Browsing by Author "Tamer, Ugur"

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A Capillary Driven Microfluidic Chip for Sers Based Hcg Detection
(Elsevier Advanced Technology, 2022) Ahi, Elcin Ezgi; Torul, Hilal; Zengin, Adem; Sucularli, Ferah; Yildirim, Ender; Selbes, Yesim; Tamer, Ugur
In this study, a capillary driven microfluidic chip-based immunoassay was developed for the determination of Human Chorionic Gonadotropin (hCG) protein, which is prohibited by the World Anti-Doping Agency (WADA). Here, we used antibody modified magnetic metal organic framework nanoparticles (MMOFs) as a capture prob in urine sample. MMOF captured hCG was transferred in a capillary driven microfluidic chip consisting of four chambers, and the interaction of MMOF with gold nanorods labelled with 5,5'-Dithiobis-(2-nitrobenzoic acid) (DTNB) as a Raman label was carried out in the capillary driven microfluidic chip. The movement of MMOF through first chamber to the last chamber was achieved with a simple magnet. In the last chamber of capillary driven microfluidic chip, SERS signals of DTNB molecules from the sandwich complex were recorded using a Raman spectrophotometer. The selectivity of the developed method was demonstrated by applying the same procedure for the detection of Human Luteinizing Hormone (hLH), Human Chorionic Gonadotropin Hormone (hGH) and Immunoglobulin G (IgG) protein. The regression coefficient and limit of detection obtained from the standard addition method were found as 0,9985 and 0,61 IU/L, respectively. Furthermore, the conventional ELISA method confirmed that the results obtained by the presented method were acceptable with the similarity of 97.9% in terms of average recovery value, for the detection of hCG in urine samples. The analysis system developed for target proteins will be an alternative technique such as Western Blot used in routine analysis that is expensive and time consuming.
The Comparison of Antioxidant Capacity and Cytotoxic, Anticarcinogenic, and Genotoxic Effects of Fe@au Nanosphere Magnetic Nanoparticles
(Tubitak Scientific & Technological Research Council Turkey, 2017) Yegenoglu, Hande; Aslim, Belma; Guven, Burcu; Zengin, Adem; Boyaci, Ismail Hakki; Suludere, Zekiye; Tamer, Ugur
Magnetic gold nanoparticles are used in various biomedical, biochemistry, and biotechnology applications due to their controllable size distribution, long-term stability, reduced toxicity, and biocompatibility. Different coating materials, such as proteins, carbohydrates, lipids, and polyphenols, are applied to enhance the biocompatibility of nanoparticles. In this study, the effects of surface coatings of core-shell structured Fe@Au nanosphere magnetic nanoparticles with regard to antioxidant capacity and cytotoxic, anticarcinogenic, and genotoxic properties were investigated. The obtained results demonstrated that avidin-coated Fe@Au nanospheres had higher antioxidant capacities than uncoated nanospheres. Neither avidin-coated nor uncoated nanoparticles had a cytotoxic effect on normal cells (human gingival fibroblast cell line, HGF-1). In addition, they had anticarcinogenic effects on human cervical carcinoma (HeLa), human breast adenocarcinoma (MCF-7), and human colorectal adenocarcinoma (CCL-221). The genotoxic effects of nanoparticles were also evaluated with DNA tail damage ratio.
Construction of a Sensitive and Selective Plasmonic Biosensor for Prostate Specific Antigen by Combining Magnetic Molecularly-Imprinted Polymer and Surface-Enhanced Raman Spectroscopy
(Elsevier, 2022) Turan, Eylem; Zengin, Adem; Suludere, Zekiye; Kalkan, Nurhan Onal; Tamer, Ugur
Selective and sensitive detection of cancer biomarkers in serum samples is critical for early diagnosis of cancer. Prostate specific antigen is an important biomarker of prostate cancer, which ranks high among cancer-related deaths of men over 50 years old. Herein, a novel analytical method was introduced for detection of PSA by combining high selectivity of molecularly-imprinted polymers and high sensitivity of surface-enhanced Raman spectroscopy (SERS). Firstly, magnetic nanoparticles were grafted with an imprinted layer by using tannic acid as a functional monomer, diethylenetriamine as a cross-linker and prostate specific antigen as a template molecule. Detailed surface characterization and re-binding experiment results indicated that the imprinting of the antigen was successful with an imprinting factor of 5.58. The prepared magnetic molecularly imprinted polymers (MMIPs) were used as an antibody-free capture probe and labeled with gold nanoparticles that were modified with anti-PSA and a Raman reporter, namely 5,5'-dithiobis-(2-nitrobenzoic acid). Thus, a plasmonic structure (sandwich complex) was formed between MMIP and the SERS label. The limit of detection and limit of quantification of the designed sensor were 0.9 pg/mL and 3.2 pg/mL, respectively. The sensor also showed high recovery rates (98.0-100.1% for healthy person and 99.0-101.3% for patient) with low standard deviations (less than 4.3% for healthy person and less than 3.3% for patient) for PSA in serum samples. Compared with the traditional immunoassays, the proposed method has several advantages like low cost, reduced detection procedure, fast response, high sensitivity and selectivity. It is believed that the proposed method can be potentially used for selective and sensitive determination of tumor marker of prostate cancer in clinical applications.
