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https://hdl.handle.net/20.500.12428/2631

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Preparation of composite hydrogels containing fly ash as low-cost adsorbent material and its use in dye adsorption
(Springer Science and Business Media Deutschland GmbH, 2022) Önder, Alper; Ilgın, Pınar; Özay, Hava; Özay, Özgür
Abstract: Recycling industrial wastes is necessary for the economy and the environment. Additionally, it is important to develop high-efficiency adsorbents to prevent severe water pollution caused by wastewater containing dye agents. Here, poly(2-acrylamido-2-methylpropane sulfonic acid)-fly ash composite hydrogel was synthesized with a variety of fly ash proportions with the radical polymerization method. The synthesized composite hydrogel was used for adsorption of methylene blue and methyl orange dyes from water containing dye agents. A variety of parameters such as initial dye concentration, solution pH, anion effects, temperature, contact time and adsorbent amount were investigated for optimization of the adsorption process. The poly(2-acrylamido-2-methylpropane sulfonic acid)-fly ash composite hydrogel was determined to be an effective adsorbent to remove both the cationic dye methylene blue (1438.68 mg g−1) and the anionic dye methyl orange (646.54 mg g−1). Experimental adsorption data were assessed with a variety of isotherm and kinetic models. It was determined that the adsorption of both dye molecules abided by the pseudo-second-order kinetic model. The thermodynamic parameters were determined as ΔH° = − 15.77 ± 5.22 kJ mol−1, ΔS = − 45.05 ± 16.42 J mol−1 K−1 and ΔG° < 0 for MB, ΔH° = − 20.13 ± 4.83 kJ mol−1, ΔS = − 72.87 ± 15.20 J mol−1 K−1 and ΔG° > 0 for MO. In conclusion, a material was synthesized that can be used as a single adsorbent composite material for both anionic and cationic dyes. In addition to the perfect adsorption capacity of this material, it offers reusability and a broad area of application for a variety of dye agents.
Super Porous Carboxymethyl Cellulose–Tannic Acid (TA@CMC) Cryogels with Antioxidant, Antibacterial, and α-Glucosidase Enzyme Inhibition Abilities
(Mdpi, 2024) Şahiner, Mehtap; Demirci, Şahin; Şahiner, Nurettin
Here, super porous carboxymethyl cellulose (CMC) cryogels were synthesized in 10-100% crosslinker and the presence of TA, at varying amounts of TA, e.g., 10 and 25 wt% of CMC under cryogenic conditions (-20 degrees C) as TA@CMCs. To control the degradation of CMC cryogel networks, the crosslinking ratio of divinyl sulfone (DVS:X) to CMC varied at 10, 25, 50, and 100% moles of the CMC repeating unit. Higher hydrolytic degradation was observed for CMC 10%X cryogels at pH 1.0 with 28.4 +/- 1.2% weight loss. On the other hand, the TA-release studies from TA@CMC-based cryogels showed that higher TA releases were observed for both TA@CMC 10% and 25% cryogels at pH 7.4, with 23.6 +/- 1.1, and 46.5 +/- 2.3 mg/g in 480 min, which are equal to almost 24% and 18% of the TA contents of the corresponding cryogels, respectively. The antioxidant properties of TA@CMC cryogels were examined, and worthy antioxidant properties were observed due to the TA. The alpha-glucosidase enzyme inhibition ability of the prepared cryogels was examined at different concentrations by grinding cryogels, and it was determined that TA@CMC 25% cryogel at 3 mg/mL concentration inhibited 70.4 + 1.3% of the enzyme. All bare CMC-based cryogels were found to be non-hemolytic with a less than 1% hemolysis ratio and also effective on the blood coagulation mechanism with blood-clotting index (BCI) values between 62.1 and 81.7% at 1 mg/mL concentrations. On the other hand, TA@CMC 25% cryogels exhibited a slight hemolytic profile with a 6.1 +/- 0.8% hemolysis ratio and did not affect the blood coagulation mechanism with 97.8 +/- 0.4% BCI value.
