2025
Aslan, Busra Canan; Ekiz, Esra; Tayyarcan, Emine Kubra; Boyaci, Ismail Hakki; Gumustas, Aysen; Yildirim, Ender; Tamer, Ugur; Evren, Ebru; Ahi, Elcin Ezgi; Martínez-Máñez, Ramón; Caglayan, Mehmet Gokhan
Bacteriophage-Gated Optical Sensor for Bacteria Detection Journal Article
In: Anal Chem, vol. 97, no. 25, pp. 13103–13109, 2025, ISSN: 1520-6882.
@article{pmid40408168,
title = {Bacteriophage-Gated Optical Sensor for Bacteria Detection},
author = {Busra Canan Aslan and Esra Ekiz and Emine Kubra Tayyarcan and Ismail Hakki Boyaci and Aysen Gumustas and Ender Yildirim and Ugur Tamer and Ebru Evren and Elcin Ezgi Ahi and Ramón Martínez-Máñez and Mehmet Gokhan Caglayan},
doi = {10.1021/acs.analchem.5c00780},
issn = {1520-6882},
year = {2025},
date = {2025-07-01},
journal = {Anal Chem},
volume = {97},
number = {25},
pages = {13103--13109},
abstract = {Bacterial infections significantly impact public health, and the growing threat of antimicrobial resistance underscores the urgent need for rapid and accessible diagnostic tools. This study presents a novel bacteriophage-gated sensor for the selective detection of . The sensor utilizes sulforhodamine B as a fluorescent reporter dye encapsulated in mesoporous silica particles, with bacteriophages acting as gatekeepers. Upon interaction with , the bacteriophages detach from the silica surface, releasing the dye and producing a measurable fluorescence signal. The sensor demonstrated high sensitivity for detection, with a detection limit of 10 CFU/mL achieved within 5 min. Integrated into a Point-of-Care Testing device, the system aligns with ASSURED criteria, offering affordability, sensitivity, specificity, and ease of use. The fluorescence response is detectable even by the naked eye using a simple LED lamp, enabling nonprofessional operation. Validation with real water samples confirmed the sensor's accuracy, with results consistent with standard culture-based methods. This bacteriophage-gated sensor provides a low-cost, rapid, and reliable tool for bacterial detection with potential applications in environmental monitoring and clinical diagnostics.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Bacterial infections significantly impact public health, and the growing threat of antimicrobial resistance underscores the urgent need for rapid and accessible diagnostic tools. This study presents a novel bacteriophage-gated sensor for the selective detection of . The sensor utilizes sulforhodamine B as a fluorescent reporter dye encapsulated in mesoporous silica particles, with bacteriophages acting as gatekeepers. Upon interaction with , the bacteriophages detach from the silica surface, releasing the dye and producing a measurable fluorescence signal. The sensor demonstrated high sensitivity for detection, with a detection limit of 10 CFU/mL achieved within 5 min. Integrated into a Point-of-Care Testing device, the system aligns with ASSURED criteria, offering affordability, sensitivity, specificity, and ease of use. The fluorescence response is detectable even by the naked eye using a simple LED lamp, enabling nonprofessional operation. Validation with real water samples confirmed the sensor’s accuracy, with results consistent with standard culture-based methods. This bacteriophage-gated sensor provides a low-cost, rapid, and reliable tool for bacterial detection with potential applications in environmental monitoring and clinical diagnostics.
Isik, Melis; Sari, Hatice Kubra; Caglayan, Mehmet Gokhan; Yilmaz, Rezzak; Derkus, Burak
Whispers in the Brain: Extracellular Vesicles in Neuropathology and the Diagnostic Alchemy of Neurological Diseases Journal Article
In: Eur J Neurosci, vol. 61, no. 8, pp. e70090, 2025, ISSN: 1460-9568.
@article{pmid40237381,
title = {Whispers in the Brain: Extracellular Vesicles in Neuropathology and the Diagnostic Alchemy of Neurological Diseases},
author = {Melis Isik and Hatice Kubra Sari and Mehmet Gokhan Caglayan and Rezzak Yilmaz and Burak Derkus},
doi = {10.1111/ejn.70090},
issn = {1460-9568},
year = {2025},
date = {2025-04-01},
journal = {Eur J Neurosci},
volume = {61},
number = {8},
pages = {e70090},
abstract = {Extracellular vesicles (EVs) have emerged as pivotal mediators in neurological diseases, showcasing multifaceted potential roles ranging from pathogenesis to diagnosis. These nano-sized membranous structures, released by various cell types including neurons, astrocytes, and microglia, encapsulate a diverse cargo of proteins, lipids, RNA species, and even DNA fragments. In neuropathology, EVs contribute significantly to intercellular communication within the central nervous system (CNS), influencing physiological or pathological cascades. Through the transfer of bioactive molecules, EVs modulate neuroinflammation, neuronal survival, synaptic plasticity, and the propagation of protein aggregates characteristic of neurodegenerative disorders. Moreover, their presence in biofluids such as cerebrospinal fluid (CSF), blood, and urine reflects the pathophysiological state of the CNS, offering a window into the diagnosis, monitoring and treatment of neurological diseases. Recent advancements in EV isolation techniques, coupled with high-throughput omics technologies, have facilitated the profiling of EV cargo, enabling the identification of disease-specific biomarkers with high sensitivity and specificity. This review explores the intricate roles of EVs in neuropathology, highlighting their involvement in Alzheimer's disease, Parkinson's disease, multiple sclerosis, and other neurological disorders. Furthermore, it delves into the diagnostic potential of EVs, discussing current challenges and prospects in harnessing EV-derived biomarkers for precision medicine in neurology. Ultimately, understanding the biology of EVs in neurological contexts promises transformative insights into disease mechanisms and therapeutic strategies, paving the way for innovative diagnostic tools and targeted interventions in clinical practice.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Extracellular vesicles (EVs) have emerged as pivotal mediators in neurological diseases, showcasing multifaceted potential roles ranging from pathogenesis to diagnosis. These nano-sized membranous structures, released by various cell types including neurons, astrocytes, and microglia, encapsulate a diverse cargo of proteins, lipids, RNA species, and even DNA fragments. In neuropathology, EVs contribute significantly to intercellular communication within the central nervous system (CNS), influencing physiological or pathological cascades. Through the transfer of bioactive molecules, EVs modulate neuroinflammation, neuronal survival, synaptic plasticity, and the propagation of protein aggregates characteristic of neurodegenerative disorders. Moreover, their presence in biofluids such as cerebrospinal fluid (CSF), blood, and urine reflects the pathophysiological state of the CNS, offering a window into the diagnosis, monitoring and treatment of neurological diseases. Recent advancements in EV isolation techniques, coupled with high-throughput omics technologies, have facilitated the profiling of EV cargo, enabling the identification of disease-specific biomarkers with high sensitivity and specificity. This review explores the intricate roles of EVs in neuropathology, highlighting their involvement in Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, and other neurological disorders. Furthermore, it delves into the diagnostic potential of EVs, discussing current challenges and prospects in harnessing EV-derived biomarkers for precision medicine in neurology. Ultimately, understanding the biology of EVs in neurological contexts promises transformative insights into disease mechanisms and therapeutic strategies, paving the way for innovative diagnostic tools and targeted interventions in clinical practice.
2023
Ozkasapoglu, Sezgin; Caglayan, Mehmet Gokhan; Akkurt, Fatih; Ensarioğlu, Hilal Kabadayi; Vatansever, H Seda; Celikkan, Huseyin
Boron-Doped Carbon Nanodots as a Theranostic Agent for Colon Cancer Stem Cells Journal Article
In: ACS Omega, vol. 8, no. 33, pp. 30285–30293, 2023, ISSN: 2470-1343.
