Synthesis of two-dimensional graphene oxide-fluorescent nanoprobe for ultrasensitive and multiplex immunochromatographic detection of respiratory bacteria

Respiratory pathogens including a variety of bacteria and viruses are highly infectious to human, cause similar clinical symptoms, and pose serious threats to public health globally. Early and accurate identification of respiratory bacteria from other pathogens is crucial for guiding the rational use of antibiotics and controlling the epidemic spread. Here, we developed a multiplexed fluorescent immunochromatographic assay (ICA) for ultrasensitive qualification of respiratory bacteria in biological samples with high accuracy. A novel two-dimensional graphene oxide (GO)-based quantum dot (QD) nanoflake was designed as film-like immunoprobe to efficiently and closely stick onto target bacteria surface, which not only provide superior fluorescence signal but also ensure the liquidity of the captured bacteria for ICA detection. By combining the GO-QD nanoflakes and ICA strip, the proposed method enables the simultaneous detection of two common respiratory bacteria, namely Streptococcus pneumoniae (S. pneumoniae) and Staphylococcus aureus (S. aureus) in biological samples with low detection limit (13, 20 cells/mL), fast detection speed (20 min), good reproducibility (RSD < 4.2 %), and high specificity. The excellent performance of our proposed GO-QD-ICA suggests its great potential for rapid and ultrasensitive diagnosis of real respiratory tract samples.