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

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3D HYDROGELS FROM DETERGENT-FREE DECELLULARIZED SPINAL CORD MENINGES REINFORCED WITH HYDROPHILIC SILK FIBROIN FOR REGENERATIVE MEDICINE APPLICATIONS
(Mary Ann Liebert, Inc, 2024) Kurt, Tuğçe; Arslan, Yavuz Emre
[No abstract available]
Tannic acid-based bio-MOFs with antibacterial and antioxidant properties acquiring non-hemolytic and non-cytotoxic characteristics
(Elsevier, 2025) Şahiner, Nurettin; Güven, Olgun; Demirci, Şahin; Sağbaş Suner, Selin; Şahiner, Mehtap; Arı, Betül; Can, Mehmet
Tannic acid (TA) based bio-metal phenolic networks (bio-MPNs) were prepared by using Cu(II), Zn(II), Bi(III), Ce(III), La(III), and Ti(IV) metal ions. TA-based bio-MPNs exhibited wedge-shaped pores between 16.4 and 25.8 nm pore size ranges. The higher gravimetric yield% was achieved for TA-Bi(III), and TA-Ti(IV) bio-MPNs with more than 90 %, and higher surface area was observed for TA-La(IIII) bio-MPNs as 56.2 m(2)/g with 17.3 nm average pore sizes. All TA-based MPNs are non-hemolytic with less than 5 % hemolysis ratio, whereas TA-based Bio-MPNs do not affect blood clotting with > 90 % blood clotting indexes except for TA-Cu(II) Bio-MPNs at 0.1 mg/mL concentration. Moreover, TA-Bi(III) and TA-Ce(III) Bio-MPNs were found to be safer materials showing no significant toxicity on L929 fibroblast cells at 100 mu g/mL concentration, along with TA-based Bio-MPNs prepared with Cu(II), Zn(II), La(III), and Ti(IV) metal ions that could be safely used in in vivo applications at 1 mu g/mL concentration. It has been proven by 2 different antioxidant tests that the prepared TA-based Bio-MPNs show antioxidant properties even if their TA-derived antioxidant properties decrease. Furthermore, all types of TA-based Bio-MPNs show great antimicrobial activity depending on the metal ion or microorganism types and the highest antibacterial/antifungal effect was determined for TA-Cu(II), and TA-Zn(II) Bio-MPNs with the lowest MBC/MFC values against Pseudomonas aeruginosa ATCC 10145, Bacillus subtilis ATCC 6633, and Candida albicans ATCC 10231.
Nanoparticles for Biomedical Use Derived from Natural Biomolecules: Tannic Acid and Arginine
(MDPI, 2025) Şahiner, Mehtap; Sağbas Suner, Selin; Şahiner, Nurettin
Background/Objectives: Tannic acid (TA) is a well-known natural phenolic acid composed of ten gallic acids linked to each other with ester bonding possessing excellent antioxidant properties in addition to antimicrobial and anticancer characteristics. Arginine (ARG) is a positively charged amino acid at physiological pH because of nitrogen-rich side chain. Method: Here, poly(tannic acid-co-arginine) (p(TA-co-ARG)) particles at three mole ratios, TA:ARG = 1:1, 1:2, and 1:3, were prepared via a Mannich condensation reaction between TA and ARG by utilizing formaldehyde as a linking agent. Results: The p(TA-co-ARG) particles in 300-1000 nm size range with smooth surfaces visualized via SEM analysis were attained. Abundant numbers of functional groups, -OH, -NH2, and -COOH stemming from TA and ARG constituent confirmed by FT-IR analysis. The isoelectric point (IEP) of the particles increased from pH 4.98 to pH 7.30 by increasing the ARG ratios in p(TA-co-ARG) particles. The antioxidant capacity of p(TA-co-ARG) particles via gallic acid (GA) and rosmarinic acid (RA) equivalents tests revealed that particles possess concentration-dependent antioxidant potency and increased by TA content. The alpha-glucosidase inhibition of p(TA-co-ARG) particles (2 mg/mL) 1:1 and 1:2 mole ratios revealed significant enzyme inhibition ability, e.g., 91.3 +/- 3.1% and 77.6 +/- 12.0%. Interestingly, p(TA-co-ARG) (1:3 ratio) possessed significant antibacterial effectiveness against Escherichia coli (ATCC 8739) and Staphylococcus aureus (ATCC 6538) bacteria. Furthermore, all p(TA-co-ARG) particles at 1000 mg/mL concentration showed >80% toxicity on L929 fibroblast cells and increased as ARG content of p(TA-co-ARG) particles is increased. Conclusions: p(TA-co-ARG) showed significant potential as natural biomaterials for biomedical use.