Polydopamine Coating of Graphitic Carbon Nitride, g-C3N4, Improves Biomedical Application
(Mdpi, 2024) Şahiner, Mehtap; Demirci, Şahin; Şahiner, Nurettin
Graphitic carbon nitride (g-C3N4) is an intriguing nanomaterial that exhibits photoconductive fluorescence properties under UV-visible light. Dopamine (DA) coating of g-C3N4 prepared from melamine was accomplished via self-polymerization of DA as polydopamine (PDA). The g-C3N4 was coated with PDA 1, 3, and 5 times repeatedly as (PDA@g-C3N4) in tris buffer at pH 8.5. As the number of PDA coatings was increased on g-C3N4, the peak intensity at 1512 cm(-1) for N-H bending increased. In addition, the increased weight loss values of PDA@g-C3N4 structures at 600 degrees C from TGA thermograms confirmed that the coating was accomplished. The band gap of g-C3N4, 2.72 eV, was reduced to 0.87 eV after five coatings with PDA. A pristine g-C3N4 was found to have an isoelectric point (IEP) of 4.0, whereas the isoelectric points of 1PDA@g-C3N4 and 3PDA@g-C3N4 are close to each other at 3.94 and 3.91, respectively. On the other hand, the IEP of 5PDA@g-C3N4 was determined at pH 5.75 assuming complete coating with g-C3N4. The biocompatibility of g-C3N4 and PDA@g-C3N4 against L929 fibroblast cell lines revealed that all PDA@g-C3N4 coatings were found to be biocompatible up to a 1000 mg/mL concentration, establishing that PDA coatings did not adversely affect the biocompatibility of the composite materials. In addition, PDA@g-C3N4 was screened for antioxidant potential via total phenol content (TPC) and total flavonoid content assays and it was found that PDA@g-C3N4 has recognizable TPC values and increased linearly with an increased number of PDA coatings. Furthermore, blood compatibility of pristine g-C3N4 is enhanced considerably upon PDA coating, affirmed by hemolysis and the blood clotting index%. Additionally, alpha-glucosidase inhibitory properties of PDA@g-C3N4 structures revealed that 67.6 + 9.8% of this enzyme was evenly inhibited by 3PDA@g-C3N4 structure.
Nitrogen Doped Carbon-Dot Embedded Poly(lactic acid-co-glycolic acid) Composite Films for Potential Use in Food Packing Industry and Wound Dressing
(Mdpi, 2022) Şahiner, Mehtap; Ari, Betül; Ram, Manoj K.; Şahiner, Nurettin
Here, nitrogen-doped carbon dots (N-doped CDs) were synthesized by the hydrothermal method embedded within poly(lactic acid-co-glycolic acid) ((PLGA)) films at different amounts. The N-doped CDs (or CD) that possess fluorescence properties also have antimicrobial properties against S. aureus and E. coli microorganisms, determined by the disc diffusion method with 19 +/- 2 and 18 +/- 1 mm zone diameters, respectively. The CD embedded PLGA films (CD@PLGA) with different CD contents revealed an increased fluorescence intensity with the increased amount of CD. Moreover, the antibacterial potency of 50% CD containing PLGA (50-CD@PLGA) films (by weight) against S. aureus and E. coli microorganisms was examined and the zone diameters were found to be 14 +/- 1 and 13 +/- 1 mm, respectively. In addition, CD release studies from different amounts of CD (2.5-50 by weight) containing composite films showed that 50-CD@PLGA film released 127 +/- 16 mg/g CD dots, which is 38 +/- 5% of the embedded CDs in about 12 days, suggesting their potential application in food packing and wound dressing. Moreover, all CD@PLGA films were found to be blood compatible via hemolysis and blood clotting index tests with 90% blood clotting indices regardless of their CD content.
Light-Activated Modified Arginine Carbon Dots as Antibacterial Particles
(Mdpi, 2022) Sağbaş Suner, Selin; Şahiner, Mehtap; Yılmaz, Aynur Sanem; Ayyala, Ramesh S.; Şahiner, Nurettin
Nitrogen-doped arginine carbon dots (Arg CDs) as light-sensitive antibacterial agents were prepared by using citric acid as the carbon source and arginine amino acid as the nitrogen source via a microwave-assisted synthesis method. Dynamic light scattering (DLS) measurements and TEM images revealed that the Arg CDs were in the 1-10 nm size range with a graphitic structure. To improve their antibacterial capability, the Arg CDs were modified with ethyleneimine (EDA), pentaethylenehexamine (PEHA), and polyethyleneimine (PEI) as different amine sources, and the zeta potential value of +2.8 +/- 0.6 mV for Arg CDs was increased to +34.4 +/- 4.1 mV for PEI-modified Arg CDs. The fluorescence intensity of the Arg CDs was significantly enhanced after the modification with EDA, and the highest antibacterial effect was observed for the PEI-modified Arg CDs. Furthermore, the photodynamic antibacterial capacity of bare and EDA-modified Arg CDs was determined upon light exposure to show their light-induced antibacterial effects. Photoexcited (315-400 nm, UVA, 300 W), EDA-modified Arg CDs at 5 mg/mL concentration were found to inhibit about 49 +/- 7% of pathogenic bacteria, e.g., Escherichia coli, with 5 min of light exposure. Furthermore, the biocompatibilities of the bare and modified Arg CDs were also investigated with blood compatibility tests via hemolysis and blood clotting assays and cytotoxicity analysis on L929 fibroblast cells.