@article{pmid37636927,
title = {Boron-Doped Carbon Nanodots as a Theranostic Agent for Colon Cancer Stem Cells},
author = {Sezgin Ozkasapoglu and Mehmet Gokhan Caglayan and Fatih Akkurt and Hilal Kabadayi Ensarioğlu and H Seda Vatansever and Huseyin Celikkan},
doi = {10.1021/acsomega.3c03154},
issn = {2470-1343},
year = {2023},
date = {2023-08-01},
journal = {ACS Omega},
volume = {8},
number = {33},
pages = {30285--30293},
abstract = {Carbon nanodots have drawn a great deal of attention due to their green and expedient opportunities in biological and chemical sciences. Their high fluorescence capabilities and low toxicity for living cells and tissues make them excellent imaging agents. In addition, they have a fluorimetric response against inorganic and organic species. Boron-doped carbon nanodots (B-CDs) with high fluorescence yield were produced from phenylboronic acid and glutamine as boron and carbon sources, respectively, by a hydrothermal method. First, the effects of the temperature on their fluorescence yield and the structural characteristics of B-CDs were investigated. Second, their cytotoxicity and cell death and proliferation behaviors were examined. The cytotoxicity was evaluated by the MTT assay. The cellular properties were evaluated with the distribution of caspase 3, Ki67, lamin B1, P16, and cytochrome after the indirect immunoperoxidase technique. After the MTT assay, 1:1 dilution of all applicants for 24 h was used in the study. After immunohistochemical analyses, the application of B-CDs synthesized at 230 °C did not change control cell (Vero) proliferation, and also apoptosis was not triggered. Colo 320 CD133+ and CD133- cell-triggered apoptosis and cellular senescence were found to be synthesis temperature dependent. In addition, Colo 320 CD133- cells were affected relatively more than CD133+ cells from B-CDs. While B-CDs did not affect the control cells, the colon cancer stem cells (Colo 320 CD133+) were affected in a time-dependent manner. Therefore, the use of the synthesized B-CD product may be an alternative method for controlling or eliminating cancer stem cells in the tumor tissue.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Carbon nanodots have drawn a great deal of attention due to their green and expedient opportunities in biological and chemical sciences. Their high fluorescence capabilities and low toxicity for living cells and tissues make them excellent imaging agents. In addition, they have a fluorimetric response against inorganic and organic species. Boron-doped carbon nanodots (B-CDs) with high fluorescence yield were produced from phenylboronic acid and glutamine as boron and carbon sources, respectively, by a hydrothermal method. First, the effects of the temperature on their fluorescence yield and the structural characteristics of B-CDs were investigated. Second, their cytotoxicity and cell death and proliferation behaviors were examined. The cytotoxicity was evaluated by the MTT assay. The cellular properties were evaluated with the distribution of caspase 3, Ki67, lamin B1, P16, and cytochrome after the indirect immunoperoxidase technique. After the MTT assay, 1:1 dilution of all applicants for 24 h was used in the study. After immunohistochemical analyses, the application of B-CDs synthesized at 230 °C did not change control cell (Vero) proliferation, and also apoptosis was not triggered. Colo 320 CD133+ and CD133- cell-triggered apoptosis and cellular senescence were found to be synthesis temperature dependent. In addition, Colo 320 CD133- cells were affected relatively more than CD133+ cells from B-CDs. While B-CDs did not affect the control cells, the colon cancer stem cells (Colo 320 CD133+) were affected in a time-dependent manner. Therefore, the use of the synthesized B-CD product may be an alternative method for controlling or eliminating cancer stem cells in the tumor tissue.
2022
Bilge, Selva; Topal, Burcu Dogan; Caglayan, Mehmet Gokhan; Unal, Mehmet Altay; Nazır, Hasan; Atici, Esen Bellur; Sınağ, Ali; Ozkan, Sibel A
Human hair rich in pyridinic nitrogen-base DNA biosensor for direct electrochemical monitoring of palbociclib-DNA interaction Journal Article
In: Bioelectrochemistry, vol. 148, pp. 108264, 2022, ISSN: 1878-562X.
@article{pmid36122426,
title = {Human hair rich in pyridinic nitrogen-base DNA biosensor for direct electrochemical monitoring of palbociclib-DNA interaction},
author = {Selva Bilge and Burcu Dogan Topal and Mehmet Gokhan Caglayan and Mehmet Altay Unal and Hasan Nazır and Esen Bellur Atici and Ali Sınağ and Sibel A Ozkan},
doi = {10.1016/j.bioelechem.2022.108264},
issn = {1878-562X},
year = {2022},
date = {2022-12-01},
journal = {Bioelectrochemistry},
volume = {148},
pages = {108264},
abstract = {Carbon material derived from the waste-based biomass human hair (H), which is naturally rich in pyridinic nitrogen, provides a significant benefit in biosensor applications with its dominant conductivity character. The carbon material was synthesized from human hair waste by the hydrothermal carbonization (HTC) method, which is a promising green synthesis. A morphological characterization of the carbon materials was performed. In this study, H and amine-functionalized multi-walled carbon nanotubes (NH-MWCNT) were combined for the first time as a modifier, which enhanced the glassy carbon electrode (GCE) surface area for deoxyribonucleic acid (DNA) biosensor studies. Palbociclib (PLB) is clinically used in the treatment of breast cancer. The novel electrochemical nanobiosensor was used to investigate the dsDNA-PLB interaction to evaluate the possibility that PLB causes conformational changes in DNA structure and/or oxidative damage. The interaction was conducted based on the voltammetric signals of deoxyguanosine (dGuo) and deoxyadenosine (dAdo) by differential pulse voltammetry (DPV) on a bare and H + NH-MWCNT modified GCE. The proposed analytical method was applied to a pharmaceutical dosage form with a satisfactory recovery of 98.25 %. The nanobiosensor was tested in the presence of some interfering agents. The binding mechanism of dsDNA-PLB was also evaluated by spectroscopic and theoretical calculations.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Carbon material derived from the waste-based biomass human hair (H), which is naturally rich in pyridinic nitrogen, provides a significant benefit in biosensor applications with its dominant conductivity character. The carbon material was synthesized from human hair waste by the hydrothermal carbonization (HTC) method, which is a promising green synthesis. A morphological characterization of the carbon materials was performed. In this study, H and amine-functionalized multi-walled carbon nanotubes (NH-MWCNT) were combined for the first time as a modifier, which enhanced the glassy carbon electrode (GCE) surface area for deoxyribonucleic acid (DNA) biosensor studies. Palbociclib (PLB) is clinically used in the treatment of breast cancer. The novel electrochemical nanobiosensor was used to investigate the dsDNA-PLB interaction to evaluate the possibility that PLB causes conformational changes in DNA structure and/or oxidative damage. The interaction was conducted based on the voltammetric signals of deoxyguanosine (dGuo) and deoxyadenosine (dAdo) by differential pulse voltammetry (DPV) on a bare and H + NH-MWCNT modified GCE. The proposed analytical method was applied to a pharmaceutical dosage form with a satisfactory recovery of 98.25 %. The nanobiosensor was tested in the presence of some interfering agents. The binding mechanism of dsDNA-PLB was also evaluated by spectroscopic and theoretical calculations.
Kaya, S Irem; Cetinkaya, Ahmet; Caglayan, Mehmet G; Ozkan, Sibel A
Recent biopharmaceutical applications of capillary electrophoresis methods on recombinant DNA technology-based products Journal Article
In: Electrophoresis, vol. 43, no. 9-10, pp. 1035–1049, 2022, ISSN: 1522-2683.
