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"Ocakoglu, Kasım"
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Synthesis of PES membranes modified with polyurethane–paraffin wax nanocapsules and performance of bovine serum albumin and humic acid rejection
by
Dizge, Nadir
,
Ozay, Yasin
,
Ocakoglu, Kasım
in
Albumins
,
Antifouling substances
,
Bovine serum albumin
2023
Membrane fouling is a serious handicap of membrane-based separation, as it reduces permeation flux and hence increases operational and maintenance expenses. Polyurethane–paraffin wax (PU/PW) nanocapsules were integrated into the polyethersulfone membrane to manufacture a composite membrane with higher antifouling and permeability performance against humic acid (HA) and bovine serum albumin (BSA) foulants. All manufactured membranes were characterized by scanning electron microscopy (SEM), scanning electron microscopy-energy dispersive spectrometry (SEM-EDS), and contact angle. The contact angle of the pristine polyethersulfone (PES) membrane was measured 73.40 ± 1.32. With the embedding of nanocapsules, the contact angle decreased to 64.55 ± 1.23 for PES/PU/PW 2.0 wt%, and the pure water flux of all composite membranes increased when compared to pristine PES. The pristine PES membrane also has shown the lowest steady-state fluxes at 45.84 and 46.59 L/m2h for BSA and HA, respectively. With the increase of PU/PW nanocapsule ratio from 0.5 to 1.0 wt%, steady-state fluxes increased from 51.96 to 71.61 and from 67.87 to 98.73 L/m2h, respectively, for BSA and HA. The results depicted that BSA and HA rejection efficiencies of PU/PW nanocapsules blended PES membranes increased when compared to pristine PES membranes.
Journal Article
Antifouling and antibacterial performance evaluation of polyethersulfone membranes modified with AZ63 alloy
by
Dizge, Nadir
,
Gonca, Serpil
,
Kulekci, Mustafa Kemal
in
Alloys
,
Anti-Bacterial Agents - chemistry
,
Anti-Bacterial Agents - pharmacology
2023
Antibacterial membranes have attracted researchers’ interest in recent years as a possible approach for dealing with biofouling on the membrane surface. This research aims to see if blending AZ63 Mg alloy into a polyethersulphone (PES) membrane can improve antifouling and separation properties. The composite membranes’ pure water flux continued to increase from pristine PES to PES/AZ63 2.00 wt%. The results showed that PES/AZ63 2.00 wt% membrane supplied the highest permeate flux of E. coli. The steady-state fluxes of AZ63 composite membranes were 113.24, 104.38 and 44.79 L/m2h for PES/AZ63 2.00 wt%, 1.00 wt%, and 0.50 wt%, respectively. The enhanced biological activity of AZ63 was studied based on antioxidant activity, DNA cleavage, antimicrobial, anti-biofilm, bacterial viability inhibition and photodynamic antimicrobial therapy studies. The maximum DPPH scavenging activity was determined as 81.25% with AZ63. AZ63 indicated good chemical nuclease activity and also showed moderate antimicrobial activity against studied strains. The highest biofilm inhibition of AZ63 was 83.25% and 71.63% towards P. aeruginosa and S. aureus, respectively. The cell viability inhibition activity of AZ63 was found as 96.34% against E. coli. The photodynamic antimicrobial therapy results displayed that AZ63 demonstrated 100% bacterial inhibition when using E. coli.
