Visual sensing of flavonoids based on varying degrees of gold nanoparticle aggregation via linear discriminant analysis

Abstract

Flavonoids are closely related to human health. The identification and determination of flavonoids is an important and difficult issue. In view of this, this work puts forward a colorimetric sensing array for flavonoid discrimination based on gold nanoparticle (AuNP) aggregation. Two substances (acetylthiocholine iodide (Atc) and S-propionylthiocholine iodide (Ptc)) are hydrolyzed to choline (Chi) under the action of acetylcholinesterase (AcChE). Choline can agglomerate AuNPs by forming AuS bond with its own sulfhydryl functional group. The presence of flavonoids inhibits the AcChE activity, resulting in the formation of different amounts of Chi and different degrees of AuNP aggregation. Controlled by Atc and Ptc as array’s receptors, the five flavonoids, including proanthocyanidin (Pro), naringenin (Nar), quercetin (que), flavone (Fla), and curcumin (Cur), were differentiated through their unique colorimetric “fingerprint” pattern-based recognition with the aid of linear discriminant analysis (LDA). The assay is validated under phosphate buffered saline (PBS) buffer conditions as well as in human serum. In addition, identification for diverse concentrations of single flavonoid and different binary and ternary mixtures of flavonoids were also demonstrated.