@article{pmid34529858,
title = {Recent biopharmaceutical applications of capillary electrophoresis methods on recombinant DNA technology-based products},
author = {S Irem Kaya and Ahmet Cetinkaya and Mehmet G Caglayan and Sibel A Ozkan},
doi = {10.1002/elps.202100193},
issn = {1522-2683},
year = {2022},
date = {2022-05-01},
journal = {Electrophoresis},
volume = {43},
number = {9-10},
pages = {1035--1049},
abstract = {Biopharmaceuticals (recombinant technology-based products, vaccines, whole blood and blood components, gene therapy, cells, tissues, etc.,) are described as biological medical products produced from various living sources such as human, microbial, animal, and so on by manufacturing, extraction, or semi-synthesis. They are complex molecules having high molecular weights. For their safety and efficacy, their structural, clinical, physicochemical, and chemical features must be carefully controlled, and they must be well characterized by analytical techniques before the approval of the final product. Capillary electrophoresis (CE) having versatile modes can provide valuable safety and efficacy information, such as amino acid sequence, size variants (low and high molecular weight variants), charged variants (acidic and basic impurities), aggregates, N-linked glycosylation, and O-linked glycosylation. There are numerous applications of CE in the literature. In this review, the most significant and recent studies on the analysis of recombinant DNA technology-based products using different CE modes in the last ten years have been overviewed. It was seen that the researches mostly focus on the analysis of mAbs and IgG. In addition, in recent years, researchers have started to prefer CE combined mass spectrometry (MS) techniques to provide a more detailed characterization for protein and peptide fragments.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Biopharmaceuticals (recombinant technology-based products, vaccines, whole blood and blood components, gene therapy, cells, tissues, etc.,) are described as biological medical products produced from various living sources such as human, microbial, animal, and so on by manufacturing, extraction, or semi-synthesis. They are complex molecules having high molecular weights. For their safety and efficacy, their structural, clinical, physicochemical, and chemical features must be carefully controlled, and they must be well characterized by analytical techniques before the approval of the final product. Capillary electrophoresis (CE) having versatile modes can provide valuable safety and efficacy information, such as amino acid sequence, size variants (low and high molecular weight variants), charged variants (acidic and basic impurities), aggregates, N-linked glycosylation, and O-linked glycosylation. There are numerous applications of CE in the literature. In this review, the most significant and recent studies on the analysis of recombinant DNA technology-based products using different CE modes in the last ten years have been overviewed. It was seen that the researches mostly focus on the analysis of mAbs and IgG. In addition, in recent years, researchers have started to prefer CE combined mass spectrometry (MS) techniques to provide a more detailed characterization for protein and peptide fragments.
2021
Ilhan, Hasan; Tayyarcan, Emine Kubra; Caglayan, Mehmet Gokhan; Boyaci, İsmail Hakki; Saglam, Necdet; Tamer, Ugur
Replacement of antibodies with bacteriophages in lateral flow assay of Salmonella Enteritidis Journal Article
In: Biosens Bioelectron, vol. 189, pp. 113383, 2021, ISSN: 1873-4235.
@article{pmid34087727,
title = {Replacement of antibodies with bacteriophages in lateral flow assay of Salmonella Enteritidis},
author = {Hasan Ilhan and Emine Kubra Tayyarcan and Mehmet Gokhan Caglayan and İsmail Hakki Boyaci and Necdet Saglam and Ugur Tamer},
doi = {10.1016/j.bios.2021.113383},
issn = {1873-4235},
year = {2021},
date = {2021-10-01},
journal = {Biosens Bioelectron},
volume = {189},
pages = {113383},
abstract = {In this study, the analytical performance of bacteriophages for Salmonella Enteritidis was investigated using lateral flow assay (LFA) technique. The analytical performance characteristics of bacteriophages were compared with antibodies which are regularly used as analyte-specific agents in the lateral flow immunoassay test strip. Bacteriophages could be an alternative analyte-specific agents to antibodies in lateral flow assay testing of bacteria since they offer comparable sensitivity, specificity, and accuracy. In the present study, Surface Enhanced Raman Spectroscopy (SERS) and colorimetric measurements were combined in one platform and sensitive quantitation of target bacteria was accomplished with a total quantitative analysis time of less than 30 min. The developed Salmonella Enteritidis F5-4 phage-based LFA specifically responds to Salmonella Enteritidis, while lower SERS responses to different bacteria types including Bacillus subtilis, Micrococcus luteus, Escherichia coli, Salmonella Typhimurium were observed. The developed test strips were also applied for the determination of Salmonella Enteritidis in spiked chicken and egg samples.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In this study, the analytical performance of bacteriophages for Salmonella Enteritidis was investigated using lateral flow assay (LFA) technique. The analytical performance characteristics of bacteriophages were compared with antibodies which are regularly used as analyte-specific agents in the lateral flow immunoassay test strip. Bacteriophages could be an alternative analyte-specific agents to antibodies in lateral flow assay testing of bacteria since they offer comparable sensitivity, specificity, and accuracy. In the present study, Surface Enhanced Raman Spectroscopy (SERS) and colorimetric measurements were combined in one platform and sensitive quantitation of target bacteria was accomplished with a total quantitative analysis time of less than 30 min. The developed Salmonella Enteritidis F5-4 phage-based LFA specifically responds to Salmonella Enteritidis, while lower SERS responses to different bacteria types including Bacillus subtilis, Micrococcus luteus, Escherichia coli, Salmonella Typhimurium were observed. The developed test strips were also applied for the determination of Salmonella Enteritidis in spiked chicken and egg samples.
2020
Mollarasouli, Fariba; Dogan-Topal, Burcu; Caglayan, Mehmet Gokhan; Taskin-Tok, Tugba; Ozkan, Sibel A
Electrochemical, spectroscopic, and molecular docking studies of the interaction between the anti-retroviral drug indinavir and dsDNA Journal Article
In: J Pharm Anal, vol. 10, no. 5, pp. 473–481, 2020, ISSN: 2214-0883.
@article{pmid33133731,
title = {Electrochemical, spectroscopic, and molecular docking studies of the interaction between the anti-retroviral drug indinavir and dsDNA},
author = {Fariba Mollarasouli and Burcu Dogan-Topal and Mehmet Gokhan Caglayan and Tugba Taskin-Tok and Sibel A Ozkan},
doi = {10.1016/j.jpha.2020.08.004},
issn = {2214-0883},
year = {2020},
date = {2020-10-01},
journal = {J Pharm Anal},
volume = {10},
number = {5},
pages = {473--481},
abstract = {In this study, an electrochemical DNA biosensor was developed using a straightforward methodology to investigate the interaction of indinavir with calf thymus double-stranded deoxyribonucleic acid (ct-dsDNA) for the first time. The decrease in the oxidation signals of deoxyguanosine (dGuo) and deoxyadenosine (dAdo), measured by differential pulse voltammetry, upon incubation with different concentrations of indinavir can be attributed to the binding mode of indinavir to ct-dsDNA. The currents of the dGuo and dAdo peaks decreased linearly with the concentration of indinavir in the range of 1.0-10.0 μg/mL. The limit of detection and limit of quantification for indinavir were 0.29 and 0.98 μg/mL, respectively, based on the dGuo signal, and 0.23 and 0.78 μg/mL, respectively, based on the dAdo signal. To gain further insights into the interaction mechanism between indinavir and ct-dsDNA, spectroscopic measurements and molecular docking simulations were performed. The binding constant (K) between indinavir and ct-dsDNA was calculated to be 1.64 × 10 M, based on spectrofluorometric measurements. The obtained results can offer insights into the inhibitory activity of indinavir, which could help to broaden its applications. That is, indinavir can be used to inhibit other mechanisms and/or hallmarks of viral diseases.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In this study, an electrochemical DNA biosensor was developed using a straightforward methodology to investigate the interaction of indinavir with calf thymus double-stranded deoxyribonucleic acid (ct-dsDNA) for the first time. The decrease in the oxidation signals of deoxyguanosine (dGuo) and deoxyadenosine (dAdo), measured by differential pulse voltammetry, upon incubation with different concentrations of indinavir can be attributed to the binding mode of indinavir to ct-dsDNA. The currents of the dGuo and dAdo peaks decreased linearly with the concentration of indinavir in the range of 1.0-10.0 μg/mL. The limit of detection and limit of quantification for indinavir were 0.29 and 0.98 μg/mL, respectively, based on the dGuo signal, and 0.23 and 0.78 μg/mL, respectively, based on the dAdo signal. To gain further insights into the interaction mechanism between indinavir and ct-dsDNA, spectroscopic measurements and molecular docking simulations were performed. The binding constant (K) between indinavir and ct-dsDNA was calculated to be 1.64 × 10 M, based on spectrofluorometric measurements. The obtained results can offer insights into the inhibitory activity of indinavir, which could help to broaden its applications. That is, indinavir can be used to inhibit other mechanisms and/or hallmarks of viral diseases.