Dual Responsive Disposable Electrode for the Enumeration Ofescherichia Coliin Whole Blood
(Wiley-v C H verlag Gmbh, 2020) Panhwar, Sallahuddin; Ilhan, Hasan; Hassan, Syeda Sara; Zengin, Adem; Boyaci, Ismail Hakki; Tamer, Ugur
In this report, we have designed a dual responsive disposable electrode for the enumeration ofEscherichia coli K12 (E. coli K12). The immunomagnetic separation strategy provided easily bacterial detection in the whole blood. Metal-organic frameworks magnetic (MOFs) modified, and citrate capped gold nanoparticles were used as capture probe and spectro-electrochemical labels, respectively. The cyclic voltammetry (CV) was employed to quantifyE. coliwith a ranging from 10(1)to 10(7) cfu/mL with a LOD of 1 cfu/mL. The Surface enhanced Raman spectroscopy (SERS) measurements were also performed with using disposable electrode.
Immunomagnetic Separation and Listeria Monocytogenes Detection With Surface-Enhanced Raman Scattering
(Tubitak Scientific & Technological Research Council Turkey, 2020) Akcinar, Hande Yegenoglu; Aslim, Belma; Torul, Hilal; Guven, Burcu; Zengin, Adem; Suludere, Zekiye; Tamer, Ugur
Background/aim: We aimed to develop a rapid method to enumerate Listeria monocytogenes (L. monocytogenes) utilizing magnetic nanoparticle based preconcentration and surface-enhanced Raman spectroscopy measurements. Materials and methods: Biological activities of magnetic Au-nanoparticles have been observed to have the high biocompatibility, and a sample immunosensor model has been designed to use avidin attached Au-nanoparticles for L. monocytogenes detection. Staphylococcus aureus (S. aureus) and Salmonella typhimurium (S. typhimurium) bacteria cultures were chosen for control studies. Antimicrobial activity studies have been done to identify bio-compatibility and bio-characterization of the Au-nanoparticles in our previous study and capturing efficiencies to bacterial surfaces have been also investigated. Results: We constructed the calibration graphs in various population density of L. monocytogenes as 2.2 x 10(1) to 2.2 x 10(6) cfu/mL and the capture efficiency was found to be 75%. After the optimization procedures, population density of L. monocytogenes and Raman signal intensity showed a good linear correlation (12 2 - 0.991) between 10(2) to 10(6) cfu/ml, L. monocylogenes. The presented sandwich assay provides low detection limits and limit of quantification as 12 cfu/mL and 37 cfu/mL, respectively. We also compared the experimental results with reference plate-counting methods and the practical utility of the proposed assay is demonstrated using milk samples. Conclusion: It is focused on the enumeration of L. monocytogenes in milk samples and the comparision of results of milk analysis obtained by the proposed SERS method and by plate counting method stay in food agreement. In the present study, all parameters were optimized to select SERS-based immunoassay method for L. monocytogenes bacteria to ensure LOD, selectivity, precision and repeatablity.
