Bio-dots assembly-induced aggregation of gold nanoparticles for highly sensitive and selective colorimetric detection of methionine

Methionine (Met) is one of sulfur-containing essential amino acids, it plays an indispensable role in physiological processes. Its quantitative and sensitive determination is imperative. However, currently available analytical approaches for determination of Met are scarce and also exhibit many disadvantages, such as poor selectivity for Met towards other amino acids and biothiols. In this work, a label-free colorimetric biosensor based on bio-dots assembly-triggered aggregation of gold nanoparticles (AuNPs) for detecting Met is firstly developed. In the presence of Met, Met effectively prevents the bio-dots assembly-induced aggregation of AuNPs since that AuNPs are protected inside the Met layer. This colorimetric biosensor provides a simple, fast, highly sensitive and highly selective method for Met detection. It presents lower detection limit of 3.2 nM and exhibits highly selectivity toward bio-thiols surprisingly. Furthermore, this proposed biosensor has been successfully applied for the determination of Met in human serum. (C) 2017 Elsevier B.V. All rights reserved.