Yalcin, Ergin; Erkmen, Cem; Taskin-Tok, Tugba; Caglayan, Mehmet Gokhan
Fluorescence chemosensing of meldonium using a cross-reactive sensor array Journal Article
In: Analyst, vol. 145, no. 9, pp. 3345–3352, 2020, ISSN: 1364-5528.
@article{pmid32226998,
title = {Fluorescence chemosensing of meldonium using a cross-reactive sensor array},
author = {Ergin Yalcin and Cem Erkmen and Tugba Taskin-Tok and Mehmet Gokhan Caglayan},
doi = {10.1039/d0an00209g},
issn = {1364-5528},
year = {2020},
date = {2020-05-01},
journal = {Analyst},
volume = {145},
number = {9},
pages = {3345--3352},
abstract = {In this paper, we report a fluorescent sensor array approach for the urinary detection of a prohibited substance in sports, meldonium. Four chemosensors with ethidium bromide scaffolds were employed in this method. The interaction between meldonium and chemosensors was investigated by different techniques, such as ultraviolet-visible absorption and fluorescence spectroscopy, nuclear magnetic resonance, and mass spectrometry. Molecular dynamics simulation was also used to elucidate and support the interaction mechanisms between meldonium and the chemosensors. Differential responses obtained from the sensor array enabled the qualitative and quantitative analyses of meldonium with low error values. This method was able to detect and quantify meldonium at the nM level, fulfilling the requirements of minimum performance defined by the World Anti-Doping Agency.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In this paper, we report a fluorescent sensor array approach for the urinary detection of a prohibited substance in sports, meldonium. Four chemosensors with ethidium bromide scaffolds were employed in this method. The interaction between meldonium and chemosensors was investigated by different techniques, such as ultraviolet-visible absorption and fluorescence spectroscopy, nuclear magnetic resonance, and mass spectrometry. Molecular dynamics simulation was also used to elucidate and support the interaction mechanisms between meldonium and the chemosensors. Differential responses obtained from the sensor array enabled the qualitative and quantitative analyses of meldonium with low error values. This method was able to detect and quantify meldonium at the nM level, fulfilling the requirements of minimum performance defined by the World Anti-Doping Agency.
2019
Shahzad, Suniya; Dogan-Topal, Burcu; Karadurmus, Leyla; Caglayan, Mehmet Gokhan; Tok, Tuğba Taskin; Uslu, Bengi; Shah, Afzal; Ozkan, Sibel A
Electrochemical, spectroscopic and molecular docking studies on the interaction of calcium channel blockers with dsDNA Journal Article
In: Bioelectrochemistry, vol. 127, pp. 12–20, 2019, ISSN: 1878-562X.
@article{pmid30623791,
title = {Electrochemical, spectroscopic and molecular docking studies on the interaction of calcium channel blockers with dsDNA},
author = {Suniya Shahzad and Burcu Dogan-Topal and Leyla Karadurmus and Mehmet Gokhan Caglayan and Tuğba Taskin Tok and Bengi Uslu and Afzal Shah and Sibel A Ozkan},
doi = {10.1016/j.bioelechem.2018.12.007},
issn = {1878-562X},
year = {2019},
date = {2019-06-01},
journal = {Bioelectrochemistry},
volume = {127},
pages = {12--20},
abstract = {This study presents evaluation of the possible interaction mechanism between calf thymus dsDNA and three calcium antagonists; nifedipine, lercanidipine and amlodipine. The interactions between Nifedipine-dsDNA and Lercanidipine-dsDNA were investigated by differential pulse voltammetry using two different interaction methods; at the dsDNA-electrochemical biosensor surface and in bulk incubated solution. Amlodipine was used as model drug in bulk incubated solution. The decrease in the peak current of guanine and adenine were used as an indicator for confirmation of the interaction event in acetate buffer of pH 4.70. In bulk incubated solution, after interaction with Nifedipine and Amlodipine the guanine signal was almost disappeared. At the dsDNA modified glassy carbon electrode surface, the peak currents of guanine and adenine were decreased while Nifedipine and Lercanidipine interacts with DNA. The interactions between Nifedipine-dsDNA and Lercanidipine-dsDNA were further studied by UV-Vis absorption spectroscopy which indicates the intermolecular interaction between these drugs and ds-DNA can be mainly through hydrogen bonding and van der Waals forces. Molecular docking calculations shown that the AMP-1-2, NDP and LDP-1-2-ctDNA having groove binding. Beside spectral data, docking studies elicited that AMP-1-2, NDP and LDP-1-2 complexes have different interaction and conformation trends to target (ctDNA).},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
This study presents evaluation of the possible interaction mechanism between calf thymus dsDNA and three calcium antagonists; nifedipine, lercanidipine and amlodipine. The interactions between Nifedipine-dsDNA and Lercanidipine-dsDNA were investigated by differential pulse voltammetry using two different interaction methods; at the dsDNA-electrochemical biosensor surface and in bulk incubated solution. Amlodipine was used as model drug in bulk incubated solution. The decrease in the peak current of guanine and adenine were used as an indicator for confirmation of the interaction event in acetate buffer of pH 4.70. In bulk incubated solution, after interaction with Nifedipine and Amlodipine the guanine signal was almost disappeared. At the dsDNA modified glassy carbon electrode surface, the peak currents of guanine and adenine were decreased while Nifedipine and Lercanidipine interacts with DNA. The interactions between Nifedipine-dsDNA and Lercanidipine-dsDNA were further studied by UV-Vis absorption spectroscopy which indicates the intermolecular interaction between these drugs and ds-DNA can be mainly through hydrogen bonding and van der Waals forces. Molecular docking calculations shown that the AMP-1-2, NDP and LDP-1-2-ctDNA having groove binding. Beside spectral data, docking studies elicited that AMP-1-2, NDP and LDP-1-2 complexes have different interaction and conformation trends to target (ctDNA).
2018
Gumustas, Mehmet; Caglayan, Mehmet Gokhan; Onur, Feyyaz; Ozkan, Sibel A
Simultaneous determination and validation of emtricitabine, rilpivirine and tenofovir from biological samples using LC and CE methods Journal Article
In: Biomed Chromatogr, vol. 32, no. 4, 2018, ISSN: 1099-0801.
