Related Experiment Video
Updated: Mar 8, 2026

Author Spotlight: Exploring Intrinsically Disordered Protein Dynamics Through NMR Relaxation Experiments
Published on: November 1, 2024
Time-domain NMR relaxometry as an alternative method for analysis of chitosan-paramagnetic ion interactions in
Flávio Vinícius Crizóstomo Kock1, Tatiana Monaretto1, Luiz Alberto Colnago2
1Instituto de Química de São Carlos, Universidade de São Paulo, Avenida Trabalhador São Carlense 400, 13566-590 São Carlos, São Paulo, Brazil.
Abstract:
Chitosan (CHI)-paramagnetic ion interactions in aqueous solution as affected by pH were studied using time-domain NMR (TD-NMR) relaxometry. Longitudinal (T1) and transverse (T2) relaxation times of CHI solutions with Fe3+, Cu2+, and Mn2+ were measured using a single-shot pulse sequence named CP-CWFPx-x. The results indicate that CHI interacted with Fe3+ ions or iron oxide nanoparticles, maintaining the metal ion in solution at pH ranging from 3 to 5. Above this pH, CHI coagulated and removed Fe ions or nanoparticles, resulting in a clear supernatant. CHI probably interacted with Cu ions at pH 6.2 through the deprotonated CHI-NH2 groups maintaining the relaxation effect in alkaline solution, whereas Mn2+ did not interact with CHI strongly enough to produce a complex of high stability. The proposed method can also be further exploited in the study of interactions paramagnetic ions with others CHI and CHI derivatives as well as of other water-soluble polysaccharides.
More Related Videos
07:24Paramagnetic Relaxation Enhancement for Detecting and Characterizing Self-Associations of Intrinsically Disordered Proteins
Published on: September 23, 2021
08:0915N CPMG Relaxation Dispersion for the Investigation of Protein Conformational Dynamics on the µs-ms Timescale
Published on: April 19, 2021
Related Concept Videos
¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
Atomic Nuclei: Types of Nuclear Relaxation
In spin–lattice or longitudinal relaxation, the excited spins exchange energy with the surrounding lattice as they return to the lower energy level. Among several mechanisms that contribute to spin–lattice relaxation, magnetic dipolar interactions are significant. Here, the excited nucleus transfers...
¹H NMR of Conformationally Flexible Molecules: Variable-Temperature NMR
Atomic Nuclei: Nuclear Relaxation Processes
¹H NMR: Interpreting Distorted and Overlapping Signals
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are...