Yazar "Paunov, Vesselin N." seçeneğine göre listele

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    Fabrication of albumin-micropatterned surfaces by colloidal microcontact printing technique
    (ROYAL SOC CHEMISTRY, 2013) Özmen, Mustafa; Ertekin, Betül; Ersöz, Mustafa; Paunov, Vesselin N.
    We report a versatile method for selective patterning of solid surfaces with albumin by a combination of microcontact printing of polymer colloids and surface charge aided protein adsorption. The technique allows formation of biocomposite arrays including colloid particles with different albumin functionalities. Micropatterns of functionalised monodisperse colloid particles were formed on the solid surfaces by using a microcontact printing method. We used polyelectrolyte multilayers (PEMs) as a coating system for poly (methylmethacrylate) acrylic acid (PMMA-AAc) patterning on glass substrate and albumin deposition onto colloid patterns by electrostatic interactions. We demonstrate that the colloid micropattern greatly improves the fluorescence imaging contrast for the deposited albumin due to its larger surface area and its immobilisation compared with patterning of albumin on a plane glass surface. This technique can be used to enhance the fluorescence imaging of biomarkers and other assays.
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    Fabrication of novel anisotropic magnetic microparticles
    (ROYAL SOC CHEMISTRY, 2009) Dyab, Amro K. F.; Özmen, Mustafa; Ersöz, Mustafa; Paunov, Vesselin N.
    We report a novel technique for fabrication of magnetically anisotropic microparticles based on "arresting" of the alignment of oleic acid coated magnetite nanoparticles (OCMNs) dispersed within the oil drops of a polymerisable oil-in-water emulsion. This was achieved by polymerising the oil drops after gelling the continuous aqueous phase in the presence of an external magnetic field. This approach allowed us to produce magnetic Janus particles with anisotropic optical and magnetic properties which form unusual zig-zag chains and structures when exposed to an external magnetic field. We studied the magnetic properties of these novel microparticles and showed that they retained remanence magnetisation with high coercivity values indicative of ferromagnetic behaviour. This indicates that the composite polymeric Janus microparticles posses a net magnetic dipole and behave like micromagnets due to the "arrested" orientation of the OCMNs in their polymeric matrix. Utilizing the same technique, magnetic Janus microparticles have been prepared based on emulsions stabilised only by OCMNs without the use of surfactants, and the effect of pH of continuous aqueous phase on the morphology of these microparticles has been investigated.
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    Functionalization of whole-cell bacterial reporters with magnetic nanoparticles
    (WILEY, 2011) Zhang, Dayi; Fakhrullin, Rawil F.; Ozmen, Mustafa; Wang, Hui; Wang, Jian; Paunov, Vesselin N.; Li, Guanghe
    We developed a biocompatible and highly efficient approach for functionalization of bacterial cell wall with magnetic nanoparticles (MNPs). Three Acinetobacter baylyi ADP1 chromosomally based bioreporters, which were genetically engineered to express bioluminescence in response to salicylate, toluene/xylene and alkanes, were functionalized with 18 +/- 3 nm iron oxide MNPs to acquire magnetic function. The efficiency of MNPs functionalization of Acinetobacter bioreporters was 99.96 +/- 0.01%. The MNPs-functionalized bioreporters (MFBs) can be remotely controlled and collected by an external magnetic field. The MFBs were all viable and functional as good as the native cells in terms of sensitivity, specificity and quantitative response. More importantly, we demonstrated that salicylate sensing MFBs can be applied to sediments and garden soils, and semi-quantitatively detect salicylate in those samples by discriminably recovering MFBs with a permanent magnet. The magnetically functionalized cells are especially useful to complex environments in which the indigenous cells, particles and impurities may interfere with direct measurement of bioreporter cells and conventional filtration is not applicable to distinguish and harvest bioreporters. The approach described here provides a powerful tool to remotely control and selectively manipulate MNPs-functionalized cells in water and soils. It would have a potential in the application of environmental microbiology, such as bioremediation enhancement and environment monitoring and assessment.