Quantitative Characterization of Magnetic Mobility of Nanoparticle in Solution-Based Condition
(Bentham Science Publ Ltd, 2015) Rodoplu, Didem; Boyaci, Ismail H.; Bozkurt, Akif G.; Eksi, Haslet; Zengin, Adem; Tamer, Ugur; Tugcu Demiroz, Fatmanur
Magnetic nanoparticles are considered as the ideal substrate to selectively isolate target molecules or organisms from sample solutions in a wide variety of applications including bioassays, bioimaging and environmental chemistry. The broad array of these applications in fields requires the accurate magnetic characterization of nanoparticles for a variety of solution based-conditions. Because the freshly synthesized magnetic nanoparticles demonstrated a perfect magnetization value in solid form, they exhibited a different magnetic behavior in solution. Here, we present simple quantitative method for the measurement of magnetic mobility of nanoparticles in solution-based condition. Magnetic mobility of the nanoparticles was quantified with initial mobility of the particles using UV-vis absorbance spectroscopy in water, ethanol and MES buffer. We demonstrated the efficacy of this method through a systematic characterization of four different core-shell structures magnetic nanoparticles over three different surface modifications. The solid nanoparticles were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD) and saturation magnetization (Ms). The surfaces of the nanoparticles were functionalized with 11-mercaptoundecanoic acid and bovine serum albumin BSA was selected as biomaterial. The effect of the surface modification and solution media on the stability of the nanoparticles was monitored by zeta potentials and hydrodynamic diameters of the nanoparticles. Results obtained from the mobility experiments indicate that the initial mobility was altered with solution media, surface functionalization, size and shape of the magnetic nanoparticle. The proposed method easily determines the interactions between the magnetic nanoparticles and their surrounding biological media, the magnetophoretic responsiveness of nanoparticles and the initial mobilities of the nanoparticles.
Rapid Bacterial Detection Through Microfluidic Integration With a Glucometer
(Elsevier Science Sa, 2025) Eryilmaz, Merve; Ilbasmis-Tamer, Sibel; Panhwar, Sallahuddin; Tayyarcan, Emine Kubra; Boyaci, Ismail Hakki; Suludere, Zekiye; Tamer, Ugur
We present a novel approach for sensitive and portable detection of pathogenic bacteria, which is crucial for household and clinical practice. Our method employs immunoliposomes, antibodies, and microchip to detect specific pathogens quantitatively. Gold and metal metal-organic nanoparticles and liposomes were characterized using high-resolution techniques like TEM and SEM. Utilizing a commercial, personal glucose meter (PGM), we initially detected released glucose from antibody-modified liposomes and microchips with MOF-NPs. Detection on the microchip was achieved within 30 min, while the PGM analysis took only one minute for targeted bacteria, yielding glucose signals of 66 mg/dL and 69 mg/dL, respectively. Serial dilutions with group A-Streptococcus pyogenes (GAS) (1.4 x 10<<^>>4-1.4 x 10<<^>>8 CFU/mL) demonstrated quantitative measurement applicability. This innovative approach and a portable PGM hold promise for various industries, including physician labs, hospitals, and households.
Rapid Quantification of Total Protein With Surface-Enhanced Raman Spectroscopy Using O-Phthalaldehyde
(Wiley, 2017) Eryilmaz, Merve; Zengin, Adem; Boyaci, Ismail Hakki; Tamer, Ugur
In this study, surface-enhanced Raman spectroscopy (SERS) based quantification method for the total protein using o-phthalaldehyde is reported for the first time. For this purpose, o-phthalaldehyde was chosen to form a complex with protein, and SERS signal was observed in the presence of gold nanoparticles. A calibration curve was obtained by plotting the intensity of the SERS signal at 727cm(-1)versus the concentration of protein standard (bovine serum albumin, BSA). Thus, the correlation was found to be linear within the range of 0.054-0.72mg/ml of BSA, and the limit of detection was determined to be 0.08mg/ml. All tests were carried out using a portable Raman instrument with an analysis time of 5min. In addition, the ability of the developed method to quantify total protein in milk samples was investigated, and the obtained results were compared to the conventional ultraviolet methods. Copyright (c) 2017 John Wiley & Sons, Ltd.