Journal Article
Solution-Processable Growth and Characterization of Dandelion-like ZnO:B Microflower Structures
by
Kasapoğlu, Ahmet Emre
,
Braun, Artur
,
Harputlu, Ersan
in
Activation energy
,
Aqueous solutions
,
Boron
2022
Intrinsic and dandelion-like microflower nano-rod structures of boron-doped ZnO thin films were synthesized with an ecofriendly and cost-effective chemical bath deposition technique from an aqueous solution of zinc nitrate hexahdyrate [Zn(NO3)2.6H2O] as a precursor solution and boric acid as a doping solution. The boron concentrations were 0.1, 0.3, 0.5, 1.0, 3.0, 5.0, and 7.0 by volume. Scanning electron micrographs showed that doping with boron appears to hinder the vertical alignment of crystallites. Additionally, independent hexagonal nano-rod structures were observed to coalesce together to form dandelion-like structures on the film’s surface. The atomic ratio of the elements was determined via the X-ray photoemission spectrum technique. There were no substantial changes in the vibration structure of the film upon doping in terms of the Raman spectra. The optical band gap of ZnO (3.28 eV) decreased with B doping. The band gap of the ZnO:B film varied between 3.18 and 3.22 eV. The activation energy of the ZnO was calculated as 0.051 eV, whereas that of the ZnO:B film containing 1.0% B was calculated as 0.013 eV at low temperatures (273–348 K), versus 0.072 eV and 0.183 eV at high temperatures (348–523 K), respectively. Consequently, it can be interpreted that the 1% B-doped ZnO, which has the lowest activation energy at both low and high temperatures, may find some application areas such as in sensors for gases and in solar cells.
Journal Article
High-Capacitance Hybrid Supercapacitor Based on Multi-Colored Fluorescent Carbon-Dots
by
Genc, Rukan
,
Alas, Melis Ozge
,
Harputlu, Ersan
in
140/133
,
639/301/357/1017
,
639/925/927/1064
2017
Multi-colored, water soluble fluorescent carbon nanodots (C-Dots) with quantum yield changing from 4.6 to 18.3% were synthesized in multi-gram using dated cola beverage through a simple thermal synthesis method and implemented as conductive and ion donating supercapacitor component. Various properties of C-Dots, including size, crystal structure, morphology and surface properties along with their Raman and electron paramagnetic resonance spectra were analyzed and compared by means of their fluorescence and electronic properties. α-Manganese Oxide-Polypyrrole (PPy) nanorods decorated with C-Dots were further conducted as anode materials in a supercapacitor. Reduced graphene oxide was used as cathode along with the dicationic bis-imidazolium based ionic liquid in order to enhance the charge transfer and wetting capacity of electrode surfaces. For this purpose, we used octyl-bis(3-methylimidazolium)diiodide (C8H16BImI) synthesized by N-alkylation reaction as liquid ionic membrane electrolyte. Paramagnetic resonance and impedance spectroscopy have been undertaken in order to understand the origin of the performance of hybrid capacitor in more depth. In particular, we obtained high capacitance value (C = 17.3 μF/cm
2
) which is exceptionally related not only the quality of synthesis but also the choice of electrode and electrolyte materials. Moreover, each component used in the construction of the hybrid supercapacitor is also played a key role to achieve high capacitance value.
Journal Article
Novel Copper Bearing Schiff Bases with Photodynamic Anti-Inflammatory and Anti-Microbial Activities
by
Ilyas, Gonul
,
Ayaz Furkan
,
Demirbag Burcu
in
Antiinfectives and antibacterials
,
Bacteria
,
Biological activity
2020
Schiff bases and their copper complexes have been previously studied for their anti-inflammatory, anti-tumor as well as anti-microbial activities. Schiff bases can be derivatized to gain photoluminiscence capacity. This property of the schiff bases enables the transfer of the electrons upon absorption of the light at a specific wavelength. In this study, we exploited this attribute of novel copper bearing schiff bases and tested their photodynamic biological activities. These compounds exerted photodynamic anti-inflammatory activities on the in vitro activated mammalian macrophages. Compared with salicylic acid control groups, these novel schiff bases had stronger activity which became more prominent with photo-induction. Moreover, they also had anti-microbial activity on gram negative bacteria E.coli and gram positive bacteria S.aureus.This anti-microbial activity was stronger than that of Neomycin on both bacterial strains. Our results suggest their potential use as anti-inflammatory and anti-microbial agents both in the dark as well as after photo-induction.
