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Öğe A Review on Phyto-Therapeutic Approaches in Alzheimer's Disease(MDPI, 2023) Şahiner, Mehtap; Yılmaz, Aynur Sanem; Güngör, Buket; Şahiner, NurettinNeurodegenerative diseases occur due to progressive and sometimes irreversible loss of function and death of nerve cells. A great deal of effort is being made to understand the pathogenesis of neurodegenerative diseases. In particular, the prevalence of Alzheimer’s disease (AD) is quite high, and only symptomatic therapy is available due to the absence of radical treatment. The aim of this review is to try to elucidate the general pathogenesis of AD, to provide information about the limit points of symptomatic treatment approaches, and to emphasize the potential neurologic effects of phytocompounds as new tools as therapeutic agents for disease prevention, retardation, and therapy. This survey also covers the notable properties of herbal compounds such as their effects on the inhibition of an enzyme called acetylcholinesterase, which has significant value in the treatment of AD. It has been proven that phytopharmaceuticals have long-term effects that could protect nervous system health, eliminate inflammatory responses, improve cognitive damage, provide anti-aging effects in the natural aging process, and alleviate dementia sequelae. Herbal-based therapeutic agents can afford many advantages and can be used as potentially as new-generation therapeutics or complementary agents with high compliance, fewer adverse effects, and lower cost in comparison to the traditional pharmaceutical agents in the fight against AD.Öğe 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, NurettinBackground/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.Öğe Application of superporous magnetic cationic cryogels for persistent chromate (toxic chromate and dichromate) uptake from aqueous environments(Wiley, 2016) Şahiner, Nurettin; Demirci, Şahin; Şahiner, Mehtap; Yılmaz, SelehattinPoly((3-Acrylamidopropyl) trimethylammonium chloride) (p(APTMACl)) cryogels were prepared with cryopolymerization technique and employed for the removal of toxic chromate and dichromate anions from aqueous media. The maximum adsorption capacities of 94 mg/g and 135 mg/g for chromate and dichromate anions, respectively, were determined with the application of the Langmuir isotherm. These values are very close to the experimental values of about 77 and 128 mg/g from 100 mL, 100 ppm chromate, and dichromate solutions using 0.03 g cryogel. The removal efficiency of chromate and dichromate anions were increased with the increase in the amount of cryogel and the removal percentage of chromate and dichromate toxic anions were estimated as 99.21 and 93.61%, respectively, for 0.15 g of p(APTMACl) cryogels used in 100 mL, 100 ppm chromate, and dichromate solutions. Furthermore, magnetic p(APTMACl) cryogels were also prepared and used in the removal of chromate and dichromate, and the maximum adsorption capacities were 30 mg/g and 40 mg/g, respectively. Additionally, the adsorption of these anions were investigated from different media such as drinking water, tap water, seawater, and creek water; and the maximum adsorption amounts in drinking water were 65.5 +/- 15, and 125.5 +/- 11 mg/g for chromate and dichromate anions, respectively. The reusability of p(APTMACl) cryogels for the removal of chromate and dichromate anions was also investigated, and it was found that the adsorption capacity for chromate anions decreased to 71.23 +/- 4.3 from 97.37 +/- 4.5 mg/g, whereas the adsorption capacity of dichromate anions only decreased to 123.69 +/- 3.5 mg/g from 129.9 +/- 7 mg/g at the end of five adsorption-desorption cycles. (C) 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43438.