@article{pmid29216682,
title = {Simultaneous determination and validation of emtricitabine, rilpivirine and tenofovir from biological samples using LC and CE methods},
author = {Mehmet Gumustas and Mehmet Gokhan Caglayan and Feyyaz Onur and Sibel A Ozkan},
doi = {10.1002/bmc.4158},
issn = {1099-0801},
year = {2018},
date = {2018-04-01},
journal = {Biomed Chromatogr},
volume = {32},
number = {4},
abstract = {A combination of antiretroviral agents is frequently used in effective treatment of the human immunodeficiency virus infection. In this study, two different separation methods are presented for the simultaneous determination of emtricitabine, rilpivirine and tenofovir from raw materials and urine samples. Developed liquid chromatography and capillary electrophoresis methods were thoroughly optimized for high analytical performances. Optimization of multiple variables at the same time by performing a minimum number of experiments was achieved by the Box-Behnken design, which is an experimental design in response surface methodology, in capillary electrophoresis. The results of the experimental design ensure minimum analysis time with well-separated analytes. Separation conditions, such as different stationary phases, pH level, organic modifiers and temperatures in liquid chromatography method, were also optimized. In particular, among stationary phases, the core-shell column especially enhanced the effectiveness of separation in liquid chromatography. Both methods were fully validated and applied to real samples. The main advantage of the developed methods is the separation of the drug combination in a short time with high efficiency and without any time-consuming steps.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A combination of antiretroviral agents is frequently used in effective treatment of the human immunodeficiency virus infection. In this study, two different separation methods are presented for the simultaneous determination of emtricitabine, rilpivirine and tenofovir from raw materials and urine samples. Developed liquid chromatography and capillary electrophoresis methods were thoroughly optimized for high analytical performances. Optimization of multiple variables at the same time by performing a minimum number of experiments was achieved by the Box-Behnken design, which is an experimental design in response surface methodology, in capillary electrophoresis. The results of the experimental design ensure minimum analysis time with well-separated analytes. Separation conditions, such as different stationary phases, pH level, organic modifiers and temperatures in liquid chromatography method, were also optimized. In particular, among stationary phases, the core-shell column especially enhanced the effectiveness of separation in liquid chromatography. Both methods were fully validated and applied to real samples. The main advantage of the developed methods is the separation of the drug combination in a short time with high efficiency and without any time-consuming steps.
2017
Bakar, Filiz; Kilic-Kurt, Zuhal; Caglayan, Mehmet Gokhan; Olgen, Sureyya
The Effects of 1,3,5-trisubstituted Indole Derivatives on Cell Growth, Apoptosis and MMP-2/9 mRNA Expression of MCF-7 Human Breast Cancer Cells Journal Article
In: Anticancer Agents Med Chem, vol. 17, no. 5, pp. 762–767, 2017, ISSN: 1875-5992.
@article{pmid27491936,
title = {The Effects of 1,3,5-trisubstituted Indole Derivatives on Cell Growth, Apoptosis and MMP-2/9 mRNA Expression of MCF-7 Human Breast Cancer Cells},
author = {Filiz Bakar and Zuhal Kilic-Kurt and Mehmet Gokhan Caglayan and Sureyya Olgen},
doi = {10.2174/1871520616666160802115737},
issn = {1875-5992},
year = {2017},
date = {2017-01-01},
journal = {Anticancer Agents Med Chem},
volume = {17},
number = {5},
pages = {762--767},
abstract = {BACKGROUND: Matrix metalloproteinases are known as extracellular matrix degrading enzymes and have important role on tumor progression.nnOBJECTIVE: This study reports the effects of 1,3,5-trisubstituted indole derivatives on cytotoxicity, apoptosis and MMP- 2/MMP-9 mRNA expression of MCF-7 human breast carcinoma cells.nnMETHOD: The cytotoxic effects of the compounds on MCF-7 cells were performed by MTT test, and cell proliferation was determined via BrdU incorporation. The apoptotic effects were observed by cell death detection elisa. The effects of the compounds on MMP-2/-9 enzyme activity and mRNA expression were also performed.nnRESULTS: The compounds inhibited the proliferation of MCF-7 breast carcinoma cells significantly in a dose dependent manner. All compounds were able to induce DNA fragmentation, especially compound 1. The IC50 values of compound 2 and 4 for MMP-2 were 0.42 μM and 1.88 μM, respectively. MMP-2 mRNA expression results were correlated with the inhibition of enzyme activity, such compound 4 inhibited MMP-2 mRNA expression at all treated concentrations. Docking simulation has also been performed to analyze the binding mode of compounds and the results showed that compound 2, the most active compound, formed a hydrogen bond with Glu202 for binding to the MMP-2 active site. In addition, the hydrophobic parts of compound 2 are in contact with nonpolar surface areas of MMP-2, such as His201, His211, Tyr223 and Tyr193.nnCONCLUSION: According to the molecular docking results along with the biological assay data, it is suggested that compound 2 might be used for further design and development of MMP-2 inhibitors.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
BACKGROUND: Matrix metalloproteinases are known as extracellular matrix degrading enzymes and have important role on tumor progression.nnOBJECTIVE: This study reports the effects of 1,3,5-trisubstituted indole derivatives on cytotoxicity, apoptosis and MMP- 2/MMP-9 mRNA expression of MCF-7 human breast carcinoma cells.nnMETHOD: The cytotoxic effects of the compounds on MCF-7 cells were performed by MTT test, and cell proliferation was determined via BrdU incorporation. The apoptotic effects were observed by cell death detection elisa. The effects of the compounds on MMP-2/-9 enzyme activity and mRNA expression were also performed.nnRESULTS: The compounds inhibited the proliferation of MCF-7 breast carcinoma cells significantly in a dose dependent manner. All compounds were able to induce DNA fragmentation, especially compound 1. The IC50 values of compound 2 and 4 for MMP-2 were 0.42 μM and 1.88 μM, respectively. MMP-2 mRNA expression results were correlated with the inhibition of enzyme activity, such compound 4 inhibited MMP-2 mRNA expression at all treated concentrations. Docking simulation has also been performed to analyze the binding mode of compounds and the results showed that compound 2, the most active compound, formed a hydrogen bond with Glu202 for binding to the MMP-2 active site. In addition, the hydrophobic parts of compound 2 are in contact with nonpolar surface areas of MMP-2, such as His201, His211, Tyr223 and Tyr193.nnCONCLUSION: According to the molecular docking results along with the biological assay data, it is suggested that compound 2 might be used for further design and development of MMP-2 inhibitors.
2016
Selbes, Yesim Somay; Caglayan, Mehmet Gokhan; Eryilmaz, Merve; Boyaci, Ismail Hakki; Saglam, Necdet; Basaran, Arif Ahmet; Tamer, Ugur
Surface-enhanced Raman probe for rapid nanoextraction and detection of erythropoietin in urine Journal Article
In: Anal Bioanal Chem, vol. 408, no. 29, pp. 8447–8456, 2016, ISSN: 1618-2650.
