An array consisting of glycosylated quantum dots conjugated to MoS2 nanosheets for fluorometric identification and quantitation of lectins and bacteria

A fluorescent array based on the use of saccharide-functionalized multicolored quantum dots (s-QDs) and of 4-mercaptophenylboronic acid-functionalized MoS 2 nanosheets (PBA-MoS 2 ) was constructed for multiple identification and quantitation of lectins and bacteria. In this array, the fluorescence of the s-QDs is quenched by the PBA-MoS 2 nanosheets. In the presence of multiple lectins, s-QDs differentially detach from the surface of PBA-MoS 2 nanosheets, producing distinct fluorescence response patterns due to both quenching and enhancement of fluorescence. By analyzing the fluorescence responses with linear discriminant analysis, multiple lectins and bacteria were accurately identified with 100% accuracy. The limits of detection of Concanavalin A , Pisum sativum agglutinin, Peanut agglutinin, and Ricius communis I agglutinin are as low as 3.7, 8.3, 4.2 and 3.9 nM, respectively. The array has further been evidenced to be potent for distinguishing and quantifying different bacterial species by recognizing their surface lectins. The detection limits of Escherichia coli and Enterococcus faecium are 87 and 66 cfu mL −1 , respectively. Schematic of a fluorometric array based on the use of saccharides-functionalized quantum dots (s-QDs) and 4-mercaptophenylboronic acid-functionalized MoS 2 (PBA- MoS 2 ) nanosheets. This array was successfully applied to simultaneously analysis of lectins, bacteria in real samples with high sensitivity and accuracy.