Browsing by Author "Erdem, E. Yegan"

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Open Access
Antibacterial properties and osteoblast interactions of microfluidically synthesized chitosan – SPION composite nanoparticles
(Wiley Periodicals LLC, 2023-05-26) Kafali, M.; Şahinoğlu, O. Berkay; Tufan, Y.; Orsel, Z. C.; Aygun, Elif; Alyuz, Beril; Saritas, Emine Ulku; Erdem, E. Yegan; Ercan, B.
In this research, a multi-step microfluidic reactor was used to fabricate chitosan – superparamagnetic iron oxide composite nanoparticles (Ch – SPIONs), where composite formation using chitosan was aimed to provide antibacterial property and nanoparticle stability for magnetic resonance imaging (MRI). Monodispersed Ch – SPIONs had an average particle size of 8.8 ± 1.2 nm with a magnetization value of 32.0 emu/g. Ch – SPIONs could be used as an MRI contrast agent by shortening T2 relaxation parameter of the surrounding environment, as measured on a 3 T MRI scanner. In addition, Ch – SPIONs with concentrations less than 1 g/L promoted bone cell (osteoblast) viability up to 7 days of culture in vitro in the presence of 0.4 T external static magnetic field. These nanoparticles were also tested against Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa), which are dangerous pathogens that cause infection in tissues and biomedical devices. Upon interaction of Ch – SPIONs with S. aureus and P. aeruginosa at 0.01 g/L concentration, nearly a 2-fold reduction in the number of colonies was observed for both bacteria strains at 48 h of culture. Results cumulatively showed that Ch – SPIONs were potential candidates as a cytocompatible and antibacterial agent that can be targeted to biofilm and imaged using an MRI.
Open Access
Capillary origami as a new method for obtaining folded structures with interior nanoparticle coating
(Elsevier, 2020) Özkazanç, Gökçe; Erdem, E. Yegan
We introduce capillary origami as a new method to obtain 3D enclosures with coated nanoparticles on their inner surfaces. When a liquid droplet that contains nanoparticles is placed on the surface of a thin and flexible membrane, the membrane folds around the droplet. As the droplet evaporates nanoparticles deposit on folded surfaces and eventually a 3D enclosure is obtained. In this study, both magnetic iron-oxide (Fe3O4) and gold (Au) nanoparticles are used and it is shown that with both types of nanoparticles the enclosures remain closed after the complete evaporation of the droplet. It is also demonstrated that the magnetic nanoparticles can be concentrated at a chosen location on the folded geometry by using a magnet during evaporation. The origami based coating method is applied on different geometries and distribution of nanaparticles depending on the surface orientation is quantified. As part of the study, the capillary origami behavior of liquids with and without nanoparticles is compared.
Open Access
Chitosan coated iron-oxide nanoparticle synthesis using a droplet based microfluidic reactor
(IEEE, 2019-06) Wahab, Malik Abdul; Erdem, E. Yegan
A microfluidic reactor for the synthesis of chitosan coated iron-oxide nanoparticles is described. Tapered double T-junction is used to generate droplets of reactants (iron chloride solution and chitosan solution) which were merged using a pillar array. Third reactant ammonia solution is introduced after the mixing of already merged droplets. Ammonia solution initiates the reaction and precipitates are collected at the outlet. Transmission electron microscope (TEM) imaging along with Fourier transform infrared spectroscopy (FTIR) is used to characterize the nanoparticles. These nanoparticles have applications in nano-medicine where they can be used as drug carriers.
Open Access
Multi-step microfludic reactor for the synthesis of hybrid nanoparticles
(Institute of Physics Publishing, 2020) Wahab, Malik Abdul; Erdem, E. Yegan
We introduce a multi-step microfluidic reactor for the synthesis of hybrid nanoparticles. As part of this study, nanoparticles composed of chitosan and iron-oxide are synthesized at room temperature by forming sequential droplets of reagents in the microreactor followed by merging and mixing them in a step by step process. The obtained nanoparticles were characterized by transmission electron microscopy, Fourier transform infrared spectrometry, and energy dispersive x-ray analysis. Results were compared with nanoparticles of the same composition synthesized with batch-wise conventional techniques. As a result, the obtained nanoparticles showed better size distribution. This microfluidic device can be used for the synthesis of other types of nanoparticles that require multi-step procedures.