@article{pmid27722945,
title = {Surface-enhanced Raman probe for rapid nanoextraction and detection of erythropoietin in urine},
author = {Yesim Somay Selbes and Mehmet Gokhan Caglayan and Merve Eryilmaz and Ismail Hakki Boyaci and Necdet Saglam and Arif Ahmet Basaran and Ugur Tamer},
doi = {10.1007/s00216-016-9966-1},
issn = {1618-2650},
year = {2016},
date = {2016-11-01},
journal = {Anal Bioanal Chem},
volume = {408},
number = {29},
pages = {8447--8456},
abstract = {We present a surface-enhanced Raman probe (SERS) platform for the determination of a prohibited substance, recombinant erythropoietin (rEPO), in urine matrix, using nanoparticles as substrate. Rod-shaped gold nanoparticles (GNR) were modified with a Raman label and an antibody as SERS probe. We developed two SERS-based immunoassays for detection and quantification of rEPO in urine. In the first assay, rEPO was determined by a sandwich assay with gold surfaces and GNR. In the second assay, rEPO was extracted by using core shell-structured magnetic iron oxide gold nanoparticles, and again sandwich assay was performed by using GNR. We also demonstrated the ability of the proposed method to discriminate rEPO and urinary erythropoietin (uEPO). A good linear correlation was obtained between logarithms of rEPO concentrations in urine and Raman intensities within the range of 10-10 pg mL rEPO concentrations. Detection limits which are smaller than 0.1 pg mL levels were achieved owing to the high extractive performance of the nanoextraction techniques. Graphical Abstract Schematic represantation of surface-enhanced Raman probe for rapid nanoextraction and detection of erythropoietin.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We present a surface-enhanced Raman probe (SERS) platform for the determination of a prohibited substance, recombinant erythropoietin (rEPO), in urine matrix, using nanoparticles as substrate. Rod-shaped gold nanoparticles (GNR) were modified with a Raman label and an antibody as SERS probe. We developed two SERS-based immunoassays for detection and quantification of rEPO in urine. In the first assay, rEPO was determined by a sandwich assay with gold surfaces and GNR. In the second assay, rEPO was extracted by using core shell-structured magnetic iron oxide gold nanoparticles, and again sandwich assay was performed by using GNR. We also demonstrated the ability of the proposed method to discriminate rEPO and urinary erythropoietin (uEPO). A good linear correlation was obtained between logarithms of rEPO concentrations in urine and Raman intensities within the range of 10-10 pg mL rEPO concentrations. Detection limits which are smaller than 0.1 pg mL levels were achieved owing to the high extractive performance of the nanoextraction techniques. Graphical Abstract Schematic represantation of surface-enhanced Raman probe for rapid nanoextraction and detection of erythropoietin.
Akdeniz, Ali; Caglayan, Mehmet Gokhan; Polivina, Irina; Anzenbacher, Pavel
Detection and quantification of ATP in human blood serum Journal Article
In: Org Biomol Chem, vol. 14, no. 31, pp. 7459–7462, 2016, ISSN: 1477-0539.
@article{pmid27454442,
title = {Detection and quantification of ATP in human blood serum},
author = {Ali Akdeniz and Mehmet Gokhan Caglayan and Irina Polivina and Pavel Anzenbacher},
doi = {10.1039/c6ob01378c},
issn = {1477-0539},
year = {2016},
date = {2016-08-01},
journal = {Org Biomol Chem},
volume = {14},
number = {31},
pages = {7459--7462},
abstract = {Two fluorometric sensors based on the tri-serine tri-lactone scaffold and thiourea or sulfonamide moieties serving as hydrogen bond donors allowing for anion binding are described. The sensor utilizing thiourea as a recognition moiety shows fluorescence enhancement while the sensor with sulfonamide shows quenching upon addition of phosphates. Sensor arrays composed of two sensors are able to discriminate structurally similar organic phosphates in the presence of interferents in human blood serum. The quantitative analysis of ATP in human blood serum shows high accuracy (the root mean square error of prediction, 1.65%) without requiring any sample pretreatment.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Two fluorometric sensors based on the tri-serine tri-lactone scaffold and thiourea or sulfonamide moieties serving as hydrogen bond donors allowing for anion binding are described. The sensor utilizing thiourea as a recognition moiety shows fluorescence enhancement while the sensor with sulfonamide shows quenching upon addition of phosphates. Sensor arrays composed of two sensors are able to discriminate structurally similar organic phosphates in the presence of interferents in human blood serum. The quantitative analysis of ATP in human blood serum shows high accuracy (the root mean square error of prediction, 1.65%) without requiring any sample pretreatment.
Caglayan, Mehmet Gokhan; Sheykhi, Sara; Mosca, Lorenzo; Anzenbacher, Pavel
Fluorescent zinc and copper complexes for detection of adrafinil in paper-based microfluidic devices Journal Article
In: Chem Commun (Camb), vol. 52, no. 53, pp. 8279–8282, 2016, ISSN: 1364-548X.
@article{pmid27293080,
title = {Fluorescent zinc and copper complexes for detection of adrafinil in paper-based microfluidic devices},
author = {Mehmet Gokhan Caglayan and Sara Sheykhi and Lorenzo Mosca and Pavel Anzenbacher},
doi = {10.1039/c6cc03640f},
issn = {1364-548X},
year = {2016},
date = {2016-07-01},
journal = {Chem Commun (Camb)},
volume = {52},
number = {53},
pages = {8279--8282},
abstract = {Recognition of electroneutral Lewis bases and anions in aqueous media is extremely difficult. We show that fluorescent coordinatively unsaturated metal complexes can recognize various Lewis bases while providing an easy-to-detect fluorescence response. This approach is applied to the detection of adrafinil, a banned performance-enhancing drug.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Recognition of electroneutral Lewis bases and anions in aqueous media is extremely difficult. We show that fluorescent coordinatively unsaturated metal complexes can recognize various Lewis bases while providing an easy-to-detect fluorescence response. This approach is applied to the detection of adrafinil, a banned performance-enhancing drug.
Akdeniz, Ali; Caglayan, Mehmet Gokhan; Anzenbacher, Pavel
A tri-serine tri-lactone scaffold for the quantification of citrate in urine Journal Article
In: Chem Commun (Camb), vol. 52, no. 9, pp. 1827–1830, 2016, ISSN: 1364-548X.
@article{pmid26669653,
title = {A tri-serine tri-lactone scaffold for the quantification of citrate in urine},
author = {Ali Akdeniz and Mehmet Gokhan Caglayan and Pavel Anzenbacher},
doi = {10.1039/c5cc08759g},
issn = {1364-548X},
year = {2016},
date = {2016-01-01},
journal = {Chem Commun (Camb)},
volume = {52},
number = {9},
pages = {1827--1830},
abstract = {Tri-serine tri-lactone based C3 symmetry fluorescent sensors were synthesized. Citrate is shown to bind to sensors, while displaying an increase in fluorescence intensity for the sensor with thiourea and a quenching for the sensor with sulfonamide. Information-rich responses of the sensors enable us to discriminate structurally similar anions, including mono-, di- and tri-carboxylates with 100% correct classification. A simple two-sensor array enables the determination of the concentration of citrate in urine without any sample preparation with high accuracy (error < 2%).},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Tri-serine tri-lactone based C3 symmetry fluorescent sensors were synthesized. Citrate is shown to bind to sensors, while displaying an increase in fluorescence intensity for the sensor with thiourea and a quenching for the sensor with sulfonamide. Information-rich responses of the sensors enable us to discriminate structurally similar anions, including mono-, di- and tri-carboxylates with 100% correct classification. A simple two-sensor array enables the determination of the concentration of citrate in urine without any sample preparation with high accuracy (error < 2%).
2015
Bakar, Filiz; Caglayan, Mehmet G; Onur, Feyyaz; Nebioglu, Serpil; Palabiyik, Ismail M
Gold nanoparticle-lignan complexes inhibited MCF-7 cell proliferation in vitro: a novel conjugation for cancer therapy Journal Article
In: Anticancer Agents Med Chem, vol. 15, no. 3, pp. 336–344, 2015, ISSN: 1875-5992.