Öğe 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, NurettinHere, 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 areÖğe Biocompatible and biodegradable poly(Tannic Acid) hydrogel with antimicrobial and antioxidant properties(Elsevier, 2016) Şahiner, Nurettin; Sağbaş, Selin; Şahiner, Mehtap; Sılan, Coşkun; Aktaş, Nahit; Türk, MustafaA novel resourceful bulk poly(Tannic Acid) (p(TA)) hydrogel was prepared by crosslinking TA molecules with an epoxy crosslinker, trimethylolpropane triglycidyl ether (TMPGDE), in an autoclave at 90 degrees C for 2 h. The obtained p(TA) hydrogels were in disk form and have highly porous morphology. The swelling characteristics of p(TA) hydrogels were investigated in wound healing pH conditions of pH 5.4, 7.4, and 9 at 37.5 degrees C, and the hydrogels showed good swelling and moisture content behavior. Especially, p(TA) hydrogels were found to be sensitive to pH 9 with 1669% maximum swelling. P(TA) hydrogels were completely degraded at pH 9 hydrolytically in 9 days. Total phenol contents and the effects of scavenging ABTS radicals of degraded p(TA) hydrogels at pH 5.4, 7.4, and 9 were evaluated and calculated in terms of gallic acid equivalent and trolox equivalent antioxidant capacity, respectively, and found to be very effective. Moreover, degraded p(TA) hydrogels display strong antimicrobial behavior against gram positive Staphylococcus aureus, Bacillus subtilis, gram negative Pseudomonas aeruginosa bacteria strains and Candida albicans fungus strain. The WST-1 results indicated that bulk p(TA) hydrogels have no cyctotoxicity to the L929 fibroblast cell line in vitro. (C) 2015 Elsevier B.V. All rights reserved.Öğe Biocompatible Glycol Chitosan Microgels as Effective Drug Carriers(MDPI, 2023) Şahiner, Mehtap; Yılmaz, Aynur Sanem; Ayyala, Ramesh S.; Şahiner, NurettinGlycol chitosan (GC) is a chitosan (CH) derivative with improved water solubility with regards to CH which affords significant solubility advantages. In this study, microgels of GC as p(GC) were synthesized by a microemulsion technique at various crosslinking ratios e.g., 5%, 10%, 50%, 75%, and 150% based on the repeating unit of GC using divinyl sulfone (DVS) as a crosslinker. The prepared p(GC) microgels were tested for blood compatibility and it was found that p(GC) microgels at 1.0 mg/mL concentration possessed a 1.15 ± 0.1% hemolysis ratio and 89 ± 5% blood clotting index value confirming their hemocompatibility. In addition, p(GC) microgels were found biocompatible with 75.5 ± 5% cell viability against L929 fibroblasts even at a 2.0 mg/mL concentration. By loading and releasing tannic acid (TA) (a polyphenolic compound with high antioxidant activity) as an active agent, p(GC) microgels’ possible drug delivery device application was examined. The TA loading amount of p(GC) microgels was determined as 323.89 mg/g, and TA releases from TA loaded microgels (TA@p(GC)) were found to be linear within 9 h and a total amount of TA released was determined as 42.56 ± 2 mg/g within 57 h. According to the Trolox equivalent antioxidant capacity (TEAC) test, 400 µL of the sample added to the ABTS+ solution inhibited 68.5 ± 1.7% of the radicals. On the other hand, the total phenol content (FC) test revealed that 2000 μg/mL of TA@p(GC) microgels resulted in 27.5 ± 9.5 mg/mL GA eq antioxidant properties.Öğe Biodiverse Properties of Tannic Acid-Based Fibers(Springer, 2021) Şahiner, Mehtap; Kurt, Saliha B.; Şahiner, NurettinTannic acid (TA) is a plant-based polyphenolic molecule with enticing anti-oxidant, anti-bacterial, antiinflammatory and anti-cancer features, making it a valuable material in bio-medicinal applications. To establish whether TA-based fibers are useful tools in potential medical textiles, e.g., as wound dressing material for prophylaxis against infections and diseases, TA fibers were prepared and employed in biological assays. TA fibers were prepared with 55 weight% TA in ethanol-DI water mixture and fabricated by the electrospinning