Degradable and Non-Degradable Chondroitin Sulfate Particles with the Controlled Antibiotic Release for Bacterial Infections
(Mdpi, 2022) Sağbaş Suner, Selin; Şahiner, Mehtap; Ayyala, Ramesh S.; Şahiner, Nurettin
Non-degradable, slightly degradable, and completely degradable micro/nanoparticles derived from chondroitin sulfate (CS) were synthesized through crosslinking reactions at 50%, 40%, and 20% mole ratios, respectively. The CS particles with a 20% crosslinking ratio show total degradation within 48 h, whereas 50% CS particles were highly stable for up to 240 h with only 7.0 +/- 2.8% weight loss in physiological conditions (pH 7.4, 37 degrees C). Tobramycin and amikacin antibiotics were encapsulated into non-degradable CS particles with high loading at 250 g/mg for the treatment of corneal bacterial ulcers. The highest release capacity of 92 +/- 2% was obtained for CS-Amikacin particles with sustainable and long-term release profiles. The antibacterial effects of CS particles loaded with 2.5 mg of antibiotic continued to render a prolonged release time of 240 h with 24 +/- 2 mm inhibition zones against Pseudomonas aeruginosa. Furthermore, as a carrier, CS particles significantly improved the compatibility of the antibiotics even at high particle concentrations of 1000 g/mL with a minimum of 71 +/- 7% fibroblast cell viability. In summary, the sustainable delivery of antibiotics and long-term treatment of bacterial keratitis were shown to be afforded by the design of tunable degradation ability of CS particles with improved biocompatibility for the encapsulated drugs.
The Use of Low-Quality Cotton-Derived Cellulose Films as Templates for In Situ Conductive Polymer Synthesis as Promising Biomaterials in Biomedical Applications
(Wiley-V C H Verlag Gmbh, 2025) Demirci, Şahin; Şahiner, Mehtap; Rumi, Shaida S.; Sağbaş Suner, Selin; Abidi, Noureddine; Şahiner, Nurettin
Here, the use of cellulose films (CFs) produced from low-quality cotton is reported as a template for in situ synthesis of well-known conductive polymers, e.g., polyaniline (PANI) and polypyrrole (PPY) via oxidative polymerization. Three successive monomer loading/polymerization cycles of aniline (ANI) and pyrrole (PY) within CFs as PANI@CF or PPY@CF are carried out to increase the amount of conductive polymer content. The contact angle (CA) for three times ANI and PPY loaded and polymerized CFs as 3PANI@CF and 3PPY@CF are determined as 26.3 +/- 2.8 and 42.3 +/- 0.6 degrees, respectively. As the electrical conductivity is increased with increased number of conductive polymer synthesis within CF, the higher conductivity values, 3x10-4 +/- 8.1x10-5 S.cm-1 and 2.1x10-3 +/- 5.8x10-4 S.cm-1, respectively are measured for 3PANI@CF and 3PPY@CF composites. It is found that PANI@CF composites are hemolytic, whereas PPY@CF composites are not at 1 mg mL-1 concentrations. All PPY@CF composites exhibit better biocompatibility than PANI@CF composites on L929 fibroblast cells with more than 70 +/- 8% viability at 1 mg of CF-based conductive polymer composites. Moreover, MIC and MBC values of 3PPY@CF composites for Escherichia coli (ATCC8739) and Staphylococcus aureus (ATCC6538) are determined as 2.5 and 5.0 mg.mL-1, whereas these values are estimated as 5 and 10 mg.mL-1 for Candida albicans (ATCC10231). Cotton fibers are dissolved in N, N-dimethylacetamide/lithium chloride (DMAc/LiCl) solvent system and converted cellulose solutions to strong, transparent, and flexible films through casting, gelation, regeneration, plasticization, and hot-pressing. The prepared cellulose films (CFs) are used as a template for in situ synthesis of polyaniline (PANI) and polypyrrole (PPY) polymers to attain electroactive cellulose based composites with intriguing biomedical properties. image
