Search

This paper investigates how and why Alevis in Turkey have insisted that they are not a minority community and have been reluctant to formulate their religio-cultural demands in the framework of min...

In this study, a microfluidic paper-based analytical device (mu PAD) was integrated with a smartphone app capable of offline (without internet access) image processing and analysis for the rapid colorimetric detection of glucose. A self-inking stamp was used to form hydrophobic channels on a piece of paper-towel due to its superior water absorption efficiency. As demonstrated, the developed sensor was employed for the colorimetric detection of glucose in artificial saliva in the linear scope of 0 - 1 mM with a calculated detection limit of 29.65 mu M. The experimental results show that the quantitative analysis of glucose with the proposed smartphone platform could be completed in less than one minute. The app developed for the smartphone platform is capable of extracting the color-changing area with an embedded image processing tool which could address the problem of color uniformity in the detection zones of mu PAD. The integrated platform has great potential to be used for non-invasive measurements of glucose in body fluids, like tears, sweat and saliva.

Herein, we report the fabrication of zinc oxide nanowire (ZnO NW) coated carbon fiber (CF) ultra-microelectrodes (UME). ZnO NWs were grown on commercial multifilament CFs through hydrothermal process in a teflon-lined autoclave at 90 degrees C for 4 h. X-ray diffraction (XRD), Raman and scanning electron microscopy characterizations showed that crystalline and well oriented NW structures were successfully obtained. The fabrication of the pH sensitive UME was carried out by a novel approach which allowed controlling the protruding length of the modified CF surface. The UME was then integrated with a metal-oxide-semiconductor field effect transistor (MOSFET) for the construction of an EGFET pH-microsensor. The present pH microsensor is expected to be useful for localized pH measurement in small volumes such single cell analysis.

Even though large number of individually addressable electrodes can be effectively assembled in a small area, electrochemical detection methods have a relatively limited ability to detect multiple analytes compared to microdialysis probes and other analytic techniques. Here, we report a facile method for the electro-addressable functionalization of a probe comprising of closely spaced three individually addressable carbon fiber electrodes (CFEs) for the detection of nucleic acids. First, a multi electrode array probe comprising three adjacent CFEs was fabricated through pulling a three-barrel glass capillary with a single carbon fiber in each barrel. Second, electropolymerization based doping was used for the electro-addressable functionalization of the multi-electrode array probe. To demonstrate that the current strategy works, anti-miR-34a was electrografted on only one of three electrodes by the electropolymerization of pyrrole on a specific electrode. A second electrode was coated only with polypyrrole (PPy) and the third was left unmodified. The results demonstrate that the present strategy has great potential for constructing multiplex nucleic acid micro/nano biosensors for local and in situ detection of multiple nucleic acid molecules, such as miRNAs at a time.

WOS: 000452084600028, PubMed ID: 30514892, Optimization of nanofiber (NF) surface properties is critical to achieve an adequate cellular response. Here, the impact of conjugation of biomimetic aspartic acid (ASP) and glutamic acid (GLU) templated peptides with poly(lactic-co-glycolic acid) (PLGA) electrospun NF on osteogenic differentiation of human bone marrow-derived mesenchymal stem cells (hMSCs) was evaluated. Cold atmospheric plasma (CAP) was used to functionalize the NF surface and thus to mediate the conjugation. The influence of the CAP treatment following with peptide conjugation to the NF surface was assessed using water contact angle measurements, Fourier-Transform Infrared Spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS). The effect of CAP treatment on morphology of NF was also checked using Scanning Electron Microscopy (SEM). Both the hydrophilicity of NF and the number of the carboxyl (-COOH) groups on the surface increased with respect to CAP treatment. Results demonstrated that CAP treatment significantly enhanced peptide conjugation on the surface of NF. Osteogenic differentiation results indicated that conjugating of biomimetic ASP templated peptides sharply increased alkaline phosphatase (ALP) activity, calcium content, and expression of key osteogenic markers of collagen type I (Col-I), osteocalcin (OC), and osteopontin (OP) compared to GLU conjugated (GLU-pNF) and CAP treated NF (pNF). It was further depicted that ASP sequences are the major fragments that influence the mineralization and osteogenic differentiation in non-collagenous proteins of bone extracellular matrix., TUBITAK (The Scientific and Technological Research Council of Turkey)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [117S429]; BAP (Scientific Research Projects Fund of Izmir Katip Celebi University) [2016-ONP-MUMF-0022], Authors acknowledge funding from TUBITAK (The Scientific and Technological Research Council of Turkey) through the Research Project 117S429 and BAP (Scientific Research Projects Fund of Izmir Katip Celebi University) through the Research Projects of 2016-ONP-MUMF-0022. Finally, authors would like to acknowledge Bonegraft Biomaterials Co. (Izmir, Turkey) for providing DNA quantification kit, respectively.

