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

Figure 4

Mass peaks of (a) CH₂OFe⁺, (b) CH₃CH₂OFe⁺, (c) OCHCH₂OFe⁺, and (d) OCH₂CH₂OFe⁺ fragments in the TOF-SIMS spectrum of GC-AuNPs (blue) and Fe³⁺-GC-AuNPs (red). These molecular fragments were expected based on the Fe³⁺-GC-AuNP structural elements in the zoomed circle in Scheme 1.

(a)

(b)

(c)

(d)