Slightly degradable, naturally antibacterial hydrogel matrixes derived from polyvinyl alcohol and linear/branched-polyethyleneimine as a wound dressing material
(Taylor & Francis Inc, 2024) Ari, Betül; Sağbaş Suner, Selin; Şahiner, Mehtap; Demirci, Şahin; Şahiner, Nurettin
PVA:PEI based film gels were prepared at various weight ratios, 10-100% of linear-PEI (L-PEI) and branched-PEI (B-PEI) to PVA as PVA:L-PEI or PVA:B-PEI to demonstrate the effect of PEI types on hydrolytic degradation, blood compatibility, antibacterial properties, and cytotoxicity. The hydrolytic degradation studies, done at similar to skin pH, 5.4 and revealed that PVA:PEI-based film gels, 1:0.1 wt% are degradable with a gravimetric weight losses of16.80 +/- 1.39% and 17.20 +/- 1.21% up to 7 days, and decreased as the wt% of L-PEI and B-PEI were increased in the matrix. The blood compatibility assays done through hemolysis and blood clotting tests disclosed only PVA:B-PEI film gels at 1.0 mg/mL concentration were found blood compatible. The antimicrobial studies revealed that regardless of the types and weight ratio of L-PEI or B-PEI, all PVA:L-PEI and PVA:B-PEI based film gels possess a potent antibacterial activity against Pseudomonas aeruginosa, a gram-negative bacteria and Staphylococcus aureus, a gram-positive bacteria. Moreover, the cytotoxicity test results examined on the L929 cell line uncovered that only PVA:L-PEI and PVA:B-PEI even at very low concentrations of L-PEI or B-PEI, for example, PVA:L-PEI and PVA:B-PEI at 1:0.1 weight ratio film gel at 10 mg/mL show toxic effect, for example <50% cell viability suggesting lesser concentration use in biomedical applications.
Bio-MOFs Based on Natural Phenolic, Hematoxylin Leverages Biomedical Applications: Enzyme Inhibition, Antioxidant, and Antibacterial Properties
(Wiley-V C H Verlag Gmbh, 2024) Şahiner, Mehtap; Tian, Zhi; Demirci, Şahin; Sunol, Aydın; Allen-Gipson, Diane S.; Şahiner, Nurettin
Here, using natural hematoxylin (HT) as linker, metal-organic frameworks (MOFs) from Cu(II), Fe(II), and Fe(III) ions was prepared. The SEM images and DLS analyses revealed HT-based MOFs are
Carboxymethyl Chitosan Microgels for Sustained Delivery of Vancomycin and Long-Lasting Antibacterial Effects
(Mdpi, 2023) Şahiner, Mehtap; Yılmaz, Aynur Sanem; Ayyala, Ramesh S.; Şahiner, Nurettin
Carboxymethyl chitosan (CMCh) is a unique polysaccharide with functional groups that can develop positive and negative charges due to the abundant numbers of amine and carboxylic acid groups. CMCh is widely used in different areas due to its excellent biocompatibility, biodegradability, water solubility, and chelating ability. CMCh microgels were synthesized in a microemulsion environment using divinyl sulfone (DVS) as a crosslinking agent. CMCh microgel with tailored size and zeta potential values were obtained in a single stem by crosslinking CMCh in a water-in-oil environment. The spherical microgel structure is confirmed by SEM analysis. The sizes of CMCh microgels varied from one micrometer to tens of micrometers. The isoelectric point of CMCh microgels was determined as pH 4.4. Biocompatibility of CMCh microgels was verified on L929 fibroblasts with 96.5 & PLUSMN; 1.5% cell viability at 1 mg/mL concentration. The drug-carrying abilities of CMCh microgels were evaluated by loading Vancomycin (Van) antibiotic as a model drug. Furthermore, the antibacterial activity efficiency of Van-loaded CMCh microgels (Van@CMCh) was investigated. The MIC values of the released drug from Van@CMCh microgels were found to be 68.6 and 7.95 & mu;g/mL against E. coli and S. aureus, respectively, at 24 h contact time. Disk diffusion tests confirmed that Van@CMCh microgels, especially for Gram-positive (S. aureus) bacteria, revealed long-lasting inhibitory effects on bacteria growth up to 72 h.