In this study, sensitive electrochemical detection of H2O2 and dopamine (DA) was demonstrated using a nanoporous carbon fiber electrode (CFE). SEM images confirmed the surface modification and elemental composition analysis demonstrated an increase in the C/O ratio favoring higher conductivity and electron-transfer rate. Nanoporous CFEs were first used for electrochemical oxidation and reduction of H2O2 and results were compared with those of unmodified CFEs. Oxidation current drastically increased with heat treatment and unlike unmodified CFEs, nanoporous CFEs demonstrated a concentration-dependent current change for the reduction of H2O2. Next, the performance of nanoporous CFEs was assessed for DA detection in comparison to unmodified CFEs and they showed remarkable electrocatalytic activity in terms of both sensitivity and selectivity. The nanoporous CFEs have great potential to be used in various applications ranging from measurements in localized volumes to tissue analysis.

The PC12 cell line has been widely used as an in vitro model for studying neuronal differentiation and identifying the factors affecting the process. It has the ability to differentiate in the presence of nerve growth factor (NGF), resulting in neural extensions called dendrites and axons. In this study, first the impact of randomly distributed multi-walled carbon nanotubes (MWCNTs) in poly(ethylene glycol) dimethacrylate (PEGDMA) on PC12 cell differentiation was investigated in terms of neurite length, number of neurite per cell and differentiation marker gene expression profile. Then, dielectrophoretically aligned MWCNTs in PEGDMA was used to guide and support the neuronal differentiation of PC12 cells in the presence of NGF. The method is expected to be useful in revealing the nanotopographical role in fundamental studies and understanding of nanotopographical effects for biomedical applications on nerve regeneration.

Potassium iodide (KI) and 3,3 ′ ,5,5 ′ -tetramethylbenzidine (TMB) are frequently used as chromogenic agents in μ PADs for glucose determination. Chitosan (Chi) has peroxidase like activity and improves the analytic performance of μ PADs when used in combination with a chromogenic agent. Here, a portable platform incorporating a μ PAD with a smartphone application based on machine learning was developed to quantify glucose concentration in artificial saliva. The detection zones of the μ PAD were modified with three different detection mixtures containing; (i) KI, (ii) KI+Chi and (iii) TMB. After the color change, the images of the μ PADs were taken with four different smartphones under seven different illumination conditions. The images were first processed for feature extraction and then used to train machine learning classifiers, resulting in a more robust and adaptive platform against illumination variation and camera optics. Different machine learning classifiers were tested and the best machine learning classifier for each detection mixture was obtained. Next, a special application called “GlucoSensing” capable of image capture, cropping and processing was developed to make the system more user-friendly. A cloud system was used in the application to communicate with a remote server running machine learning classifiers. Among the three different detection mixtures, the mixture with TMB demonstrated the highest classification accuracy (98.24%) with inter-phone repeatability under versatile illumination.

Proper surface characteristics for a titanium implant are crucial for the formation of different cellular protrusions known as filopodia and lamellipodia, both of which have a significant impact on cell attachment, spreading, migration, and proliferation. Microstructural features such as grain boundaries and defects of implant surface can modulate the cellular components and structure at the leading edge of cells. Here, a nano-grained Ti–29Nb–13Ta–4.6Zr (NG TNTZ) substrate was produced by high-pressure torsion (HPT) for improved biofunctionality. Cellular response of human osteoblast cells on nano-grained TNTZ substrates is evaluated and compared with the cellular response of those on coarse-grained TNTZ. High wettability, which depends on high internal energy due to the nano-sized grains that are full of boundaries, interfaces, and high dislocation density, influenced the hOBs cells on NG TNTZ to form highly developed cellular protrusions. Large number of filopodia protrusions resulted in excellent cell attachment as consistent with high level of vinculin and superior cell proliferation. This study demonstrates the advantages of nanocrystalline surface modification using HPT for processing metallic biomaterials that are proper for orthopedic implants.