Journal Article
Selective Photokilling of Human Pancreatic Cancer Cells Using Cetuximab-Targeted Mesoporous Silica Nanoparticles for Delivery of Zinc Phthalocyanine
2018
Background: Photodynamic therapy (PDT) is a non-invasive and innovative cancer therapy based on the photodynamic effect. In this study, we sought to determine the singlet oxygen production, intracellular uptake, and in vitro photodynamic therapy potential of Cetixumab-targeted, zinc(II) 2,3,9,10,16,17,23,24-octa(tert-butylphenoxy))phthalocyaninato(2-)-N29,N30,N31,N32 (ZnPcOBP)-loaded mesoporous silica nanoparticles against pancreatic cancer cells. Results: The quantum yield (ΦΔ) value of ZnPcOBP was found to be 0.60 in toluene. In vitro cellular studies were performed to determine the dark- and phototoxicity of samples with various concentrations of ZnPcOBP by using pancreatic cells (AsPC-1, PANC-1 and MIA PaCa-2) and 20, 30, and 40 J/cm2 light fluences. No dark toxicity was observed for any sample in any cell line. ZnPcOBP alone showed a modest photodynamic activity. However, when incorporated in silica nanoparticles, it showed a relatively high phototoxic effect, which was further enhanced by Cetuximab, a monoclonal antibody that targets the Epidermal Growth Factor Receptor (EGFR). The cell-line dependent photokilling observed correlates well with EGFR expression levels in these cells. Conclusions: Imidazole-capped Cetuximab-targeted mesoporous silica nanoparticles are excellent vehicles for the selective delivery of ZnPcOBP to pancreatic cancer cells expressing the EGFR receptor. The novel nanosystem appears to be a suitable agent for photodynamic therapy of pancreatic tumors.
Journal Article
Surface modification of polyethersulfone membranes with alkaline protease-activated L-histidine zwitterion carbon dots to improve anti-protein fouling
by
Dizge, Nadir
,
Elsehly, Emad M.
,
Ocakoglu, Kasim
in
Acids
,
Activated carbon
,
Alkaline protease
2025
In this study, L-histidine zwitterionic carbon dots (HZCDs) were synthesized using the hydrothermal method. The synthesized HZCDs were used to modify polyethersulfone (PES) membranes. Additionally, the HZCDs-modified membranes were activated using the protease enzyme to prepare protease-activated composite membranes. The prepared materials underwent extensive characterization and validation using various techniques, including Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), and X-ray Diffraction (XRD) analyses. The blending or activation of HZCDs by the protease enzyme reduced the contact angle of the prepared membranes. The contact angle decreased from 78.75° to 50.12° and 40.02° for 2.0 wt.% HZCDs-PES and PES/Protease-HZCDs membranes, respectively. As the contact angle decreased, the hydrophilic nature of the prepared membranes increased, reflecting a strong affinity for water and efficient wettability. In this context, the pure water flux (PWF) values of PES membranes increased from 140.5 ± 5.3 to 248.7 ± 8.4 L/m
2
.h with rising HZCDs amount from 0 to 2 wt.% HZCDs-PES. Additionally, PWF values for protease-activated composite membranes increased from 140.5 ± 5.3 to 321.1 ± 9.2 L/m
2
. h. BSA flux values of PES membranes increased from 56.4 ± 2.4 to 82.9 ± 0.9 L/m
2
.h with increasing HZCDs amount from 0 to 2.0 wt.% HZCDs-PES. Besides, BSA values for protease-activated composite membranes increased from 56.4 ± 2.4 to 89.8 ± 2.2 L/m
2
.h. The purpose of this modification was to impart hydrophilic properties to the PES membrane and address the issue of membrane fouling, which is a common problem in filtration processes. 2.0 wt.% HZCDs-PES and enzyme-activated membranes PES membranes demonstrated 100% BSA removal efficiency. Also, 2.0 wt.% HZCDs-blended membranes and 2.0 wt.% protease-HZCDs-blended membranes demonstrated remarkable antifouling properties up to 87.7% and 88.8% flux recovery ratio (FRR), respectively. In contrast, BSA flux recovery reached only 67.8% for the pristine PES. When compared to pristine PES membranes, enzyme-activated membranes demonstrated superior filtration and protein rejection efficiencies.
Journal Article
The electronic and optoelectronic properties of Al/hydroxymethyl functionalized Zn(II)Pc/p-Si photonic device
by
Al-Sehemi, Abdullah G.