Super-Macroporous Pulluan Cryogels as Controlled Active Delivery Systems with Controlled Degradability
(Mdpi, 2023) Ari, Betül; Şahiner, Mehtap; Sağbaş Suner, Selin; Demirci, Şahin; Şahiner, Nurettin
Here, super-macroporous cryogel from a natural polysaccharide, pullulan was synthesized using a cryo-crosslinking technique with divinyl sulfone (DVS) as a crosslinker. The hydrolytic degradation of the pullulan cryogel in various simulated body fluids (pH 1.0, 7.4, and 9.0 buffer solutions) was evaluated. It was observed that the pullulan cryogel degradation was much faster in the pH 9 buffer solution than the pH 1.0 and 7.4 buffer solutions in the same time period. The weight loss of the pullulan cryogel at pH 9.0 within 28 days was determined as 31% & PLUSMN; 2%. To demonstrate the controllable drug delivery potential of pullulan cryogels via degradation, an antibiotic, ciprofloxacin, was loaded into pullulan cryogels (pullulan-cipro), and the loading amount of drug was calculated as 105.40 & PLUSMN; 2.6 & mu;g/mg. The release of ciprofloxacin from the pullulan-cipro cryogel was investigated in vitro at 37.5 & DEG;C in physiological conditions (pH 7.4). The amount of drug released within 24 h was determined as 39.26 & PLUSMN; 3.78 & mu;g/mg, which is equal to 41.38% & PLUSMN; 3.58% of the loaded drug. Only 0.1 mg of pullulan-cipro cryogel was found to inhibit half of the growing Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) colonies for 10 min and totally eradicated within 2 h by the release of the loaded antibiotic. No significant toxicity was determined on L929 fibroblast cells for 0.1 mg drug-loaded pullulan cryogel. In contrast, even 1 mg of drug-loaded pullulan cryogel revealed slight toxicity (e.g., 66% & PLUSMN; 9% cell viability) because of the high concentration of released drug.
Therapeutic and Nutraceutical Effects of Polyphenolics from Natural Sources
(Mdpi, 2022) Şahiner, Mehtap; Yılmaz, Aynur Sanem; Güngör, Buket; Ayoubi, Yasmin; Şahiner, Nurettin
The prevalence of cardiovascular disease, oxidative stress-related complications, and chronic age-related illnesses is gradually increasing worldwide. Several causes include the ineffectiveness of medicinal treatment therapies, their toxicity, their inability to provide radical solutions in some diseases, and the necessity of multiple drug therapy in certain chronic diseases. It is therefore necessary for alternative treatment methods to be sought. In this review, polyphenols were identified and classified according to their chemical structure, and the sources of these polyphenol molecules are indicated. The cardioprotective, ROS scavenging, anti-aging, anticancer properties of polyphenolic compounds have been demonstrated by the results of many studies, and these natural antioxidant molecules are potential alternative therapeutic agents.
Fluorescent Graphitic Carbon Nitride (g-C3N4)-Embedded Hyaluronic Acid Microgel Composites for Bioimaging and Cancer-Cell Targetability as Viable Theragnostic
(Mdpi, 2024) Sağbaş Suner, Selin; Şahiner, Mehtap; Demirci, Şahin; Umut, Evrim; Şahiner, Nurettin
Fluorescent graphitic carbon nitride (g-C3N4) doped with various heteroatoms, such as B, P, and S, named (B)g-C3N4, (P)g-C3N4, and (S)g-C3N4, were synthesized with variable band-gap values as diagnostic materials. Furthermore, they were embedded within hyaluronic acid (HA) microgels as g-C3N4@HA microgel composites. The g-C3N4@HA microgels had a 0.5-20 mu m size range that is suitable for intravenous administration. Bare g-C3N4 showed excellent fluorescence ability with 360 nm excitation wavelength and 410-460 emission wavelengths for possible cell imaging application of g-C3N4@HA microgel composites as diagnostic agents. The g-C3N4@HA-based microgels were non-hemolytic, and no clotting effects on blood cells or cell toxicity on fibroblasts were observed at 1000 mu g/mL concentration. In addition, approximately 70% cell viability for SKMEL-30 melanoma cells was seen with Sg-C3N4 and its HA microgel composites. The prepared g-C3N4@HA and Sg-C3N4@HA microgels were used in cell imaging because of their excellent penetration capability for healthy fibroblasts. Furthermore, g-C3N4-based materials did not interact with malignant cells, but their HA microgel composites had significant penetration capability linked to the binding function of HA with the cancerous cells. Flow cytometry analysis revealed that g-C3N4 and g-C3N4@HA microgel composites did not interfere with the viability of healthy fibroblast cells and provided fluorescence imaging without any staining while significantly decreasing the viability of cancerous cells. Overall, heteroatom-doped g-C3N4@HA microgel composites, especially Sg-C3N4@HA microgels, can be safely used as multifunctional theragnostic agents for both diagnostic as well as target and treatment purposes in cancer therapy because of their fluorescent nature.
