Highly Sensitive Colorimetric Assay for Determining Fe³⁺ Based on Gold Nanoparticles Conjugated with Glycol Chitosan

Scheme 1

Schematic illustration of a AuNP capped with GC, aggregation of GC-AuNPs reacting with Fe³⁺ ions, accompanied by a color change, and the predicted coordination bond between Fe³⁺ ions and GC-AuNP. AuNPs, gold nanoparticles; GC-AuNPs, gold nanoparticles conjugated with GC.