,
Ince, Mine
,
Karabulut, Abdulkerim
in
Aluminum
,
Characterization and Evaluation of Materials
,
Chemistry
2024
In this study, the effects of illumination on the electronic and optoelectronic properties of Al/hydroxymethyl functionalized Zn(II)Pc/
p
-Si/Al photonic device have been investigated under dark and various lighting conditions. The diode’s electronic parameters have been extracted from the current–voltage characteristics. It is observed that the dark current value increases when the light is illuminated on the device, and thus, the photocurrent is formed, and this result has shown that the studied device exhibits a photoconductive behavior. The photoresponse properties of the fabricated device have been examined by transient photocurrent measurements under 100 mW/cm
2
illumination, and they have also been analyzed using photocapacitance and photoconductivity measurements at different frequencies (100 kHz, 500 kHz, and 1 MHz). However, the capacitance data that may occur between the poles of the produced device have also been investigated, and it is thought that the device can also be developed as a capacitor. These results confirm that the hydroxymethyl functionalized Zn(II)Pc and
p
-silicon semiconductor-based device can be used particularly in electro-optic and photonic applications.
Journal Article
Development of a Novel Nanoarchitecture of the Robust Photosystem I from a Volcanic Microalga Cyanidioschyzon merolae on Single Layer Graphene for Improved Photocurrent Generation
by
Ersan Harputlu
,
Shinya Miyagishima
,
Takayuki Fujiwara
in
biohybrid nanodevices
,
biophotovoltaics
,
Cell division
2021
Here, we report the development of a novel photoactive biomolecular nanoarchitecture based on the genetically engineered extremophilic photosystem I (PSI) biophotocatalyst interfaced with a single layer graphene via pyrene-nitrilotriacetic acid self-assembled monolayer (SAM). For the oriented and stable immobilization of the PSI biophotocatalyst, an His6-tag was genetically engineered at the N-terminus of the stromal PsaD subunit of PSI, allowing for the preferential binding of this photoactive complex with its reducing side towards the graphene monolayer. This approach yielded a novel robust and ordered nanoarchitecture designed to generate an efficient direct electron transfer pathway between graphene, the metal redox center in the organic SAM and the photo-oxidized PSI biocatalyst. The nanosystem yielded an overall current output of 16.5 µA·cm−2 for the nickel- and 17.3 µA·cm−2 for the cobalt-based nanoassemblies, and was stable for at least 1 h of continuous standard illumination. The novel green nanosystem described in this work carries the high potential for future applications due to its robustness, highly ordered and simple architecture characterized by the high biophotocatalyst loading as well as simplicity of manufacturing.
Journal Article
Separation and preconcentration of mercury in water samples by ionic liquid supported cloud point extraction and fluorimetric determination
by
Ocakoglu, Kasim
,
Bozkurt, Serap Seyhan
,
Merdivan, Melek
in
Analysis
,
Analytical Chemistry
,
Aqueous solutions
2012
We have developed a cloud point extraction procedure based on room temperature ionic liquid for the preconcentration and determination of mercury in water samples. Mercury ion was quantitatively extracted with tetraethyleneglycol-bis(3- methylimidazolium) diiodide in the form of its complex with 5,10,15,20-tetra-(4-phenoxyphenyl)porphyrin. The complex was back extracted from the room temperature ionic liquid phase into an aqueous media prior to its analysis by spectrofluorimetry. An overall preconcentration factor of 45 was accomplished upon preconcentration of a 20 mL sample. The limit of detection obtained under the optimal conditions is 0.08 μg mL
−1
, and the relative standard deviation for 10 replicate assays (at 0.5 g mL
−1
of Hg) was 2.4%. The method was successfully applied to the determination of mercury in tap, river and mineral water samples.
Figure
In this work, a novel and sensitive analytical methodology for mercury preconcentration and determination in different water samples using ionic liquid was developed. The use of room temperature ionic liquid‘s biphasic systems as an alternative to conventional solvents offers several advantages including safety and high capacity to extract Hg(II) and other elements with high recoveries. İonic liquid in combination with porphyrin complexing reagent was successfully applied in this study for the extraction and preconcentration of Hg(II). Likewise, a fast and quantitative back extraction of the analyte from room temperature ionic liquid phase into aqueous phase was possible, allowing its further determination by spectrofluorimetry. The preconcentration method allowed mercury determination in tap, river and mineral water samples at trace levels with high accuracy and reproducibility.
Journal Article