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
Formulation and characterization of an oleuropein-enriched oral spray gel: Microbiological performance and in ovo histopathological safety
(MDPI Publishing, 2026) Alparslan, Levent; Özdemir, Samet; Karacan, Burak; Tutar, Ömer Faruk; Doğan, Tunay; Akar, Remzi Okan; Yıldırım, Elifnur Gizem; Erdoğan, Nusret
Background/Objectives: Oleuropein is a bioactive phenolic compound from olive leaves with antimicrobial and antioxidant activity. This study aimed to develop a sprayable oral gel containing an oleuropein-rich aqueous extract and to evaluate its pharmaceutical performance antimicrobial efficacy and in ovo biological response. Methods: Oleuropein content was quantified using a validated chromatographic method. Polymeric systems were screened to select an optimized sprayable formulation. Physicochemical stability, dose uni formity, and antimicrobial activity against major cariogenic bacteria were evaluated. In ovo biological evaluation was conducted using the chick chorioallantoic membrane angiogene sis model together with histopathological examination of embryonic heart and liver tissues. Results: Oleuropein content was determined as 288.6 µg/mL in the olive leaf extract and 255.1 µg/mL in the final formulation. The optimized oral spray showed stable physico chemical properties, with pH maintained at 6.90 ± 0.02 and no relevant changes in viscosity during storage. The mean delivered dose per actuation was 0.128 ± 0.015 g, corresponding to 32.6 µg oleuropein per spray. The formulation exhibited inhibitory activity against all tested cariogenic microorganisms, with MIC values ranging from 13.3 to 170.7 µg/mL and MBC values generally two-fold higher. In the CAM assay, significant concentration- and time-dependent antiangiogenic effects were observed after 24–48 h at moderate and higher concentrations. Histopathological evaluation revealed dose-dependent acute degenerative and congestive changes in heart and liver tissues without evidence of fibrosis or steatosis. Conclusions: The oleuropein-based sprayable oral gel is a promising localized delivery system with adequate stability dose uniformity and antimicrobial efficacy. In ovo findings provide a conservative assessment of systemic exposure and support further development for oral biofilm and caries-related applications.
Development of brimonidine-loaded ethosomes for glaucoma: Investigation of intraocular pressure-lowering potential in vivo
(MDPI Publishing, 2026) Özdemir, Samet; Sağıroğlu, Ali Asram; Şen, Eslim; Gelmez Yıldız, Büşra; Karimli, Laman; Ezgi Durgun, Meltem; Çelebi, Ali Riza Cenk; Özsoy, Yıldız
Background/Objectives: Brimonidine tartrate (BRT), a selective α2-adrenergic receptor agonist, is commonly used in the treatment of glaucoma. However, conventional eye drop formulations suffer from poor ocular bioavailability and rapid elimination. This study aimed to develop and evaluate BRT-loaded ethosomes as a nanocarrier-based alternative to enhance intraocular delivery and therapeutic efficacy. Methods: Ethosomes were prepared using the thin-film hydration method and optimized via central composite design. The optimized formulation was subjected to physicochemical characterization, in vitro release testing, and ocular irritation assessment using the Hen egg test—chorioallantoic membrane (HET-CAM) model. Additionally, the intraocular pressure (IOP)-lowering efficacy of the formulation was evaluated in a rat glaucoma model. Results: The optimized ethosomal formulation exhibited favorable physicochemical properties, including a mean particle size of 122.6 ± 0.7 nm, zeta potential of −1.8 ± 0.9 mV, and encapsulation efficiency of 87.33 ± 0.04%. In vitro release data followed Higuchi kinetics. HET-CAM analysis indicated non-irritancy. In vivo, the ethosomal BRT formulation achieved comparable IOP-lowering effects to the marketed eye drops at one-third of the dose. Conclusions: The developed BRT loaded ethosomal system demonstrated promising physicochemical stability, sustained release, and therapeutic potential. These findings suggest that ethosomes may offer a safe and effective strategy for enhancing the ocular delivery of BRT in glaucoma therapy.