Polyelectrolyte Chondroitin Sulfate Microgels as a Carrier Material for Rosmarinic Acid and Their Antioxidant Ability
(Mdpi, 2022) Şahiner, Mehtap; Suner, Selin S.; Yılmaz, Aynur S.; Şahiner, Nurettin
Polyelectrolyte microgels derived from natural sources such as chondroitin sulfate (CS) possess considerable interest as therapeutic carriers because of their ionic nature and controllable degradation capability in line with the extent of the used crosslinker for long-term drug delivery applications. In this study, chemically crosslinked CS microgels were synthesized in a single step and treated with an ammonia solution to attain polyelectrolyte CS-[NH4](+) microgels via a cation exchange reaction. The spherical and non-porous CS microgels were injectable and in the size range of a few hundred nanometers to tens of micrometers. The average size distribution of the CS microgels and their polyelectrolyte forms were not significantly affected by medium pH. It was determined that the -34 +/- 4 mV zeta potential of the CS microgels was changed to -23 +/- 3 mV for CS- [NH4](+) microgels with pH 7 medium. No important toxicity was determined on L929 fibroblast cells, with 76 +/- 1% viability in the presence of 1000 mu g/mL concentration of CS-[NH4](+) microgels. Furthermore, these microgels were used as a drug carrier material for rosmarinic acid (RA) active agent. The RA-loading capacity was about 2.5-fold increased for CS-[R](+) microgels with 32.4 +/- 5.1 mu g/mg RA loading, and 23% of the loaded RA was sustainably release for a long-term period within 150 h in comparison to CS microgels. Moreover, RA-loaded CS-[R](+) microgels exhibited great antioxidant activity, with 0.45 +/- 0.02 mu mol/g Trolox equivalent antioxidant capacity in comparison to no antioxidant properties for bare CS particles.
Enhanced Bioactive Properties of Halloysite Nanotubes via Polydopamine Coating
(Mdpi, 2022) Şahiner, Mehtap; Demirci, Şahin; Şahiner, Nurettin
Halloysite nanotubes (HNT) were coated five times with dopamine (DOPA) in a tris buffer medium at pH 8.5 to acquire polydopamine-coated HNTs (PDOPA@HNT), e.g., PDOPA1@HNT, PDOPA3@HNT, and PDOPA5@HNT. Upon coating HNT with PDOPA, the surface area, pore volume, and pore size were decreased depending on the number of coatings. While the surface area of HNT was 57.9 m(2)/g, by increasing the number of coatings from 1 to 5, it was measured as 55.9, 53.4, 53.3, 47.4, and 46.4 m(2)/g, respectively. The isoelectric point (IEP) for HNTs was determined as 4.68, whereas these values are estimated as 2.31 for PDOPA1@HNTs, 3.49 for PDOPA3@HNT, and 3.55 for PDOPA5@HNT. Three different antioxidant studies were conducted for HNT and PDOPA@HNT, and the total phenol (TPC) value of HNT was found to be 150.5 +/- 45.9 mu mol gallic acid (GA) equivalent. The TPC values for PDOPA1@HNT, PDOPA3@HNT and PDOPA5@HNT coatings were found to be 405.5 +/- 25.0, 750.0 +/- 69.9, and 1348.3 +/- 371.7 mu mol GA equivalents, respectively. The Fe(II) chelation capacity of HNT was found to be 20.5% +/- 1.2%, while the PDOPA1@HNT, PDOPA3@HNT and PDOPA5@HNT values were found to be 49.9 +/- 6.5, 36.6 +/- 12.7 and 25.4 +/- 1.2%, respectively. HNT and PDOPA@HNTs inhibited the alpha-glucosidase (AG) enzyme to greater extents than acetylcholinesterase (AChE). As a result, the DOPA modification of HNTs was rendered to provide additional characteristics, e.g., antioxidant properties and higher AChE and AG enzymes inhibition capabilities. Therefore, PDOPA@HNTs have great potential as biomaterials.