Natural Molecule-Derived Nanogels from Hematoxylin and l-lysine for Biomedical Use with Antimicrobial Properties
(MDPI, 2025) Şahiner, Mehtap; Tian, Zhi; Allen-Gipson, Diane; Sunol, Aydın K.; Şahiner, Nurettin
Hematoxylin (HT) is a natural staining dye used in histopathology, often combined with Eosin for H&E staining. A poly(hematoxylin-co-l-lysine) (p(HT-co-l)) nanonetwork was synthesized through a one-step Mannich condensation reaction using formaldehyde as a linking agent. The resulting p(HT-co-l) nanogels had an average size of about 200 nm and exhibited a smooth surface and desirable functional groups such as -OH, -NH2, and -COOH, as recognized by FT-IR analysis. The isoelectric point (IEP) of the p(HT-co-l) nanogel was determined as pH 7.9, close to physiological environments, despite HT being acidic IEP at pH 1.7 and l-lysine being basic IPE at pH 8.7. The time-dependent swelling studies of p(HT-co-l) nanogels were carried out using dynamic light scattering (DLS) in different salt solutions, e.g., MgCl2, KNO3, KCl, PBS, and DI water environments revealed that nanogels have high swelling ability depending on the medium, e.g., >10-fold in a saline solution compared to distilled water within 1.5 h. Hydrolytic degradation studies in PBS demonstrated a linear release profile up to 125 h at 37.5 degrees C. The p(HT-co-l) nanogels also demonstrated significant antimicrobial and antifungal activities against E. coli (ATCC 8739), S. aureus (ATCC 6538), and C. albicans (ATCC 10231). Furthermore, biocompatibility tests indicated that p(HT-co-l) nanogels are more biocompatible than HT alone, as tested with human Nuli-1 bronchial epithelial cells.
AChE Inhibition Capability of Nanogels Derived from Natural Molecules: Tannic Acid and Lysine for Alzheimer's Disease
(MDPI, 2025) Şahiner, Mehtap; Sağbaş Suner, Selin; Şahiner, Nurettin
Background/Objectives: Tannic acid (TA), a known natural polyphenolic acid with many bioactivities including antioxidants, antibacterial, and antiviral, can be combined with a natural essential amino acid L-lysine (LYS) in nanogel formulations to produce p(TA-co-LYS) (p(TA-co-LYS)) nanogels. Methods: A 1:1 mole ratio of TA:LYS was used to prepare corresponding spherical nanogels employing formaldehyde as a linker via the Mannich reaction. Results: The attained p(TA-co-LYS) particles were in 283 +/- 57 nm size ranges (via SEM analysis) and possessed smooth surfaces. The zeta potential measurements of p(TA-co-LYS) nanogels suspension at different solution pHs revealed the isoelectric point (IEP) of pH 4.9, suggesting that the particles are negatively charged at the physiological pH range (e.g., at 7.4). In addition to the antioxidant efficacy of nanogels confirmed by three different tests, p(TA-co-LYS) particles showed significant Fe(II) ion chelating capacity at 350 mu g/mL concentrations compared to bare TA, which is 21%, whereas the LYS molecule had a chelating capacity of 100% at the same concentrations. Moreover, it was found that p(TA-co-LYS) nanogels inhibited the Acetylcholinesterase enzyme (AChE) at a concentration-dependent profile, e.g., at 333 mu g/mL concentration of p(TA-co-LYS), 57.2% of the enzyme AChE activity was inhibited. Furthermore, the minimum inhibition concentrations of p(TA-co-LYS) nanogels of Gram-negative Escherichia coli (ATCC 8739) and Gram-positive Staphylococcus aureus (ATCC 6538) were determined as 12.5 mg/mL. Conclusions: As cytotoxicity studies of p(TA-co-LYS) nanogels on L929 fibroblast cells also ascertained that these particles can be safely used in many biomedical applications, including antioxidant materials, drug delivery devices, and enzyme inhibitors.