Open Access
Silica nanoparticle formation by using droplet-based microreactor
(American Society of Mechanical Engineers, 2017) Nikdoost, Arsalan; Özkan, Alican; Kelestemur, Yusuf; Demir, Hilmi Volkan; Erdem, E. Yegan
This paper describes a method for the synthesis of silica nanoparticles that can be later used for coating of quantum dots inside a microfluidic reactor. Here, a droplet-based system is used where two reagents were mixed inside the droplets to obtain silica. Particles in the size range of 25±2.7 nm were obtained with comparable size distribution to controlled batchwise synthesis methods. This method is suitable to be used later to coat CdSe nanoparticles inside the microreactor.
Open Access
Size and shape analysis of silica (SiO2) and gold (Au) nanoparticles
(Taylor & Francis Inc., 2023-06-26) Bilgili, Devrim; Naji, Mayssam; Erdem, E. Yegan
In nanotechnology, the size and shape control of nanoparticles is crucial as their properties are highly dependent on their morphology. This obliges researchers to work on obtaining uniform size and shape distribution in synthesized particles so that their electrical, optical, and magnetic properties remain uniform within the same batch. This brings the problem of how to quantify the shape and size of nanoparticles in the most accurate way. The most common way to determine size distribution is using UV-vis spectrometry; however, this method disregards the existence of agglomerated particles and may sometimes give an incorrect measurement. Therefore a technique that can obtain this data directly from the transmission electron microscopy (TEM) images of particles would be more reliable as it would capture data for every single particle in the batch. In a classical statistical sense, our interest is the shape and size distribution of nanoparticles. In this paper, we quantify the size and shape of nanoparticles using the statistical techniques applied on TEM images of particles: Functional Data and Shape Analysis. By using this shape theory we obtain the geodesic distances not only between the particles but also among the frames. We further cluster the nanoparticles in terms of their similarities. We want to emphasize the importance of the deformation and how it is done of one nanoparticle onto another.
Open Access
Synthesis of anisotropic magnetic polymeric janus particles by in situ separation of magnetic nanoparticles in a microfluidic device
(American Chemical Society, 2023-11-20) Saqib, Muhammad; Ercan, Batur; Erdem, E. Yegan
Magnetic Janus particles have been studied extensively for medical and biological applications owing to their controllable mobility in fluid media. In this work, we report a novel microfluidic device designed for the synthesis of magnetically anisotropic Janus particles made of poly(ethylene glycol) diacrylate and embedded with magnetic iron oxide nanoparticles. Our method consists of a droplet generation step followed by magnetic separation using an external magnetic field and ultraviolet polymerization. The synthesized particles exhibit a monodisperse size distribution with a standard deviation of less than 3.5%, which is among the best size distributions obtained in the literature for magnetic Janus particles. The anisotropic magnetic property of the particles enable them to rotate about their own axes in the presence of an external magnetic field, introducing another degree of freedom to their motion. This microfluidic technique is simple, one-step, and versatile, offering control over the size distribution to synthesize magnetically anisotropic Janus particles.
Open Access
Textured surfaces as a new platform for nanoparticle synthesis
(Royal Society of Chemistry, 2018) Baştopçu, Melih; Derinöz, Anıl E.; Yılmaz, Asil C.; Erdem, E. Yegan
We present a new, surface-based microfluidic platform for the synthesis of nanoparticles. In this platform chemical reagents are carried in separate droplets, then mixed and later transported to a desired location on the surface using surface textured ratchet tracks. This brings the advantages of both synthesizing and transporting nanoparticles in situ without having cross-contamination between samples and addressing each sample independently. This platform is also capable of carrying multiple synthesis reactions concurrently.