technique. Bare TA-based fibers were examined and were 1.2 +/- 0.1 % non-hemolytic and had 8.7 +/- 1.7 blood clotting index up to 2 mg/ml concentration. Degradation of bare TA-based fibers was completed in 5 minutes; however, degradation of crosslinked TA-based fibers were 98.3 +/- 2.3 % and 83.1 +/- 5.4 % for TA-Ibu and TA in 168 hours. Anti-oxidant activity of TA-based fibers was investigated by TEAC, total phenol content (TPC) and total flavonoid content (TFC) assays. Bare TA fibers possessed the highest anti-oxidant activity of 5.7 +/- 0.5 mM trolox equivalent/g, 168.0 +/- 2.0 gallic acid equivalent mu g/ml and 193.0 +/- 17.0 quercetin equivalent mu g/ml. Anti-bacterial activity was investigated by the disc diffusion method and the highest inhibition zone diameter was measured as 3.5 +/- 0.2 cm against S. aureus (gram +) bacteria; however, the same fiber was detected as producing 2.2 +/- 0.5 cm zone diameter for E. coli (gram -) bacteria.Öğe Biomedical applications of nanofibers(wiley, 2022) Şahiner, Mehtap; Kurt, Saliha B.; Şahiner, NurettinElectrospinning is one of the most convenient and effective techniques in the production of fibers that employs high voltage. The tunable parameters of the electrospinning technique, e.g. flow rate of the polymer solution, voltage, distance between needle and the collector, and viscosity of polymer solution, allow fibers with different sizes and characteristics to be produced, i.e. micro-to nanosized fibers with different types and extent of porosity. Electrospun fibers are well suited for a broad range of applications including environmental, energy, biotechnology, health care, and biomedical applications. Recently, electrospun fibers have attracted great interest for drug delivery, wound healing, and biosensor applications in the biomedical field. The electrospinning technique is attractive due to its simplicity and low cost and is widely employed in both academia and industry. In this chapter, the utilization of the electrospinning technique in the fabrication of nanofibers from various natural and synthetic polymers and their biomedical applications will be discussed. © 2022 John Wiley & Sons, Inc.Öğe Carboxymethyl Chitosan Microgels for Sustained Delivery of Vancomycin and Long-Lasting Antibacterial Effects(Mdpi, 2023) Şahiner, Mehtap; Yılmaz, Aynur Sanem; Ayyala, Ramesh S.; Şahiner, NurettinCarboxymethyl 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.Öğe Cell Staining Microgels Derived from a Natural Phenolic Dye: Hematoxylin Has Intriguing Biomedical Potential(Multidisciplinary Digital Publishing Institute (MDPI), 2024) Şahiner, Mehtap; Sunol, Aydin K.; Şahiner, NurettinHematoxylin (HT) as a natural phenolic dye compound is generally used together with eosin (E) dye as H&E in the histological staining of tissues. Here, we report for the first time the polymeric particle preparation from HT as poly(Hematoxylin) ((p(HT)) microgels via microemulsion method in a one-step using a benign crosslinker, glycerol diglycidyl ether (GDE). P(HT) microgels are about 10 µm and spherical in shape with a zeta potential value of −34.6 ± 2.8 mV and an isoelectric point (IEP) of pH 1.79. Interestingly, fluorescence properties of HT molecules were retained upon microgel formation, e.g., the fluorescence emission intensity of p(HT) at 343 nm was about 2.8 times less than that of the HT molecule at λex: 300 nm. P(HT) microgels are hydrolytically degradable and can be controlled by using an amount of crosslinker, GDE, e.g., about 40%, 20%, and 10% of p(HT) microgels was degraded in 15 days in aqueous environments for the microgels prepared at 100, 200, and 300% mole ratios of GDE to HT, respectively. Interestingly, HT molecules at 1000 mg/mL showed 22.7 + 0.4% cell viability whereas the p(HT) microgels exhibited a cell viability of 94.3 + 7.2% against fibroblast cells. Furthermore, even at 2000 mg/mL concentrations of HT and p(HT), the inhibition% of α-glucosidase enzyme were measured as 93.2 ± 0.3 and 81.3 ± 6.3%, respectively at a 0.03 unit/mL enzyme concentration, establishing some potential application of p(HT) microgels for neurogenerative diseases. Moreover, p(HT) microgels showed two times higher MBC values than HT molecules, e.g., 5.0 versus 2.5 mg/mL MIC values against Gram-negative E. coli and Gram-positive S. aureus, respectively.