@article{pmid25469627,
title = {Gold nanoparticle-lignan complexes inhibited MCF-7 cell proliferation in vitro: a novel conjugation for cancer therapy},
author = {Filiz Bakar and Mehmet G Caglayan and Feyyaz Onur and Serpil Nebioglu and Ismail M Palabiyik},
doi = {10.2174/1871520614666141202144152},
issn = {1875-5992},
year = {2015},
date = {2015-01-01},
journal = {Anticancer Agents Med Chem},
volume = {15},
number = {3},
pages = {336--344},
abstract = {Nanoparticles, including gold nanoparticles (AuNP), have been used in imaging in cancer treatment and as therapeutic agents and drug delivery vehicles. Particularly lignans, also called phytoestrogens, have strong effects on the treatment of carcinomas due to their antiestrogenic, antiangiogenic and proapoptotic mechanism. The aim of this study is to investigate the antiproliferative effects of three lignans-AuNP conjugates, pinoresinol (PINO), lariciresinol (LARI) and secoisolariciresinol (SECO), on the MCF-7 cell lines. For this purpose, first, thiolated β-cyclodextrin (β-CD) was synthesized to achieve a surface modification of AuNP, and then the β-CD modified AuNP was characterized using the transmission electron microscopy (TEM), UV-Visible and Nuclear Magnetic Resonance (NMR) spectroscopy. Then, the selected lignans were conjugated to the β-CD-modified AuNP, and the antiproliferative effect of these conjugates was monitored. The results suggest that when compared to their non-conjugated forms, the AuNP-bound lignan conjugates prevented the proliferation of the MCF-7 cells significantly. Therefore, these AuNP-conjugated derivatives can be new candidate agents for breast cancer therapy.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Nanoparticles, including gold nanoparticles (AuNP), have been used in imaging in cancer treatment and as therapeutic agents and drug delivery vehicles. Particularly lignans, also called phytoestrogens, have strong effects on the treatment of carcinomas due to their antiestrogenic, antiangiogenic and proapoptotic mechanism. The aim of this study is to investigate the antiproliferative effects of three lignans-AuNP conjugates, pinoresinol (PINO), lariciresinol (LARI) and secoisolariciresinol (SECO), on the MCF-7 cell lines. For this purpose, first, thiolated β-cyclodextrin (β-CD) was synthesized to achieve a surface modification of AuNP, and then the β-CD modified AuNP was characterized using the transmission electron microscopy (TEM), UV-Visible and Nuclear Magnetic Resonance (NMR) spectroscopy. Then, the selected lignans were conjugated to the β-CD-modified AuNP, and the antiproliferative effect of these conjugates was monitored. The results suggest that when compared to their non-conjugated forms, the AuNP-bound lignan conjugates prevented the proliferation of the MCF-7 cells significantly. Therefore, these AuNP-conjugated derivatives can be new candidate agents for breast cancer therapy.
2014
Amanova, Anara; Celebi, Zeynep Kendi; Bakar, Filiz; Caglayan, Mehmet G; Keven, Kenan
Colchicine levels in chronic kidney diseases and kidney transplant recipients using tacrolimus Journal Article
In: Clin Transplant, vol. 28, no. 10, pp. 1177–1183, 2014, ISSN: 1399-0012.
@article{pmid25125128,
title = {Colchicine levels in chronic kidney diseases and kidney transplant recipients using tacrolimus},
author = {Anara Amanova and Zeynep Kendi Celebi and Filiz Bakar and Mehmet G Caglayan and Kenan Keven},
doi = {10.1111/ctr.12448},
issn = {1399-0012},
year = {2014},
date = {2014-10-01},
journal = {Clin Transplant},
volume = {28},
number = {10},
pages = {1177--1183},
abstract = {BACKGROUND: Tacrolimus is a CYP3A4 inhibitor and can alter colchicine metabolism. In this study, we aimed to evaluate plasma colchicine levels in different stages of kidney disease as well as in kidney transplant (KTx) recipients using tacrolimus.nnMETHOD: This study included six familial Mediterranean fever (FMF) patients with normal glomerular filtration rate (GFR) as controls, three patients with low GFR, six FMF patients on hemodialysis (HD), and six FMF patients who were KTx recipients using tacrolimus. After a three-d washout period, plasma colchicine levels were measured at 0 (pre-dose), one, two, four, eight, and 24 h post-dose of 1 mg oral colchicine. Area under the curve 0-24 h (AUC0-24 ) and maximum concentration (Cmax ) were evaluated and compared between the groups.nnRESULTS: Colchicine AUC0-24 was six-fold higher in HD (p < 0.001) and three-fold higher in KTx recipients (p < 0.001) when compared to the control. The low GFR group had mildly higher AUC0-24 than the control group. Cmax levels were also higher in HD (p = 0.011) and KTx recipient (p = 0.06) groups and mildly elevated in low GFR patients in comparison with controls.nnCONCLUSION: Colchicine AUC0-24 and Cmax were significantly increased in HD patients and KTx recipients using tacrolimus. Therefore, dose adjustments are needed to avoid toxicity in both circumstances.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
BACKGROUND: Tacrolimus is a CYP3A4 inhibitor and can alter colchicine metabolism. In this study, we aimed to evaluate plasma colchicine levels in different stages of kidney disease as well as in kidney transplant (KTx) recipients using tacrolimus.nnMETHOD: This study included six familial Mediterranean fever (FMF) patients with normal glomerular filtration rate (GFR) as controls, three patients with low GFR, six FMF patients on hemodialysis (HD), and six FMF patients who were KTx recipients using tacrolimus. After a three-d washout period, plasma colchicine levels were measured at 0 (pre-dose), one, two, four, eight, and 24 h post-dose of 1 mg oral colchicine. Area under the curve 0-24 h (AUC0-24 ) and maximum concentration (Cmax ) were evaluated and compared between the groups.nnRESULTS: Colchicine AUC0-24 was six-fold higher in HD (p < 0.001) and three-fold higher in KTx recipients (p < 0.001) when compared to the control. The low GFR group had mildly higher AUC0-24 than the control group. Cmax levels were also higher in HD (p = 0.011) and KTx recipient (p = 0.06) groups and mildly elevated in low GFR patients in comparison with controls.nnCONCLUSION: Colchicine AUC0-24 and Cmax were significantly increased in HD patients and KTx recipients using tacrolimus. Therefore, dose adjustments are needed to avoid toxicity in both circumstances.
2013
Aybaba, Cigdem; Palabiyik, Ismail Murat; Caglayan, Mehmet Gokhan; Onur, Feyyaz
In: J AOAC Int, vol. 96, no. 4, pp. 723–729, 2013, ISSN: 1060-3271.
@article{pmid24000743,
title = {Multivariate optimization of separation conditions for simultaneous determination of acemetacin and chlorzoxazone in a pharmaceutical preparation by HPLC using response surface methodology},
author = {Cigdem Aybaba and Ismail Murat Palabiyik and Mehmet Gokhan Caglayan and Feyyaz Onur},
doi = {10.5740/jaoacint.11-092},
issn = {1060-3271},
year = {2013},
date = {2013-01-01},
journal = {J AOAC Int},
volume = {96},
number = {4},
pages = {723--729},
abstract = {A new, fast, accurate, precise, and sensitive RP-HPLC method for the simultaneous determination of acemetacin and chlorzoxazone has been developed. Response surface methodology with a central composite design was used to optimize the acetonitrile and ammonium acetate percentage in the mobile phase and pH of ammonium acetate. The optimum separation was achieved on a C18 column (250 x 4.6 mm id, 5 microm particle size) using the mobile phase methanol-acetonitrile-0.02 M ammonium acetate, pH 9.4 (25 + 35 + 40, v/v/v) at a flow rate of 1.5 mL/min; UV detection at 270 nm, and cyanocobalamin as an internal standard. This developed method was validated and successfully applied to a coated tablet pharmaceutical preparation.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A new, fast, accurate, precise, and sensitive RP-HPLC method for the simultaneous determination of acemetacin and chlorzoxazone has been developed. Response surface methodology with a central composite design was used to optimize the acetonitrile and ammonium acetate percentage in the mobile phase and pH of ammonium acetate. The optimum separation was achieved on a C18 column (250 x 4.6 mm id, 5 microm particle size) using the mobile phase methanol-acetonitrile-0.02 M ammonium acetate, pH 9.4 (25 + 35 + 40, v/v/v) at a flow rate of 1.5 mL/min; UV detection at 270 nm, and cyanocobalamin as an internal standard. This developed method was validated and successfully applied to a coated tablet pharmaceutical preparation.