Synthesis and Characterization of a New Cryogel Matrix for Covalent Immobilization of Catalase
(MDPI, 2022) Altunbaş, Canan; Aslan, Ahmet; Kusat, Kevser; Şahiner, Mehtap; Akgöl, Sinan; Şahiner, Nurettin
The advantages of cryogels for enzyme immobilization applications include their mechanical and chemical robustness, ease of production, superior porosity, and low cost. Currently, many researchers are exploring porous material-based systems for enzyme immobilization that are more efficient and economically viable. Here, poly(2-Hydroxyethyl methacrylate-co-allyl glycidyl ether) (p(HEMA-co-AGE)) cryogel matrices were synthesized via the free radical cryopolymerization method to be employed as the support material. For the immobilization of the catalase enzyme onto the p(HEMA-co-AGE) cryogel matrix (catalase@p(HEMA-co-AGE), the best possible reaction conditions were determined by altering parameters such as pH, catalase initial concentration, and flow rate. The maximum catalase immobilization amount onto the p(HEMA-co-AGE) cryogel was found to be 48 mg/g cryogel. To determine the advantages of the cryogel matrix, e.g., the stability and reusability of the cryogel matrix, the adsorption-desorption cycles for the catalase enzyme were repeated five times using the same cryogel matrix. At the end of the reusability tests, it was found that the cryogel was very stable and maintained its adsorption capacity with the recovery ratio of 93.8 +/- 1.2%. Therefore, the p(HEMA-co-AGE) cryogel matrix affords repeated useability, e.g., up to five times, without decreasing its catalase binding capacities significantly and has promising potential for many industrial applications. Cryogels offer clear distinctive advantages over common materials, e.g., micro/nano particles, hydrogels, films, and composites for these applications. At present, many researchers are working on the design of more effective and economically feasible, porous material-based systems for enzyme immobilization
Functionalized carbon nanomaterials: Fabrication, properties and potential applications
(Elsevier, 2022) Polat, Osman; Gizer, S. Gorkem; Şahiner, Mehtap; Şahiner, Nurettin
Carbon nanomaterials are particles, generally composed of sp2 and sp3 bonded carbon atoms, that have attracted a lot of interest because of their fascinating properties. Because of the recent advances in nanotechnology, a wide range of nanoscale materials, including carbon nanomaterial allotropes, fullerenes, graphene, graphene oxide, and carbon nanotubes, have been developed to be used in a variety of applications, e.g., electronics, biomedical, energy, catalysis, drug delivery, targeting, and sensors. As significant improvements in physical, chemical, optical, electrical, mechanical, and thermal properties of carbon-based materials are readily achieved, groundbreaking applications of these materials are becoming conventional. Moreover, with the appropriate functionalization, carbon nanomaterials can be modified for multiple specific tasks such as theragnostic applications. These functionalized carbon nanomaterials (FCNMs) can easily be integrated into molecular diagnostic applications, making in vivo applications more comfortable for the patient. This chapter aims to give an overview on the state-of-the-art fabrication, property changes, and potential application of FCNMs summarizing the recent advances that happened in the last few years, especially in theragnostic applications. © 2023 Elsevier Ltd. All rights reserved.