Anatomical study of the superficial and deep circumflex iliac arteries: Morphology, variability, and surgical relevance
(Springer Nature Link, 2026) Ok, Fatma; Nteli Chatzioglou, Gkionoul; Karip, Burak; Önal, Vildan; Yıldız, Nilay; Tatar, Burak Ergün; Gayretli, Özcan
Purpose The vascular anatomy of the groin region plays an important role in reconstructive surgery and regional anesthesia, yet data on the precise morphology and topography of the superficial and deep circumflex iliac arteries remain limited. Methods 28 lower extremities of fourteen formalin-fixed male cadavers were dissected to examine the superficial and deep circumflex iliac arteries. Their origins, branching patterns, diameters, and spatial relationships to the inguinal ligament and femoral triangle were recorded. Morphometric distances were measured with a digital caliper, and correlations between parameters were analyzed statistically. Results The superficial circumflex iliac artery arose exclusively from the femoral artery in all cases and was consistently located within the femoral triangle. Its mean origin diameter was 1.83±0.46 mm. The deep circumflex iliac artery showed greater variability, originating from the external iliac artery in half of the cases and from the femoral artery in the other half. Its mean origin diameter was 2.25±0.40 mm, and it was located outside the femoral triangle in 71.4% of cases. Multiple significant correlations were identified between vessel diameters, bifurcation points, and their spatial relationships with the inguinal ligament. Conclusion The superficial circumflex iliac artery displays consistent anatomy, whereas the deep circumflex iliac artery demonstrates notable variability in origin and topography, though with stable vessel caliber. These findings provide detailed morphometric insights that may support safer flap design and improve surgical and anesthetic planning in the groin region.
Influence of drying methods on redispersibility and dissolution of canagliflozin nanocrystals: A comparative approach
(MDPI Publishing, 2026) Pirinçci Tok, Yağmur; Demiralp, Burcu; Güngör, Sevgi; Sarıkaya, Ali Osman; Aldeniz, Emre Erol; Dude, Udaya Kumar; Özsoy, Yıldız
Background/Objectives: Canagliflozin (CFZ) is the first sodium glucose co-transporter 2 (SGLT-2) inhibitor and is characterized by poor water solubility and permeability, resulting in low oral bioavailability. In this study, a CFZ nanosuspension (CFZ-NS) was converted into a solid form to improve the physical stability of CFZ nanocrystals (CFZ-NCs) and to enable formulation as a tablet dosage form. Methods: To achieve adequate redispersibility of dried CFZ-NCs, fluid bed granulation and spray-drying methods were employed, and the effects of critical process parameters were investigated. The stability of spray dried nanocrystal tablets (NCs-SD-TAB) was evaluated over a three-month period under storage conditions of 25 ± 2 ◦C with 60 ± 5% relative humidity (RH) and 40 ± 2 ◦C with 75 ± 5% RH. Results: The highest redispersibility index (94%) was obtained using the spray-drying method. Tablets prepared with spray-dried NCs-SD-TAB exhibited a significantly higher in vitro dissolution rate under non-sink conditions compared with control tablets prepared using unprocessed CFZ with the same excipients, as well as the marketed product. NCs-SD-TAB showed an approximately three-fold increase in drug release at 15 min in 0.1 N HCl, with a pH 4.5 acetate buffer and pH 6.8 phosphate buffer, which simulate gastrointestinal pH conditions, relative to the marketed product. Conclusions: Overall, these results indicate that nanocrystal technology represents a promising approach for CFZ as an improved oral drug-delivery system, primarily due to its solubility enhancement capabilities.
Energy production from gas hydrates
(Elsevier, 2025) Çifci, Günay; Parlaktuna, Mahmut; Çelebi, Serdar Suut; Okay Günaydın, Seda
Gas hydrates are a type of natural formation that contains large amounts of mostly methane, which is also known as natural gas, and water, in the form of ice. Methane hydrates are cages of water molecules that surround and trap methane molecules. Gas hydrate is geophysical, geologically and economically important for several reasons: Gas hydrates are good cap rocks for oil and natural gas. The methane hydrate itself is an important energy source. A volume of gas hydrate can store up to 164 times per volume of gas as zipped gas, and the fact that gas hydrate occurs almost all around the world. Methane seepage may indicate the existence of a deeper hydrocarbon reservoir, and the methane production and migration in the slope sediments may cause massive slope failure. Last but not least Methane gas has a minimum 22 times more global warm absorption capacity compared to carbon dioxide if it is released into the atmosphere. In other words, greenhouse gas is due to its contribution to climate change. Gas hydrates have drawn significant interest as a potential near future energy resource. Research in the production field of gas hydrates has focused on several key areas, including the feasibility of commercial production, the environmental impacts, and the technological improvements associated with the safe recovery of gas.