Öğe Chemically Cross-Linked Poly(?-Cyclodextrin) Particles as Promising Drug Delivery Materials(Amer Chemical Soc, 2021) Demirci, Şahin; Khiev, Dawin; Can, Mehmet; Şahiner, Mehtap; Biswal, Manas R.; Ayyala, Ramesh S.; Şahiner, NurettinOne-pot synthesis of poly(β-cyclodextrin) (p(β-CD)) micro-/nanoparticles was accomplished using two different cross-linkers, divinyl sulfone (DVS) as p(β-CD)-1 and trimethylolpropane glycidyl ether (TMPGDE) as p(β-CD)-2. High gravimetric yields of 84 ± 4 and 62 ± 6%, respectively, were attained for p(β-CD)-1 and p(β-CD)-2 particles. The p(β-CD)-1 and p(β-CD)-2 particles had spherical shapes with 5.09 ± 0.24 and 0.60 ± 0.01 μm diameters, respectively, and exhibited good water dispersibility at physiological pH, and their isoelectric points were calculated correspondingly to be pH 1.1 and 1.2. The surface areas of p(β-CD)-1 and p(β-CD)-2 particles were determined to be 4.76 ± 0.6 and 2.18 ± 0.2 m2/g, respectively. Moreover, p(β-CD) particles were found to be biocompatible with more than 98% cell viability on human retinal pigment epithelial (ARPE-19) cells at 0.1 mg/mL concentration. Also, p(β-CD)-1 particles exhibited 52.81 ± 9.5% Fe(II) chelation capacity at 1.0 mg/mL concentration. The hemolysis and coagulation tests revealed that p(β-CD)-1 particles possessed excellent blood compatibility with a 1.18 ± 0.60% hemolysis ratio and a 92.02 ± 1.02% clotting index even at 2.0 mg/mL concentration, whereas the safety limit of p(β-CD)-2 particles for blood interactions was determined to be 0.5 mg/mL. The in vitro drug release performances of p(β-CD)-1 and p(β-CD)-2 particles for hydrophobic acyclovir and hydrophilic vancomycin model drugs at pH 7.4 PBS showed sustained releases of 2.14 ± 0.34 and 1.34 ± 0.43 mg/g acyclovir and 51.90 ± 1.09 and 61.26 ± 3.71 mg/g vancomycin within 24 h, respectively. Kinetic modeling of experimental release data revealed the best fit for drug release from p(β-CD) particles mediated by the Korsmeyer-Peppas model. ©Öğe Chondroitin Sulfate-Based Cryogels for Biomedical Applications(MDPI, 2021) Demirci, Şahin; Şahiner, Mehtap; Ari, Betül; Sunol, Aydın K.; Şahiner, NurettinCryogels attained from natural materials offer exceptional properties in applications such as tissue engineering. Moreover, Halloysite Nanotubes (HNT) at 1:0.5 weight ratio were embedded into CS cryogels to render additional biomedical properties. The hemolysis index of CS cryogel and CS:HNT cryogels was calculated as 0.77 ± 0.41 and 0.81 ± 0.24 and defined as non-hemolytic mate-rials. However, the blood coagulation indices of CS cryogel and CS:HNT cryogels were determined as 76 ± 2% and 68 ± 3%, suggesting a mild blood clotting capability. The maximum% swelling capacity of CS cryogel was measured as 3587 ± 186%, 4014 ± 184%, and 3984 ± 113%, at pH 1.0, pH 7.4 and pH 9.0, respectively, which were reduced to 1961 ± 288%, 2816 ± 192, 2405 ± 73%, respectively, for CS:HNT cryogel. It was found that CS cryogels can hydrolytically be degraded 41 ± 1% (by wt) in 16-day incubation, whereas the CS:HNT cryogels degraded by 30 ± 1 wt %. There is no chelation for HNT and 67.5 ± 1% Cu(II) chelation for linear CS was measured. On the other hand, the CS cryogel and CS:HNT cryogel revealed Cu(II) chelating capabilities of 60.1 ± 12.5%, and 43.2 ± 17.5%, respectively, from 0.1 mg/mL Cu(II) ion stock solution. Additionally, at 0.5 mg/mL CS, CS:HNT, and HNT, the Fe(II) chelation capacity of 99.7 ± 0.6, 86.2 ± 