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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 Highly re-usable porous carbon-based particles as adsorbents for the development of CO2 capture technologies(Elsevier Sci Ltd, 2024) Ari, Betül; Sunol, Aydin K.; Şahiner, NurettinCombating climate change and global warming focuses generally on eliminating carbon emissions from energy production or transportation. For this purpose, CO2 capture, storage and utilization technologies were developed to remove or uptake carbon from the atmosphere. Here, porous carbon particles (PCPs) were prepared via hydrothermal and carbonization methods from various disaccharides sources, sucrose (S) as S-PCPs, lactose (L) as L-PCPs, and maltose (M) as M-PCPs as adsorbents for CO2 capture. Surface areas, pore volumes, and pore sizes of all adsorbents were determined using the N-2 adsorption-desorption method and as S-PCP is the adsorbent with the highest surface area, 460 m(2)/g exhibited the highest CO2 capture capacity which are 3.58 +/- 0.03 mmol CO2/g absorbent at 273 K and 2.48 +/- 0.02 mmol CO2/g absorbent at 298 K at about 1 atm pressure. Furthermore, S-PCP was found to be practically completely stable for at least 10 successive uses and the adsorption capacity >90 % at the end 10th use. More importantly, S-PCPs can be re-activatable by simple NaOH treatments at the end of 10 times adsorption-desorption cycle via simple NaOH treatment. Here, S-PCP particles after 10 repetitive uses were re-activated and continued to total 15th CO2 adsorption-desorption and CO2 adsorption capacity decreased to only 82 +/- 1.6 % of its first use.Öğe PEI modified natural sands of Florida as catalysts for hydrogen production from sodium borohydride dehydrogenation in methanol(John Wiley and Sons Ltd, 2021) Inger, Erk; Demirci, Şahin; Can, Mehmet; Sunol, Aydin K.; Philippidis, George; Şahiner, NurettinSand samples from Tampa (T) and Panama (P) City beaches in Florida were used as catalysts for dehydrogenation of NaBH4 in methanol. T and P sand samples were sieved to [removed]500 μm sizes, and the smallest fractions resulted in faster hydrogen generation rates (HGR), 565 ± 18 and 482 ± 24 mL H2 (min.g of catalyst)−1, respectively. After various base/acid treatments, HGR values of 705 ± 51 and 690 ± 47 mL H2 (min g of catalyst)−1 for HCl-treated T and P sand samples were attained, respectively. Next, T and P sand samples were modified with polyethyleneimine (PEI) that doubled the HGR values, 1344 ± 103, and 1190 ± 87 mL H2 (min.g of catalyst)−1 and increased ~8-fold, 4408 ± 187, and 3879 ± 169 mL H2 (min g of catalyst)−1, correspondingly after protonation (PEI+). The Ea values of T and P sand samples were calculated as 24.6 and 25.9 kJ/mol, and increased to 36.1, and 36.6 kJ/mol for T-PEI+ and P-PEI+ samples, respectively.Öğe Surface-modified carbon black derived from used car tires as alternative, reusable, and regenerable catalysts for H2 release studies from sodium borohydride methanolysis(Wiley, 2019) Ari, Betül; Ay, Mehmet; Sunol, Aydin K.; Şahiner, NurettinCarbon black (CB) obtained from used car tire rubbers were treated with concentrated sulfuric and nitric acids. The oxidized CB (CB-COO-Na+) is subsequently modified with epichlorohydrin (ECH) and amines including polyethylene imine (PEI). These modified CBs such as CB-PEI are used as metal-free catalysts in methanolysis of sodium borohydride (NaBH4) to produce hydrogen. The hydrogen generation rate (HGR) of 3089 +/- 44.69 mL.min(-1).g(-1) is accomplished at room temperature with CB-PEI-hydrochloric acid (HCl) catalyst. The resulting activation energy of 34.7 kJ/mol for the temperature range of -20 degrees C to +30 degrees C compares favorably to most of alternative catalysts reported in literature while reaction catalyzing capabilities of CB-PEI-HCl particles extend to the subzero temperature range (-20 degrees C-0 degrees C). The reuse and regeneration studies conducted for the CB-PEI-HCl catalyst showed that these catalysts do provide complete conversion at every use up to five consecutive runs and retain 50 +/- 2.5% of the original hydrogen generation rate at the fifth consecutive reuse. The CBs-based catalysts are fully regenerated with HCl treatment.
