A point-of-care testing sensor based on fluorescent nanoclusters for rapid detection of septicemia in children

A diagnostic fluorometric assay was developed for ultrafast analysis of infectious bacteria including Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli and Pseudomonas aeruginosa in the serum samples which are the main causes of sepsis in children. The sensing system was composed of six different gold and copper nanoclusters immobilized on a piece of paper. The sensor was exposed to normal or infected serum sample. Fluorescence emission of sensing elements was monitored under UV light and the relevant images were recorded with a smartphone. Collecting the data took only 15 s. The specific responses were observed for each studied samples. The fingerprint patterns provide a clear distinction between gram positive and gram negative bacteria. The sensor showed greater performance for determination of analytes at very low concentration. The response of sensor was linear in the range of 50.0-1.0 x 10(8) Cfu. mL(-1) for Staphylococcus aureus, 70.0-1.0 x 10(8) Cfu. mL(-1) for Streptococcus pyogenes, 30.0-1.0 x 10(8) Cfu. mL(-1) for Escherichia coli, 50.0-1.0 x 10(8) Cfu. mL(-1) for Pseudomonas aeruginosa. The detection limit was equal to 43.0, 63.5, 26.0 and 47.0 Cfu. mL(-1) for Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli and Pseudomonas aeruginosa, respectively. The assay was successfully applied to diagnose the septicemia in 40 children.