In this study, we investigated the ionic current rectification of glass nanopipettes modified with bovine serum albumin - glutaraldehyde (BSA-GA) artificial membrane using solutions with various pHs. Ionic current rectification is a phenomenon that is observed with nanopores as asymmetric I-V curves, where the ionic currents recorded through a nanopore differ at the same magnitude of applied electrical potentials biased with opposite polarities. The results clearly showed that modifying the tip of a nanopipette results in a pH dependent ionic current behavior. The proposed strategy is a facile method for fabrication of a pH responsive nanoprobe that has a potential for intracellular pH measurement., in Turkish, Biomedical Engineering Meeting (BIYOMUT), 2016 20th National

In this study, a facile strategy for fabricating a microfluidic flow cytometer using two glass micropipettes with different sizes and a 3D printed millifluidic aligner was presented. Particle confinement was achieved by hydrodynamic focusing using a single sample and sheath flow. Device performance was extracted using the forward and side-scattered optical signals obtained using fiber-coupled laser and photodetectors. The 3-D printing assisted glass capillary microfluidic device is ultra-low-cost, not labor-intensive and takes less than 10 min to fabricate. The present device offers a great alternative to conventional benchtop flow cytometers in terms of optofluidic configuration.

Vascular grafts should possess the features of being biocompatible, nonthrombogenic, mechanically durable, and simultaneously degraded along with the native vascular tissue formation. Vascular tissue engineering focuses on developing ideal synthetic vascular scaffolds by combining many scaffold manufacturing and modification parameters. Electrospun fibers have received considerable attention due to their features of mimicking the extracellular matrix of many types of tissues, providing high surface area for cell adhesion, proliferation, and adequate porosity for designing vascular tissue-engineered scaffolds. In this chapter, we mainly focused on presenting the features of vascular tissue, fabrication parameters of electrospun scaffolds, and natural and synthetic biomaterials used for vascular tissue engineering along with biological and mechanical properties determining the success of electrospun scaffolds. Finally, we summarized the recent in vivo applications of such scaffolds. Overall, electrospun scaffolds reflect promising results from both in vitro and in vivo studies. However, the gold standard material combination and modification techniques have not yet been optimized. Therefore, long-term stability and satisfactory biological performance of developed electrospun scaffolds should be presented by in vivo studies prior to clinical trials.

In this study, we developed a simple, cost-efficient, and time-saving approach for producing gold (Au) ultramicroelectrodes (UMEs) with different shapes and sizes ranging from one micron to several microns in diameter. A microneedle, in combination with a flame-etched carbon fiber (CF), acts as a template for electrochemical fabrication of Au electrodes. To fabricate spherical and disk-shaped electrodes, a small gap at the tip of the microneedle was formed using CFs whose tips were flame-etched to a size larger than that of the microneedle tip opening. The gap was then electrochemically filled with Au using chronoamperometry. However, to fabricate rod-shaped electrodes, the size of the CF tip was flame-etched to a size smaller than the microneedle tip opening, which resulted in CF to protrude from the microneedle tip opening. Then, the CF surface was electrochemically modified with Au. The whole fabrication process for each electrode took less than 15 min. The fabrication method is quite useful for researchers with limited resources, and the fabricated UMEs have great potential to be used in various applications ranging from constructing nano-/micro-biosensors to single-cell analysis.

Due to their small sizes, carbon based microelectrodes are commonly used for local and highly sensitive detection of electroactive molecules like dopamine in cell and tissues. Increasing the electrode number at the tip of a micro-electrode probe enables simultaneous detection of molecules at multiple points. In this study, probes containing single and multiple carbon fibers were fabricated, respectively. In order to fabricate such electrodes, single and 3-barrel glass capillaries were used. Briefly, carbon fibers were fixed to copper wires so that they can be easily inserted into glass capillaries as one in each barrel. Then the glass capillaries were pulled using a micropuller to insulate the carbon fibers with glass. The probes have the potential to be used for direct detection of dopamine like electroactive molecules as well as for detection of different analytes when each carbon fiber electrode is modified with different enzymes or antibodies.