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    Gold nanoparticles having dipicolinic acid imprinted nanoshell for Bacillus cereus spores recognition
    (Elsevier, 2009) Gultekin, Aytac; Ersoz, Arzu; Hur, Deniz; Sariozlu, Nalan Yilmaz; Denizli, Adil; Say, Ridvan
    Taking into account the recognition element for sensors linked to molecular imprinted polymers (MIPs), a proliferation of interest has been witnessed by those who are interested in this subject. Indeed, MIP nanoparticles are theme which recently has come to light in the literature. In this study, we have proposed a novel thiol ligand-capping method with polymerizable methacryloylamidocysteine (MAC) attached to gold nanoparticles, reminiscent of a self-assembled monolayer. Furthermore, a surface shell by synthetic host polymers based on molecular imprinting method for recognition has been reconstructed. In this method, methacryloyl iminodiacetic acid-chrome (MAIDA-Cr(III)) has been used as a new metal-chelating monomer via metal coordination-chelation interactions and dipicolinic acid (DPA) which is the main participant of Bacillus cereus spores has been used as a template. Nanoshell sensors with templates produce a cavity that is selective for DPA. The DPA can simultaneously chelate to Cr(III) metal ion and fit into the shape-selective cavity. Thus, the interaction between Cr(III) ion and free coordination spheres has an effect on the binding ability of the gold nanoparticles nanosensor. The interactions between DPA and MIP particles were studied observing fluorescence measurements. DPA addition caused significant decreases in fluorescence intensity because they induced photoluminescence emission from Au nanoparticles through the specific binding to the recognition sites of the crosslinked nanoshell polymer matrix. The binding affinity of the DPA imprinted nanoparticles has been explored by using the Langmuir and Scatchard methods and the analysis of the quenching results has been performed in terms of the Stern-Volmer equation. (C) 2009 Elsevier B.V. All rights reserved.
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    Gold-silver nanoclusters having dipicolinic acid imprinted nanoshell for Bacillus cereus spores recognition
    (Elsevier, 2009) Gultekin, Aytac; Diltemiz, S. Emir; Ersoz, Arzu; Sariozlu, N. Yilmaz; Denizli, Adil; Say, Ridvan
    Molecular imprinted polymers (MIPs) as a recognition element for sensors are increasingly of interest and MIP nanoclusters have started to appear in the literature. in this study, we have proposed a novel thiol ligand-capping method with polymerizable methacryloylamidocysteine (MAC) attached to gold-silver nanoclusters, reminiscent of a self-assembled monolayer and have reconstructed surface shell by synthetic host polymers based on molecular imprinting method for recognition. In this method, methacryloyl iminodiacetic acid-chrome (MAIDA-Cr(III)) has been used as a new metal-chelating monomer via metal coordination-chelation interactions and dipicolinic acid (DPA) which is a main participant of Bacillus spores has been used as a template. Nanoshell sensors with templates give a cavity that is selective for DPA. The DPA can simultaneously chelate to Cr(III) metal ion and fit into the shape-selective cavity. Thus, the interaction between Cr(III) ion and free coordination spheres has an effect on the binding ability of the gold-silver nanoclusters nanosensor. The binding affinity of the DPA imprinted nanoclusters has been investigated by using the Langmuir and Scatchard methods and determined affinity constants (K-affinity) were found as 18 x 10(6) mol L-1 and 9 x 10(6) mol L-1, respectively. (C) 2009 Elsevier B.V. All rights reserved.
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    Microscopic examination and comparison of exine layer of bee pollen and bee bread (Perga)
    (Istanbul Univ, Fac Pharmacy, 2022) Ozkok, Ash; Bakhshpour, Monireh; Mayda, Nazli; Denizli, Adil; Sorkun, Kadriye
    Background and Aims: Thanks to their high nutritional content and therapeutic effects, bee pollen and bee bread (perga) are used as a food supplement. Studies have shown that bee bread has more bioavailability than bee pollen. This situation has been explained by the fragmentation of the exine layers of pollen in bee bread in some studies. However, there is no clear microscopic study showing that the exine layer is broken. This study investigated for the first time whether the pollen grains in bee bread were fragmented in the exine layers after fermentation, in comparison with the pollen grains in bee pollen samples. Methods: Bee pollen and bee bread samples were collected from the same hives and pollen slides were prepared for examination with light and SEM microscopes. Both of the pollen slides were compared and microscopic photographs were taken. Results: No deformation was observed in the exine layers of the pollen grains in bee bread after fermentation. Conclusion: In many studies, the higher bioavailability of bee bread has been explained by the deformation at exine structure of the pollen grains. But it has not been supported microscopically in detail with both light and SEM microscopes. Our study's conclusion was that no deformation was observed in the exine structures of the pollen in bee bread after fermentation.
