Electrogenerated chemiluminescence on smartphone with graphene quantum dots nanocomposites for Escherichia Coli detection

Graphene quantum dots (GQDs) have recently exhibited great potential in electrogenerated chemiluminescence (ECL) due to their catalyst and amplification effect towards luminophores. Here, we prepared GQDs nanocomposites to amplify the ECL signals in tris(2,2′-bipyridyl)ruthenium(II)/tripropylamine (Ru(bpy)₃²⁺/TPA) assay. Universal serial bus interface on smartphone was used as the excitation source for ECL. The luminescence signals were then captured by the smartphone camera and processed by a smartphone-based image analysis application (APP). By immobilizing layer of sensitive Escherichia coli (E.coli) antibody on the electrode surface, our smartphone-based ECL system exhibited excellent linear response towards detection of E.coli in the concentration range of 10 cfu/mL to 10⁷ cfu/mL. Due to the vast popularity and portability of smartphone, the scope of application in our system would be able to greatly satisfy the need for point-of-care testing. Thus, in this work, the quantum dots-amplified luminescence detection was integrated with portable analytical devices, offering low-cost and real-time electrochemical analysis.