Sers Detection of Hepatitis B Virus Dna in a Temperature-Responsive Sandwich-Hybridization Assay
(Wiley, 2017) Zengin, Adem; Tamer, Ugur; Caykara, Tuncer
In this study, we report the design of a DNA sensor for the detection of a DNA sequence representative of the hepatitis B virus (HBV) based on a sandwich assay and surface-enhanced Raman scattering (SERS) measurement. The temperature-responsive hybrid silicon substrate was first prepared via immobilization of capture DNA strand at the surface of gold nanoparticles on the hybrid silicon substrate. A sandwich strategy was then applied for the detection of target DNA that brings a reporter DNA labeled with indocyanine green to the proximity of the surface, leading to high SERS signals. The temperature-responsive hybrid silicon substrate-based SERS platform can detect the remarkably lowest HBV DNA concentrations at similar to 0.44fm at 25 degrees C and similar to 0.14fm at 37 degrees C, respectively, which are comparable with the lowest HBV DNA concentration ever via other techniques. We expect this highly sensitive and robust hybrid silicon substrate-based SERS platform can be extended to detect other biomolecules and chemical species such as viruses, proteins, and small molecules without any labeling. Copyright (c) 2017 John Wiley & Sons, Ltd.
Sers Detection of Polyaromatic Hydrocarbons on a -Cyclodextrin Containing Polymer Brush
(Wiley, 2018) Zengin, Adem; Tamer, Ugur; Caykara, Tuncer
We have designed a new surface-enhanced Raman scattering (SERS) sensor composed of -cyclodextrin (-CD) containing poly(glycidyl methacrylate) (PGMA) brush coated silicon substrate and per-6-deoxy-(6-thio)--cyclodextrin (-CD-SH) modified gold nanoparticles for detection of polyaromatic hydrocarbons (PAHs; pyrene and anthracene). The -CD containing PGMA brushes were synthesized by the interface-mediated Reversible addition-fragmentation chain transfer (RAFT) polymerization of glycidyl methacrylate and followed an epoxide ring-opening reaction to attach -CD molecules. Some PAHs, such as pyrene and anthracene, can be introduced into the hydrophobic space of -CD, which allows them to detect the SERS of PAHs. After separating pyrene or anthracene from the solution by the -CD containing PGMA brush coated silicon substrate, they were sandwiched with the SERS substrate consisting of per-6-deoxy-(6-thio)--cyclodextrin and rhodamine 6G (Raman reporter) on gold nanoparticles. The correlation between PAH concentrations and SERS signal was found to be linear in the range of 2.5 to 10nM for anthracene and 10 and 25nM for anthracene. The limit of detection values for pyrene and anthracene are 0.8 and 2.4nM, respectively. Furthermore, the SERS sensor was also evaluated for the investigation of pyrene or anthracene specificity on different organic molecules and polyaromatic hydrocarbons.
Surface Molecularly-Imprinted Magnetic Nanoparticles Coupled With Sers Sensing Platform for Selective Detection of Malachite Green
(Elsevier Science Sa, 2020) Ekmen, Elvan; Bilici, Mustafa; Turan, Eylem; Tamer, Ugur; Zengin, Adem
Herein, a novel analytical method was reported for sensitive and selective quantification of malachite green (MG) in tap water and carp samples based on a combination of surface-enhanced Raman spectroscopy (SERS) and molecular imprinting technology. For this purpose, surface molecularly-imprinted magnetic nanoparticles (MIP@Fe3O4 NPs) were synthesized through recently developed living/controlled radical polymerization mechanism referred to as reversible chain transfer catalyzed polymerization (RTCP). Surface characterization of MIP@Fe3O4 NPs was carried out in detail by using the combination of several analytical techniques and the results showed the presence of a thin polymer layer on the nanoparticles. Rebinding properties, selectivity and reusability of the nanoparticles were investigated and the obtained results indicated the prepared nanoparticles had excellent selectivity, high adsorption capacity, fast adsorption kinetics and multiple-uses with an imprinting factor of 3.86. Then, silver dendrites (Ag NPs) were deposited on silicon wafers and used as SERS sensing platform. Moreover, surface properties of the SERS substrate were also investigated in detail in terms of stability, reusability and homogeneity. After that, the eluted MG from the imprinted nanoparticles was dropped on the sensing platform and SERS analysis was carried out. Under optimized conditions, limit of detection and limit of quantification were determined to be 1.50 pM and 4.96 pM for tap water, respectively and 1.62 pM and 5.38 pM for carp samples, respectively within acceptable recovery rates and standard deviations. The overall results indicated that the proposed method can be effectively used for the quantification of trace amounts of MG in tap water and carp samples. Moreover, the proposed method is promising for development of new ways to prepare MIPs via surface-initiated RTCP.