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Öğe Corrigendum to “Online monitoring of dopamine particle formation via continuous light scattering intensity measurement” (European Polymer Journal (2019) 112 (749–753), (S0014305718316203), (10.1016/j.eurpolymj.2018.10.046))(Elsevier Ltd, 2019) Wu, Aide; Şahiner, Nurettin; Reed, Wayne F.The authors of the manuscript would like to perform the below correction to the article's data attribution as follows. FROM: Data availability The raw/processed data required to reproduce these findings is available upon request to the corresponding author. TO: Data availability Data are publicly available through the Gulf of Mexico Research Initiative Information & Data Cooperative (GRIIDC) at https://data.gulfresearchinitiative.org (https://dx.doi.org/10.7266/n7-smd8-rm34). © 2018 Elsevier LtdÖğe Online monitoring of dopamine particle formation via continuous light scattering intensity measurement(Elsevier Ltd, 2019) Wu, Aide; Şahiner, Nurettin; Reed, Wayne F.Using time resolved total intensity light scattering a two phase process was found in the conversion of 2-(3,4-dihyroxyphenyl)ethylamine, dopamine (DP), into microparticles. Phase 1 appears to involve oxidation of the DP, and may also include oligomerization below the light scattering threshold of detectability. After a certain lag time, the ‘Phase 1 Period’ (P1P), dependent upon reaction conditions, the light scattering increases sharply, heralding the onset of Phase 2. Precipitating particles are eventually formed in latter Phase 2. The solution goes through a series of color changes throughout Phase 1 and 2, starting as pink in Phase 1, and culminating in black particles in Phase 2. The reaction proceeds under virtually any conditions; purged with O2 or N2, unpurged, stirred or unstirred, under different pH conditions, etc. Stirring, increasing temperature, and adding potassium persulfate (KPS), all accelerate the reaction. P1P varied over nearly four orders of magnitude, from 10 s (pHinitial = 9.5) to 8 × 104 s (T = 25 °C, no pH control). Arrhenius behavior is found for P1P with low activation energies in the range of 10–25 Kcal/Mole. The precipitating particulates rapidly formed in Phase 2 suggest that they may involve non-covalent associations of oligomers formed in Phase 1, possibly due to loss of oligomeric solubility, in addition to possibly involving covalent polymer branching and cross-linking. Non-covalent aggregation of oligomers formed in Phase 1 seems most likely. © 2018 Elsevier LtdÖğe Polydopamine particles as nontoxic, blood compatible, antioxidant and drug delivery materials(Elsevier Science Bv, 2018) Şahiner, Nurettin; Sağbaş, Selin; Şahiner, Mehtap; Blake, Diane A.; Reed, Wayne F.Herein, the potential biomedical application of poly(3,4-dihyroxyphenyl)ethylamine, (poly(dopamine)-p(DA)) particles is reported. P(DA) particles with the size about 100 nm, 18.05 m(2)/g specific surface area, and mesoporous structure (7.19 nm pore width) were prepared and shown to be chemically modifiable using chlorosulfonic acid (CSA) and 3-CHloro-2 hydroxypropyl) trimethylammonium chloride solution (CHPACl) to obtain sulfonic acid and quaternary amine group containing modified p(DA) particles, m-p(DA)-CSA and m-p (DA)-CHPACl particles, respectively. The hydrolytic degradation of p(DA) particles at different pHs, including 1, 7.4 and 11, was carried out at 37.5 degrees C. These degradation studies revealed that p(DA) is slightly degradable at pH 1 and pH 7.4 with weight losses of 13.01 +/- 0.08% and 7.26 +/- 0.23% in 11 days, respectively. At pH 11, a sustained degradation that is almost linear degradation with time was observed for up to 30 days, with a total weight loss of 21.42 +/- 0.88%. Furthermore, p(DA) particles were tested for cell toxicity against COS-1 cells and found non-toxic up to 50 mu g/mL with 95.6 +/- 4.5% cell viability as compared to 37.5 +/- 0.03% for DA molecules. The p(DA) particles and DA were also compared for their ability to inhibit alpha-glucosidase; both inhibited alpha-glucosidase inhibition activity a concentration-dependent fashion: at concentrations of 500-4000 mu g/mL, p(DA) provided 8.52-27.67% inhibition while DA inhibited 42.8-67.7% over the same concentration range. Furthermore, p(DA) particles were found to be blood compatible e.g., non-hemolytic with 1.87 +/- 0.97% hemolysis ratio up to 50 mu g/mL concentration and with 86.7% blood clotting index. Interestingly, p(DA) particle can be considered as an effective antioxidant with 33.5 +/- 3.9 mu g/mL total phenol content in terms of gallic acid equivalency and 0.89 +/- 0.30 mu mol/g trolox equivalent antioxidant capacity (TEAC). Finally, p(DA) particles and their modified forms, m-p(DA)-CSA, and m-p(DA)-CHPACl, were shown to be useful as active agent/drug delivery devices by using acyclovir as a model drug that can be readily loaded into particles and released at longer times at higher amounts for the modified p(DA) particles at physiological conditions.Öğe Responsive biopolymer-based microgels/nanogels for drug delivery applications(Woodhead Publ Ltd, 2018) Sağbaş Suner, Selin; Şahiner, Mehtap; Bütün Şengel, Sultan; Rees, Daniel J.; Reed, Wayne F.; Şahiner, Nurettin