Toxicity Evaluation of Sulfobetainized Branched Polyethyleneimine via Antibacterial and Biocompatibility Assays
(MDPI, 2025) Şahiner, Mehtap; Sağbaş Suner, Selin; Demirci, Şahin; Ayyala, Ramesh S.; Şahiner, Nurettin
Branched polyethyleneimine (PEI), possessing different types of amines-e.g., primary, secondary, and tertiary-in the polymer chains are well known for their antibacterial properties and DNA condensing ability, affording substantial advantages in many biomedical uses, including gene therapy. However, because of PEI's toxicity, depending on the molecular weight, its widespread biomedical use is hindered. Therefore, in this study, PEIs with different molecular weights-i.e., 600, 1200, and 1800 g/mol-were modified with 1,3-propane sultone, undergoing a sulfobetainization reaction in a single step to attain a zwitterionic structure: sulfobetainized PEI (b-PEI). The sulfobetainization reaction was carried out twice to increase the zwitterionic repeating unit on PEI chains. The increasing number of SO3- groups on the PEI chains was confirmed by the increased peak intensities around 1160 and 1035 cm-1 on the FT-IR spectrum, which are assigned to symmetric and asymmetric S=O peaks. The elemental analysis results for first- and second- betainization PEIs, abbreviated as b1-PEI and b2-PEI, respectively, were revealedthe increased wt% of S confirming the successful multiple-sulfobetainization of the PEI chains. Thermal stability analyses of PEIs and their corresponding multiple-sulfobetainized forms showed that multiple-sulfobetainization reactions increased the thermal stability of bare PEI chains. PEIs with lower molecular weights exhibited more antimicrobial properties. As PEI is sulfobetainated, its antimicrobial properties can be further adjusted via sulfobetainization (once or twice), or by adjusting the corresponding solution pH, or by protonating them with different acids with different counter anions. The cell toxicity of PEI on L929 fibroblast cells was slightly increased by increasing the molecular weight of the PEI, but all forms of sulfobetainized PEIs were found to be safe (no toxicity), even at 1000 mu g/mL concentrations.
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.
Effect of deposition charges on the wettability performance of electrochromic polymers
(Elsevier, 2015) Çağlar, Aysel; Cengiz, Uğur; Yıldırım, Mehmet; Kaya, İsmet
Electrochromic polymers have been designed as future candidates for electrochromic displays (ECDs) and smart windows. This class of conducting polymers has been studied with their several optical properties as well as spectroelectrochemical stabilities. In practical use their contamination and abrasion could be expected to be main problem as exposed to moisture and other possible pollutants. In this study, we present a perspective to well-known electrochromic polymers in the words of their durable use. For this aim, a series of electrochromic polymers are deposited on indium tin oxide (ITO) coated glass plates by bulk electrolysis. Polymeric films are deposited by varied deposition charges (Q(s)) ranging from 62 to 620 mC cm(-2) for comparison. Equilibrium water contact angle (theta(equ)(water)) measurements of the prepared surfaces are measured by Attention Theta Optical Tensiometer. Surface roughness parameters (RMS) are determined by atomic force microscopy (AFM) technique and used for interpretation of hydrophobic-hydrophilic characteristics. The results clearly indicate that; poly(ethylenedioxythiophene) (PEDOT) has a hydrophilic surface whose hydrophilicity is increased by applied deposition charge and becomes a superhydrophile at high deposition charges. Among the tested polymers polycarbazole (PCarb) is the most promising long lifetime candidate due to its relatively hydrophobic character. Also, the hydrophobicity of PCarb is linearly increased by increasing deposition charge and reaches an optimum point at a particular condition. (C) 2015 Elsevier B.V. All rights reserved.
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.

Güncel Gönderiler