Poly(vinyldiaminotriazine) nanoparticle adsorption of small drug molecules in aqueous phase and the role of synergistic
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Poly(vinyldiaminotriazine) nanoparticle adsorption of small drug molecules in aqueous phase and the role of synergistic interaction between hydrogen bonding and hydrophobic affinity Xiaotao Wang 1 & Junyang Xu 1 & Xun Xie 1 & Xuefeng Li 1 & Zuifang Liu 1 Received: 11 August 2020 / Revised: 21 September 2020 / Accepted: 3 October 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Poly(vinyldiaminotriazine) nanoparticles adsorbed 5-fluorouracil, thymine, theobromine, and xanthine in aqueous phase. Each drug molecule formed triple hydrogen bonds with a diaminotriazine moiety at the nanoparticle surface. Adsorption isotherm studies suggested monolayer adsorption while the adsorption capacity was strongly dependent on the drug compositions/ structures (0.053 mmol/g 5-fluorouracil, 0.094 mmol/g thymine, 0.0078 mmol/g theobromine, and 0.0065 mmol/g xanthine). The drug compositional/structural effects were also reflected in the adsorption kinetics. In addition to neutral pH adsorption, studies were performed at pH below the polymer’s pKa and above the drugs’ pKa, separately. Reducing hydrophobicity of the hydrogen bonding sites by protonating the diaminotriazine moieties at pH 4.5 resulted in more than 3 times decrease in adsorption capacities whereas deprotonating the drug molecules at pH 9 increased the adsorption capacity due to electrostatic attraction between the negatively charged drugs and the positively charged nanoparticles, which was supported by strong dependency of the adsorption capacity on ionic strength. The adsorption was reversible for all the four drugs. While increasing temperature caused faster desorption, reducing hydrophobicity of the diaminotriazine moieties by protonation at pH 4.5 had a stronger effect on both cumulative desorption and burst release. The results of this study demonstrated an important role of synergistic interaction between hydrogen bonding and hydrophobic affinity in poly(vinyldiaminotriazine) nanoparticle adsorption of the drugs in the aqueous phase. Keywords 2-Vinyl-4,6-diamino-1,3,5-triazine polymer nanoparticles . Drug molecules . Hydrogen bonding . Hydrophobic affinity . Physical adsorption in aqueous phase . pH and ionic strength Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00396-020-04765-7) contains supplementary material, which is available to authorized users. * Zuifang Liu [email protected] Xiaotao Wang [email protected] Junyang Xu [email protected] Xun Xie [email protected] Xuefeng Li [email protected] 1
Hubei Provincial Key Laboratory of Green Materials for Light Industry, Collaborative Innovation Center for Green Light-weight Materials and Processing, School of Materials Science and Engineering, Hubei University of Technology, Wuhan 430068, People’s Republic of China
Introduction Liquid-phase adsorption refers to a phenomenon of accumulation of dissolved adsorbate molecules by the solid surface of an adsorbent, either physical or chemical in nature. Physical
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