Fluorescent sensor array for discrimination of biothiols based on poly(thymine/cytosine)-templated copper nanoparticles

Abstract

In medicine, the detection and identification of biothiols have received increasing attention due to their crucial roles in life activities. Hence, we present a facile, rapid, and effective method for identification of five kinds of biothiols including glutathione (GSH), l-cysteine (Cys), dithiothreitol (DTT), 2-mercaptoethanol (MCE), and 3-mercaptopropionic acid (MPA). The proposed sensor array is fabricated based on single-stranded poly (thymine/cytosine)-templated fluorescent copper nanoparticles (CuNPs), which are controlled through thymine-Hg²⁺-thymine (T-Hg²⁺-T) and cytosine-Ag⁺-cytosine (CAg⁺C) coordination. The results show that single-stranded poly T and poly C are used as a highly efficient template, and ascorbic acid acts as a reductant to form CuNPs. Owing to the different thiol binding affinity between Hg²⁺ (pK_d = 3.90) and Ag⁺ (pK_d = 5.50), the sensor array produces a unique pattern of fluorescence variations when it interacts with the five biothiols. Linear discriminant analysis (LDA) is applied to analyze the fluorescence pattern and generated a clustering map for a clear identification of the five biothiols. By employing this "turn-on" sensor array, five thiols were successfully discirminated at the 50 nM level in buffer solution and serum samples.

Keywords: Biothiol; Cytosine-Ag(+)-cytosine; Fluorescence pattern; Sensor array; Thymine-Hg(2+)-thymine.