From a plant secretion to the promising bone grafts: Cryogels of silicon-integrated quince seed mucilage by microwave-assisted sol-gel reaction
(Elsevier B.V., 2021) Yılmaz, Hilal Deniz; Cengiz, Uğur; Arslan, Yavuz Emre; Kıran, Fadime; Ceylan, Ahmet
Design and fabrication of biologically active cryogels using novel biopolymer(s) are still of great importance at regenerating bone defects such as traumatic bone injuries, maxillofacial surgery, osteomyelitis, and osteoporosis. Nowadays, plant mucilage, an herbal biomaterial, has been drawn attention by scientists due to their marvelous potential to fabricate 3-dimensional (3D) physical constructs for the field of regenerative medicine. Herein, a 3D cryogel from silicon-integrated quince seed mucilage (QSM) is constructed using microwave-assisted sol–gel reaction, characterized in-depth by attenuated total reflectance Fourier transform-infrared spectroscopy (ATR-FTIR), solid-state silicon cross-polarization magic-angle nuclear magnetic resonance (29Si-CP-MAS NMR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimeter (DSC), micro-mechanical testing, porosity, and swelling tests, contact angle measurements, Brunauer-Emmet-Teller and Barret-Joyner-Halenda (BET-BJH) analysis, enzymatic biodegradation test, and field emission-scanning electron microscopy-energy dispersive X-ray spectroscopy (FE-SEM-EDX) mapping. The osteobiologic capacity of the cryogels is determined using human adipose-derived mesenchymal stem cells (hAMSCs) under in vitro conditions. Osteogenic differentiation of hAMSCs on both QSM and silica-modified QSM (Si-QSM) cryogels is analyzed by histochemistry, immunohistochemistry, and quantitative-real time (q-RT) PCR techniques. The results obtained from in vitro experiments demonstrate that the upregulation of osteogenesis-related genes in Si-QSM cryogels presents a stronger and earlier development over QSM cryogels throughout the culture period, which in turn reveals the great potential of this novel Si-incorporated QSM cryogels for bone tissue engineering applications.
A nano-composite based regenerative neuro biosensor sensitive to Parkinsonism-associated protein DJ-1/Park7 in cerebrospinal fluid and saliva
(Elsevier B.V., 2021) Sonuç Karaboğa, Münteha Nur; Sezgintürk, Mustafa Kemal
In this study, we developed an electrochemical-based single-use neurobiosensor based on multiwalled carbon nanotube (MWCNT)-gold nanoparticle (AuNP) nanocomposite doped, 11-amino-1-undecanethiol (11-AUT)-modified polyethylene terephthalate coated indium tin oxide (ITO-PET) electrodes. This electrode was used for the sensitive determination of DJ-1, a protein responsible for mitochondrial dysfunction in Parkinson's disease (PD) with the task of eliminating oxidative stress. The design strategy and analytical studies for the neurobiosensor were monitored with electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and single frequency impedance (SFI) techniques. The selective determination range for DJ-1 of the developed neurobiosensor system is 4.7–4700 fg mL−1 in accordance with the charge transfer resistance (Rct) associated with a limit of detection of 0.5 fg mL−1. Since changes in the expression of DJ-1 protein is particularly important in cerebrospinal fluid (CSF) and saliva, the ability of the developed neurobiosensor system to detect the DJ-1 protein in these media was tested by the standard addition method. The statistical results show that the biosensor decorated with MWCNT-AuNP-AUT may be recommended for the selective determination of DJ-1 protein.
Ultrasensitive detection of interleukin 1? using 3-phosphonopropionic acid modified FTO surface as an effective platform for disposable biosensor fabrication
(Elsevier B.V., 2021) Aydın, Elif Burcu; Sezgintürk, Mustafa Kemal
In this study, we utilized a carboxyalkylphosphonic acid covered fluorine doped tin oxide (FTO) as an electrode material for fabrication of Interleukin 1α (IL-1α) immunosensor. For this aim, anti-IL-1α antibodies were attached on the 3-phosphonopropionic acid (PHP) modified FTO surface covalently. Electrochemical (electrochemical impedance spectroscopy and cyclic voltammetry) and morphological (scanning electron microscopy and atomic force microscopy) characterizations were performed to monitor the successful fabrication of immunoelectrodes. After incubation of anti-IL-1α antibody immobilized FTO electrodes in IL-1α antigen solutions, increases were seen in impedimetric responses. IL-1α antigen was determined in a linear detection range from 0.02 to 2 pg/mL by EIS. The detection limit of the suggested immunosensor was 6 fg/mL. The applicability of the designed biosensor was tested by using human serum and saliva samples and acceptable results were obtained. In addition, high sensitivity, good specificity, low detection limit made the proposed immunosensor a potential technique for IL-1α antigen determination in routine clinical analysis.

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