Browsing by Author "Can, Gizem Kaleli"

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Citation - WoS: 17
Citation - Scopus: 22
Amyloid-Like Protein Nanofibrous Membranes as a Sensing Layer Infrastructure for the Design of Mass-Sensitive Biosensors
(Elsevier Advanced Technology, 2017-11) Kabay, Gözde; Can, Gizem Kaleli; Mutlu, Mehmet
Quartz crystal microbalances (QCMs) have been used in the literature for mass sensitive biosensor applications. However, their performance, reliability and stability have been limited by the chemical treatment steps required for the functionalization and activation of the QCM surface, prior to antibody immobilization. Specifically, these steps cause increased film thickness, which diminishes performance by mass overload, and create a harsh environment, which reduces biological activity. In this work, we eliminated this chemical step by introducing a sensing layer modification using electrospun amyloid like-bovine serum albumin (AL-BSA) nanofibers on QCM surfaces. Owing to the self-functionality of AL-BSA nanofibers, these modified QCM surfaces were directly activated by glutaraldehyde (GA). To assess the performance of these modified electrodes, a model protein, lysozyme (Lys), was selected as the biological agent to be immobilized. Frequency measurements were performed in batch (dip-and-dry) and continuous (flow-cell) processes, and binding performances were compared. AL-BSA modified surfaces were characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), quartz crystal microbalance (QCM), contact angle (CA) and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). Protein detection was measured based on the frequency shift before and after the covalent bonding of Lys. Under optimized conditions, the proposed immobilization platforms could bind 335 ng/mL and 250 ng/mL of Lys for batch and continuous processes, respectively. Our results demonstrate the potential usage of these self-functional electrospun AL-BSA infrastructure sensing layers on QCM surfaces. This modification enables the direct immobilization of bioactive agents by eliminating any surface functionalization process for further mass-sensitive biosensor applications.
Citation - WoS: 29
Citation - Scopus: 29
A Comparative Study of Single-Needle and Coaxial Electrospun Amyloid-Like Protein Nanofibers To Investigate Hydrophilic Drug Release Behavior
(Elsevier B. V., 2018-07-15) Kabay, Gözde; Demirci, Ceyhun; Can, Gizem Kaleli; Meydan, Ahmet Ersin; Daşan, Beyhan Günaydın; Mutlu, Mehmet
In this study, nanofibers containing an amyloid-like bovine serum albumin (AL-BSA) carrier and a model drug (ampicillin) were produced by electrospinning. The release behavior of ampicillin was compared from electrospun nanofibers prepared as either coaxial or single-needle types. SEM images showed that the membranes had a uniform and smooth structure and the core/shell fibers were found to be thicker than the core fibers. Core/shell production was proved by transmission electron microscopy images. Fourier transform infrared spectroscopy indicated the existence of compatibility between ampicillin and the AL-BSA matrix. The in vitro antimicrobial properties of ampicillin were studied through the comparison of bacterial inhibition zones and ampicillin was found to be more effective against Gram-positive Staphylococcus aureus than Gram-negative Escherichia coli. Moreover, in vitro drug release tests were conducted to explore the relationship between the shell thickness and the drug release rate. A burst release was observed for all membranes owing to the small fiber diameters and thus short diffusion lengths. For core membranes, the drug release mechanism followed Fickian transport, which was close to zero-order kinetic. A typical biphasic release mechanism was observed for the core/shell nanofibers. Overall, we present the first evidence of AL-BSA as a potential core/shell drug mediator.
Citation - WoS: 10
Citation - Scopus: 10
Quartz Tuning Fork as a Mass Sensitive Biosensor Platform With a Bi-Layer Film Modification Via Plasma Polymerization
(Cambridge University Press, 2019-06) Özgüzar, Hatice Ferda; Can, Gizem Kaleli; Kabay, Gözde; Mutlu, Mehmet
Due to the lack of the stability of amine films, a promising transducer, quartz-tuning fork (QTF) prongs were modified by a bi-layer film of plasma-polymerized n-heptane (hep) and then by ethylenediamine (EDA), respectively. For this purpose, the authors investigate the stability of amine-rich thin films both in air and aqueous medium. EDA films were deposited on QTF substrates by using an RF plasma system. The final amine-rich thin film was used to immobilize biologic recognition element. Model protein studies were showed that selected thin films could be adapted to QTF transducers to be used as a biosensor template.