4.7% and only 11.9 ± 4.5% were measured, respectively, while no Fe(II) was chelated by linear CS chelated Fe(II). As the adjustable and con-trollable swelling properties of cryogels are important parameters in biomedical applications, the swelling properties of CS cryogels, at different solution pHs, e.g., at the solution pHs of 1.0, 7.4 and 9.0, were measured as 3587 ± 186%, 4014 ± 184%, and 3984 ± 113%, respectively, and the maximum selling% values of CS:HNT cryogels were determined as 1961 ± 288%, 2816 ± 192, 2405 ± 73%, re-spectively, at the same conditions. Alpha glucosidase enzyme interactions were investigated and found that CS-based cryogels can stimulate this enzyme at any CS formulation.Öğe Colloidal bioactive nanospheres prepared from natural biomolecules, catechin and L-lysine(Springer, 2022) Can, Mehmet; Şahiner, Mehtap; Şahiner, NurettinRecently, major attention has been devoted to exploring and increase biomedical applications of catechins by directly employing them as constituents of nano-vehicles. Here, (+)-catechin (CAT) was integrated with another benign biomolecule, L-Lysine (LYS) using formaldehyde (FA) via single-step Mannich condensation reaction and self-assembled supramolecular CAT-LYS networks were synthesized. By using various molar feed ratios of CAT, LYS, and FA (CAT:LYS:FA), different formulations of CAT-LYS particles were obtained as CAT-LYS-1(1:1:1), CAT-LYS-2(2:1:1), CAT-LYS-3(1:2:1), and CAT-LYS-4(1:1:2) particles. The CAT-LYS-4 particles with the highest gravimetric yield of 68.9 +/- 6.0% and 783.6 +/- 56.6 nm hydrodynamic diameter was chosen for bioactivity studies. The CAT-LYS-4 particles exhibited 190.4 +/- 1.3 mu g/mL CAT-equivalent antioxidant capacity at 1000 mu g/mL concentration with TEAC value of 0.24 +/- 0.01 mu mole Trolox-equivalent/g antioxidant activity. They showed 16.81 +/- 3.47% Fe(II) chelation capacity at 350 mu g/mL and 185.8 +/- 22.8 mu mole Fe(III) reducing power at 500 mu g/mL concentration. Moreover, the CAT-LYS-4 particles retained more than half of the alpha-glucosidase inhibition activity of CAT in particulate form. Besides, a 50-fold improvement was achieved on the hemolytic blood compatibility of CAT-LYS-4 particles upon integration of LYS into CAT backbone (4.7 +/- 1.2% at 250 mu g/mL) compared to hemolysis ratio of native CAT molecules. They did not show coagulation effects up to 500 mu g/mL concentration with > 94% clotting indices. Hence, the CAT-LYS particles with enhanced blood compatibilities and well-retained inherent bioactivities of their precursors in 3D colloidal particulate structures can serve as natural biocolloids for drug/active molecule transport applications in biomedicine.Öğe 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, NurettinNon-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.Öğe Degradable natural phenolic based particles with micro-and nano-size range(Bentham Science Publishers B.V., 2018) Şahiner, Nurettin; Sağbaş, Selin; Şahiner, Mehtap; Aktaş, NahitBackground: Degradable polymeric particles derived from phenolic compounds are promising materials for biomedical applications due to their inherently antioxidant, antimicrobial, and anticancerogenic properties. We revise all the patent regarding to the biomedical and food additive formulations of Rutin (RT) and Quercetin (QC) as phenolic compounds. Objective: Prepare degradable Poly(Rutin) (p(RT)) and Poly(Quercetin) (p(QC)) particles from natural phenolic compounds, Rutin (RT) and Quercetin (QC). Method: P(RT), and p(QC) particles were prepared using microemulsion crosslinking method employing phenolic compounds such as RT and QC as monomer and poly(ethylene glycol) diglycidyl ether (PEGGE) as a crosslinker in a single step. The degradability of these particles was investigated at physiological conditions, pH 5.4, 7.4, and 9 at 37.5°C. The antioxidant capacity of RT, QC and their corresponding