner particles obtained from used printer cartridges were used as sorbent material for preconcentration of Cd2+ ions. Opti mization studies were performed univariately for the achievement of the highest extraction efficiency and the limit of detection (LOD) was found to be 0.55 µg L-1 under optimal operating conditions. By comparing the slopes of the linear plot equations for FAAS and waste toner-based DSPE-FAAS systems, the increase in sensitivity was calculated to be 40.9 times. The feasibility of the developed method was evaluated by spiking recovery studies on cinnamon tea samples and good recovery results between 90.4 % and 119.0 % determined by the matrix matching calibration strategy showed that the method is applicable to cinnamon tea and similar matrices.
NiO-SnO2 nanocomposite as an adsorbent for the preconcentration of manganese ions in chamomile tea extract
(Elsevier, 2026) Şaylan, Meltem; Gürsoy, Selim; Zaman, Buse Tuğba; Bakırdere, Sezgin
Matricaria chamomilla L., referred to as chamomile, is a well-known medicinal plant that is widely distributed throughout the world. In this study, a novel NiO-SnO2 nanocomposite- assisted preconcentration method was established for efficient extraction and separation of manganese ions from chamomile tea extract. This pre concentration method was coupled with flame atomic absorption spectroscopy (FAAS). NiO-SnO2 nano composites were synthesized using simple one-pot co-precipitation procedure and calcined at 650 ◦C to obtain nanoparticles with sizes below 100 nm. X-ray diffraction (XRD) analysis indicated that the crystallite size of NiO SnO2 nanocomposites was estimated to be 46.03 nm using the Monshi–Scherrer equation. The LOD (limit of detection) and linear working range were determined as 3.6 μg/L and 10–100 μg/L, respectively. The proposed method was successfully validated, and recoveries ranged from 87.2 %–117.0 %. NiO-SnO2 nanocomposites represent a promising low-cost adsorbent for the preconcentration and subsequent determination of other heavy metal ions in diverse herbal extracts.
Feeding the mind: Preliminary insights into the effects of anthocyanin-rich extract from black carrots on brain activity and gut microbiota in patients with cognitive impairments
(Nature Research, 2025) Müdüroğlu Kırmızıbekmez, Aynur; Önder, Alparslan; Özdemir, Mustafa Yasir; Gürerk, Gamze; Aydın, Sevcan; Eryiğit, Önder Yüksel; Güloğlu, Mehmet Oktar; Kara, İhsan
Anthocyanins, known for their antioxidant and anti-inflammatory properties, have been associated with cognitive benefits, potentially mediated by gut-brain axis interactions. This study investigates the effects of a 12-week Anthocyanin-Rich Extract (ARE) intervention on brain activity and gut microbiota composition in older adults with neurocognitive impairments. In this study, 50 participants underwent electroencephalography (EEG) recordings and gut microbiota analyses before and after the intervention. EEG data were analyzed using connectivity and entropy metrics across multiple frequency bands. Gut microbiota composition was assessed via 16S rRNA sequencing to evaluate taxonomic shifts. Results revealed increased EEG connectivity, particularly in alpha, beta, and gamma frequency bands, suggesting improved neural communication and complexity following ARE consumption. Significant changes in nonlinear EEG metrics were observed, consistent with previous findings in the literature. Microbiota analysis indicated non-significant alterations in overall diversity but revealed increases in Alistipes, Streptococcus thermophilus, and Flavonifractor, alongside a decrease in Hungatella, potentially implicating SCFA metabolism and inflammatory regulation. These findings suggest ARE may enhance cognitive health by modulating neural activity and gut microbiota composition. While these results provide preliminary evidence of neuroprotective effects, further research with larger, disorder-specific cohorts and placebo-controlled designs is necessary to validate outcomes and explore gut-brain axis mechanisms in cognitive decline.
Computational insights into iron coordination disruption in the human transferrin–neisseria meningitidis bacterial protein complex
(MDPI Publishing, 2025) Dervişoğlu Özdemir, Celile; Duran, Gizem Nur; Fındık, Volkan; Özbil, Mehmet; Sağ Erdem, Safiye
Among many metal ions in biological systems, iron plays a fundamental role. Transferrins are iron-binding glycoproteins responsible for transporting Fe3+ in vertebrate blood. Neisse ria meningitidis, a Gram-negative pathogen causing meningitis, relies on iron for survival and acquires it from human transferrin (hTf) using two surface proteins, TbpA and TbpB. These proteins interact with hTf to form a ternary TbpA–TbpB–hTf complex, enabling iron capture from the host. The absence of an experimental crystal structure for this complex has hindered computational studies, a detailed understanding of Fe3+ dissociation, and designing efficient therapeutics. This study presents the first computational model of the ternary complex, its validation, and molecular dynamics simulations. Structural analyses revealed key electrostatic interactions regulating Fe3+ coordination and essential contact regions between proteins. The role of Lys359 from TbpA was investigated via QM/MM calculations by evaluating Fe3+ binding energies of isolated hTf, the ternary complex, and Lys359Ala, Lys359Arg, Lys359Asp mutant models. Results revealed that the proton trans fer from Lys359 leads to disruption of Tyr517–Fe3+ coordination, facilitating iron transfer to the bacterial system. Natural bond orbital analysis confirmed this mechanism. The findings provide new molecular insight into N. meningitidis iron acquisition and identify Lys359 as a potential target for covalent inhibitor design, guiding the development of novel therapeutics against meningococcal infection.
Mechanical performance of nonabsorbable monofilament suture materials tied with different suturing techniques under various knot configurations: An in vitro study
(MDPI Publishing, 2025) Tayşi, Nuri Mert; Erten Tayşi, Ayşegül; Erçal, Pınar; Şişmanoğlu, Soner
This study compared widely used nonabsorbable and monofilament suture materials tied with three different configurations and two different suture techniques. Three su ture materials (polytetrafluoroethylene, polypropylene, and nylon) were tied with either Laurell–Gottlow or the horizontal mattress suturing techniques using three different knot configurations: A (2 = 1 = 1 = 1 = 1), B (2 × 1 = 1 = 1 = 1), and C (1 × 2 = 1 = 1 = 1) on an experimental platform manufactured using a three-dimensional printer. Specimens underwent microtensile testing to determine maximum load failure and elongation rates at baseline and after 7 days of artificial saliva immersion. The Laurell–Gottlow yielded significantly lower elongation rates and higher failure load than the horizontal mattress suturing technique using nylon and polypropylene sutures at both time points (p < 0.001). Nylon had a significantly higher failure load and elongation than polypropylene and polyte trafluoroethylene at baseline for both suturing techniques and all three knot configurations (p < 0.001). Configuration C had low failure load values following immersion for all suture materials when using horizontal mattress suturing. Configuration A demonstrated superior failure load following the immersion period for all materials using both techniques. The polytetrafluoroethylene suture remained more stable over time. These findings indicate that the Laurell–Gottlow suturing technique with Configuration A provides better mechanical resistance to external forces when using nonabsorbable monofilament suture materials.
