ACTA

Rehydration of CTMA Modified DNA Powders Observed by NMR

H. Harańczyk^a, J. Kobierski^a, D. Zalitacz^a, P. Nowak^a, A. Romanowicz^b, M. Marzec^a, J. Nizioł^b, E. Hebda^c and J. Pielichowski^c
^aInstitute of Physics, Jagiellonian University, Kraków, Poland
^bAGH University of Science and Technology, Faculty of Physics and Applied Computer Science, Kraków, Poland
^cDepartment of Chemistry and Technology of Polymers, Cracow Technical University, Kraków, Poland

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The rehydration of salmon sperm deoxyribonucleic acid (DNA) and cetyltrimethylammonium chloride (C₁₉H₄₂ClN) complexes was observed using hydration kinetics, sorption isotherm, and high power proton relaxometry (at 30 MHz). The hydration kinetics shows (i) a very tightly bound water not removed by incubation over silica gel (A₀^h = 0.061 ± 0.004), (ii) a tightly bound water saturating at A₁^h = 0.039 ± 0.011, with the hydration time t₁^h = (1.04 ± 0.21) h, a loosely bound water fraction (iii) with the hydration time t₂^h = (19.1 ± 3.2) h and the contribution progressively increasing with the air humidity. For the hydration at p/p₀ = 100%, after t₀ = (152.6 ± 2.5) h of incubation the swelling process begins. The swelling time was t₃^h = (12.5 ± 5.4) h, and the swelling amplitude A₃^h = 0.140 ± 0.016. The sorption isotherm is sigmoidal in form and is fitted by the Dent model with the mass of water saturating primary binding sites Δ M/m₀ = 0.102 ± 0.021. Proton free induction decay is a superposition of the immobilized proton signal (Gaussian, with T_2S^* ≈ 30 μs) and two liquid signal components coming from tightly bound (T_2L₁^* ≈ 100 μs) and loosely bound water fraction with the amplitude proportional to the mass of water added (T_{2 L₂}^* ≈ 1000 μs).

DOI: 10.12693/APhysPolA.121.485
PACS numbers: 82.56.Na