particles was determined by means of total phenol content and ABTS + scavenging assay. The blood compatibility of the particles is determined with hemolysis and blood clotting tests, and the cytotoxicity of the particles on L929 fibroblast cell and A549 cancer cells was done by WST-1 tests. Results: The size of the prepared phenolic particles was in the size range of 0.4-4 ?m with negative zeta potentials,-20.29±1.7 and-31.31±2.0 mV for p(RT) and p(QC) particles, respectively. The highest amount of degradation was obtained for p(QC) particles in almost a linear profile with relatively longer time degrading kinetics at pH 9, e.g., 197±23 mg/g QC was released up to 130 h. The antioxidant capacities of phenolic compounds were decreased about ten-fold upon the particle formations of the phenolic compound, and the antioxidant capacity of p(QC) particles was found to be better than p(RT) particles with 0.22±0.01 and 0.05±0.001 ?mol trolox equivalent g -1 , respectively. The blood compatibility test of p(RT) and p(QC) particles revealed that both particles are blood compatible up to 1 mg/mL concentration and possess clotting of blood over 1 mg/mL concentrations. Furthermore, the cytotoxicity tests showed that p(RT) particles are more biocompatible than p(QC) on the fibroblast cell as 91% cell viability versus 50% for p(QC) was observed at 75 ?g/mL particle concentrations. Additionally, at this concentration 42.3% of cancer cells were inhibited by p(RT) particles. Conclusion: Degradable p(RT) and p(QC) particles that are prepared in a single step offer great avenue for biomedical applications as highly antioxidant materials and with good biocompatibility in contact with blood and fibroblast cells, as well as great anticancerogenic capability against the cancer cells. © 2018 Bentham Science Publishers.Öğe Degradable poly(catechin) nanoparticles as a versatile therapeutic agent(Taylor and Francis Ltd., 2021) Suner, Selin S.; Şahiner, Mehtap; Mohapatra, Subhra; Ayyala, Ramesh S.; Bhethanabotla, Venkat R.; Şahiner, NurettinPoly(catechin) (p(CAT)) nanoparticles (NPs), 173 +/- 4 nm was prepared as a therapeutic agent with hydrolytic degradability affording sustainable CAT release over 20 d at carcinogenic conditions, pH 5.5 and 37.5 degrees C. Cell viability studies on MC38 colon cancer cells revealed the anticancer potential of p(CAT) NPs with 691 mu g/mL IC50 value while being well-tolerated by nonmalignant CCD841 CoN colon cells at 72 h incubation-time. P(CAT) NPs showed effective antioxidant capacity with 241 +/- 7 and 456 +/- 54 mu g/mL of GA equivalency of total phenol content (TPC), and total flavonoid content (TFC) values and 1.19 +/- 0.8 mu mol/g Trolox equivalent antioxidant capacity by 2,2'-Azino-bis-(3-ethylbenzothioazoline-6-sulfonic acid (ABTS(center dot+)) scavenging assay.Öğe Degradable tannic acid/polyethyleneimine polyplex particles with highly antioxidant and antimicrobial effects(Elsevier Sci Ltd, 2016) Şahiner, Nurettin; Sağbaş, Selin; Şahiner, Mehtap; Demirci, ŞahinTannic acid/Polyethylene imine (TA/PEI) polyplex particles in spherical form were synthesized via the electrostatic interaction between the TA molecules' phenolic groups and PEI positively charged ammonium groups. The size of polyplex particles was observed to be between 500 nm and 5 mu m via SEM images. It was found that the TA/PEI polyplex particles showed thermal durability of 4.8 wt residue in comparison to both components, TA or PEI, at 900 degrees C. Hydrolytic degradation of TA/PEI polyplex particles at different pHs e.g., pH 1.5 similar to stomach conditions, pH 7.4 similar to physiologic conditions, and pH 9 similar to intestinal conditions were investigated by UV-Vis spectroscopy by measuring degraded TA amount at 37.5 degrees C over two days and 65%, 31%, and 52% weight losses were found, respectively. FC, TEAC, and DPPH tests were used to determine the antioxidant