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Article Citation - WoS: 29Citation - Scopus: 36Development of Electrochemical Aptasensors Detecting Phosphate Ions on Tmb Substrate With Epoxy-Based Mesoporous Silica Nanoparticles(Pergamon-elsevier Science Ltd, 2022) Altuner, Elif Esra; Ozalp, Veli Cengiz; Yilmaz, M. Deniz; Sudagidan, Mert; Aygun, Aysenur; Acar, Elif Esma; Sen, FatihThis study, it is aimed to develop an electrochemical aptasensor that can detect phosphate ions using 3.3 & PRIME;5.5 & PRIME; tetramethylbenzidine (TMB). It is based on the principle of converting the binding affinity of the target molecule phosphate ion (PO43-) into an electrochemical signal with specific aptamer sequences for the aptasensor to be developed. The aptamer structure served as a gate for the TMB to be released and was used to trap the TMB molecule in mesoporous silica nanoparticles (MSNPs). The samples for this study were characterized by transmission electron spectroscopy (TEM), Brunner-Emmet-Teller, dynamic light scattering & electrophoretic light scattering, and induction coupled plasma atomic emission spectroscopy. According to TEM analysis, MSNPs have a morphologically hexagonal structure and an average size of 208 nm. In this study, palladium-carbon nano particles (Pd/C NPs) with catalytic reaction were used as an alternative to the biologically used horseradish peroxidase (HRP) enzyme for the release of TMB in the presence of phosphate ions. The limit of detection (LOD) was calculated as 0.983 mu M, the limit of determination (LOQ) was calculated as 3.276 mu M, and the dynamic linear phosphate range was found to be 50-1000 mu M. The most important advantage of this bio-based aptasensor assembly is that it does not contain molecules such as a protein that cannot be stored for a long time at room temperature, so its shelf life is very long compared to similar systems developed with antibodies. The proposed sensor shows good recovery in phosphate ion detection and is considered to have great potential among electrochemical sensors.Article Selection of DNA Aptamers Against Parathyroid Hormone for Electrochemical Impedimetric Biosensor System Development(John Wiley and Sons Inc, 2025) Didarian, Reza; Bargh, Saharnaz; Gulerman, Almina; Ozalp, Veli Cengiz; Erel, Ozcan; Yildirim-Tirgil, NimetThis work presents the pioneering development of an aptamer-based electrochemical biosensor for real-time monitoring of parathyroid hormone (PTH) levels, with a focus on intraoperative assessment during parathyroid surgery. It introduces, for the first time, the selection and characterization of aptamers targeting distinct segments of the PTH peptide. The study demonstrates the feasibility and efficacy of the biosensing platform through a precisely designed experimental framework, including SELEX-based aptamer selection, aptamer-peptide interaction analysis, and biosensor fabrication. The SELEX process yields aptamers with notable binding affinities to different fragments of PTH, with the PTH (53-84) aptamer showing particularly sensitive binding to the hormone's C terminus, allowing for precise PTH analysis. Electrochemical characterization reveals significant changes in electrochemical impedance spectroscopy (EIS) signals upon exposure to varying PTH concentrations, highlighting the sensor's sensitivity and selectivity. The increase in charge transfer resistance (Rct) values with rising PTH concentrations underscores the biosensor's capability to detect PTH-induced structural changes, validating its potential for accurate measurement. The biosensor shows remarkable selectivity in the presence of common interferents in serum samples, ensuring precise PTH detection. Stability assessments over a 45-day storage period demonstrate the biosensor's robustness and long-term reliability, affirming its practical suitability. In summary, the developed aptamer-based biosensor represents a promising tool for sensitive and selective PTH detection, with potential applications in biomedical research and clinical diagnostics, particularly for intraoperative PTH analysis during parathyroidectomy. Continued research and optimization efforts hold promise for enhancing its performance and expanding its utility in diverse healthcare settings.Article Development and In-Vitro Evaluation of Gallium-68 Labelled Staphylococcus Aureus-Specific Aptamer as a Potential PET Agent for Infection Imaging(Novin Medical Radiation Institute, 2025) Bargh, S.; Özkul, C.; Timur, S.S.; Ozalp, V.C.; Erdoǧan, S.Background: Staphylococcus aureus (S. aureus) is the most common causative pathogen associated with a wide range of infections, from mild to life-threatening conditions such as osteomyelitis, endocarditis, and pneumonia. Early detection and reliable differentiation between infection and sterile inflammation are essential for accurate diagnosis and effective treatment. However, most radiopharmaceuticals currently available fail to discriminate between these conditions, underscoring the need for infection-specific imaging agents. Materials and Methods: In this study, a Gallium-68 (Ga-68)-labeled S. aureus-specific aptamer was developed as a potential PET infection imaging probe. Aptamers were selected using the cell-systematic evolution of ligands by exponential enrichment (SELEX) method, and their specificity was verified by fluorescence-based binding assays. Radiolabeling was achieved via DOTA chelation, and radiochemical purity was determined. Additionally, in vitro binding assays were performed with S. aureus, while Escherichia coli (E. coli) served as a control. Results: The aptamer exhibited an affinity constant (Kₐ) of 2260 ± 634 CFU/ mL and a linear detection range of 250-2×10⁴ CFU/mL, with a limit of detection of 171 CFU/mL for S. aureus. The Ga-68-labeled aptamer demonstrated radiochemical purity greater than 99%. In vitro binding increased linearly with rising S. aureus concentrations (10³-2×10⁴ CFU/mL), while minimal binding to E. coli confirmed its specificity. Conclusion: These results demonstrate that the Ga-68-labeled S. aureus-specific aptamer holds promise as an infection-targeted PET imaging agent. Although currently limited to in vitro evaluation, such aptamer-based radiopharmaceuticals may contribute to improved diagnosis and imaging of infectious diseases. © 2025, Novin Medical Radiation Institute. All rights reserved.