2011
Karacan, Elif; Cağlayan, Mehmet Gokhan; Palabiyik, Ismail Murat; Onur, Feyyaz
Liquid chromatographic and spectrophotometric determination of diflucortolone valerate and isoconazole nitrate in creams Journal Article
In: J AOAC Int, vol. 94, no. 1, pp. 128–135, 2011, ISSN: 1060-3271.
@article{pmid21391489,
title = {Liquid chromatographic and spectrophotometric determination of diflucortolone valerate and isoconazole nitrate in creams},
author = {Elif Karacan and Mehmet Gokhan Cağlayan and Ismail Murat Palabiyik and Feyyaz Onur},
issn = {1060-3271},
year = {2011},
date = {2011-01-01},
journal = {J AOAC Int},
volume = {94},
number = {1},
pages = {128--135},
abstract = {A new RP-LC method and two new spectrophotometric methods, principal component regression (PCR) and first derivative spectrophotometry, are proposed for simultaneous determination of diflucortolone valerate (DIF) and isoconazole nitrate (ISO) in cream formulations. An isocratic system consisting of an ACE C18 column and a mobile phase composed of methanol-water (95 + 5, v/v) was used for the optimal chromatographic separation. In PCR, the concentration data matrix was prepared by using synthetic mixtures containing these drugs in methanol-water (3 + 1, v/v). The absorbance data matrix corresponding to the concentration data matrix was obtained by measuring the absorbances at 29 wavelengths in the range of 242-298 nm for DIF and ISO in the zero-order spectra of their combinations. In first derivative spectrophotometry, dA/dlambda values were measured at 247.8 nm for DIF and at 240.2 nm for ISO in first derivative spectra of the solution of DIF and ISO in methanol-water (3 + 1, v/v). The linear ranges were 4.00-48.0 microg/mL for DIF and 50.0-400 microg/mL for ISO in the LC method, and 2.40-40.0 microg/mL for DIF and 60.0-260 microg/mL for ISO in the PCR and first derivative spectrophotometric methods. These methods were validated by analyzing synthetic mixtures. These three methods were successfully applied to two pharmaceutical cream preparations.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A new RP-LC method and two new spectrophotometric methods, principal component regression (PCR) and first derivative spectrophotometry, are proposed for simultaneous determination of diflucortolone valerate (DIF) and isoconazole nitrate (ISO) in cream formulations. An isocratic system consisting of an ACE C18 column and a mobile phase composed of methanol-water (95 + 5, v/v) was used for the optimal chromatographic separation. In PCR, the concentration data matrix was prepared by using synthetic mixtures containing these drugs in methanol-water (3 + 1, v/v). The absorbance data matrix corresponding to the concentration data matrix was obtained by measuring the absorbances at 29 wavelengths in the range of 242-298 nm for DIF and ISO in the zero-order spectra of their combinations. In first derivative spectrophotometry, dA/dlambda values were measured at 247.8 nm for DIF and at 240.2 nm for ISO in first derivative spectra of the solution of DIF and ISO in methanol-water (3 + 1, v/v). The linear ranges were 4.00-48.0 microg/mL for DIF and 50.0-400 microg/mL for ISO in the LC method, and 2.40-40.0 microg/mL for DIF and 60.0-260 microg/mL for ISO in the PCR and first derivative spectrophotometric methods. These methods were validated by analyzing synthetic mixtures. These three methods were successfully applied to two pharmaceutical cream preparations.
2010
Cağlayan, Mehmet Gökhan; Palabiyik, Ismail Murat; Onur, Feyyaz
Development and validation of spectrophotometric and high-performance column liquid chromatographic methods for the simultaneous determination of dienogest and estradiol valerate in pharmaceutical preparations Journal Article
In: J AOAC Int, vol. 93, no. 3, pp. 862–868, 2010, ISSN: 1060-3271.
@article{pmid20629388,
title = {Development and validation of spectrophotometric and high-performance column liquid chromatographic methods for the simultaneous determination of dienogest and estradiol valerate in pharmaceutical preparations},
author = {Mehmet Gökhan Cağlayan and Ismail Murat Palabiyik and Feyyaz Onur},
issn = {1060-3271},
year = {2010},
date = {2010-01-01},
journal = {J AOAC Int},
volume = {93},
number = {3},
pages = {862--868},
abstract = {Simultaneous determination of dienogest (DIE) and estradiol valerate (EST) in sugar-coated tablets was performed by using HPLC and spectrophotometry. In HPLC, the separation was achieved on an ACE C8 column using the mobile phase acetonitrile-NH4NO3 (0.03 M, pH 5.4; 70 + 30, v/v) at a flow rate of 2 mL/min. The detection wavelength was 280 nm, and cyproterone acetate was selected as an internal standard. The linearity range was 3.0-45.0 microg/mL for DIE and 18.0-100.0 microg/mL for EST. As spectrophotometric methods, two chemometric methods, principal component regression and partial least-squares, were developed. In the chemometric techniques, the concentration data matrix was prepared by using mixtures containing these drugs in methanol-water (3 + 1, v/v). The absorbance data matrix corresponding to the concentration data matrix in these methods was obtained by the measurement of absorbances in their zero-order spectra; then, the calibration was obtained by using the data matrix for the prediction of unknown concentrations of DIE and EST in their binary mixture. Working ranges were found as 2.0-24.0 microg/mL for DIE and 20.0-270.0 microg/mL EST in the methods. These three developed methods were validated and successfully applied to a pharmaceutical preparation, a sugar-coated tablet, and the results were compared with each other.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Simultaneous determination of dienogest (DIE) and estradiol valerate (EST) in sugar-coated tablets was performed by using HPLC and spectrophotometry. In HPLC, the separation was achieved on an ACE C8 column using the mobile phase acetonitrile-NH4NO3 (0.03 M, pH 5.4; 70 + 30, v/v) at a flow rate of 2 mL/min. The detection wavelength was 280 nm, and cyproterone acetate was selected as an internal standard. The linearity range was 3.0-45.0 microg/mL for DIE and 18.0-100.0 microg/mL for EST. As spectrophotometric methods, two chemometric methods, principal component regression and partial least-squares, were developed. In the chemometric techniques, the concentration data matrix was prepared by using mixtures containing these drugs in methanol-water (3 + 1, v/v). The absorbance data matrix corresponding to the concentration data matrix in these methods was obtained by the measurement of absorbances in their zero-order spectra; then, the calibration was obtained by using the data matrix for the prediction of unknown concentrations of DIE and EST in their binary mixture. Working ranges were found as 2.0-24.0 microg/mL for DIE and 20.0-270.0 microg/mL EST in the methods. These three developed methods were validated and successfully applied to a pharmaceutical preparation, a sugar-coated tablet, and the results were compared with each other.