Colorimetric detection of homocysteine by a pyridylazo dye-based Cu2+ complex via indicator displacement mechanism

• Published in: Analytical biochemistry 2021-05, Vol.621, p.114185-114185, Article 114185
• Main Authors: Fukushima, Yasumasa, Aikawa, Shunichi
• Format: Article
• Language: English
• Subjects: Chemosensor; Colorimetric detection; Copper ion; Homocysteine; Pyridylazo dye
• ISSN: 0003-2697; 1096-0309
• DOI: 10.1016/j.ab.2021.114185

A BrPAPS based Cu2+ complex has been developed as a colorimetric probe for the selective recognition of homocysteine (Hcy) over cysteine (Cys) and glutathione (GSH) in an aqueous solution via the indicator displacement assay. BrPAPS formed a complex with Cu2+ in a 1:1 ratio (BrPAPS-Cu2+) accompanied by the color change from yellow to red. Detecting Hcy is based on high affinity of Hcy for Cu2+. The addition of Hcy to BrPAPS-Cu2+ caused the complex formation of Hcy with Cu2+ in a 2:1 stoichiometry, resulting a hypsochromic shift with change back of color from red to yellow by the release of BrPAPS from BrPAPS-Cu2+. The absorption response is linear with the Hcy concentration in the range of 0–20 μM with a detection limit of 1.46 μM. Moreover, the detection of Hcy was not significantly affected by other amino acids from the competition experiments. Thus, BrPAPS-Cu2+ can be used as a simple probe for Hcy in aqueous solution. [Display omitted] •A colorimetric chemosensor for homocysteine was developed using a BrPAPS-based Cu2+ complex in aqueous solution.•It could selectively detect homocysteine by color change from red to yellow.•The detection limit was 1.46 μM, which is within the range of normal level of homocysteine found in plasma.