Role of Metal Ions in Dopamine Oxidation

Abstract

This is an easy and cheap experiment where chemistry Masters students can evaluate the role of some metal ions (i.e., CuII and MnII) in dopamine oxidation, related to Parkinsonism. The required prior knowledge is being familiar with the basis of UV–vis spectroscopy. Details of the activity, including procedure and experimental data, are provided.

Comparison of the Impact of NaIO4-Accelerated, Cu2+/H2O2-Accelerated, and Novel Ion-Accelerated Methods of Poly(l-DOPA) Coating on Collagen-Sealed Vascular Prostheses: Strengths and Weaknesses

“…Besides, Cu 2+ can bind to catechol systems with chelate formation and can induce electron transfer to oxygen to give semiquinone-type species following deprotonation. For the ion-accelerated method, the enhancement of l -DOPA polymerization was also expected because it was reported that some ions other than Cu 2+ (Na 2+ , Mg 2+ , Ca 2+ ) can slowly oxidize dopamine to aminochrome. , In the collected spectra (Figure ) of both ion-accelerated (P–C–I) and Cu 2+ /H 2 O 2 -accelerated (P–C–H) l -DOPA polymerization processes, very slow aminochrome formation detectable at around 304 nm and a flattened band at 480 nm persisting after several hours were observed. This different behavior is similar to that observed by Ponzio et al for ammonium peroxodisulfate-mediated catalysis and is probably attributed to the slow kinetics of oxidation, which proceeds via several concurrent pathways.…”

“…For the ion-accelerated method, the enhancement of L-DOPA polymerization was also expected because it was reported that some ions other than Cu 2+ (Na 2+ , Mg 2+ , Ca 2+ ) can slowly oxidize dopamine to aminochrome. 51,52 In the collected spectra (Figure 2) of both 28 for ammonium peroxodisulfate-mediated catalysis and is probably attributed to the slow kinetics of oxidation, which proceeds via several concurrent pathways. As a consequence, uncyclized dopamine units are likely to be incorporated to a major extent into the growing polymers, with only a low proportion of aminochrome-derived cyclized units.…”

Preparation of self‐adhesive microcapsules and their application in functional textiles

“…Fe 3+ generate coordination bonds between the microcapsules and cotton fabric, making the microcapsules adhere more firmly. According to (5) and (6) in Figure 7a,b, cotton fabric modified by COS–CMβCD–DA–GG treatment could only remove a small portion of microcapsules by washing with deionized water, whereas washing with an EDTA solution remove most of the microcapsules on cotton fabric, indicating that EDTA could combine with Fe 3+ and destroy the binding of microcapsules to the fabric 55,56 …”

“…According to (5) and (6) in Figure 7a,b, cotton fabric modified by COS-CMβCD-DA-GG treatment could only remove a small portion of microcapsules by washing with deionized water, whereas washing with an EDTA solution remove most of the microcapsules on cotton fabric, indicating that EDTA could combine with Fe 3+ and destroy the binding of microcapsules to the fabric. 55,56 Figure 6a shows the self-adhesive process. CA-modified cotton fabric impregnated in a FeCl 3 solution and Fe 3+ grafted by metal coordination and then impregnated in COS-CMβCD-DA-GG could achieve microcapsule adhesion and controlled adhesion of microcapsules to cotton fabrics by EDTA and Fe 3+ .…”