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    Nanosensors having dipicolinic acid imprinted nanoshell for Bacillus cereus spores detection
    (Springer, 2010) Gultekin, Aytac; Ersoz, Arzu; Sariozlu, Nalan Yilmaz; Denizli, Adil; Say, Ridvan
    Molecular imprinted polymers (MIPs) as a recognition element for sensors are increasingly of interest and MIP nanoclusters have started to appear in the literature. In this study, we have proposed a novel thiol ligand-capping method with polymerizable methacryloylamido-cysteine (MAC) attached to gold-silver nanoclusters, reminiscent of a self-assembled monolayer and have reconstructed surface shell by synthetic host polymers based on molecular imprinting method for recognition. In this method, methacryloylamidoantipyrine-terbium ((MAAP)(2)-Tb(III)) has been used as a new metal-chelating monomer via metal coordination-chelation interactions and dipicolinic acid (DPA) which is main participant of Bacillus cereus spores used as a model. Nanoshell sensors with templates give a cavity that is selective for DPA. The DPA can simultaneously chelate to Tb(III) metal ion and fit into the shape-selective cavity. Thus, the interaction between Tb(III) ion and free coordination spheres has an effect on the binding ability of the gold-silver nanoclusters nanosensor. The binding affinity of the DPA imprinted nanoclusters has been investigated by using the Langmuir and Scatchard methods, and the respective affinity constants (K (affinity)) determined were found to be 1.43 x 10(4) and 9.1 x 10(6) mol L(-1).
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    Preparation of new molecularly imprinted nanosensor for cholic acid determination
    (Elsevier Science Sa, 2012) Gultekin, Aytac; Ersoz, Arzu; Denizli, Adil; Say, Ridvan
    Molecular imprinted polymers (MIPs) as a recognition element for sensors are increasingly of interest and MIP-nanoparticles have started to appear in the literature. In this study, we have proposed a novel thiol ligand-capping method with polymerizable methacryloylamido-cysteine (MAC) attached to gold nanoparticles, reminiscent of a self-assembled monolayer and have reconstructed surface shell by synthetic host polymers based on molecular imprinting method for recognition. In this method, methacryloylamidohistidine-Pt(II) [MAH-Pt(II)] has used as a new metal-chelating monomer via metal coordination-chelation interactions and cholic acid. Nanoshell sensors with templates give a cavity that is selective for cholic acid. The cholic acid can simultaneously chelate to Pt(II) metal ion and fit into the shape-selective cavity. Thus, the interaction between Pt(II) ion and free coordination spheres has an effect on the binding ability of the gold nanoparticles nanosensor. The binding affinity of the cholic acid imprinted nanoparticles has investigated by using the Langmuir and Scatchard methods and determined affinity constant (K-affinity) were found as 1.48 x 10(4) mol L-1 and 6.59 x 10(6) mol L-1, respectively. At the last step of this procedure, cholic acid level in blood serum and urine which belong to healthy people was determined by the prepared Au nanosensor. (C) 2012 Elsevier B.V. All rights reserved,
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    Preparation of new molecularly imprinted quartz crystal microbalance hybride sensor system for 8-hydroxy-2?-deoxyguanosine determination
    (Elsevier, 2009) Say, Ridvan; Gultekin, Aytac; Ozcan, Ayca Atilir; Denizli, Adil; Ersoz, Arzu
    The routine measurement of 8-hydroxy-2'-deoxyguanosine (8-OHdG) in biological samples is a difficult analytical problem due to the low levels of the analyte and complex matrix. A new 8-OHdG imprinted quartz crystal microbalance (QCM) sensor has been developed for selective determination of 8-OHdG in serum samples. To fulfil the desired results, we have used methacryloyl aminoantipyrine-Fe(III) [MAAP-Fe(III)] and methacryloyl histidine-Pt(II) [MAH-Pt(II)] as metal-chelating monomers via double metal coordination-chelation interactions for the preparation of additional selective molecular imprinted polymers (MIP). The study includes the measurement of binding interaction of 8-OHdG imprinted quartz crystal microbalance (QCM) sensor, selectivity experiments and analytical performance of QCM chip. The obtained results have showed that the application of double metal-chelate monomer systems has been more effective than single metal-chelate monomer systems. In this study, the detection limit and the linear working range were found to be 0.0075 and 0.0100-3.5 mu M, respectively. The affinity constant (K-affinity) was found to be 1.54 x 10(5) M-1 for 8-OHdG using MAH-Pt-8-OHdG-MAAP-Fe based thin film. Also, selectivity of prepared QCM sensor was found as being very high in the presence of competitive species. At the last step of this procedure, 8-OHdG level in blood serum which belongs to a intestinal cancer patient was determined by the prepared QCM sensor. (c) 2009 Elsevier B.V. All rights reserved.