properties of TA/PEI polyplex particles. The antimicrobial properties of TA/PEI polyplex particles were determined using micro-dilution and disc diffusion methods against gram-negative Escherichia coli ATCC 8739, Pseudomonas aeruginosa ATCC 10145, gram-positive Staphylococcus aureus ATCC 6538, Bacillus subtilis ATCC 6633 bacteria strains, and Candida albicans ATCC 10231 yeast strain. MIC values of TA/PEI polyplex particles were found to change between 0.025 and 0.1 mg/mL concentration depending on the type of microorganism and indicate that the polyplex particles possess strong antimicrobial activity. (C) 2016 Elsevier Ltd. All rights reserved.Öğe Enhanced Bioactive Properties of Halloysite Nanotubes via Polydopamine Coating(Mdpi, 2022) Şahiner, Mehtap; Demirci, Şahin; Şahiner, NurettinHalloysite 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.Öğe Enhanced enzymatic activity and stability by in situ entrapment of α Glucosidase within super porous p(HEMA) cryogels during synthesis(Elsevier B.V., 2020) Demirci, Şahin; Şahiner, Mehtap; Yılmaz, Selehattin; Karadağ, Erdener; Şahiner, NurettinHere, poly(2-hydroxyethyl methacrylate) (p(HEMA)) cryogel were prepared in the presence 0.48, 0.96, and 1.92 mL of α-Glucosidase enzyme (0.06 Units/mL) solutions to obtain enzyme entrapped superporous p(HEMA) cryogels, donated as α-Glucosidase@p(HEMA)-1, α-Glucosidase@p(HEMA)-2, and α-Glucosidase@p(HEMA)-3, respectively. The enzyme entrapped p(HEMA) cryogels revealed no interruption for hemolysis and coagulation of blood rendering viable biomedical application in blood contacting applications. The α-Glucosidase@p(HEMA)-1 was found to preserve its’ activity% 92.3 ± 1.4 % and higher activity% against free α-Glucosidase enzymes in 15–60℃ temperature, and 4–9 pH range. The Km and Vmax values of α-Glucosidase@p(HEMA)-1 cryogel was calculated as 3.22 mM, and 0.0048 mM/min, respectively versus 1.97 mM, and 0.0032 mM/min, for free enzymes. The α-Glucosidase@p(HEMA)-1 cryogel was found to maintained enzymatic activity more than 50 % after 10 consecutive uses, and also preserved their activity more than 50 % after 10 days of storage at 25 ℃, whereas free α-Glucosidase enzyme maintained only 1.9 ± 0.9 % activity under the same conditions.Öğe Enhancement of biocompatibility and carbohydrate absorption control potential of rosmarinic acid through crossinking into microparticles(Elsevier, 2019) Şahiner, Mehtap; Blake, Diane A.; Fullerton, Mitchell L.; Sağbaş Suner, Selin; Sunol, Aydın K.; Şahiner, NurettinRosmarinic acid (RA), a bioflavonoid and antioxidant that exists in plants of the Lamiaceae family, was crosslinked into particles as poly(Rosmarinic Acid) (p(RA)) via an emulsion crosslinking method. The particles were characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, solid state nuclear magnetic resonance C-13 NMR spectroscopy, and thermal gravimetric analysis. The zeta potential values of p(RA) particles were determined at different pHs; the isoelectric point was estimated as pH 1.2. The release of monomeric RA from the particles at 37.5 degrees C was found to be similar at different pHs, 1.0, 7.4, and 11.0. The effects of p(RA) on hemolysis and coagulation were found to be minimal. The antioxidant activity of p(RA) particles and RA monomer were almost indistinguishable suggesting that p(RA) particles may be used as an antioxidant. On a per weight basis, p(RA) particles were similar to 66% less cytotoxic to mammalian cells that RA monomer, as assessed using COS-1 cells. In addition, p(RA) was an 8.6-fold stronger inhibitor of alpha-glycosidase than RA; the IC(50)s of the monomer and particles were 0.121 and 0.014 mg/mL, respectively. The strong inhibitory effect of p(RA) on alpha-glycosidase, coupled with its reduced cytotoxicity and antioxidant activity, provide new opportunities for the use of p(RA). (C) 2019 Elsevier B.V. All rights reserved.
