Effects of histidine modification of chitosan microparticles on metal ion adsorption

• Published in: Reactive & functional polymers 2020-09, Vol.154, p.104694, Article 104694
• Main Authors: Maia, Marcella T., Sena, Débora N., Calais, Guilherme B., Luna, Francisco Murilo T., Beppu, Marisa M., Vieira, Rodrigo S.
• Format: Article
• Language: English
• Subjects: Adsorption; Alzheimer's disease; Amyloid-β; Blood-brain barrier; Chelates; Chitosan; Copper; Ferric ions; Histidine; Imidazole; Ion adsorption; Ions; Mass transfer; Metal ions; Microparticles; Oxidative stress; Resistance factors; Scanning electron microscopy; Titration
• ISSN: 1381-5148; 1873-166X
• DOI: 10.1016/j.reactfunctpolym.2020.104694

Imbalances in metal ions (Cu2+, Fe3+, and Zn2+) augment oxidative stress, and can lead to amyloid-β (Aβ) peptide aggregation, a phenomenon that is associated with Alzheimer's disease (AD) progression. As such, the use of particles that can cross the blood-brain barrier (BBB) and chelate metals could potentially provide a therapy to restore ionic balance in AD. Herein, we functionalized chitosan microparticles (CM) with histidine (an amino acid that contains an imidazole group, therefore mimicking Aβ) to chelate Cu2+, Fe3+, and Zn2+. CM were prepared by spray-drying and and functionalized with histidine (CM-Histidine). The CM, before and after functionalization, and interacting with metal ions were characterized by scanning electron microscopy with energy dispersive spectroscopy, x-ray diffraction and potentiometric titration. The adsorption capacity of CM-Histidine increased for Cu2+ and decreased for Zn2+ and Fe3+, when compared to unmodified CM. However, the adsorption kinetics for Cu2+ ions was lower for CM-histidine, than for CM, and the reverse was observed for Zn2+ and Fe3+. External mass resistance was the major factor that defined the mass transfer mechanism onto the active sites of CM-histidine. Diffusional effects were more relevant for Zn2+ and Fe3+ in the sorption process than for Cu2+. [Display omitted] •Histidine as a coupling agent to mimic amyloid-β and improve metal adsorption.•Adsorption increased for Cu2+ and decreased for Zn2+/Fe3+ on chitosan-histidine.•Affinity of Cu2+ decreased for chitosan-histidine, while it increased for Zn2+/Fe3+.•Diffusional effects were more relevant for Zn2+/Fe3+ than for Cu2+ in the adsorption.